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Thermodynamics and Fluid Mechanics Problems
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Thermodynamics and Fluid Mechanics Problems
Thermodynamics and Fluid Mechanics Problems
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1
Question
Q1: What is the work possessed by helium gas at 20°C?
Page 1
Answer
609 kJ/kg
2
Question
Q2: A 2 kg gas confined in a 1 m³ tank at 200 kPa and 88°C. What type of gas is in the tank?
Page 1
Answer
Helium
3
Question
Q3: Calculate the enthalpy of Helium if its internal energy is 200 kJ/kg.
Page 1
Answer
333.42 kJ/kg
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Question
Q4: Compute the mass of 2 m³ of propane at 280 kPa and 40°C.
Page 1
Answer
6.47 kg
5
Question
Q5: Determine the air flow in ft³/min of mechanical ventilation required to exhaust 4 lbs of refrigerant due to system leaks.
Page 1
Answer
200 ft³/min
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Question
Q6: Compute the free aperture cross section in m³ for machinery room ventilation if the mass of refrigerant is 9 kg.
Page 2
Answer
0.314 m³
7
Question
Q7: A 29.53” x 39.37” pressure vessel contains ammonia with f = 0.041. Compute the minimum required discharge capacity of the relief device in kg/hr.
Page 2
Answer
106.71 kg/hr
8
Question
Q8: Compute the maximum length of the discharge pipe for a pressure-relief device with a 0.5 inch internal diameter, 8 lb/min air discharge capacity, and 10 psig rated pressure.
Page 2
Answer
0.286 ft
9
Question
Q9: A thermal power plant has a heat rate of 11,363 Btu/kW-hr. What is the thermal efficiency of the plant?
Page 2
Answer
30%
10
Question
Q10: What is the hydraulic gradient of a 1 mile, 17 inches inside diameter pipe when 3300 gal/min of water flow with f = 0.03?
Page 2
Answer
0.00714
11
Question
Q11: Find the loss of head in the pipe entrance if the speed of flow is 10 m/s.
Page 3
Answer
2.55 m
12
Question
Q12: Wet material containing 220% moisture (dry basis) is dried at 1.5 kg/s to 10% moisture (dry basis). Find the moisture removed in kg/hr.
Page 3
Answer
3543.75 kg/hr
13
Question
Q13: Copra enters a dryer containing 70% moisture and leaves 7% moisture. Find the moisture removed per pound of solid in the final product.
Page 3
Answer
2.258 lbs
14
Question
Q14: A 1 m x 1.5 m cylindrical tank is full of oil with SG = 0.92. Find the force acting at the bottom of the tank in dynes.
Page 3
Answer
106.33 x 10⁵ dynes
15
Question
Q15: Find the pressure at the 100 fathom depth of water in kPa.
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Answer
1,893.96 kPa
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Question
Q16: Find the depth in furlong of the ocean (SG = 1.03) if the pressure at the sea bed is 2,032.56 kPa.
Page 4
Answer
4 furlong
17
Question
Q17: Find the mass of 10 quarts of water.
Page 4
Answer
9.46 kg
18
Question
Q18: Find the mass of carbon dioxide having a pressure of 20 psia at 200°F with 10 ft³ volume.
Page 4
Answer
1.04 lbs
19
Question
Q19: Find the heat needed to raise the temperature of water from 30°C to 100°C with 60% quality at 101.325 kPa atmospheric pressure, using the approximate enthalpy formula of liquid.
Page 4
Answer
1,772.90 kJ/kg
20
Question
Q20: Find the enthalpy of water at 212°F and 14.7 psi if the dryness factor is 30%. Use the approximate enthalpy formula of liquid.
Page 5
Answer
461 Btu/lb
21
Question
Q21: An air compressor consumes 1200 kW-hr/day. The electric motor driving it has an 80% efficiency. If the indicated power of the compressor is 34 kW, find the mechanical efficiency of the compressor.
Page 5
Answer
117.65%
22
Question
Q22: A refrigeration system consumes 28,800 kW-hr/month. With 20% energy loss in the cooling system and 90% motor efficiency, if the COP is 6, find the mechanical efficiency of the compressor.
Page 5
Answer
43.15 TR
23
Question
Q23: A 23-ton refrigeration system has a heat rejected of 100 kW. Find the energy efficiency ratio of the system.
Page 5
Answer
15.42
24
Question
Q24: A 200 mm x 250 mm, 8-cylinder, 4-stroke diesel engine has a brake power of 150 kW. Mechanical efficiency is 80%. If two cylinders are cut off, what is the new friction power?
Page 6
Answer
31.50 kW
25
Question
Q25: If the energy efficiency ratio (EER) of a refrigeration system is 12.6, what is the Coefficient of Performance (COP) of the system?
Page 6
Answer
3.69
26
Question
Q26: An air compressor has a power of 40 kW at 4% clearance. If the clearance increases to 7%, what is the new power?
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Answer
53 kW
27
Question
Q27: What is the approximate temperature of water having an enthalpy of 208 Btu/lb?
Page 6
Answer
138.67°C
28
Question
Q28: Convert 750°R to Kelvin.
Page 7
Answer
416.33 K
29
Question
Q29: An Otto cycle has a compression ratio of 8. Find the pressure during compression, assuming an initial pressure of 1 atm.
Page 7
Answer
18.38
30
Question
Q30: A diesel cycle has a cut-off ratio of 2.5 and an expansion ratio of 4. Find the clearance of the cycle.
Page 7
Answer
11.11%