New Semester
Started
Get
50% OFF
Study Help!
--h --m --s
Claim Now
Question Answers
Textbooks
Find textbooks, questions and answers
Oops, something went wrong!
Change your search query and then try again
S
Books
FREE
Study Help
Expert Questions
Accounting
General Management
Mathematics
Finance
Organizational Behaviour
Law
Physics
Operating System
Management Leadership
Sociology
Programming
Marketing
Database
Computer Network
Economics
Textbooks Solutions
Accounting
Managerial Accounting
Management Leadership
Cost Accounting
Statistics
Business Law
Corporate Finance
Finance
Economics
Auditing
Tutors
Online Tutors
Find a Tutor
Hire a Tutor
Become a Tutor
AI Tutor
AI Study Planner
NEW
Sell Books
Search
Search
Sign In
Register
study help
engineering
mechanical engineering
Fundamentals Of Thermodynamics 8th Edition Claus Borgnakke, Richard E. Sonntag - Solutions
A boiler delivers steam at 10 MPa, 550C to a two-stage turbine as shown in Fig. 11.17. After the first stage, 25% of the steam is extracted at 1.4 MPa for a process application and returned at 1 MPa, 90C to the feedwater line. The remainder of the steam continues through the
Consider an ideal air-standard Brayton cycle in which the air into the compressor is at 100 kPa, 20C, and the pressure ratio across the compressor is 12:1. The maximum temperature in the cycle is 1100C, and the air flow rate is 10 kg/s. Assume constant specific heat for the air,
Repeat Problem 11.46, but assume variable specific heat for the air, table A.7.
An ideal regenerator is incorporated into the ideal air-standard Brayton cycle of Problem 11.46. Find the thermal efficiency of the cycle with this modification.
A Brayton cycle inlet is at 300 K, 100 kPa and the combustion adds 670kJ/kg. The maximum temperature is 1200 K due to material considerations. What is the maximum allowed compression ratio? For this calculate the net work and cycle efficiency assuming variable specific heat for the air, table A.7.
A large stationary Brayton cycle gas-turbine power plant delivers a power output of 100 MW to an electric generator. The minimum temperature in the cycle is 300 K, and the maximum temperature is 1600 K. The minimum pressure in the cycle is 100 kPa, and the compressor pressure ratio is 14 to 1.
Repeat Problem 11.50, but assume that the compressor has an isentropic efficiency of 85% and the turbine an isentropic efficiency of 88%.
Repeat Problem 11.51, but include a regenerator with 75% efficiency in the cycle.
A gas turbine with air as the working fluid has two ideal turbine sections, as shown in Fig. P11.53, the first of which drives the ideal compressor, with the second producing the power output. The compressor input is at 290 K, 100 kPa, and the exit is at 450 kPa. A fraction of flow, x, bypasses the
The gas-turbine cycle shown in Fig P11.54 is used as an automotive engine. In the first turbine, the gas expands to pressure P5, just low enough for this turbine to drive the compressor. The gas is then expanded through the second turbine connected to the drive wheels. The data for the engine are
Repeat Problem 11.54, but assume that the compressor has an efficiency of 82%, that both turbines have efficiencies of 87%, and that the regenerator efficiency is 70%.
Repeat the questions in Problem 11.54 when we assume that friction causes pressure drops in the burner and on both sides of the regenerator. In each case, the pressure drop is estimated to be 2% of the inlet pressure to that component of the system, so P3 = 588 kPa, P4 = 0.98 P3 and P6 = 102 kPa.
Consider an ideal gas-turbine cycle with two stages of compression and two stages of expansion. The pressure ratio across each compressor stage and each turbine stage is 8 to 1. The pressure at the entrance to the first compressor is 100 kPa, the temperature entering each compressor is 20C,
Repeat Problem 11.57, but assume that each compressor stage and each turbine stage has an isentropic efficiency of 85%. Also assume that the regenerator has an efficiency of 70%.
