# Home / Mechanical Engineering / Heat Transfer,Refrigeration and Air Conditioning :: Section 1

### Mechanical Engineering :: Heat Transfer,Refrigeration and Air Conditioning

1. The wet bulb temperature during sensible heating of air

2.  A. remains constant B. increases C. decreases   3. The C.O.P. of an absorption type refrigerator is given by (where T1 = Temperature at which the working substance receives heat, T2 = Temperature of cooling water, and T3 = Evaporator temperature)

4.  A. B. C. D.    5. Which of the following statement is wrong?

6.  A. The heat transfer in liquid and gases takes place according to convection. B. The amount of heat flow through a body is dependent upon the material of the body. C. The thermal conductivity of solid metals increases with rise in temperature, D. Logarithmic mean temperature difference is not equal to the arithmetic mean temperature difference.   7. In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the

8.  A. Reynold's number B. Grashoff's number C. Reynold's number, Grashoff's number D. Prandtl number, Grashoff's number   9. In a refrigerating machine, heat rejected is __________ heat absorbed.

10.  A. equal to B. less than C. greater than   11. The humidity ratio or specific humidity is the mass of water vapour present in

12.  A. 1 m3 of wet air B. 1 m3 of dry air C. 1 kg of wet air D. 1 kg of dry air   13. The formation of frost on cooling coils in a refrigerator

14.  A. increases heat transfer B. improves C.O.P. of the system C. increases power consumption D. reduces power consumption   15. The by-pass factor for a cooling coil

16.  A. increases with increase in velocity of air passing through it B. decreases with increase in velocity of air passing through it C. remains unchanged with increase in velocity of air passing through it D. may increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering   17. The difference between dry bulb temperature and wet bulb temperature, is called

18.  A. dry bulb depression B. wet bulb depression C. dew point depression D. degree of saturation   19. Defrosting of a refrigerator may be done by stopping the compressor for a short period.

20.  A. Correct B. Incorrect   