Combined gasvapor power cycles the continued quest for higher thermal efficiencies has resulted in rather innovative modifications to conventional power plants. Let us examine the pressurevolume behavior of a liquidvapor system at constant temperature. Four different types of gas power cycles are commonly used. A gas turbine expands gas from 1 mpa pressure and 600oc to 100 kpa pressure. The power required to pump the water is much less than that required to compress the vapour if it was possible. Take a childs water pistol with a large reservoir into class together with a bucket and an electric kettle. Thermodynamic cycles can also be categorized as gas cycles or vapor cycles, depending on the phase of the working fluidthe substance that circulates through the cyclic device. Ideal working fluid in vapour power cycles mcqs with answe. Operating principles vapor power plants the ideal rankine vapor power cycle efficiency improved efficiency superheat 12312016 jhangirabad institute of technology 2 3. In the compression process the energy used to compress the vapour turns into heat and increases its temperature and enthalpy, so that at the end of compression the vapour. B power cycles with twophase media vapor power cycles.
Mcqs with answers on simple steam power cycle, rankine cycle, comparison of rankine and carnot cycles, reheat cycle, feedwater heater, ideal working fluid in vapour power cycles, steam power plant, gas power cycle, air standard cycle etc. Compression cycle an overview sciencedirect topics. Power plant analysis vapour cycles uni study guides. Combustion in a diesel engine takes place at a much slower rate than it does in a spark. In vapour power cycle, the working fluid exists in vapor phase during one part of the cycle and in liquid phase during another part whereas in a gas power cycle, the working fluid remains in the gaseous phase. In state a the gas is temperature th and the cylinder is fully insulated. Calculate the exit temperature and the power output. The power to weight ratios are generally high for high throughout gas turbine power plants and hence are favoured for the aviation and also for power generation.
These idealized cycles serve as starting point for more indepth studies. A common exam question which is a culmination of the material covered in the course is an analysis of the efficiency of the steam power plant, which is a form of vapour cycle. Due to its use as working substance in vapour power cycle. The combined cycle of greatest interest is the gasturbine brayton cycle topping a steam turbine rankine cycle. Thermal power plants where chemical energy of a fossil fuel coal, oil, gas is released into heat by combustion to raise steam. Vapor power cycle gas turbine cycles typically operate at considerably higher temperatures than steam cycles. Solve problems based on the otto, diesel, stirling, and ericsson cycles. The purpose of a refrigerator is the removal of heat, called the cooling load, from a lowtemperature medium. However, the ideal closed vapor power cycle and ideal open gas cycles look remarkably similar when plotted on a temperatureentropy ts diagram with the. The simple vapour compression cycle is superimposed on the ph diagram in fig. Chapter 9 gas power cycles universiti tenaga nasional.
Rankine cycle in hindivapour power cycle 1 youtube. The power input to the feed pump is very small compared to the power output of the turbine and you can often neglect it altogether. If the windows in the room open, then perhaps you can fire the water pistol out of the window, otherwise use the bucket. Many of the impracticalities associated with the carnot cycle can be eliminated by superheating the steam in the boiler and condensing it completely in the condenser. The power cycle, that is a combination of two cycles, one in the high temperature area and the other in the low temperature area, termed as. The above figure shows the objectives of refrigerators and heat pumps. Two primary classes of thermodynamic cycles are power cycles and heat pump cycles. In the thermodynamic analysis of power cycles, our chief interest lies in estimating the energy conversion efficiency or the thermal efficiency. Thermodynamics vapor power cycle the carnot vapour cycle.
Power cycles most power producing devices operate on cycles. The two cycles on which most power generation plants are based are the joulebrayton cycle for gas power plants and the rankine cycle for vapour power plants. The joulebrayton cycle in its basic reversible form, with a perfect gas as the working fluid, is readily amen able to analysis, and even with allowance for irrevers. It does not involve and internal ireversibilites and consists of the following four processes. Air continuously circulates in a closed loop and behaves as an ideal gas all the processes are internally reversible combustion is replaced by a heat addition process from the outside heat rejection replaces the exhaust process also assume a constant value for c. In vapour power cycle, there will be a phase change of the fluid. In vapour cycles the ideal gas laws do not apply because the fluid tends to change phase during the various processes which comprise the cycle such that it is not always. Among these, we discuss the reheat and regen investigate ways to modify the basic rankine vapor power erative cycles, as well as combined gas.
