| A four-cylinder four-stroke engine operates at 4000 rpm. The bore and stroke are 100 mm each, the MEP is measured as 0.6 MPa, and the thermal efficiency is 35%. Determine (a) the power produced by the engine in kW, (b) the waste heat in kW, (c) and the volumetric air intake in L/s. [Manual Solution*] | Reciprocating Cycle |
| Answers: (a) 60.67 kW, (b) 112.6 kW, (c) 26.2 L/s |
|
A six-cylinder four-stroke engine operating at 3000 rpm produces 200 kW of total brake power. If the cyclinder displacement is 1 L, determine (a) net work output in kJ per cylinder per cycle, (b) the MEP, and (c) the fuel consumption rate in kg/h. Assume the heat release per kg of fuel to be 30 MJ and the thermal efficiency to be 40%. [Manual Solution*] | |
| Answers: (a) 1.33 kJ, (b) 1333 kPa, (c) 60 kg/h |
|
A six-cylinder engine with a volumetric efficiency of 90% and a thermal efficiency of 38% produces 200 kW of power at 3000 rpm. The cylinder bore and stroke are 100 mm and 200 mm respectively. If the condition of air in the intake manifold is 95 kPa and 300 K, determine (a) the mass flow rate of air in kg/s, (b) the fuel consumption rate in kg/s, and (c) the specific fuel consumption in kg/kW.hr. Assume the heating value of the fuel to be 35 MJ/kg of fuel. [Manual Solution*] | |
| Answers: (a) 0.234 kg/s, (b) 0.0156 kg/s, (c) 0.281 kg/kW.h |
| A Carnot cycle running on a closed system has 1.5 kg of air. The temperature limits are 300 K and 1000 K, and the pressure limits are 20 and 1900 kPa. Determine (a) the efficiency and (b) the net work output. Use the PG model. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 70%, (b) 103.7 kJ |
|
Consider a Carnot cycle executed in a closed system with 0.003 kg of air. The temperature limits are 25oC and 730oC, and the pressure limits are 15 and 1700 kPa. Determine (a) the efficiency, (b) the net work output per cycle. Use the PG model for air. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 70%, (b) 0.30 kJ |
|
An air standard Carnot cycle is executed in a closed system between the temperature limits if 300 K and 1000 K. The pressure before and after the isothermal compression are 100 and 300 kPa, respectively. If the net work output per cycle is 0.22 kJ, determine (a) the maximum pressure in the cycle, (b) the heat transfer to air, and (c) the mass of air. Use the PG model. (d) What-if scenario: How would the answer in (c) change if the IG model was used? [Manual Solution] [TEST Solution] |
|
| Answers: (a) 20.2 MPa, (b) 0.314 kJ, (c) 0.001 kg, (d) 0.001kg |
|
An air standard carnot cycle is executed in a closed system between the temperature limits of 350 and 1200 K. The pressure before and after the isothermal compression are 150 and 300 kPa respectively. If the net work output per cycle is 0.5 kJ, determine (a) the maximum pressure in the cycle, (b) the heat transfer to air, and (c) the mass of air. Assume variable specific heats for air [Manual Solution] [TEST Solution] |
|
| Answers: (a) 20.2 MPa, (b) 0.094 kJ, (c) 0.001 kg |
| An ideal Otto cycle has a compression ratio of 9. At the beginning of compression, air is at 14.4 psia and 80oF. During constant-volume heat addition 450 Btu/lbm of heat is transferred. Calculate (a) the maximum temperature, (b) efficiency, and (c) the net work output. Use the IG model. (d) What-if-scenario: How would the answer in (b) change if the air was at 100oF at the beginning of compression? [Manual Solution] [TEST Solution] |
|
| Answers: (a) Tmax = 3381.27oR, (b) 53.3%, (c) 240.28 Btu/lbm , (d) 50.2% |
|
An ideal Otto cycle with air as the working fluid has a compression ratio of 8. The minimum and maximum temperatures in the cycle are 25oC and 1000oC respectively. Using the IG model, determine (a) the amount of heat transferred to the air during the heat addition process, (b) the thermal efficiency, and (c) the mean effective pressure. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 512 kJ/kg, (b) 53%, (c) 311 kPa |
|
