In the given formula for overall heat transfer coefficient in Rising film evaporators, What is the term hOD? ( frac{1}{U}= frac{1}{ho}+ frac{1}{h_{OD}}+( frac{Do}{Di})( frac{1}{h_{ID}})+ ( frac{Do}{Di})( frac{1}{hi}) )

Outside film heat transfer coefficient

Inside film heat transfer coefficient

If the evaporator operates at very high liquid velocity so that the boiling occurs at the top end of the tube, which one of the following correlation can be used?

hiD xa0 xa0Ksolution = 0.003 Re0.8 Pr0.4

hiD xa0 xa0Kpure = 0.003 Re0.8 Pr0.4

hiD xa0 xa0Kpure = 0.027 Re0.8 Pr0.4

hiD xa0 xa0Ksolution = 0.0278 Re0.8 Pr0.4

hiD xa0 xa0Ksolution = 0.003 Re0.8 Pr0.4

11 + Mcqs in Evaporators Heat Transfer Coefficients in Heat Transfer Operations Page 1 McqOptions

1.	When the flow rate of the fluid decreases the temperature plot shifts towards __________
A.	Steam exit
B.	Middle of the tube
C.	Feed inlet
D.	Feed exit
Answer» C. Feed inlet

Discussion

2.	Which one of the following axes representation is correct?
A.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11a.png"><img alt="The following axes representation is correct - option a" class="alignnone size-full wp-image-248332" height="270" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11a.png" width="260"/></a>
B.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11b.png"><img alt="The following axes representation is correct - option b" class="alignnone size-full wp-image-248333" height="281" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11b.png" width="265"/></a>
C.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11c.png"><img alt="The following axes representation is correct - option c" class="alignnone size-full wp-image-248334" height="279" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11c.png" width="261"/></a>
D.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11d.png"><img alt="The following axes representation is correct - option d" class="alignnone size-full wp-image-248335" height="284" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11d.png" width="268"/></a>
Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11b.png"><img alt="The following axes representation is correct - option b" class="alignnone size-full wp-image-248333" height="281" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q11b.png" width="265"/></a>

Discussion

3.	What is the real temperature driving force of the evaporator in the given diagram?
A.	T<sub>BP</sub> T<sub>w</sub>
B.	T<sub>W</sub> T<sub>BP</sub>
C.	T<sub>W</sub> T<sub>steam</sub>
D.	T<sub>steam</sub> T<sub>BP</sub>
Answer» E.

Discussion

4.	The liquid temperature in the tubes increases up to certain height and then the temperature decreases due to ___________
A.	Loss of superheat
B.	Loss of pressure
C.	Concentration increase
D.	Concentration decrease
Answer» B. Loss of pressure

Discussion

5.	When the flow velocity of the fluid increases the temperature plot maxima shifts towards __________
A.	Steam exit
B.	Middle of the tube
C.	Feed inlet
D.	Feed exit
Answer» E.

Discussion

6.	In the given formula for overall heat transfer coefficient in Rising film evaporators, What is the term h_OD? ( frac{1}{U}= frac{1}{ho}+ frac{1}{h_{OD}}+( frac{Do}{Di})( frac{1}{h_{ID}})+ ( frac{Do}{Di})( frac{1}{hi}) )
A.	Outside dirt coefficient
B.	Inside dirt coefficient
C.	Outside film heat transfer coefficient
D.	Inside film heat transfer coefficient
Answer» B. Inside dirt coefficient

Discussion

7.	Which one of the following is the correct temperature profile in an evaporator?
A.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-entrance-exams-q5a.png"><img alt="The following is the correct temperature profile in an evaporator - option a" class="alignnone size-full wp-image-249863" height="209" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-entrance-exams-q5a.png" width="248"/></a>
B.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5b.png"><img alt="The following is the correct temperature profile in an evaporator - option b" class="alignnone size-full wp-image-248329" height="205" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5b.png" width="244"/></a>
C.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5c.png"><img alt="The following is the correct temperature profile in an evaporator - option c" class="alignnone size-full wp-image-248330" height="209" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5c.png" width="243"/></a>
D.	<a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5d.png"><img alt="The following is the correct temperature profile in an evaporator - option d" class="alignnone size-full wp-image-248331" height="213" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5d.png" width="240"/></a>
Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5b.png"><img alt="The following is the correct temperature profile in an evaporator - option b" class="alignnone size-full wp-image-248329" height="205" src="https://www.sanfoundry.com/wp-content/uploads/2019/10/heat-transfer-operations-questions-answers-evaporators-heat-transfer-coefficients-q5b.png" width="244"/></a>

