Thermodynamics: An Engineering Approach
9th Edition
ISBN: 9781259822674
Author: Yunus A. Cengel Dr., Michael A. Boles
Publisher: McGraw-Hill Education
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Textbook Question
Chapter 8.8, Problem 131RP
Obtain a relation for the second-law efficiency of a heat engine that receives heat QH from a source at temperature
TH and rejects heat QL to a sink at TL, which is higher than T0 (the temperature of the surroundings), while producing work in the amount of W.
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Students have asked these similar questions
As shown in the figure below, two reversible cycles arranged in series each produce the same net work, Wcycle. The first cycle receives
energy QH by heat transfer from a hot reservoir at TH-1000°R and rejects energy Q by heat transfer to a reservoir at an intermediate
temperature, T. The second cycle receives energy Q by heat transfer from the reservoir at temperature T and rejects energy Qc by
heat transfer to a reservoir at Te - 500°R. All energy transfers are positive in the directions of the arrows.
Determine:
Hot reservoir at TH
lH
R1
Reservoir Q
at T
20
R2
lc
Cold reservoir at Tc
We
cycle
W
Wcycle
(a) the intermediate temperature T, in °R, and the thermal efficiency for each of the two power cycles.
(b) the thermal efficiency of a single reversible power cycle operating between hot and cold reservoirs at 1000°R and 500°R,
respectively. Also, determine the ratio of the network developed by the single cycle to the network developed by each of the two
cycles, Wcycle-
One kg of fluid expands reversibly according to a linear law from 4.2 bar to 1.4
bar. The initial and final volume are 0.004 and 0.02 m² respectively. The fluid
then cooled reversibly at constant pressure, and finally compressed reversibly
according to a law PV=C back to initial condition of 4.2 bar and 0.004 m².
Calculate the work done for each process, the net work done and sketch the cycle
on the P-V diagram.
(4480, -1120, -1845 &1515 N-m)
b- A 2kg/s of steam enters a turbine at 1Mpa ,400 °C with a velocity of
10m/s and leaves at very slow velocity with 0.3Mpa .determine the
specific work and power produced .
Superheated Vapor Water
Temp.
("C)
(m³kg)
(kJ/kg)
(kJ/kg)
(kJ/kg-K)
(m'/kg)
(k/kg)
(KJ/kg)
(kJ/kg-K)
300 kPa (133.55)
400 kPa (143.63)
250
0.79636
2728.69
2967.59
7.5165
0.59512
2726.11
2964.16
7.3788
300
0,87529
2806.69
3069.28
7.7022
0.65484
28C4.81
3066.75
7.5661
800 kPa (170.43)
1000 kPa (179.91)
Sat.
0.24043
2576.79
2769.13
6.6627
0.19444
2583,64
2778.08
6.5864
200
0.26080
2630.61
2839.25
6.8158
0.20596
2521.90
2827.86
6.6939
250
0.29314
2715.46
2949.97
7.0384
0.23268
2709.91
2942.59
6.9246
300
0.32411
2797.14
3056.43
7.2327
0.25794
2793.21
3051.15
7.1228
350
0.35439
2878.16
3161.68
7.4088
0.28247
2875.18
3157.65
7,3010
400
0.38426
2959.66
3267.07
7.5715
0.30659
2957.29
3263,88
7.4650
500
0.44331
3125.95
3480.60
7.8672
0.35411
3124.34
3478.44
7.7621
Chapter 8 Solutions
Thermodynamics: An Engineering Approach
Ch. 8.8 - What final state will maximize the work output of...Ch. 8.8 - Is the exergy of a system different in different...Ch. 8.8 - Under what conditions does the reversible work...Ch. 8.8 - How does useful work differ from actual work? For...Ch. 8.8 - How does reversible work differ from useful work?Ch. 8.8 - Is a process during which no entropy is generated...Ch. 8.8 - Consider an environment of zero absolute pressure...Ch. 8.8 - It is well known that the actual work between the...Ch. 8.8 - Consider two geothermal wells whose energy...Ch. 8.8 - Consider two systems that are at the same pressure...