An ideal Otto cycle has a compression ratio 7. At the beginning of the compression process, air is at 98 kPa and 30oC, and 766 kJ/kg of heat is transferred to air during the constant-volume heat addition process. Determine (a) the pressure and temperature at the end of the heat addition pressure, (b) the net work output, (c) the thermal efficiency, and (d) the mean effective pressure for the cycle. Use the IG model. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 3465.9 kPa, 1531.6 K (b) 382.54 kJ/kg, (c) 49.94%, (d) 502.72 kPa |
|
An engine equipped with a single cylinder having a bore of 12 cm and a stroke of 50 cm operates on an Otto cycle. At the beginning of the compression stroke air is at 100 kPa, 25°C. The maximum temperature in the cycle is 1100°C. (a) If the clearance volume is 1500 cm3, determine the air standard efficiency. (b) At 300 rpm, determine the engine output in kW. Use the PG model. (c) What-if-scenario: How would the answers change if the clearance volume was reduced to 1200 cc? [Manual Solution] [TEST Solution] |
|
|
Answers: (a) 46.5%, (b) 11.35 kW, (c) 43%, 12.44 kW |
|
The temperature at the beginning of the compression process of an air standard Otto cycle with a compression ratio of 8 is 27oC, the pressure is 101 kPa, and the cylinder volume is 566 cm3. The maximum temperature during the cycle is 1726oC. Determine (a) the thermal efficiency, and (b) the mean effective pressure. Use the PG model for air. (c) What-if scenario: How would the answers change if the IG model was used? [Manual Solution] [TEST Solution] |
|
| Answers: (a) 56.5%, (b) 710.2 kPa, (c) 51%, 806 kPa |
|
The Compression ratio of an air standard otto cycle is 8. Prior to isentropic compression, the air is at 100 kPa, 20oC and 500 cm3. The temperature at the end of combustion process is 900 K. Determine (a) the highest pressure in the cycle, (b) the amount of heat transferred in kJ, (c) thermal efficiency, and (d) M.E.P. Use the PG model. (e) What-if scenario: How would the efficiency change if the compression ratio was increased to 10? Explain the change with the help of a T-s diagram. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 2456.1 kPa, (b) 0.096 kJ, (c) 56.5%, (d) 124.2 kPa, (e) 60.2% |
|
At the beginning of the compression process of an air standard Otto cycle, pressure is 100 kPa, temperature is 16oC, and volume is 300 cm3. The maximum temperature in the cycle is 2000oC and the compression ratio is 9. Determine (a) the heat addition in kJ, (b) the net work in kJ, (c) thermal efficiency, and (d) M.E.P. Use the PG model. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 0.408 kJ, (b) 0.2389 kJ, (c) 58.52%, (d) 895.9 kPa |
|
The compression ratio in an air standard Otto cycle is 8. At the beginning of the compression stroke, the pressure is 101 kPa and the temperature is 289 K. The heat transfer to the air per cycle is 1860 kJ/kg. Determine (a) the thermal efficiency and (b) the mean effective pressure. Use the PG model. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 56.5 %, (b) 1463 kPa |
|
An air standard Otto cycle has a compression ratio of 9. At the beginning of the compression, pressure is 95 kPa and temperature is 30oC. Heat addition to the air is 1 kJ, and the maximum temperature in the cycle is 750oC. Using the IG model for air, determine (a) the net work in kJ, (b) thermal efficiency, and (c) M.E.P. Assume mass of air as 0.005 kg. [Manual Solution] [TEST Solution] |
|
|
Answers: (a) 0.425 kJ, (b) 42.5 %, (c) 104.4 kPa |
|
The compression ratio of an air standard Otto cycle is 8.7. Prior to the isentropic compression process, the air is 120 kPa, 19oC, and 660 cm3. The temperature at the end of the isentropic expansion process is 810 K. Using the PG model, determine (a) the highest temperature and pressure in the cycle, (b) the amount of heat transfer in kJ, (c) the thermal efficiency, and (d) M.E.P. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 1926.6 K, 6884.8 kPa, (b) 0.83 kJ, (c) 57.96%, (d) 827.2 kPa |
|
The compression ratio in an air standard Otto cycle is 8. At the beginning of the compression stroke the pressure is 0.1 MPa and the temperature is 21oC. The heat transfer to the air per cycle is 2000 kJ/kg. Determine (a) the thermal efficiency, and (b) the mean effective pressure. Use the PG model for air. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 56.5 %, (b) 1530 kPa |
