Applied Heat Past Examination Questions
Applied Heat past Examination Questions
1. An Ammonia refrigerator is to produce 2 tonne of ice per day at -4°C from water at 20°C. if the temperature range in the compressor is between 25°C and -6°C,
Calculate horse power required to derive the compressor.
Latent Heat of ice = 80 kcal/kg, and specific heat of ice= 0.5
2. A compressor draws 42.5 m3 of air per minute in the cylinder, at a pressure of 1.05 kg/cm abs. It is compressed Polytropically pV1.3=C to a pressure 4.2 kg/cm2 abs, before being delivered to a receiver.
Assuming a mechanical efficiency of 80%
Calculate:
a. Indicated horse power;
b. Shaft horse power, and
c. Overall isothermal efficiency.
3. A single stage impulse turbine has a speed of 1000rpm and a mean blade ring diameter of 60 cm. The nozzles are inclined at 22° to the plane of rotation and the specific enthalpy drop is 190 KJ/kg.
Determine:
a. The relative velocity of the steam at inlet, and
b. The blade inlet angle.
4. An engine consumes fuel of calorific value 44MJ/Kg at a rate of 45tonne/day. It the indicated thermal efficiency is 39% and break thermal efficiency is 33%.
Calculate:
a. The indicated power,
b. The brake power, and
c. The power lost to friction.
5. The air in a ship’s saloon is maintained at 19°C and is changed twice every hour from the outside atmosphere which is at 7°C. The saloon is 27m by 15m by 3m high.
Calculate the kilowatt loading to heat this air taking the saloon to be at atmospheric
Pressure = 1.013 bar.
R for air =0.287 KJ/kg K.
6. 0.23kg of air has an initial pressure of 1.7 MN/m2 and a temperature of 200°C. it is expanded to a pressure of 0.34 MN/m2 according to the law pV 1.35 = Constant.
Determine the work transferred during the expansion.
Take R = 0.29 KJ/kg K.
7. The equivalent evaporation of a boiler from and at 100°C is 10.4 kg steam/kg fuel.
1. An Ammonia refrigerator is to produce 2 tonne of ice per day at -4°C from water at 20°C. if the temperature range in the compressor is between 25°C and -6°C,
Calculate horse power required to derive the compressor.
Latent Heat of ice = 80 kcal/kg, and specific heat of ice= 0.5
2. A compressor draws 42.5 m3 of air per minute in the cylinder, at a pressure of 1.05 kg/cm abs. It is compressed Polytropically pV1.3=C to a pressure 4.2 kg/cm2 abs, before being delivered to a receiver.
Assuming a mechanical efficiency of 80%
Calculate:
a. Indicated horse power;
b. Shaft horse power, and
c. Overall isothermal efficiency.
3. A single stage impulse turbine has a speed of 1000rpm and a mean blade ring diameter of 60 cm. The nozzles are inclined at 22° to the plane of rotation and the specific enthalpy drop is 190 KJ/kg.
Determine:
a. The relative velocity of the steam at inlet, and
b. The blade inlet angle.
4. An engine consumes fuel of calorific value 44MJ/Kg at a rate of 45tonne/day. It the indicated thermal efficiency is 39% and break thermal efficiency is 33%.
Calculate:
a. The indicated power,
b. The brake power, and
c. The power lost to friction.
5. The air in a ship’s saloon is maintained at 19°C and is changed twice every hour from the outside atmosphere which is at 7°C. The saloon is 27m by 15m by 3m high.
Calculate the kilowatt loading to heat this air taking the saloon to be at atmospheric
Pressure = 1.013 bar.
R for air =0.287 KJ/kg K.
6. 0.23kg of air has an initial pressure of 1.7 MN/m2 and a temperature of 200°C. it is expanded to a pressure of 0.34 MN/m2 according to the law pV 1.35 = Constant.
Determine the work transferred during the expansion.
Take R = 0.29 KJ/kg K.
7. The equivalent evaporation of a boiler from and at 100°C is 10.4 kg steam/kg fuel.