Ch. 8.8 - Prob. 11PCh. 8.8 - Does a power plant that has a higher thermal...Ch. 8.8 - Prob. 13PCh. 8.8 - Saturated steam is generated in a boiler by...Ch. 8.8 - One method of meeting the extra electric power...Ch. 8.8 - A heat engine that receives heat from a furnace at...Ch. 8.8 - Consider a thermal energy reservoir at 1500 K that...Ch. 8.8 - A heat engine receives heat from a source at 1100...Ch. 8.8 - A heat engine that rejects waste heat to a sink at...Ch. 8.8 - A geothermal power plant uses geothermal liquid...Ch. 8.8 - A house that is losing heat at a rate of 35,000...Ch. 8.8 - A freezer is maintained at 20F by removing heat...Ch. 8.8 - Prob. 24PCh. 8.8 - Prob. 25PCh. 8.8 - Prob. 26PCh. 8.8 - Can a system have a higher second-law efficiency...Ch. 8.8 - A mass of 8 kg of helium undergoes a process from...Ch. 8.8 - Which is a more valuable resource for work...Ch. 8.8 - Which has the capability to produce the most work...Ch. 8.8 - The radiator of a steam heating system has a...Ch. 8.8 - A well-insulated rigid tank contains 6 lbm of a...Ch. 8.8 - A pistoncylinder device contains 8 kg of...Ch. 8.8 - Prob. 35PCh. 8.8 - Prob. 36PCh. 8.8 - Prob. 37PCh. 8.8 - A pistoncylinder device initially contains 2 L of...Ch. 8.8 - A 0.8-m3 insulated rigid tank contains 1.54 kg of...Ch. 8.8 - An insulated pistoncylinder device initially...Ch. 8.8 - Prob. 41PCh. 8.8 - An insulated rigid tank is divided into two equal...Ch. 8.8 - A 50-kg iron block and a 20-kg copper block, both...Ch. 8.8 - Prob. 45PCh. 8.8 - Prob. 46PCh. 8.8 - Prob. 47PCh. 8.8 - A pistoncylinder device initially contains 1.4 kg...Ch. 8.8 - Prob. 49PCh. 8.8 - Prob. 50PCh. 8.8 - Prob. 51PCh. 8.8 - Air enters a nozzle steadily at 200 kPa and 65C...Ch. 8.8 - Prob. 54PCh. 8.8 - Prob. 55PCh. 8.8 - Argon gas enters an adiabatic compressor at 120...Ch. 8.8 - Prob. 57PCh. 8.8 - Prob. 58PCh. 8.8 - The adiabatic compressor of a refrigeration system...Ch. 8.8 - Refrigerant-134a at 140 kPa and 10C is compressed...Ch. 8.8 - Air enters a compressor at ambient conditions of...Ch. 8.8 - Combustion gases enter a gas turbine at 900C, 800...Ch. 8.8 - Steam enters a turbine at 9 MPa, 600C, and 60 m/s...Ch. 8.8 - Refrigerant-134a is condensed in a refrigeration...Ch. 8.8 - Prob. 66PCh. 8.8 - Refrigerant-22 absorbs heat from a cooled space at...Ch. 8.8 - Prob. 68PCh. 8.8 - Prob. 69PCh. 8.8 - Air enters a compressor at ambient conditions of...Ch. 8.8 - Hot combustion gases enter the nozzle of a...Ch. 8.8 - Prob. 72PCh. 8.8 - A 0.6-m3 rigid tank is filled with saturated...Ch. 8.8 - Prob. 74PCh. 8.8 - Prob. 75PCh. 8.8 - An insulated vertical pistoncylinder device...Ch. 8.8 - Liquid water at 200 kPa and 15C is heated in a...Ch. 8.8 - Prob. 78PCh. 8.8 - Prob. 79PCh. 8.8 - A well-insulated shell-and-tube heat exchanger is...Ch. 8.8 - Steam is to be condensed on the shell side of a...Ch. 8.8 - Prob. 82PCh. 8.8 - Prob. 83PCh. 8.8 - Prob. 84PCh. 8.8 - Prob. 85RPCh. 8.8 - Prob. 86RPCh. 8.8 - An aluminum pan has a flat bottom whose diameter...Ch. 8.8 - Prob. 88RPCh. 8.8 - Prob. 89RPCh. 8.8 - A well-insulated, thin-walled, counterflow heat...Ch. 8.8 - Prob. 92RPCh. 8.8 - Prob. 93RPCh. 8.8 - Prob. 94RPCh. 8.8 - Prob. 95RPCh. 8.8 - Nitrogen gas enters a diffuser at 100 kPa and 110C...Ch. 8.8 - Prob. 97RPCh. 8.8 - Steam enters an adiabatic nozzle at 3.5 MPa and...Ch. 8.8 - Prob. 99RPCh. 8.8 - A pistoncylinder device initially contains 8 ft3...Ch. 8.8 - An adiabatic turbine operates with air entering at...Ch. 8.8 - Steam at 7 MPa and 400C enters a two-stage...Ch. 8.8 - Prob. 103RPCh. 8.8 - Steam enters a two-stage