A gas turbine cycle has two stages of compression, with an intercooler between the stages. Air enters the first stage at 100 kPa, 300 K. The pressure ratio across each compressor stage is 5 to 1, and each stage has an isentropic efficiency of 82%. Air exits the intercooler at 330 K. The maximum
A two-stage air compressor has an intercooler between the two stages as shown in Fig. P11.60, the inlet state is 100 kPa, 290 K, and the final exit pressure is 1.6 MPa. Assume that the constant pressure intercooler cools the air to the inlet temperature, T3 T1. It can be shown, see
Repeat Problem 11.60 when the intercooler brings the air to T3320 K. The corrected formula for the optimal pressure is P2 = [P1P4 (T3/T1) n/ (n-1)] 1/2 see Problem 9.131, where n is the exponent in the assumed polytropic process.
Consider an ideal air-standard Ericsson cycle that has an ideal regenerator as shown in Fig. P11.62, the high pressure is 1 MPa and the cycle efficiency is 70%. Heat is rejected in the cycle at a temperature of 300 K, and the cycle pressure at the beginning of the isothermal compression process is
An air-standard Ericsson cycle has an ideal regenerator. Heat is supplied at 1000C and heat is rejected at 20C. Pressure at the beginning of the isothermal compression process is 70 kPa. The heat added is 600kJ/kg. Find the compressor work, the turbine work, and the cycle efficiency.
Consider an ideal air-standard cycle for a gas-turbine, jet propulsion unit, such as that. The pressure and temperature entering the compressor are 90 kPa, 290 K. The pressure ratio across the compressor is 14 to 1, and the turbine inlet temperature is 1500 K. When the air leaves the turbine, it
The turbine in a jet engine receives air at 1250 K, 1.5 MPa. It exhausts to a nozzle at 250 kPa, which in turn exhausts to the atmosphere at 100 kPa. The isentropic efficiency of the turbine is 85% and the nozzle efficiency is 95%. Find the nozzle inlet temperature and the nozzle exit velocity.
Repeat Problem 11.64, but assume that the isentropic compressor efficiency is 87%, the isentropic turbine efficiency is 89%, and the isentropic nozzle efficiency is 96%.
Consider an air standard jet engine cycle operating in a 280K, 100 kPa environment. The compressor requires a shaft power input of 4000 kW. Air enters the turbine state 3 at 1600 K, 2 MPa, at the rate of 9 kg/s, and the isentropic efficiency of the turbine is 85%. Determine the pressure and
A jet aircraft is flying at an altitude of 4900 m, where the ambient pressure is approximately 55 kPa and the ambient temperature is 18C. The velocity of the aircraft is 280 m/s, the pressure ratio across the compressor is 14:1 and the cycle maximum temperature is 1450 K. Assume the
Air flows into a gasoline engine at 95 kPa, 300 K. The air is then compressed with a volumetric compression ratio of 8; 1. In the combustion process 1300 kJ/kg of energy is released as the fuel burns. Find the temperature and pressure after combustion.
A gasoline engine has a volumetric compression ratio of 9. The state before compression is 290 K, 90 kPa, and the peak cycle temperature is 1800 K. Find the pressure after expansion, the cycle net work and the cycle efficiency using properties from Table A.7.
To approximate an actual spark-ignition engine consider an air-standard Otto cycle that has a heat addition of 1800 kJ/kg of air, a compression ratio of 7, and a pressure and temperature at the beginning of the compression process of 90 kPa, 10C. Assuming constant specific heat, with the
Repeat Problem 11.71, but assume variable specific heat. The ideal gas air tables, Table A.7, are recommended for this calculation (and the specific heat from Fig. 5.10 at high temperature).
A gasoline engine takes air in at 290 K, 90 kPa and then compresses it. The combustion adds 1000 kJ/kg to the air after which the temperature is 2050 K. Use the cold air properties (i.e. constant heat capacities at 300 K) and find the compression ratio, the compression specific work and the highest
Answer the same three questions for the previous problem, but use variable heat capacities.
When methanol produced from coal is considered as an alternative fuel to gasoline for automotive engines, it is recognized that the engine can be designed with a higher compression ratio, say 10 instead of 7, but that the energy release with combustion for a stoichiometric mixture with air is
It is found experimentally that the power stroke expansion in an internal combustion engine can be approximated with a polytropic process with a value of the polytropic exponent n somewhat larger than the specific heat ratio k. Repeat Problem 11.71 but assume that the expansion process is
In the Otto cycle all the heat transfer qH occurs at constant volume. It is more realistic to assume that part of qH occurs after the piston has started its downward motion in the expansion stroke. Therefore, consider a cycle identical to the Otto cycle, except that the first two-thirds of the
A diesel engine has a compression ratio of 20:1 with an inlet of 95 kPa, 290 K, state 1, with volume 0.5 L. The maximum cycle temperature is 1800 K. Find the maximum pressure, the net specific work and the thermal efficiency.