|
An ideal Otto cycle with argon as the working fluid has a compression ratio of 8.5. The minimum and maximum temperatures in the cycle are 350 and 1630 K. Accounting for variation of specific heats with temperature (that is, using the IG model for air), determine (a) the amount of heat transferred to the air during the heat addition process, (b) the thermal efficiency, and (c) the thermal efficiency of a Carnot cycle operating between the same temperature limits. [Manual Solution] [TEST Solution] |
|
|
Answers: (a) 53.83 kJ/kg, (b) 75.99%, (c) 78.53% |
|
An ideal Otto cycle has a compression ratio of 8.3. At the beginning of the compression process, the air is at 100 kPa and 25oC, and 1000 kJ/kg of heat is transferred to air during the constant volume heat addition process. Using the PG model for air, determine (a) the maximum temperature and pressure that occur during the cycle, (b) the thermal efficiency, and (c) the mean effective pressure for the cycle. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 5.02 MPa, 1533oC, (b) 52.1.%, (c) 692 kPa |
|
In , assume the heat addition can be modeled as heat transfer from a source at 1700oC. Determine the exergy transferred from the reservoir and the exergy rejected to the atmosphere from the engine per unit mass of the gas. Assume the atmospheric conditions to be 100 kPa and 25oC. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 849 kJ/kg, (b) 193 kJ/kg |
|
An engine equipped with a single cylinder having a bore of 12 cm and a stroke of 50 cm operates on an Otto cycle. At the beginning of the compression stroke air is at the atmospheric conditions of 100 kPa, 25°C. The maximum temperature in the cycle is 1100°C and the heat addition can be assumed to take place from a reservoir at 1500°C. If the clearance volume is 1500 cm3 and the engine runs at 300 rpm, determine (a) the engine output in kW, (b) the exergy destruction over an entire cycle, and (c) the rate of exergy destruction in kW. Use the PG model. [Manual Solution*] [TEST Solution] |
|
|
Answers: (a) 8.5 kW |
| An ideal cold air standard Diesel cycle has a compression ratio of 20. At the beginning of compression, air is at 95 kPa and 20oC. If the maximum temperature during the cycle is 2000oC, determine (a) the thermal efficiency and (b) the mean effective pressure. Use the PG model. (c) What-if-scenario: How would the answer in (b) change if the compression ratio was reduced to 10? Explain the change with the help of a T-s diagram. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 63.2%, (b) 983 kPa, (c) 922 kPa |
|
The displacement volume of an internal combustion engine is 3 L. The processes within each cylinder of the engine are modeled as an air standard diesel cycle with a cut off ratio of 2. The state of air at the beginning of the compression is fixed by p1= 100 kPa, T1= 25oC, and Vol1= 3.5 L. Determine (a) the net work per cycle, (b) efficiency, and (c) the power developed by the engine, if the cycle is executed 1500 times per min. (d) What-if-scenario: How would the answer in (b) and (c) change if the cut-off ratio was 2.5? Explain the changes with the help of a T-s diagram. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 1.24 kJ, (b) 46.3 %, (c) 31 kW, (d) 43%, 43 kW |
|
An air standard Diesel cycle has a compression ratio of 15 and cutoff ratio of 3. At the beginning of the compression process, air is at 97 kPa and 30oC. Using the PG model for air, determine (a) the temperature after the heat addition process, (b) the thermal efficiency, and (c) the mean effective pressure. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 2690.57 K, (b) 55.8%, (c) 1200.9 kPa |
|
An air standard Diesel cycle has a compression ratio of 16 and cutoff ratio of 2. At the beginning of the compression process, air is at 100 kPa, 15oC and has a volume of 0.014 m3. Determine (a) the temperature after the heat addition process, (b) the thermal efficiency, and (c) the mean effective pressure. Use the PG model. (d) What-if-scenario: How would the answer in (b) change if the IG model was used? [Manual Solution] [TEST Solution] |
