## Heat Transfer Miscellaneous

#### Heat-Transfer

1. In certain heat exchanger, both the fluids have identical mass flow rate specific heat product. The hot fluid enters at 76°C and leaves at 47°C, and the cold fluid entering at 28°C leave at 55°C, the effectiveness of the HE is

1.  ε = Ch(Th1 - Th2) Cmin(Th1 - Tc1)

Here , Ch = Cc'
 ε = Th1 - Th2 = 76 - 47 = 0.604 Th1 - Tc1 76 - 28

##### Correct Option: B

 ε = Ch(Th1 - Th2) Cmin(Th1 - Tc1)

Here , Ch = Cc'
 ε = Th1 - Th2 = 76 - 47 = 0.604 Th1 - Tc1 76 - 28

1. In a heat exchanger, it is observed that ∆T1 = ∆T2 where ∆T1 is the temperature difference between the two single phase fluid streams at one end and ∆T2 is the temperature difference at the other end. This heat exchanger is

1. NA

##### Correct Option: C

NA

1. Hot oil is cooled from 80 to 50°C in an oil cooler which uses air as the coolant. The air temperature rises from 30 to 40°C. The designer uses a LMTD value of 26°C. The type of heat exchanger is

1.  θ = θ1 - θ2 ln θ1 θ2

θ1 = 50° , θ2 = 10°
θ1 = 40° , θ2 = 20°
As given value is between these two, so cross flow is the best option.

##### Correct Option: D

 θ = θ1 - θ2 ln θ1 θ2

θ1 = 50° , θ2 = 10°
θ1 = 40° , θ2 = 20°
As given value is between these two, so cross flow is the best option.

1. The practice to use steam on the shell side and water on the tube side in condensers of steam power plant is because

1. Air leaked into the condensor can be easily extracted.

##### Correct Option: D

Air leaked into the condensor can be easily extracted.

1. In shell and tube heat exchanger, baffles are mainly used to

1. Baffles are used to deflect the flow.

##### Correct Option: C

Baffles are used to deflect the flow.