EBK THERMODYNAMICS: AN ENGINEERING APPR
8th Edition
ISBN: 8220102809444
Author: CENGEL
Publisher: YUZU
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Chapter 10.9, Problem 112RP
Show that the thermal efficiency of a combined gas–steam power plant ηcc can be expressed as
where ηg = Wg /Qin and ηs = Ws/Qg,out are the thermal efficiencies of the gas and steam cycles, respectively. Using this relation, determine the thermal efficiency of a combined power cycle that consists of a topping gas-turbine cycle with an efficiency of 40 percent and a bottoming steam-turbine cycle with an efficiency of 30 percent.
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You are an operating engineer in a steam power plant which is working on a regenerative Rankine cycle and you are requested to find the thermal efficiency of this cycle. You read the following data from the measuring devices used in the power plant:
The pressure and temperature of the steam at the inlet of the turbine are 7000kPa and 550 °C, respectively.
The pressure at the inlet of the condenser is 22 kPa.
The extracted steam from the turbine is at 500 kPa and it is used to heat the
feed water in an open feed water heater.
The pumps and turbine efficiencies are 80% and 85%, respectively. Don't forget to show the evele on a T-s diagram.
A medium size power station is used to produce 30 MW net power for a refinery. The station uses steam as the operating fluid and operates according to the Carnot cycle between the pressure limits of 0.4 bar and 35 bar. Steam enters the boiler as a saturated liquid and leaves it as a dry saturated vapour.
(x) State the name of the cycle that is used in practice in power stations, along with three key benefits over the Carnot cycle.
A power cycle operates between two thermal reservoirs at 300 K and 800 K. The working fluid of the cycle is air, which can be considered to be an ideal gas. Specific heats are not assumed to be constant. An inventor claims that for a heat input of 250 kJ, the net work from the cycle is 80 kJ. The work generating component in the cycle is a reversible, steady state turbine. The inlet pressure and temperature are 1000 kPa and 600 K and the exit temperature is 550 K. The turbine receives 150 kJ/kg of heat from the high temperature reservoir and loses 10 kJ/kg of heat to the ambient at 298 K. (a) Prove whether or not the overall cycle is possible using second law arguments. (b) determine the work done by the turbine [kJ/kg]
Chapter 10 Solutions
EBK THERMODYNAMICS: AN ENGINEERING APPR
Ch. 10.9 - Why is the Carnot cycle not a realistic model for...Ch. 10.9 - Prob. 2PCh. 10.9 - A steady-flow Carnot cycle uses water as the...Ch. 10.9 - A steady-flow Carnot cycle uses water as the...Ch. 10.9 - Consider a steady-flow Carnot cycle with water as...Ch. 10.9 - Consider a simple ideal Rankine cycle with fixed...Ch. 10.9 - Consider a simple ideal Rankine cycle with fixed...Ch. 10.9 - Consider a simple ideal Rankine cycle with fixed...Ch. 10.9 - How do actual vapor power cycles differ from...Ch. 10.9 - The entropy of steam increases in actual steam...
Ch. 10.9 - Is it possible to maintain a pressure of 10 kPa in...Ch. 10.9 - 10–12 A steam power plant operates on a simple...Ch. 10.9 - 10–13 Refrigerant-134a is used as the working...Ch. 10.9 - 10–14 A simple ideal Rankine cycle which uses...Ch. 10.9 - 10–15E A simple ideal Rankine cycle with water as...Ch. 10.9 - Consider a 210-MW steam power plant that operates...Ch. 10.9 - Consider a 210-MW steam power plant that operates...Ch. 10.9 - A steam Rankine cycle operates between the...Ch. 10.9 - A steam Rankine cycle operates between the...Ch. 10.9 - Prob. 20PCh. 10.9 - Prob. 21PCh. 10.9 - A simple Rankine cycle uses water as the working...Ch. 10.9 - The net work output and the thermal efficiency for...Ch. 10.9 - A binary geothermal power plant uses geothermal...Ch. 10.9 - Consider a coal-fired steam power plant that...Ch. 10.9 - Show the ideal Rankine cycle with three stages of...Ch. 10.9 - How do the following quantities change when a...Ch. 