Gas power cycle the devices or systems used to produce a net power output are often called engines, and the thermodynamic cycles they operate on are called power cycles. We often study the ideal cycle in which internal irreversibilities and complexities the actual intake of air and fuel, the actual combustion process. How to download r k rajput engineering thermodynamics pdf. In chapters 15 and 16 we attempt to apply the fundamental work of previous chapters to vapour and gas power cycles respectively. Ppt vapour compression cycle powerpoint presentation free. Power cycles are cycles which convert some heat input into a mechanical work output, while heat pump cycles transfer heat from low to high temperatures by using mechanical work as the input. In these two chapters, we will study types of thermodynamic cycles in more detail. Thermodynamic power cycles are the basis for the operation of heat engines, which supply most of the worlds electric power and run the vast majority of motor vehicles.
This chapter and the following one break from this trend. We will use the first and second laws of thermodynamics to analyze the performance of ower and refrigeration cycles. The power cycles are accordingly classified into two groups as. The rankine cycle is the ideal cycle for vapor power plants. May 05, 2020 vapour power cycle rankine cycles power plant engineering, gate mechanical engineering notes edurev is made by best teachers of mechanical engineering. Additionally, when condensed it is easy to handle it in liquid form.
If you are not ignoring the power input, then you need to find h1. Pdf chapter 10 vapor and combined power cycles ruben. The combined cycle of greatest interest is the gasturbine brayton cycle topping a. The nature of the working fluids can be classified into two groups. Mar 01, 2017 gas power cycle the devices or systems used to produce a net power output are often called engines, and the thermodynamic cycles they operate on are called power cycles. Vapor power cycle gasturbine cycles typically operate at considerably higher temperatures than steam cycles.
Binary vapor cycle, vapor power cycles, assignment help. The project on development of remaining three quadrants to nptel phasei under grant in aid nmeict, mhrd, new delhi. It was also used to study the performance of reciprocating steam engines. Rankine cycle efficiency of a good steam power plant may be in the range of a 15 to 20% b 35 to 45% c 70 to 80%. A popular modification involves a gas power cycle topping a vapor power cycle, which is called the combined gasvapor cycle, or just the combined cycle. Steam is the most common working fluid used in vapor power cycles because of its many desirable characteristics, such as low cost, availability, and high enthalpy of vaporization. Refrigeration cycles the vapor compression refrigeration cycle is a common method for transferring heat from a low temperature to a high temperature. The vapour compression cycle is used for refrigeration in preference to gas cycles. Take cv 718 jkg k and cp 1005 jkg k solution the process is adiabatic so the ideal temperature t2 is given by t2t1rp 11. Thermodynamics vapor power cycle the carnot vapour. Evaluate the performance of gas power cycles for which the working fluid remains a gas throughout the entire cycle. In this chapter, various gas power cycles are analyzed under some. Power cycles otto cycle spark ignition diesel cycle brayton cycle gas turbine rankinecycle.
A simple gt power plant is shown in the image below. Combined gasvapour power cycle t214 heat exchanger hrsg. Develop simplifying assumptions applicable to gas power cycles. Heat engines are designed to convert thermal energy to work. Operating principles vapor power plants the ideal rankine vapor power cycle efficiency improved efficiency superheat 12312016 jhangirabad institute of technology 2.
This document is highly rated by mechanical engineering students and has been viewed 28 times. The cycle that results is the rankine cycle, which is the ideal cycle for vapor power plants. The steam cycle is a practical one, it is the basis of virtually all steam power plants and hence electricity generation. Feb 10, 2012 1steam superheated has all properties of a gas with reference to heat transfer. A steam turbine is a prime mover in which potential energy is converted into kinetic energy and then to mechanical energy. To acquire the high thermal efficiency of the power plant, by employing two functioning fluids like water and mercury, the binary vapor cycle has been build up. The power cycles are categorised as vapor power cycle and gas power cycle, depending upon the working fluids used in the cycle. Combined gasvapor power cycles a more popular modification involves a gas power cycle topping a vapor power cycle, which is called the combined gasvapor cycle, or just the combined cycle. The rankine cycle is an idealized thermodynamic cycle of a heat engine that converts heat into mechanical work while undergoing phase change.
