# Heat Transfer - Mechanical Engineering (MCQ) questions and answers

Dear Readers, Welcome to Heat Transfer multiple choice questions and answers with explanation. These objective type Heat Transfer questions are very important for campus placement test, semester exams, job interviews and competitive exams like GATE, IES, PSU, NET/SET/JRF, UPSC and diploma.

Specially developed for the Mechanical Engineering freshers and professionals, these model questions are asked in the online technical test and interview of many companies.

These tutorial are also important for your viva in university exams like Anna university, Pune, VTU, UPTU, CUSAT etc.

1)   For the same heat transfer Q and same overall heat transfer coefficient Uo, surface area required for cross flow operation is always
- Published on 12 Aug 15

a. less than LMTD for parallel flow
b. more than LMTD for parallel flow
c. same as LMTD for parallel flow
d. unpredictable
 Answer  Explanation  Related Ques ANSWER: less than LMTD for parallel flow Explanation: No explanation is available for this question!

2)   In parallel flow heat exchangers,
- Published on 12 Aug 15

a. the exit temperature of hot fluid is always equal to the exit temperature of cold fluid
b. the exit temperature of hot fluid is always less than the exit temperature of cold fluid
c. the exit temperature of hot fluid is always more than the exit temperature of cold fluid
d. we cannot predict comparison between exit temperatures of hot fluid and cold fluid
 Answer  Explanation  Related Ques ANSWER: the exit temperature of hot fluid is always more than the exit temperature of cold fluid Explanation: No explanation is available for this question!

3)   For the same heat transfer Q and same overall heat transfer coefficient Uo, surface area required for parallel flow operation is always
- Published on 12 Aug 15

a. less than LMTD for counter flow
b. more than LMTD for counter flow
c. same as LMTD for counter flow
d. unpredictable
 Answer  Explanation  Related Ques ANSWER: more than LMTD for counter flow Explanation: No explanation is available for this question!

4)   For the same inlet and exit temperatures of two fluids, the LMTD for counterflow is always
- Published on 12 Aug 15

a. smaller than LMTD for parallel flow
b. greater than LMTD for parallel flow
c. same as LMTD for parallel flow
d. unpredictable
 Answer  Explanation  Related Ques ANSWER: greater than LMTD for parallel flow Explanation: No explanation is available for this question!

5)   Which of the following temperature difference is safer than other to consider in designing of heat exchangers?
- Published on 12 Aug 15

a. Arithmetic Mean Temperature Difference (ΔTam)
b. Logarithmic Mean Temperature Difference (LMTD)
c. Both have nothing to do with safety
d. Other
 Answer  Explanation  Related Ques ANSWER: Logarithmic Mean Temperature Difference (LMTD) Explanation: No explanation is available for this question!

6)   How can the arithmetic mean temperature difference and LMTD of a same heat exchanger be compared?
- Published on 12 Aug 15

a. the arithmetic mean temperature difference is less than LMTD of a same heat exchanger
b. the arithmetic mean temperature difference is more than LMTD of a same heat exchanger
c. the arithmetic mean temperature difference and LMTD of a same heat exchanger are equal
d. none of the above
 Answer  Explanation  Related Ques ANSWER: the arithmetic mean temperature difference is more than LMTD of a same heat exchanger Explanation: No explanation is available for this question!

7)   When is the arithmetic mean temperature difference of heat exchanger used instead of LMTD?
- Published on 12 Aug 15

a. when the temperature profiles of two fluids of heat exchanger are sloping downward with curve
b. when the temperature profiles of two fluids of heat exchanger are sloping upward with curve
c. when the temperature profiles of two fluids of heat exchanger are straight
d. none of the above
 Answer  Explanation  Related Ques ANSWER: when the temperature profiles of two fluids of heat exchanger are straight Explanation: No explanation is available for this question!

8)   The Grashof number in natural convection plays same role as
- Published on 12 Aug 15

a. Prandtl number (Pr) in forced convection
b. Reynolds number (Re) in forced convection
c. Nusselt number (Nu) in forced convection
d. none of the above
 Answer  Explanation  Related Ques ANSWER: Reynolds number (Re) in forced convection Explanation: No explanation is available for this question!

9)   If there are no externally induced flow velocities, then the Nusselt number (Nu) does not depend upon
- Published on 12 Aug 15

a. Prandtl number (Pr)
b. Reynolds number (Re)
c. Grashof number (Gr)
d. none of the above
 Answer  Explanation  Related Ques ANSWER: Reynolds number (Re) Explanation: No explanation is available for this question!

10)   Which of the following condition is correct for natural convection?
- Published on 12 Aug 15

a. (Gr / Re2) = 1
b. (Gr / Re2) << 1
c. (Gr / Re2) >> 1
d. none of the above
 Answer  Explanation  Related Ques ANSWER: (Gr / Re2) >> 1 Explanation: No explanation is available for this question!

1 2 3 4 5 6 7 8 9 10 ...