Chapter 1INTRODUCTION

A gas turbine is a rotary machine. It consists of three main components a compressor, a combustion chamber and a turbine. The air after being compressed into the compressor is heated either by directly burning fuel in it or by burning fuel externally in a heat exchanger. The heated air with or without products of combustion is expanded in a turbine resulting in work output, a substantial part, about two-thirds, of which is used to drive the compressor. Rest, about one-third, is available as useful work output.1.1 Development of Gas TurbineThe concept of turbine prime mover can be traced back to Hero of Alexandria who lived about 2000 years ago. John Barber, an Englishman, was first to develop an important design in 1871. The design used an impulse turbine, a reciprocating compressor, a gas producer and a combustion chamber with injection. Prof. Dr. R. Stodola, the world famous teacher at the Swiss Federal Institute of Technology (from 1892 to 1929) who established the scientific and engineering basis for the steam turbine and predicted a bright future for the gas turbine at a very early date.The development of gas turbines was hampered for a long time despite this general theory because of two basic reasons:-i. The lack of materials to withstand high temperatures.ii. The lack of thermodynamic and aerodynamic knowledge of flow mechanism.1.2 Classifications of Gas TurbineGas turbines are classified into two main types:1. Open cycle gas turbine2. Closed cycle gas turbineIn an open cycle gas turbine [see Fig 1.2 (a)] air is taken from the atmosphere in the compressor, and after compression its temperature is raised by burning fuel in it. The products of combustion along with the excess air are passed through the turbine, developing power and then exhausted into the atmosphere. For next cycle fresh air is taken in the compressor.In a closed cycle gas turbine [see Fig 1.2 (b)] air is heated in an air heater by burning fuel externally. The working air does not come in contact with the products of combustion. The hot air expands in the turbine and then cooled in a precooler and supplied back to the compressor. The same working fluid circulates over and again in the system.

Fig 1.2 (a) Schematic diagram of open cycle gas turbine

Fig 1.2 (b) Schematic diagram of closed cycle gas turbine1.3 Advantages of Gas turbine1. A gas turbine being a rotary machine has a simple mechanism and higher operational speed. Due to absence of reciprocating parts such as connecting rod and piston etc., the vibrations are virtually absent resulting in better and easy balancing. 2. Because of less number of parts gas turbine is easier to maintain.3. Capacity of gas turbine seems to be unlimited since the gas turbine still has immense development possibilities.4. The lubricating oil consumption is small. The cost of lubricating oil in gas turbine is about 0.5 to 1 % of the total fuel cost.5. It is simpler to control the gas turbine.6. Gas turbine especially the closed cycle gas turbine can burn almost any fuel ranging from kerosene to heavy oil and even coal slurry. This results in a great economic advantage. 7. In addition to reduced fuel costs, turbine fuels are less volatile, so fire hazards are reduced. The gas turbine can be used where low quality cheap fuel is available.8. Gas turbine is a comparatively rugged machine which can be left uncared for a long period.1.4 Disadvantages of Gas turbine1. The maximum efficiency of simple gas turbine is lower. To obtain higher efficiencies gas turbine should be provided with regenerator, reheater etc., which increases the complexity and cost.2. The part load efficiency of gas turbine is poor. 3. The gas turbine is not a self starting unit. The power required to start is also quite high, so an additional motor of high power is necessary.4. The cost of manufacture of a gas turbine plant, at present, is higher due to the use of high heat resistant materials and special manufacturing processes used for blades.5. The gas turbine is slow in its acceleration response. This is a big disadvantage for automotive use.6. Gas turbines run at comparatively higher speeds and require a reduction gear to be used for normal industrial applications.7. The gas turbine is sensitive to component efficiencies. Any reduction in compressor or turbine efficiency will greatly affect the overall efficiency of the plant so, it require highly matched turbine and compressor combination.1.5 Applications of Gas turbineThe applications of gas turbine can be divided into three broad categories:1. Industrial2. Power generation3. Propulsion1.5.1 Industrial Gas Turbine Since the gas turbine has many qualities which an industry prime mover must have, its use has spread over a wide range of industrial applications ranging from petro-chemical, thermal-process industries to general utility industries. The lower man power requirements and the excellent reliability of up to 99% along with its basic simplicity has made the industrial gas turbine very much popular.For the industrial gas turbine, selection for a particular application depends on long life, availability, thermal efficiency, pressure losses and other parameters of importance for the industry are considered. Generally, the industrial turbine is a continuous duty unit with large power requirements and long life. The following is the brief discussion of some of the many industrial applications of the gas turbine a) Thermal process industries: For industries which have large mechanical and thermal energy requirements, the industrial gas turbines are ideally suited. Examples of such industries are cement, lime, and light weight aggregate manufacturing unit. The turbine can supply the power needed while the exhaust gases which contain a large amount of heat can be used to raise steam for thermal processing.b) Petro-chemical Industries: These industries are unique in that they simultaneously need compressed air, hot gases and mechanical power in various combinations. The gas turbine provides a heat balance for these requirements which is much superior than all other prime movers. A simple gas turbine plant can produce power supply, compressed air, and the hot gases or steam simultaneously. In addition to this the gas turbine can be used to drive a large number of generators, compressors and pumps etc.c) Gas compression and processing: Gas compression and processing of the natural gas from gas generation site to users requires the use of high speed centrifugal compressors. This is because of the small space requirements, less maintenance and less pipe vibrations and pulsations due to the smooth discharge of gases from a rotary compressor. The gas turbine is ideally suited for such applications because it altogether avoids the use of a costly reduction gear and its mechanically troubles.1.5.2 Power generationThe rapid development in the gas turbine field has established gas turbine use in power generation. It is now widely used for base load, peaking and standby operation. Due to its ability to start from cold and carry the full load in less than two minutes, it is especially suited for the peaking and standby purposes.The gas turbine as a part of the combined high efficiency cycle is now widely used as a base load prime mover. During the last decade the electric utility industry has experienced a tremendous and continuing load growth. The short supply time, cheap fuel and higher availability were the main reasons for the use of gas turbines in mainly peaking and standby load applications.1.5.3 PropulsionOf the three modes of transport namely, air, land and water, the gas turbines have enjoyed phenomenal success for the first, and attracted by this success it has been applied to the other two fields also. The use of gas turbine for the aircraft field hardly needs any stress. It is only because of the development in the gas turbine technology that the present aviation progress has been possible. Turbojet, turboprop, by-pass engine and even the helicopters are the examples of successful application of the gas turbine in aviation field.The great success in the aviation field attracted use of gas turbine in automobiles and now a large number of automobile models have come up in the power range of 140h.p. to 300h.p.

