ISRO 2018 Thermodynamics Booster Quiz 2

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Question 1

A refrigerator is used to produce 2 ton of refrigeration having coefficient of performance 3.5. if the cost of electricity is Rs.10/kW-hr. Find the monthly bill in a month of 30 days. Assume mechanical efficiency of compressor 100%.

• A15400
• B13400
• C14400
• D12400

Question 2

Degree of superheat of moist air is 30and dry bulb temperature of air is 60. If the vapor pressure of water vapour is 1.2 KPa. Find the relative humidity of moist air (in %)__________.

• A66
• B74
• C60
• D72

Question 3

For an otto cycle mean effective pressure is 15 bar. Bore diameter of the cyclinder is 0.2m and stroke length is 0.5 m. Heat supplied at constant volume is 30 kJ/cycle. Find cycle efficiency.

• A65.62%
• B78.53%
• C65.85%
• D63.85%

Question 4

Air fuel ratio of a mixture entering the combustion chamber of an engine is 20 and thermal efficiency of the engine is 60%. The work done produce during expansion is 324KJ/kg of air. Find the calorific value (KJ/Kg) of fuel which enter the combustion chamber.

• A20500
• B40500
• C18500
• D10800

Question 5

The diesel engine and Otto engine has same compression ratio r. The cut-off ratio of diesel engine is S. The air-std efficiency of these cycles will be equal when

• As^γ – γ(s-1) + γ = 0
• Bs^γ – γ(s-1) + 1 = 0
• Cs^γ – γ(s-1) - 1 = 0
• Ds^γ – (s-1) - γ = 0

Question 6

Calculate the efficiency of engine for an engine working on air-standard Otto cycle has a clearance volume, 10% of swept volume.

• A55.4%
• B61.6%
• C39%
• D49.9%

Question 7

The specific heat capacity of the system during a certain process is given by
c_n = (0.4 + 0.004 T) kJ/kg °C
If heat transferred is 420 kJ, and the mass of the gas is 6 kg and its temperature changes from 30 °C to 120 °C find Mean specific heat of the gas.

• A0.88 kJ/kg °-C
• B0.38 kJ/kg °-C
• C0.98 kJ/kg °-C
• D0.78 kJ/kg °-C

Question 8

A 800-MW steam power plant, which is cooled by a nearby river, has a thermal efficiency of 40% Rate of heat transfer to the river water is _______ MW.

• A1200
• B1400
• C1600
• D1800

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