Practice Pakistan's most useful MCQs for competitive exams

Temperature profile in steady state heat transfer is________________?

• (A)  Asymptotic
• (B)  Hyperbolic
• (C)  Parabolic
• (D)  Linear

Answer

Submitted By :Ali Uppal

Maximum water velocity in tubes of a 1-2 shell and tube heat exchanger may be around _____________ metres/second?

• (A)  1
• (B)  10
• (C)  20
• (D)  30

Answer

Submitted By :Ali Uppal

A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?

• (A)  Yellow paint
• (B)  White paint
• (C)  Black paint
• (D)  Grey paint

Answer

Submitted By :Ali Uppal

The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the right face is 10 W/m2.K. At steady state, the temperature of the right face in °C is____________________?

• (A)  77.2
• (B)  71.2
• (C)  63.8
• (D)  48.7

Answer

Submitted By :Ali Uppal

Agitated film evaporator is suitable for concentrating _____________ liquids?

• (A)  Foaming
• (B)  Viscous
• (C)  Very thin
• (D)  Corrosive

Answer

Submitted By :Ali Uppal

The Dittus-Boelter equation for convective heat transfer [(i.e. h = 0.023 (K/D) (Re)0.8 (Pr)0.4] cannot be used for________________?

• (A)  Low Reynold’s number
• (B)  Very low Grashoff number
• (C)  Molten metals
• (D)  All

Answer

Submitted By :Ali Uppal

The radiation heat flux from a heating element at a temperature of 800°C, in a furnace maintained at 300°C is 8 kW/m2. The flux, when the element temperature is increased to 1000°C for the same furnace temperature is_____________________?

• (A)  11.2 kW/m2
• (B)  12.0 kW/m2
• (C)  14.6 kW/m2
• (D)  16.5 kW/m2

Answer

Submitted By :Ali Uppal

A composite flat wall of a furnace is made of two materials ‘A’ and ‘B’. The thermal conductivity of ‘A’ is twice of that of material ‘B’, while the thickness of layer of ‘A’ is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material ‘A’ is________________?

• (A)  125
• (B)  133
• (C)  150
• (D)  160

Answer

Submitted By :Ali Uppal

In forced convection, the heat transfer depends on _______________?

• (A)  Re, Pr
• (B)  Re, Gr
• (C)  Mainly Gr
• (D)  Re only

Answer

Submitted By :Ali Uppal

Kg of liquid evaporated per hour in an evaporator is defined as its_________________?

• (A)  Capacity
• (B)  Economy
• (C)  Steam load
• (D)  None of these

Answer

Submitted By :Ali Uppal