PyClz02.xml

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  <question type="cloze">

    <name>

      <text>PyClz02_000</text>

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    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 330 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |330|0.650|4.890e-04|984|4184 |4.1840e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=3641:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.2:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=12.7:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

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    <penalty>0.333</penalty>

    <hidden>0</hidden>

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  <question type="cloze">

    <name>

      <text>PyClz02_001</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 330 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |330|0.650|4.890e-04|984|4184 |4.1840e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4027:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.8:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.3:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

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      <text></text>

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    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

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  <question type="cloze">

    <name>

      <text>PyClz02_002</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 330 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |330|0.650|4.890e-04|984|4184 |4.1840e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4179:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.6:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=10.8:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

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    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_003</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 330 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |330|0.650|4.890e-04|984|4184 |4.1840e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=3641:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.1:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=9.4:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

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    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_004</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 330 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |330|0.650|4.890e-04|984|4184 |4.1840e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4027:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=2.8:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=8.4:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_005</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 330 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |330|0.650|4.890e-04|984|4184 |4.1840e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4179:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=2.7:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=8.0:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_006</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 340 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |340|0.660|4.200e-04|979|4188 |4.1880e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=3936:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.3:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=13.0:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_007</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 340 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |340|0.660|4.200e-04|979|4188 |4.1880e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4354:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.9:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.6:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_008</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 340 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |340|0.660|4.200e-04|979|4188 |4.1880e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4517:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.7:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.1:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_009</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 340 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |340|0.660|4.200e-04|979|4188 |4.1880e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=3936:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.4:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=10.1:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_010</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 340 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |340|0.660|4.200e-04|979|4188 |4.1880e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4354:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.0:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=9.0:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_011</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 340 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |340|0.660|4.200e-04|979|4188 |4.1880e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4517:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=2.9:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=8.6:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_012</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 350 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |350|0.668|3.650e-04|974|4195 |4.1950e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4223:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.5:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=13.4:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_013</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 350 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |350|0.668|3.650e-04|974|4195 |4.1950e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4672:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.0:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.9:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_014</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 350 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |350|0.668|3.650e-04|974|4195 |4.1950e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4847:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.8:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.4:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_015</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 350 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |350|0.668|3.650e-04|974|4195 |4.1950e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4223:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.6:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=10.7:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_016</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 350 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |350|0.668|3.650e-04|974|4195 |4.1950e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4672:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.2:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=9.5:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_017</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 350 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |350|0.668|3.650e-04|974|4195 |4.1950e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4847:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.0:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=9.1:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_018</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 360 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |360|0.674|3.240e-04|967|4203 |4.2030e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4470:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.6:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=13.7:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_019</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 360 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |360|0.674|3.240e-04|967|4203 |4.2030e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4945:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.1:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=12.2:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_020</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 360 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |360|0.674|3.240e-04|967|4203 |4.2030e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=5131:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.9:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.7:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_021</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 360 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |360|0.674|3.240e-04|967|4203 |4.2030e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4470:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.7:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.2:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_022</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 360 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |360|0.674|3.240e-04|967|4203 |4.2030e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4945:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.3:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=10.0:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_023</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 360 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |360|0.674|3.240e-04|967|4203 |4.2030e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=5131:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.2:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=9.5:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_024</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 365 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |365|0.677|3.060e-04|963|4209 |4.2090e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4593:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.6:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=13.9:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_025</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 365 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |365|0.677|3.060e-04|963|4209 |4.2090e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=5080:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=4.1:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=12.3:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_026</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 365 K,
and the air temperature
$$\theta_{air}$$ = 250 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |365|0.677|3.060e-04|963|4209 |4.2090e+03 |
|Air      |250  |0.022  |1.596e-05  |  1  |1006   |1.0060e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=5271:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.9:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.8:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_027</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 365 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |365|0.677|3.060e-04|963|4209 |4.2090e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.022| 0.001|0.63|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=4593:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.8:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=11.4:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



        ]]>

      </text>

     </questiontext>

    <generalfeedback format="html">

      <text></text>

    </generalfeedback>

    <penalty>0.333</penalty>

    <hidden>0</hidden>

    <idnumber></idnumber>

  </question>


  <question type="cloze">

    <name>

      <text>PyClz02_028</text>

    </name>

    <questiontext format="markdown">

      <text>

        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 365 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |365|0.677|3.060e-04|963|4209 |4.2090e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.035| 0.001|0.81|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=5080:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.4:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=10.2:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



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    <name>

      <text>PyClz02_029</text>

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        <![CDATA[

          
#Evaluation of convective exchange coefficients

Let's consider a copper pipe in which a pump
circulates water. The tube is in still air. It is considered
that the temperature of the outer surface of the tube
is almost equal to the temperature inside the tube.


By using existing correlations for forced convection
in the tube and for natural convection in the air
(based on the Grashof number), find the values of the coefficients
of convective exchange in the tube (water - tube) and outside of the tube
(air - tube) for the water temperature in the pipe
$$\theta_{water}$$ = 365 K,
and the air temperature
$$\theta_{air}$$ = 300 K.

<br/>

**Data**

*Thermo-physical properties*

|Substance|Temperature    |Conductivity   |	Viscosity     |	Density       | Specific heat  |Expansion coef.|
|---------|---------------|---------------|--------------|---------------|----------------|---------------|
|         |T [K]          |λ [W/m•K]      |μ [Pa•s]      | ρ [kg/m³]     | c [J/kg•K]     | β [1/K]       |
|_________|_______________|_______________|______________|_______________|________________|_______________|
|Water    |365|0.677|3.060e-04|963|4209 |4.2090e+03 |
|Air      |300  |0.026  |1.846e-05  |  1  |1007   |1.0070e+03   |

<br/>

*Pipe*

|Ext. diameter        | Width                | Water velocity      |
|---------------------|----------------------|---------------------|
| D [m]               | w [m]                | v [m/s]             |
|_____________________|______________________|_____________________|
|0.042| 0.001|0.89|

<br/>

**Give the values of:**

$$h_i$$ = {1:NUMERICAL:=5271:10} (±10) $$\mathrm{W/m^2K}$$,
coefficient of convective exchange between water and pipe.

$$h_{o,min}$$ = {1:NUMERICAL:=3.2:1} (±1) $$\mathrm{W/m^2K}$$,
minimum value of the convective exchange coefficient of the pipe with the air.

$$h_{o,max}$$ = {1:NUMERICAL:=9.7:1} (±1) $$\mathrm{W/m^2K}$$,
maximum value of the convective exchange coefficient of the pipe with the air.


**Fill in the sentence:**

The correlation used for forced convection in a tube is called the formula of
{1:SHORTANSWER:=Colburn}

**Choose the correct answer:**

The type of air flow is {1:MULTICHOICE:undetermined
                           ~= laminar
                           ~ turbulent}



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