|
| Answers: (a) 1476 oC , (b) 61.4 %, (c) 696 kPa, (d) 57 % |
|
At the beginning of the compression process of an air standard Diesel cycle operating with a compression ratio of 10, the temperature is 25oC and the pressure is 100 kPa. The cutoff ratio of the cycle is 2. Determine (a) the thermal efficiency, and (b) the mean effective pressure. Use the PG model. (d) What-if-scenario: How would the answer in (a) change if the compression ratio was increased to 15? [Manual Solution] [TEST Solution] |
|
|
Answers: (a) 53.4%, (b) 522 kPa, (c) 60.4% |
|
The conditions at the beginning of the compression process of an air standard Diesel cycle are 150 kPa and 100oC. The compression ratio is 15 and the heat addition per unit mass is 750 kJ/kg Determine (a) the maximum temperature, (b) the maximum pressure, (c) the cutoff ratio, (d) the net work per unit mass of air, and (e) the thermal efficiency. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 1851.33 K, (b) 6.6 MPa, (c) 1.62, (d) 465.8 kJ, (e) 62.1 % |
|
An air standard Diesel cycle has a compression ratio of 17.9. Air is at 85oF and 15.8 psia at the beginning of the compression process and at 3100oR at the end of the heat addition process. Accounting for the variation of specific heats with temperature, determine (a) the cutoff ratio, (b) the heat rejection per unit mass, and (c) the thermal efficiency. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 1.92, (b) 174.71 Btu/lbm, (c) 58.38% |
|
An ideal diesel engine has a compression ratio of 20 and uses nitrogen gas as working fluid. The state of nitrogen gas at the beginning of the compression process is 95 kPa and 20oC. If the maximum temperature in the cycle is not to exceed 2200 K, determine (a) the heat efficiency and (b) the mean effective pressure. Use the PG model for nitrogen. (c) What-if-scenario: How would the answers change if carbon-i-oxide was used as the working substance? [Manual Solution] [TEST Solution] |
|
| Answers: (a) 85.3%, (b) 1228 kPa, (c) 85.5%, (b) 1958 kPa |
|
An ideal diesel engine has a compression ratio of 22 and uses air as working fluid. The state of air at the beginning of the compression process is 95 kPa and 22oC. If the maximum temperature in the cycle is not exceed 1900oC, determine (a) the thermal efficiency and (b) the mean effective pressure. Use the PG model. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 65%, (b) 892 kPa |
|
A four cylinder 3-L (maximum volume per cylinder) diesel engine that operates on an ideal Diesel cycle has a compression ratio of 18 and a cutoff ratio of 3. Air is at 25oC and 95 kPa at the beginning of the compression process. Using the cold-air standard assumptions, determine (a) how much power the engine will deliver at 1700 rpm. (b) What-if-Scenario: How would the answer change if the engine speed decreased to 1500 rpm? [Manual Solution] [TEST Solution] |
|
| Answers: (a) 211.6 kW, (b) 187.0 kW |
|
An air standard Diesel cycle has a compression ratio of 19, and heat transfer to the working fluid per cycle is 2000 kJ/kg. At the beginning of the compression process the pressure is 105 kPa and the temperature is 20oC. Determine (a) the net work, (b) the thermal efficiency, and (c) the mean effective pressure. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 1190 kJ, (b) 59.5%, (c) 1.6 MPa |
|
An ideal dual cycle has a compression ratio of 14 and uses air as working fluid. The state of air at the beginning of the compression process is 100 kPa and 300 K. If the maximum temperature in the cycle is 2200 K, determine (a) the thermal efficiency, and (b) the mean effective pressure. Use the IG model. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 58.65%, (b) 1115.45 kPa |
|
At the beginning of the compression process of an air standard dual cycle with a compression ratio of 18, p = 100 kPa and T = 300 K. The pressure ratio for the constant volume part of the heating process is 1.5 and the volume ratio of the constant pressure part is 1.2. Determine (a) the thermal efficiency, and (b) the MEP. Use the PG model. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 68%, (b) 0.526 MPa |