adiabatic turbine at 8...Ch. 8.8 - Prob. 105RPCh. 8.8 - Prob. 106RPCh. 8.8 - Prob. 107RPCh. 8.8 - Prob. 108RPCh. 8.8 - Prob. 109RPCh. 8.8 - Prob. 111RPCh. 8.8 - A passive solar house that was losing heat to the...Ch. 8.8 - Prob. 113RPCh. 8.8 - A 4-L pressure cooker has an operating pressure of...Ch. 8.8 - Repeat Prob. 8114 if heat were supplied to the...Ch. 8.8 - Prob. 116RPCh. 8.8 - A rigid 50-L nitrogen cylinder is equipped with a...Ch. 8.8 - Prob. 118RPCh. 8.8 - Prob. 119RPCh. 8.8 - Prob. 120RPCh. 8.8 - Reconsider Prob. 8-120. The air stored in the tank...Ch. 8.8 - Prob. 122RPCh. 8.8 - Prob. 123RPCh. 8.8 - Prob. 124RPCh. 8.8 - Prob. 125RPCh. 8.8 - Prob. 126RPCh. 8.8 - Prob. 127RPCh. 8.8 - Water enters a pump at 100 kPa and 30C at a rate...Ch. 8.8 - Prob. 129RPCh. 8.8 - Prob. 130RPCh. 8.8 - Obtain a relation for the second-law efficiency of...Ch. 8.8 - Writing the first- and second-law relations and...Ch. 8.8 - Prob. 133RPCh. 8.8 - Keeping the limitations imposed by the second law...Ch. 8.8 - Prob. 135FEPCh. 8.8 - Prob. 136FEPCh. 8.8 - Prob. 137FEPCh. 8.8 - Prob. 138FEPCh. 8.8 - A furnace can supply heat steadily at 1300 K at a...Ch. 8.8 - A heat engine receives heat from a source at 1500...Ch. 8.8 - Air is throttled from 50C and 800 kPa to a...Ch. 8.8 - Prob. 142FEPCh. 8.8 - A 12-kg solid whose specific heat is 2.8 kJ/kgC is...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- 1 kg of a fluid expands reversibly according to a linear law from 4.5 bar to 1.6 bar, the initial and final volumes are 0.004 m' and 0.02 m The fluid is then cooled reversibly at C. constant pressure. and finally compressed reversibly according to a law pV back to the initial conditions of 4,5 bar and 0.004 m Determine the work done in each process and the net work of the cycle. Sketch the cycle on a p-v diagram. =constantarrow_forwardNeed help solving this problem. Please provide clear and concise steps in neat handwriting.arrow_forwardHeat engine and refrigerator. Consider a heat engine operating between temperatures Th and Tj. During each cycle with time At, work W is extracted, so Pout = W/At. (a) Assuming the processes are all reversible, what is the efficiency of this heat engine, n = Wout/Qn? (b) Now assume that the low temperature of the heat engine is lowered by a reversible refrigerator, such that the heat engine operates between Th and T. The refrigerator takes input power Pin = Win/At and operates between T and T, where Ti < T. Draw an energy- entropy flow diagram. (c) Calculate the net efficiency (Wout - Win)/Qh. Is the efficiency of this system higher, lower, or the same as your answer for (a)?arrow_forward
- The second-law efficiency of naturally occurring processes is zero if none of the work potential is recovered.arrow_forwardQ19: A stationary mass of gas is compressed without friction from an initial state of 2 m3 and 2*105 N/m2 to a final state of 1 m3 and 2*105 N/m2 , the pressure remaining the same. There is a transfer of 360 kJ of heat from the gas during the a process. How much does the internal energy of the gas changearrow_forwardQ2 In a system, 90 kJ of heat is supplied from state 1 to state 2 by constant volume process. The internal energy at state 1 is 100 kJ. The system rejects 105 kJ of heat from state 2 to state 3 by constant pressure process and 40 kJ of work is done on it. The system is brought back from state 3 to state 1 by a reversible adiabatic process. Calculate the adiabatic work and the values of internal energy at state 2 and state 3arrow_forward
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