A diesel engine has a bore of 0.1 m, a stroke of 0.11 m and a compression ratio of 19:1 running at 2000 RPM (revolutions per minute). Each cycle takes two revolutions and has a mean effective pressure of 1400 kPa. With a total of 6 cylinders find the engine power in kW and horsepower, hp.
At the beginning of compression in a diesel cycle T = 300 K, P = 200 kPa and after combustion (heat addition) is complete T = 1500 K and P = 7.0 MPa. Find the compression ratio, the thermal efficiency and the mean effective pressure.
Consider an ideal air-standard diesel cycle in which the state before the compression process is 95 kPa, 290 K, and the compression ratio is 20. Find the maximum temperature (by iteration) in the cycle to have a thermal efficiency of 60%?
Consider an ideal Sterling-cycle engine in which the state at the beginning of the isothermal compression process is 100 kPa, 25°C the compression ratio is 6, and the maximum temperature in the cycle is 1100°C. Calculate the maximum cycle pressure and the thermal efficiency of the cycle with and
An air-standard Sterling cycle uses helium as the working fluid. The isothermal compression brings helium from 100 kPa, 37°C to 600 kPa. The expansion takes place at 1200 K and there is no regenerator. Find the work and heat transfer in all of the 4 processes per kg helium and the thermal cycle
Consider an ideal air-standard Sterling cycle with an ideal regenerator. The minimum pressure and temperature in the cycle are 100 kPa, 25°C, the compression ratio is 10, and the maximum temperature in the cycle is 1000°C. Analyze each of the four processes in this cycle for work and heat
The air-standard Carnot cycle was not shown in the text; show the T–s diagram for this cycle. In an air-standard Carnot cycle the low temperature is 280 K and the efficiency is 60%. If the pressure before compression and after heat rejection is 100 kPa, find the high temperature and the pressure
Air in a piston/cylinder goes through a Carnot cycle in which TL 26.8C and the total cycle efficiency is 2/3. Find TH, the specific work and volume ratio in the adiabatic expansion for constant Cp, Cv. Repeat the calculation for variable heat
Consider an ideal refrigeration cycle that has a condenser temperature of 45C and an evaporator temperature of 15C; determine the coefficient of performance of this refrigerator for the working fluids R-12 and R-22.
The environmentally safe refrigerant R-134a is one of the replacements for R-12 in refrigeration systems. Repeat Problem 11.87 using R-134a and compare the result with that for R-12.
A refrigerator using R-22 is powered by a small natural gas fired heat engine with a thermal efficiency of 25%. The R-22 condenses at 40C and it evaporates at-20C and the cycle is standard. Find the two specific heat transfers in the refrigeration cycle. What is the overall
A refrigerator with R-12 as the working fluid has a minimum temperature of 10C and a maximum pressure of 1 MPa. Assume an ideal refrigeration cycle as in Fig. 11.32. Find the specific heat transfer from the cold space and that to the hot space, and the coefficient of performance.
A refrigerator in a meat warehouse must keep a low temperature of -15C and the outside temperature is 20C. It uses R-12 as the refrigerant which must remove 5 kW from the cold space. Find the flow rate of the R-12 needed assuming a standard vapor compression refrigeration cycle with
A refrigerator with R-12 as the working fluid has a minimum temperature of 10C and a maximum pressure of 1 MPa. The actual adiabatic compressor exit temperature is 60C. Assume no pressure loss in the heat exchangers. Find the specific heat transfer from the cold space and
Consider an ideal heat pump that has a condenser temperature of 50C and an evaporator temperature of 0C, determine the coefficient of performance of this heat pump for the working fluids R-12, R-22, and ammonia.