|
An air standard dual cycle has a compression ratio of 17. At the beginning of compression, p1 = 100 kPa and T1 = 15oC and volume is 0.5 ft3. The pressure doubles during the constant volume heat addition process. For maximum cycle temperature of 1400oC, determine (a) the thermal efficiency, and (b) the MEP. Assume variable c_p (IG model). [Manual Solution] [TEST Solution] |
|
| Answers: (a) 61.5%, (b) 596 kPa |
|
An air standard dual cycle has a compression ratio of 15 and a cutoff ratio of 1.5. At the beginning of compression, p1 = 1 bar and T1 = 290 K. The pressure doubles during the constant volume heat addition process. If the mass of air is 0.5 kg, determine (a) the net work of the cycle, (b) the thermal efficiency, and (c) the MEP. Use the PG model. (d) What-if-Scenario: How would the answers in (a) and (b) change if the compression ratio was increased to 18? Explain the changes with the help of a T-s diagram. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 475.1 kJ (b) 64.4 %, (c) 1223 kPa, (d) 530.1 kJ, 66.9% |
|
A 3-stroke cycle is executed in a closed system with 1 kg of air, and it consists of the following three processes: (1) Isentropic compression from 100 kPa, 300 K to 800 kPa, (2) p = constant heat addition in amount of 2000 kJ, (3) p = cV heat rejection to initial state. Calculate (a) the maximum temperature, and (b) efficiency. Show the cycle on T-s and p-v diagrams. Use the PG model for air. (c) What-if-scenario: How would the answer in (b) change if the constant pressure heat addition amounted to 1000 kJ? [Manual Solution] [TEST Solution] |
|
| Answers: (a) 2536.7 K, (b) 19.7%, (c) 11.13% |
|
An air standard cycle is executed in a closed system with 0.005 kg of air, and it consists of the following three processes: (1) Isentropic compression from 200 kPa, 30oC to 2 MPa, (2) p = constant heat addition in the amount of 2 kJ, (3) p = c1v + c2v heat rejection to initial state. Calculate (a) the heat rejected, and (b) the thermal efficiency. Assume constant specific heats at room temperature. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 1.5 kJ, (b) 25 % |
|
An air standard cycle is executed in a closed system with 0.001 kg of air, and it consists of the following three processes: (1) v = constant heat addition from 95 kPa 20oC to 450 kPa, (2) isentropic compression from 95 kPa, (3) p = constant heat rejection to initial state. Using PG model calculate (a) the net work per cycle in kJ, and (b) the thermal efficiency. [Manual Solution] [TEST Solution] |
|
|
Answers: (a) 0.186 kJ, (b) 24 % |
|
An air standard cycle is executed in a closed system with 1 kg of air, and it consists of the following three processes: (1) Isentropic compression from 100 kPa, 27oC to 700 kPa, (2) p = constant heat addition to initial specific volume, (3) v = constant heat rejection to initial state. Calculate (a) the maximum temperature, and (b) efficiency. Show the cycle on T-s and p-v diagrams. Use the PG model. (c) What-if-scenario: How would the answer in (a) change if isentropic compression took place from 100 kPa, 27oC to 500 kPa? [Manual Solution] [TEST Solution] |
 |
|
Answers: (a) Tmax = 1827.9oC,
(b) 18.46%, (c) Tmax = 1227.6oC |
| An air standard cycle is executed in a closed system with 1 kg of air, and it consists of the following three processes: (1) Isentropic compression from 100 kPa, 27oC to 700 kPa, (2) p = constant heat addition to initial specific volume, (3) v = constant heat rejection to initial state. Calculate (a) the maximum temperature, and (b) efficiency. Show the cycle on T-s and p-v diagrams. Use the IG model. [Manual Solution*] [TEST Solution] | |
| Answers: (a) Tmax = 1828oC, (b) 15.8 % |
|
An air standard cycle is executed in a close system and is composed of the following four processes: (1) 1-2: Isentropic compression from 110 kPa and 30oC to 900 kpa, (2) 2-3: p = constant heat addition in the amount of 3000 kJ/kg, (3) 3-4: v = constant heat rejection to 110 kPa, (4) 4-1: p = constant heat rejection to initial state. (a) Calculate the maximum temperature in the cycle, and (b) determine the thermal efficiency. Use the PG model. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 3542 K, (b) 21.39% |
