Chemical Heat Transfer Mcqs

MCQ: For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it__________________?

1. Decreases the pressure drop
2. Decreases the outlet temperature of cooling medium
3. Increases the overall heat transfer coefficient
4. None of these

MCQ: Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?

1. 35.5
2. 43.75
3. 81.25
4. 48.25

MCQ: A graph between _____________ is called Wilson plot?

1. (1/U) Vs. (1/v0.8)
2. (1/v0.8) Vs. U
3. v0.8 Vs . U
4. (1/U) Vs. (1/V)

MCQ: For a laminar flow of fluid in a circular tube, ‘h1’ is the convective heat transfer co-efficient at velocity ‘V1’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is________________?

1. 1.26 h1
2. 0.794 h1
3. 0.574 h1
4. 1.741 h1

MCQ: Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface) ?

1. U1 – U2
2. 1/U1 – 1/U2
3. 1/U2 – 1/U1
4. U2 – U1

MCQ: All analogy equations connecting friction factor and heat transfer co-efficient apply only to ___________________?

1. Wall or skin friction
2. Form friction
3. Both A. and B.
4. Turbulent flow

MCQ: Reason for operating an evaporator in multiple effects is to secure ___________________?

1. Increased steam economy
2. Decreased steam consumption
3. Both A. and B.
4. Increased capacity

MCQ: Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the_________________?

1. Existence of thermal boundary layer
2. Temperature gradient produced due to density difference
3. Buoyancy of the bubbles produced at active nucleation site
4. None of these

MCQ: Critical value of the _____________ number governs the transition from laminar to turbulent flow in free convection heat transfer?

1. Grashoff
2. Reynolds
3. Both ‘a’ & ‘b’
4. Prandtl & Grashoff

MCQ: In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is _____________ the outlet temperature of the cold fluid?

1. Equal to
2. More than
3. Less than
4. Either more or less than (depending upon the fluid)