Discussion

8.	If the Reynold s number is 24000 and the Prantl number = 4.70. Then what is the value of Nusselt number?
A.	164.8
B.	164.0
C.	163.8
D.	165.2
Answer» B. 164.0

Discussion

9.	The heat transfer coefficient for rising film and falling film evaporators is same because they can be used in the same setup.
A.	True
B.	False
Answer» C.

Discussion

10.	If the evaporator operates at very high liquid velocity so that the boiling occurs at the top end of the tube, then we use the given relation. h_iD K=0.0278 Re^0.8 Pr^0.4
A.	nWhat is the term K here?
B.	Solution thermal conductivity
C.	Solvent thermal conductivity
D.	Wall thermal conductivity
E.	Film thermal conductivity
Answer» B. Solution thermal conductivity

Discussion

11.	If the evaporator operates at very high liquid velocity so that the boiling occurs at the top end of the tube, which one of the following correlation can be used?
A.	h<sub>i</sub>D xa0 xa0K<sub>pure</sub> = 0.003 Re<sup>0.8</sup> Pr<sup>0.4</sup>
B.	h<sub>i</sub>D xa0 xa0K<sub>pure</sub> = 0.027 Re<sup>0.8</sup> Pr<sup>0.4</sup>
C.	h<sub>i</sub>D xa0 xa0K<sub>solution</sub> = 0.0278 Re<sup>0.8</sup> Pr<sup>0.4</sup>
D.	h<sub>i</sub>D xa0 xa0K<sub>solution</sub> = 0.003 Re<sup>0.8</sup> Pr<sup>0.4</sup>
Answer» D. h<sub>i</sub>D xa0 xa0K<sub>solution</sub> = 0.003 Re<sup>0.8</sup> Pr<sup>0.4</sup>

Discussion

Explore topic-wise MCQs in Heat Transfer Operations.

When the flow rate of the fluid decreases the temperature plot shifts towards __________

Which one of the following axes representation is correct?

What is the real temperature driving force of the evaporator in the given diagram?

The liquid temperature in the tubes increases up to certain height and then the temperature decreases due to ___________

When the flow velocity of the fluid increases the temperature plot maxima shifts towards __________

In the given formula for overall heat transfer coefficient in Rising film evaporators, What is the term hOD? ( frac{1}{U}= frac{1}{ho}+ frac{1}{h_{OD}}+( frac{Do}{Di})( frac{1}{h_{ID}})+ ( frac{Do}{Di})( frac{1}{hi}) )

Which one of the following is the correct temperature profile in an evaporator?

If the Reynold s number is 24000 and the Prantl number = 4.70. Then what is the value of Nusselt number?

The heat transfer coefficient for rising film and falling film evaporators is same because they can be used in the same setup.

If the evaporator operates at very high liquid velocity so that the boiling occurs at the top end of the tube, then we use the given relation.hiD K=0.0278 Re0.8 Pr0.4

If the evaporator operates at very high liquid velocity so that the boiling occurs at the top end of the tube, which one of the following correlation can be used?

In the given formula for overall heat transfer coefficient in Rising film evaporators, What is the term h_OD?
( frac{1}{U}= frac{1}{ho}+ frac{1}{h_{OD}}+( frac{Do}{Di})( frac{1}{h_{ID}})+ ( frac{Do}{Di})( frac{1}{hi}) )

If the evaporator operates at very high liquid velocity so that the boiling occurs at the top end of the tube, then we use the given relation.
h_iD K=0.0278 Re^0.8 Pr^0.4