Chapter 2LITERATURE REVIEWS

In order to have an idea of present technological development in the area of gas turbine, its performance improvement and analysis, a brief survey of available literature is made.2.1 Review of LiteratureAndreas Poullikkas et al. [1] in his work gave an overview of current and future sustainable gas turbine technologies. In his research work, the various gas turbine technologies are described and compared. Emphasis has been given to the various advance cycles involving heat recovery from the gas turbine exhaust, such as, the gas to gas regeneration cycle and the combination cycle. The thermodynamic characteristics of various cycles are considered in order to establish their relative importance to future power generation markets.Lingen Chen et al. [2] studied performance, analysis and optimization of an open cycle regenerator gas turbine power plant. The analytical formulae about the relation between power output and cycle over-all pressure ratio are derived taking into account the pressure drop losses. Also, it was shown that the power output has a maximum with respect to the full flow rate or any of the overall pressure drops and the maximized power output had an additional maximized with respect to over-all pressure ratio.Valceres V. R. Silva et al. [3] states that the performance improvement of a gas turbine can be expressed in terms of minimizing fuel consumption while maintaining nominal thrust output, maximizing thrust for same fuel consumption and minimum turbine blade temperature. Additional control layers are used to improve engine performance.H. Cohen and G. F. C. Rogers [4] had given the survey for the gas turbine cycles configuration and study of various possible gas turbine configuration, detailed account of various aspects of axial flow turbines such as basic principle, combustion process, work output and factors upon which it depends. Y. Tsujikawa et al. [5] devoted his study to the analyses of simple gas turbine cycle, particularly for various gas turbine engines to achieve maximum performance.Mallinson et al. [6] investigated the part load performance of various gas turbine cycles.D. S. Kumar, V. P. Vasandani and J. H. Horlock [7] gave evaluation and method of accounting component losses and information about temperature entropy diagram.

