Practice Pakistan's most useful MCQs for competitive exams

The main purpose of providing fins on heat transfer surface is to increase the_________________?

• (A)  Temperature gradient
• (B)  Mechanical strength of the equipment
• (C)  Heat transfer area
• (D)  Heat transfer co-efficient

Answer

Submitted By :Ali Uppal

When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as ___________________ boiling?

• (A)  Pool
• (B)  Nucleate
• (C)  Transition
• (D)  Film

Answer

Submitted By :Ali Uppal

The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe) ?

• (A)  K/h0
• (B)  2K/h0
• (C)  hi/K
• (D)  2hi/K

Answer

Submitted By :Ali Uppal

A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s-1. A 1 – 1 shell and tube heat exchanger is available. The best arrangement is_______________?

• (A)  Counter flow with process stream on shell side
• (B)  Counter flow with process stream on tube side
• (C)  Parallel flow with process stream on shell side
• (D)  Parallel flow with process stream on tube side

Answer

Submitted By :Ali Uppal

Natural convection is characterised by__________________?

• (A)  Grashoff number
• (B)  Peclet number
• (C)  Reynolds number
• (D)  Prandtl number

Answer

Submitted By :Ali Uppal

The unit of heat transfer co-efficient is_________________?

• (A)  BTU/hr. ft2°F
• (B)  BTU/hr. °F. ft
• (C)  BTU/hr. °F
• (D)  BTU/hr. ft

Answer

Submitted By :Ali Uppal

In Joule’s experiment, an insulated container contains 20 kg of water initially at 25°C. It is stirred by an agitator, which is made to turn by a slowly falling body weighing 40 kg through a height of 4 m. The process is repeated 500 times. The acceleration due to gravity is 9.8 ms-2. Neglecting the heat capacity of agitator, the temperature of water (in °C) is________________?

• (A)  40.5
• (B)  34.4
• (C)  26.8
• (D)  25

Answer

Submitted By :Ali Uppal

Multiple effect evaporators are commonly used in the manufacture of P. Paper Q. Superphosphate R. Sugar S. Fats ?

• (A)  P and Q
• (B)  P and R
• (C)  P and S
• (D)  R and S

Answer

Submitted By :Ali Uppal

Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is________________?

• (A)  Finned tube heat exchanger with air inside and steam outside
• (B)  Finned tube heat exchanger with air outside and steam inside
• (C)  Shell and tube heat exchanger with air inside tubes and steam on shell side
• (D)  Shell and tube heat exchanger with air on shell side and steam inside tubes

Answer

Submitted By :Ali Uppal

Heat exchanger tubes are never made of_________________?

• (A)  Plain carbon steel
• (B)  Stainless steel
• (C)  Lead
• (D)  Copper

Answer

Submitted By :Ali Uppal