|
An air standard cycle is executed in a close system and is composed of the following four processes: (1) 1-2: v=constant heat addition from 15 psia and 85oF in the amount of 320 Btu/lbm, (2) 2-3: p =constant heat addition to 3500oR, (3) 3-4: Isentropic expansions to 15 psia, (4) 4-1: p =constant heat rejection to initial state. (a) Calculate the maximum temperature in the cycle, and (b) determine the thermal efficiency. Use the IG model. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 605.85 Btu/lbm, (b) 24.38% |
|
An air standard cycle with a variable specific heats is executed in a close system and is composed of the following four processes: (1) 1-2: Isentropic compression from 95 kPa and 25oC to 900 kPa, (2) 2-3: v = constant heat addition to 1200oC, (3) 3-4: Isentropic expansions to 95 kPa, (4) 4-1: p =constant heat rejection to initial state. (a) Calculate the net work output per unit mass, and (b) determine the thermal efficiency. Use the PG model for air. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 408 kJ/kg, (b) 53 % |
|
An air standard cycle is executed in a close system with 0.001 kg of air and is composed of the following three processes: (1) 1-2: Isentropic compression from 110 kPa and 30oC to 1.1MPa (2) 2-3: p = constant heat addition in the amount of 1.73 kJ (3) 3-1: p=c1*v+c2 heat rejection to initial state (c1 and c2 are constant) (a) Calculate the heat rejected, and (b) determine the thermal efficiency. Use the PG model. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 1.439 kJ, (b) 16.82% |
|
An ideal Stirling cycle running on a closed system has air at 200 kPa, 300 K at the beginning of the isothermal compression process. Heat supplied from a source of 1700 K is 800 kJ/kg. Determine (a) the efficiency, and (b) the net work output per kg of air. Use the PG model. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 33.27%, (b) 658.83 kJ/kg |
|
Consider an ideal Stirling cycle engine in which the pressure and temperature at the beginning of the isothermal compression process are 95 kPa, 20oC, the compression ratio is 5, and the maximum temperature in the cycle is 1000oC. Determine (a) maximum pressure and (b) the thermal efficiency of the cycle. Use the PG model. [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 2063 kPa, (b) 35 % |
|
An ideal Stirling engine using helium as the working fluid operates between the temperature limits of 38oC and 850oC and pressure limits of 102 and 1020 kPa. Assuming the mass used in the cycle is 1 kg, determine (a) the thermal efficiency of the cycle, and (b) the net work. (c) What-if-scenario: How would the answers change if argon was used as the working fluid? [Manual Solution*] [TEST Solution] |
|
| Answers: (a) 49%, (b) 3886 kJ, (c) 49%, 389.1 kJ |
|
Consider an ideal Stirling cycle engine in which the pressure, temperature and volume at the beginning of the isothermal compression process are 100 kPa, 15oC, and 0.03 m3, the compression ratio is 8, and the maximum temperature in the cycle is 650oC. Determine (a) the net work, (b) the thermal efficiency, and (c) the mean effective pressure. [Manual Solution*] [TEST Solution] |
|
|
Answers: (a) 13.7 kJ, (b) 37.7 %, (c) 524 kPa
|
| Fifty grams of air undergoes a Stirling cycle with a compression ratio of four. At the beginning of the isothermal process, the pressure and volume are 100 kPa and 0.05 m3, respectively. The temperature during the isothermal expansion is 990 K. Determine (a) the net work output per kg, and (b) the mean effective pressure. Use the IG model. [Manual Solution*] [TEST Solution] | |
|
Answers: (a) 12.7 kJ, (b) 3.4 bar
|
| An ideal Stirling engine using helium as the working fluid operates between the temperature limits of 300 K and 1800 K and pressure limits of 150 and 1200 kPa. Assuming a mass used in the cycle is 1.5 kg, determine (a) the thermal efficiency of the cycle, (b) the amount of heat transfer in the regenerator, and (c) the work output per cycle. [Manual Solution*] [TEST Solution] | |