Chapter 3SYSTEM APPROACH

3.1 Simple Open Cycle Gas TurbineThe Brayton or Joule cycle is the most idealized cycle for the simple gas turbine power plant [see Fig (3.1)]

Fig. 3.1 Schematic diagram of Brayton or Joule CycleAtmospheric or fresh air is compressed from p1 to a high pressure p2 in the compressor and delivered to the combustion chamber where fuel is injected and burned. The combustion process occurs nearly at constant pressure. Due to combustion heat is added to the working fluid in combustor from T2 to T3. The products of combustion from the combustion chamber are expanded in the turbine from p2 to atmospheric pressure p1 and then discharged into the atmosphere as exhaust gases.The turbine and the compressor are mechanically coupled, so the network is equal to the difference between the work done by turbine and work consumed by the compressor. To first run the compressor, a starter is needed. When the turbine starts running, the starter is cut-off.3.2 Analysis of Simple Open Cycle Gas TurbineFig 3.2 shows the simple gas turbine cycle on p-v and t-s diagrams.

Fig 3.2 p-v and T-s plots of simple gas turbine cycle wherep = pressurev = volumeT = temperatures = specific entropy1-2,-3-4, represents Ideal Cycle plot 1-2-3-4 represents Actual Cycle plotThe air is compressed from 1 to 2 in a compressor and heat is added to this air during the process 2 to 3 which takes place in the combustion chamber. Process 3 to 4 represents the expansion of gases in a turbine. In the ideal cycle, processes of compression (1-2) and expansion (3-4) are assumed as isentropic and processes of heat addition (2-3) and heat rejection (4-1) are assumed as constant pressure processes.The actual performance of the gas turbine plant differs from the brayton cycle because of the deviations from the ideal cycle. These deviations include friction, shock, heat transfer and aerodynamic losses in compressor and turbine, losses in combustion chamber, piping and mechanical losses etc. with such a large number of variables affecting the performance of the gas turbine plant it will be really difficult to estimate its performance unless certain assumptions are made. To simplify the analysis following assumptions are made:1. There is no pressure loss in the combustion chamber and in piping etc.2. There is no increase in the rate of mass flow due to the addition of the fuel.3. The specific heat remains constant at all temperatures and is same for compressor as well as turbine flow.4. Radiations and mechanical losses are neglected.Assuming a flow of 1kg of air the following analysis is made: EfficiencyEfficiency of the cycle = Work required for compressor, Wc = h2 h1 = Cp (T2 T1) Heat supplied in combustion chamber qA = h3 h2 = Cp (T3 T2) Here, Cp is assumed constantWork delivered by turbine Wt = h3 h4 = Cp (T3 T4)Therefore, Thermal efficiency = = = = (Eq. 3.1)= (Eq. 3.2)The isentropic efficiency of turbine and the compressor are defined as;Isentropic efficiency of turbine, t = = (Eq. 3.2 a)ort = = (Eq. 3.2 b)=

Now, Isentropic efficiency of compressor, c= (Eq. 3.3 a)orc = (Eq. 3.3 b)= From (Eq. 3.2 b) we have,T4 = T3 (T3 T4,) t t [ since Assuming equal pressure ratio for compressor and turbine, we haveSimilarly, from (Eq. 3.3 b) we getPutting the values of and in (Eq. 3.2) we get = = where, R = = = or = (Eq. 3.4)For an ideal cycle; = Therefore, = = = (Eq. 3.5)Thus, it is evident that the ideal air standard efficiency is independent of turbine inlet temperature and depends only on pressure ratio and the value of the ratio of the specific heats. However, in an actual cycle, with irreversibilities in the compression and expansion processes, the thermal efficiency depends both upon the pressure ratio as well as turbine inlet temperature, besides being affected by compressor and turbine efficiencies. Work RatioThe work done is represented by the work ratio which is defined as the ratio of the net work output to that of the work done by the turbine. Work Ratio = = = = = Work ratio = (Eq. 3.6)The net work output,W = = = ](Eq. 3.7)Thus, the work output of a simple cycle depends on turbine and compressor inlet temperatures and pressure ratio.For ideal simple cycle gas turbine plant (Eq. 3.6)Work Ratioideal = (Eq. 3.8)and Net work outputideal = (Eq. 3.9)We see that the work specific output (defined as the work done per kg of the working medium) the cycle, efficiency and air rate (defined as the air flow per unit output) are the three parameters which decide the size of given machine. Higher the cycle efficiency and higher the air rate, lower is the machine size.