Watersteam is easily available, is cheap, is chemically stable and physiologically harmless. A gas power cycle may consist of heat transfer, work transfer, pressure variations, temperature variations, volume variations and entropy variations. Up to this point in the course, each chapter has brought a variety of new concepts and techniques for you to master. In a gas power cycle, the source of heat supply and the sink for heat rejection are considered to be external to the working fluid. Difference between gas and steam power cycle crazyengineers. We often study the ideal cycle in which internal irreversibilities and complexities the. Pdf vapor or rankine power cycles are by far the most common. Vapour power cycles are external combustion systems in which the working fluid is alternately vapourised and condensed. The main difficulties of the carnot cycle are overcome by complete condensation in the condenser and by superheating optional. Gas power cycles our study of gas power cycles will involve the study of those heat engines in which the working fluid remains in the gaseous state throughout the cycle.
Introduction to gas power cycles video lecture of gas power cycles chapter from thermodynamics subject for mechanical engineering students. Gas power cycles energy, entropy and engines wiley online. Gas power cycles energy, entropy and engines wiley. In gas cycles, the working fluid remains in the gaseous phase throughout the entire cycle, whereas in vapor cycles the working fluid exists in the vapor phase during one. Jan 11, 2017 introduction to gas power cycles video lecture of gas power cycles chapter from thermodynamics subject for mechanical engineering students. The engines which are operating on gas power cycle are a. Thermodynamic cycles can also be categorized as gas cycles and vapour cycles, depending on the phase of the working fluid. Ideal for students and professionals of mechanical engineering preparing for semester exams, gate, psus, netsetjrf and other entrance exams. Naphis ahmad assistant professor jit, barabanki 12312016 jhangirabad institute of technology 1 2. The ideal cycle for vapour power cycles the rankine cycle is the ideal cycle to represent the vapour power plants. Ppt vapour compression cycle powerpoint presentation.
In gas cycles, the working fluid remains in the gaseous phase throughout the entire cycle, where as in vapor cycles the working fluid exists in the vapor phase during one part of the cycle and in. The evaporation process or vaporisation of refrigerant is a constant pressure process and therefore it is represented by a horizontal line. The rankine cycle is a model used to predict the performance of steam turbine systems. At the same time boil the kettle and produce clouds of. What is the difference between vapour power cycle and gas. Cycles composed entirely of quasistatic processes can operate as power or heat pump cycles by controlling. The model cycle for vapor power cycles is the rankine cycle which is composed of four internally reversible processes. The maximum fluid temperature at the turbine inlet is about 620c for modern steam power plants, but over 1425c for gasturbine power plants. May 08, 2009 the ideal cycle for vapour power cycles the rankine cycle is the ideal cycle to represent the vapour power plants. For a singlephase perfect gas we know that the curve would be pv. Rankine cycle efficiency of a good steam power plant may be in the range of a 15 to 20% b 35 to 45% c 70 to 80% d 90 to 95%.
Oct 30, 2017 this is our first lecture of vapour power cycle. Ch 9, lesson a, page 1 introduction to vapor and gas power cycles. It is an idealized cycle in which friction losses in each of the four components are neglected. Rankine cycle operating on low pressure limit of p1 and high pressure limit of p 2. In this video we will discuss about different steam power plant components and also about rankine cycle.
Gas turbine power plants are lighter and compact when compared to power plants running on vapour cycles. It is over 1500c at the burner exit of turbojet engines. Solve problems based on the otto, diesel, stirling. Sometimes it will be in liquid phase, sometimes in vapour phase or sometimes in both phase while in gas power cycle, there will be no phase change in the cycle.
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