The air conditioner in a car uses R-134a and the compressor power input is 1.5 kW bringing the R-134a from 201.7 kPa to 1200 kPa by compression. The cold space is a heat exchanger that cools atmospheric air from the outside down to 10C and blows it into the car. What is the mass flow rate
A refrigerator using R-134a is located in a 20C room. Consider the cycle to be ideal, except that the compressor is neither adiabatic nor reversible. Saturated vapor at -20C enters the compressor, and the R-134a exits the compressor at 50C. The condenser temperature is 40C. The mass flow rate of
A small heat pump unit is used to heat water for a hot-water supply. Assume that the unit uses R-22 and operates on the ideal refrigeration cycle. The evaporator temperature is 15C and the condenser temperature is 60C. If the amount of hot water needed is 0.1 kg/s, determine the
The refrigerant R-22 is used as the working fluid in a conventional heat pump cycle. Saturated vapor enters the compressor of this unit at 10C; its exit temperature from the compressor is measured and found to be 85C. If the isentropic efficiency of the compressor is estimated to be
In an actual refrigeration cycle using R-12 as the working fluid, the refrigerant flow rate is 0.05 kg/s. Vapor enters the compressor at 150 kPa, 10C, and leaves at 1.2 MPa, 75C. The power input to the compressor is measured and found be 2.4 kW. The refrigerant enters the
Consider a small ammonia absorption refrigeration cycle that is powered by solar energy and is to be used as an air conditioner. Saturated vapor ammonia leaves the generator at 50C, and saturated vapor leaves the evaporator at 10C. If 7000 kJ of heat is required in the generator
The performance of an ammonia absorption cycle refrigerator is to be compared with that of a similar vapor-compression system. Consider an absorption system having an evaporator temperature of 10C and a condenser temperature of 50C. The generator temperature in this system
A heat exchanger is incorporated into an ideal air-standard refrigeration cycle, as shown in Fig. P11.101. It may be assumed that both the compression and the expansion are reversible adiabatic processes in this ideal case. Determine the coefficient of performance for the cycle.
Repeat Problem 11.101, but assume an isentropic efficiency of 75% for both the compressor and the expander.
Repeat Problems 11.101 and 11.102, but assume that helium is the cycle working fluid instead of air. Discuss the significance of the results.
A binary system power plant uses mercury for the high-temperature cycle and water for the low-temperature cycle, as shown in Fig. 11.39. The temperatures and pressures are shown in the corresponding T–s diagram. The maximum temperature in the steam cycle is where the steam leaves the super heater
A Rankine steam power plant should operate with a high pressure of 3 MPa, a low pressure of 10 kPa, and the boiler exit temperature should be 500C. The available high-temperature source is the exhaust of 175 kg/s air at 600C from a gas turbine. If the boiler operates as a counter
A simple Rankine cycle with R-22 as the working fluid is to be used as a bottoming cycle for an electrical generating facility driven by the exhaust gas from a Diesel engine as the high temperature energy source in the R-22 boiler. Diesel inlet conditions are 100 kPa, 20C, the compression
For a cryogenic experiment heat should be removed from a space at 75 K to a reservoir at 180 K. A heat pump is designed to use nitrogen and methane in a cascade arrangement (see Fig. 11.41), where the high temperature of the nitrogen condensation is at 10 K higher than the low-temperature
A cascade system is composed of two ideal refrigeration cycles. The high-temperature cycle uses R-22. Saturated liquid leaves the condenser at 40C, and saturated vapor leaves the heat exchanger at 20C. The low-temperature cycle uses a different refrigerant, R-23 (Fig. G.3 or
Consider an ideal dual-loop heat-powered refrigeration cycle using R-12 as the working fluid, as shown in Fig. P11.109. Saturated vapor at 105°C leaves the boiler and expands in the turbine to the condenser pressure. Saturated vapor at - 15°C leaves the evaporator and is compressed to the
Find the availability of the water at all four states in the Rankine cycle described in Problem 11.12. Assume that the high-temperature source is 500C and the low temperature reservoir is at 25C. Determine the flow of availability in or out of the reservoirs per kilogram of steam
The effect of a number of open feedwater heaters on the thermal efficiency of an ideal cycle is to be studied. Steam leaves the steam generator at 20 MPa, 600C, and the cycle has a condenser pressure of 10 kPa. Determine the thermal efficiency for each of the following cases. A: No
Find the availability of the water at all the states in the steam power plant described in Problem 11.36. Assume the heat source in the boiler is at 600C and the low-temperature reservoir is at 25C. Give the second law efficiency of all the components.
