ISRO 2018 Heat Transfer Booster Quiz 2

Attempt now to get your rank among 1651 students!

Question 1

The ratio of momentum diffusivity (v) to thermal diffusivity (α), is called

• APrandtl number
• BNusselt number
• CBiot number
• DLewis number

Question 2

A heat exchanger is used to heat cold water (C_P = 4.18 kJ/kg-K) entering at 15 °C at a rate of 1.2 kg/s by hot air (C_P = 1.005 kJ/kg-K) entering at 90 °C at a rate of 2.5 kg/s. The highest rate of heat transfer in the heat exchanger is _____ kW.

• A183.43
• B188.44
• C198.47
• D205.36

Question 3

A cylinder is made of a metal of a conductivity 40 W/mk is to be insulated with a material of conductivity 0.2 W/mk. If the convective heat transfer coefficient with the ambient atmosphere is 10 Wm²k, the critical radius of insulation is

• A2 cm
• B4 cm
• C8 cm
• D50 cm

Question 4

Sun’s surface at 6000 K emits radiation at a wavelength of 0.25 µ. a furnace at 500 °C will emit through a small opening radiation at a wavelength of nearly

• A10 µ
• B5 µ
• C1.94 µ
• D0.025 µ

Question 5

In the laminar flow of air (Pr = 0.7) over a heated plate. if δ and δ_T denote, respectively, the hydrodynamic and thermal boundary layer thicknesses, then

• Aδ = δ_T
• Bδ > δ_T
• Cδ < δ_T
• Dδ = 0 but δ_T ≠ 0

Question 6

A solid sphere 1 of radius ‘r’ is placed inside a hollow, closed hemispherical surface 2 of radius ‘4r’. The shape factor F_2-1 is

• A1/12
• B1/2
• C2
• D12

Question 7

Heat transfer through radiation takes place in form of:

• AElectromagnetic waves
• BSound waves
• CHeat wave
• DNone of these

Question 8

In a solar assisted air conditioning system, 0.5 kg/s of ambient air at 270 K is to be preheated by the same amount of air leaving the system at 295 K. If a counter flow heat exchanger has an area of 30 m2, and the overall heat transfer coefficient is estimated to be 25 W/m2-K, then what is the effectiveness of the heat exchanger?
[Take for air as ]

• A0.4
• B0.5
• C0.3
• D0.6

• 1651 attempts
• 18 upvotes
• 55 comments