| Answers: (a) 15.5 %, (b) 7015.5 kJ, (c) 1614.4 kJ |
| A Carnot cycle running on a closed system has 1 kg of air and executes 20 cycles every second. The temperature limits are 300 K and 1000 K, and the pressure limits are 20 and 1900 kPa. Atmospheric conditions are 100 kPa and 300 K. Using the PG model for air, (a) perform a complete exergy inventory and draw an exergy flow diagram for the cycle on a rate (kW) basis. (b) What is the exergetic efficiency of the Carnot engine? [Manual Solution] [TEST Solution] |
|
| Answers: (b) 100% |
|
Consider a Carnot cycle executed in a closed system with 0.5 kg of air. The temperature limits are 50oC and 750oC, and the pressure limits are 15 and 1700 kPa. Heat addition takes place from a reservoir at 775oC and heat rejection takes place to the atmosphere at 100 kPa, 25oC. Using the PG model for air, (a) perform a complete exergy inventory and draw an exergy flow diagram for the cycle on unit mass basis (kJ/kg). (b) What is the exergetic efficiency of the Carnot engine? [Manual Solution] [TEST Solution] |
|
| Answers: (b) 95.6% |
|
In problem , (a) perform a complete exergy inventory and draw an exergy flow diagram for the cycle on unit mass basis (kJ/kg). Assume the heat addition to take place from a reservoir at 1500°C and heat rejection to the atmosphere at 100 kPa, 25°c. Use the PG model for air. (b) What is the overall exergetic efficiency of the engine? [Manual Solution] [TEST Solution] |
|
| Answers: (b) 67.94% |
|
An IC engine with 4 cylinders operates at 3000 RPM in an air-standard Otto cycle. Data for a single cylinder are given as follows. The compression ratio is 8.7. Prior to the isentropic compression process, the air is at the atmospheric conditions of 100 kPa, 20oC, and 660 cm3. The temperature at the end of the isentropic expansion process is 810 K. Assume the heat addition to take place from a reservoir at 1500°C and heat rejection to the atmosphere. Using the PG model, (a) perform a complete exergy inventory and draw the exergy flow diagram on a rate (kW) basis. (b) Determine the overall exergetic efficiency and (c) the thermal (energetic) efficiency of the cycle. [Manual Solution] [TEST Solution] |
|
| Answers: (b) 69.39%, (c) 57.96% |
|
For each process in problem , (a) develop an exergy inventory on a rate basis (in kW) and draw an exergy flow diagram for the cycle, and (b) determine the exergetic efficiency of the engine. Assume the heat addition and heat rejection to take place with reservoirs at the maximum and minimum temperature of the cycle respectively. [Manual Solution] [TEST Solution] |
|
|
Answers: (a) |
|
A four cylinder 3-L (maximum volume per cylinder) diesel engine that operates on an ideal Diesel cycle has a compression ratio of 18 and a cutoff ratio of 3. Air is at 25oC and 100 kPa (atmospheric conditions) at the beginning of the compression process. Assume the heat addition to take place from a reservoir at 1500°C and heat rejection to the atmosphere. Using the PG model, (a) perform a complete exergy inventory and draw the exergy flow diagram on a rate (kW) basis. (b) Determine the overall exergetic efficiency and (c) the thermal (energetic) efficiency of the cycle. [Manual Solution] [TEST Solution] |
|
| Answers: (b) 70.88%, (c) 58.96% |
|
In problem assume that heat is added from a reservoir at 1800°C and the atmospheric conditions are 100 kPa and 20°C. (a) Determine the process that carries the biggest penalty in terms of exergy destruction. (b) Also develop a balance sheet for exergy for the entire cycle on a rate (kW) basis, including an exergy flow diagram. [Manual Solution] [TEST Solution] |
|
| Answers: (a) |
|
In problem assume that heat is added from a reservoir at 2000°C and the atmospheric conditions are 100 kPa and 27°C. (a) Determine the thermal and (b) exergetic efficiency of the cycle. (b) Also develop a balance sheet for exergy for the entire cycle on unit mass (kJ/kg) basis complete with an exergy flow diagram. [Manual Solution] [TEST Solution] |
|
| Answers: (a) 18.48%, (b) 24.2% |
Copyright 1998-: Subrata Bhattacharjee |