The power plant shown in Fig. 11.40 combines a gas-turbine cycle and a steam turbine cycle. The following data are known for the gas-turbine cycle. Air enters the compressor at 100 kPa, 25C, the compressor pressure ratio is 14, and the isentropic compressor efficiency is 87%; the heater input rate
For Problem 11.105, determine the change of availability of the water flow and that of the air flow. Use these to determine a second law efficiency for the boiler heat exchanger.
One means of improving the performance of a refrigeration system that operates over a wide temperature range is to use a two-stage compressor. Consider an ideal refrigeration system of this type that uses R-12 as the working fluid, as shown in Fig. P11.115. Saturated liquid leaves the condenser at
A jet ejector, a device with no moving parts functions as the equivalent of a coupled turbine-compressor unit. Thus, the turbine compressor in the dual-loop cycle of could be replaced by a jet ejector. The primary stream of the jet ejector enters from the boiler, the secondary stream enters from
A steam power plant, as shown in Fig. 11.3, operating in a Rankine cycle has saturated vapor at 600 lbf/in 2 leaving the boiler. The turbine exhausts to the condenser operating at 2 lbf/in 2. Find the specific work and heat transfer in each of the ideal components and the cycle efficiency.
Consider a solar-energy-powered ideal Rankine cycle that uses water as the working fluid. Saturated vapor leaves the solar collector at 350 F, and the condenser pressure is 1 lbf/in.2. Determine the thermal efficiency of this cycle.
A supply of geothermal hot water is to be used as the energy source in an ideal Rankine cycle, with R-134a as the cycle working fluid. Saturated vapor R-134a leaves the boiler at a temperature of 180 F, and the condenser temperature is 100 F. Calculate the thermal efficiency of this cycle.
Do Problem 11.119 with R-22 as the working fluid.
The power plant is modified to have a superheated section following the boiler so the steam leaves the super heater at 600 lbf/in 2, 700 F. Find the specific work and heat transfer in each of the ideal components and the cycle efficiency.
Consider a simple ideal Rankine cycle using water at a supercritical pressure. Such a cycle has a potential advantage of minimizing local temperature differences between the fluids in the steam generator, such as the instance in which the high-temperature energy source is the hot exhaust gas from a
Consider an ideal steam reheat cycle in which the steam enters the high-pressure turbine at 600 lbf/in 2, 700 F, and then expands to 120 lbf/in.2. It is then reheated to 700 F and expands to 2 lbf/in 2 in the low-pressure turbine. Calculate the thermal efficiency of the cycle and the moisture
A closed feedwater heater in a regenerative steam power cycle heats 40 lbm/s of water from 200 F, 2000 lbf/in.2 to 450 F, 2000 lbf/in 2, the extraction steam from the turbine enters the heater at 500 lbf/in 2, 550 F and leaves as saturated liquid. What is the required mass flow rate of the
Consider an ideal steam regenerative cycle in which steam enters the turbine at 600 lbf/in 2, 700 F, and exhausts to the condenser at 2 lbf/in 2. Steam is extracted from the turbine at 120 lbf/in 2 for an open feedwater heater. The feedwater leaves the heater as saturated liquid. The appropriate
Consider an ideal combined reheat and regenerative cycle in which steam enters the high-pressure turbine at 500 lbf/in 2, 700 F, and is extracted to an open feedwater heater at 120 lbf/in.2 with exit as saturated liquid. The remainder of the steam is reheated to 700 F at this pressure, 120 lbf/in
A steam power cycle has a high pressure of 500 lbf/in 2 and a condenser exit temperature of 110 F. The turbine efficiency is 85%, and other cycle components are ideal. If the boiler superheats to 1400 F, find the cycle thermal efficiency.
The steam power cycle has an isentropic efficiency of the turbine of 85% and that for the pump it is 80%. Find the cycle efficiency and the specific work and heat transfer in the components.