10.9 - Consider a simple ideal Rankine cycle and an ideal...Ch. 10.9 - An ideal reheat Rankine cycle with water as the...Ch. 10.9 - 10–31 A steam power plant operates on the ideal...Ch. 10.9 - Steam enters the high-pressure turbine of a steam...Ch. 10.9 - 10–34 Consider a steam power plant that operates...Ch. 10.9 - A steam power plant operates on an ideal reheat...Ch. 10.9 - Consider a steam power plant that operates on a...Ch. 10.9 - Repeat Prob. 1041 assuming both the pump and the...Ch. 10.9 - Prob. 39PCh. 10.9 - How do open feedwater heaters differ from closed...Ch. 10.9 - How do the following quantities change when the...Ch. 10.9 - Prob. 43PCh. 10.9 - 10–44 The closed feedwater heater of a...Ch. 10.9 - A steam power plant operates on an ideal...Ch. 10.9 - A steam power plant operates on an ideal...Ch. 10.9 - 10–47 A steam power plant operates on an ideal...Ch. 10.9 - Consider a steam power plant that operates on the...Ch. 10.9 - Consider a steam power plant that operates on the...Ch. 10.9 - Consider a steam power plant that operates on the...Ch. 10.9 - Consider an ideal steam regenerative Rankine cycle...Ch. 10.9 - A steam power plant operates on an ideal...Ch. 10.9 - Repeat Prob. 1060, but replace the open feedwater...Ch. 10.9 - 10–57 An ideal Rankine steam cycle modified with...Ch. 10.9 - Prob. 58PCh. 10.9 - Prob. 59PCh. 10.9 - Prob. 60PCh. 10.9 - Consider a steam power plant that operates on a...Ch. 10.9 - Prob. 63PCh. 10.9 - Prob. 64PCh. 10.9 - The schematic of a single-flash geothermal power...Ch. 10.9 - Prob. 66PCh. 10.9 - Prob. 67PCh. 10.9 - Consider a cogeneration plant for which the...Ch. 10.9 - Prob. 69PCh. 10.9 - A large food-processing plant requires 1.5 lbm/s...Ch. 10.9 - Steam is generated in the boiler of a cogeneration...Ch. 10.9 - Consider a cogeneration power plant modified with...Ch. 10.9 - Steam is generated in the boiler of a cogeneration...Ch. 10.9 - Prob. 75PCh. 10.9 - Why is the combined gassteam cycle more efficient...Ch. 10.9 - The gas-turbine portion of a combined gassteam...Ch. 10.9 - Prob. 78PCh. 10.9 - Prob. 80PCh. 10.9 - Consider a combined gassteam power plant that has...Ch. 10.9 - Why is steam not an ideal working fluid for vapor...Ch. 10.9 - Prob. 86PCh. 10.9 - What is the difference between the binary vapor...Ch. 10.9 - Why is mercury a suitable working fluid for the...Ch. 10.9 - By writing an energy balance on the heat exchanger...Ch. 10.9 - Steam enters the turbine of a steam power plant...Ch. 10.9 - Prob. 91RPCh. 10.9 - A steam power plant operates on an ideal Rankine...Ch. 10.9 - Consider a steam power plant operating on the...Ch. 10.9 - Consider a steam power plant that operates on a...Ch. 10.9 - Repeat Prob. 1098 assuming both the pump and the...Ch. 10.9 - Consider an ideal reheatregenerative Rankine cycle...Ch. 10.9 - Prob. 97RPCh. 10.9 - Prob. 98RPCh. 10.9 - A textile plant requires 4 kg/s of saturated steam...Ch. 10.9 - Consider a cogeneration power plant that is...Ch. 10.9 - Prob. 101RPCh. 10.9 - Reconsider Prob. 10105E. It has been suggested...Ch. 10.9 - Reconsider Prob. 10106E. During winter, the system...Ch. 10.9 - Prob. 104RPCh. 10.9 - Prob. 105RPCh. 10.9 - Prob. 106RPCh. 10.9 - A steam power plant operates on an ideal...Ch. 10.9 - Show that the thermal efficiency of a combined...Ch. 10.9 - Prob. 113RPCh. 10.9 - Starting with Eq. 1020, show that the exergy...Ch. 10.9 - A solar collector system delivers heat to a power...Ch. 10.9 - Consider a simple ideal Rankine cycle. If the...Ch. 10.9 - Consider a simple ideal Rankine cycle with fixed...Ch. 10.9 - Consider a simple ideal Rankine cycle with fixed...Ch. 10.9 - Consider a simple ideal Rankine cycle with fixed...Ch. 10.9 - Prob. 120FEPCh. 10.9 - A simple ideal Rankine cycle operates between the...Ch. 10.9 - Prob. 122FEPCh. 10.9 - Prob. 123FEPCh. 10.9 - Consider a combined gas-steam power plant. Water...Ch. 10.9 - Pressurized feedwater in a steam power plant is to...Ch. 10.9 - Consider a steam power plant that operates on the...
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