Steam leaves a power plant steam generator at 500 lbf/in 2, 650 F, and enters the turbine at 490 lbf/in.2, 625 F. The isentropic turbine efficiency is 88%, and the turbine exhaust pressure is 1.7 lbf/in 2. Condensate leaves the condenser and enters the pump at 110 F, 1.7 lbf/in 2. The isentropic
In one type of nuclear power plant, heat is transferred in the nuclear reactor to liquid sodium. The liquid sodium is then pumped through a heat exchanger where heat is transferred to boiling water. Saturated vapor steam at 700 lbf/in.2 exits this heat exchanger and is then superheated to 1100 F in
A boiler delivers steam at 1500 lbf/in.2, 1000 F to a two-stage turbine. After the first stage, 25% of the steam is extracted at 200 lbf/in 2 for a process application and returned at 150 lbf/in 2, 190 F to the feedwater line, the remainder of the steam continues through the low-pressure turbine
A large stationary Brayton cycle gas-turbine power plant delivers a power output of 100000 hp to an electric generator. The minimum temperature in the cycle is 540 R, and the maximum temperature is 2900 R. The minimum pressure in the cycle is 1 atm, and the compressor pressure ratio is 14 to 1.
An ideal regenerator is incorporated into the ideal air-standard Brayton cycle of Problem 11.132. Calculate the cycle thermal efficiency with this modification.
Consider an ideal gas-turbine cycle with two stages of compression and two stages of expansion. The pressure ratio across each compressor stage and each turbine stage is 8 to 1. The pressure at the entrance to the first compressor is 14 lbf/in 2, the temperature entering each compressor is 70 F,
Repeat Problem 11.134, but assume that each compressor stage and each turbine stage has an isentropic efficiency of 85%. Also assume that the regenerator has an efficiency of 70%.
An air-standard Ericsson cycle has an ideal regenerator as shown in Fig. P11.62. Heat is supplied at 1800 F and heat is rejected at 68 F. Pressure at the beginning of the isothermal compression process is 10 lbf/in 2. The heat added is 275 Btu/lbm. Find the compressor work, the turbine work, and
The turbine in a jet engine receives air at 2200 R, 220 lbf/in 2. It exhausts to a nozzle at 35 lbf/in 2, which in turn exhausts to the atmosphere at 14.7 lbf/in 2. The isentropic efficiency of the turbine is 85% and the nozzle efficiency is 95%. Find the nozzle inlet temperature and the nozzle
Air flows into a gasoline engine at 14 lbf/in 2, 540 R. The air is then compressed with a volumetric compression ratio of 8; 1. In the combustion process 560 Btu/lbm of energy is released as the fuel burns. Find the temperature and pressure after combustion.
To approximate an actual spark-ignition engine consider an air-standard Otto cycle that has a heat addition of 800 Btu/lbm of air, a compression ratio of 7, and a pressure and temperature at the beginning of the compression process of 13 lbf/in 2, 50 F. Assuming constant specific heat, with the
In the Otto cycle all the heat transfer qH occurs at constant volume. It is more realistic to assume that part of qH occurs after the piston has started it’s downwards motion in the expansion stroke. Therefore consider a cycle identical to the Otto cycle, except that the first two-thirds of the
It is found experimentally that the power stroke expansion in an internal combustion engine can be approximated with a polytropic process with a value of the polytropic exponent n somewhat larger than the specific heat ratio k. Repeat Problem 11.139 but assume the expansion process is reversible
A diesel engine has a bore of 4 in., a stroke of 4.3 in. and a compression ratio of 19:1 running at 2000 RPM (revolutions per minute). Each cycle takes two revolutions and has a mean effective pressure of 200 lbf/in 2. With a total of 6 cylinders find the engine power in Btu/s and horsepower, hp.
At the beginning of compression in a diesel cycle T = 540 R, P = 30 lbf/in2 and the state after combustion (heat addition) is 2600 R and 1000 lbf/in 2. Find the compression ratio, the thermal efficiency and the mean effective pressure.
Consider an ideal air-standard diesel cycle where the state before the compression process is 14 lbf/in 2, 63 F and the compression ratio is 20. Find the maximum temperature (by iteration) in the cycle to have a thermal efficiency of 60%.
Showing 5500 - 5600
of 18200
First
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
Last
Step by Step Answers
Get 50% OFF
Claim Now
.PNG)
.PNG)
.PNG)