Chapter 4EXPERIMENTAL SETUP AND MODELLING

4.1 Effect of thermodynamic variables on the performance of simple gas turbine From Eq. 3.4 it can be seen that under the assumptions made above there are five main thermodynamic variables affecting the performance of a simple gas turbine plant. These are compressor and turbine inlet temperatures, T1 and T2, the pressure ratio, , and compressor and turbine efficiencies . 4.1.1 Effect of Turbine Inlet TemperatureThe ideal air standard efficiency of a simple gas turbine plant is independent of turbine inlet temperature. From (Eq. 3.4) we can say that, the turbine inlet temperature greatly affects the efficiency of an actual plant. An increase in temperature T3 increases the work output from the turbine which tends to increase the thermal efficiency at a given pressure ratio but at the same time the heat supplied in the combustion chamber increases which decrease the efficiency. The rate of increase in the turbine work is greater than the rate of increase in heat added and hence for all pressure ratios increasing the turbine inlet temperature increases the cycle efficiency at a steady but decreasing rate.4.1.2 Effect of Compressor Inlet TemperatureFor a given peak temperature the effect of compressor inlet temperature is two fold. An increase in T1 increases the work input to the compressor, thereby, reducing thermal efficiency, but at the same time temperature T2 is increased and the heat supplied for obtaining a given value of T3 reduces which tends to increase the efficiency. The work output of turbine is not affected by T1. Since the rate of increase of compressor work is greater than the rate of reduction in heat supply, net effect of increasing T1 is a decrease in efficiency of the simple gas turbine plant. The net work output decreases with an increase in T1. A reduction in T1 increases the shaft output as well as efficiency. 4.1.3 Effect of Pressure RatioHigher pressure ratio cycles are more sensitive to the efficiency of the compressors and turbines. As the pressure ratio increases the work done in turbine increases and less heat is rejected to the atmosphere, so the efficiency and work done both increases. But beyond a certain value of pressure ratio the efficiency of compression reduces, more compression work is required and compressor outlet temperature increases. The optimum pressure ratio can be calculated for a given value of compressor and turbine efficiencies and turbine inlet temperature with the help of (Eq. 3.9).For an ideal cycle, with isentropic compression and expansion the work output is given by:W = (Eq. 3.9)Differentiating above equation with respect to R assuming T3 and T1 to be constant, we get R = = (Eq. 3.10)or rp = = The optimum pressure ratio for maximum work output can be obtained by differentiating (Eq. 3.7) and equating it to zero.R = ) = (Eq. 3.11) The above equation denotes the optimum pressure ratio for maximum work output.4.1.4 Effect of Turbine and Compressor EfficienciesFrom (Eq. 3.4) it is evident that the cycle efficiency greatly depends on the efficiencies of the turbine and the compressor. For a given value of turbine and compressor inlet temperatures the efficiency of a simple cycle is linearly proportional to the turbine efficiency. The effect of compressor efficiency is not linearly related in that it affects the heat supplied as well as the work output. A decrease in the compressor efficiency decreases the heat supplied but this decrease in heat supplied is more than offset by the increase in compressor work. A change of 1% in the efficiencies of compressor and turbine can result in 3 to 5% change in cycle efficiency. Usually the turbine has a higher efficiency than the compressor and the turbine develops much more power than the compressor consumes ( the net output is the difference between the turbine and compressor work), a loss in turbine efficiency reduces the cycle efficiency by a larger amount than would be the case if compressor efficiency is reduced by the same amount.4.2 Performance Evaluation and Improvement in Simple Gas TurbineThe efficiency and the specific work output of the simple gas turbine cycle is quite low inspite of increased component efficiencies. Therefore, certain modifications in the simple gas turbine are necessary, and for that we can look towards three main processes regeneration, intercooling and reheating4.2.1 Regenerative Gas Turbine CycleOne of the main reasons for the low efficiency of a simple gas turbine plant is the large amount of heat which is rejected in the turbine exhaust. Due to limitations of maximum turbine inlet temperature and the pressure ratio which may be used with it, the turbine exhaust temperature is always greater than the temperature at the outlet of compressor. So, if this temperature difference is used to increase the temperature of the compressed air before entering the combustion chamber and, thereby, reducing the heat which must be supplied in the combustion chamber for a given turbine inlet temperature, an improvement in efficiency can be attained. This utilization of the heat in turbine exhaust can be affected in a heat exchanger called Re-generator. Fig.4.2.1 shows a schematic diagram of such an arrangement. The exhaust gases from the turbine pass through the regenerator and give their heat to the compressed air before it enters the combustion chamber, thereby, reducing the amount of heat which must be supplied in the combustion chamber to get a given turbine inlet temperature T3. Thus, regeneration improves fuel economy. The power output will be slightly reduced because of the pressure losses in regenerator and its associated pipe work.

Fig 4.2.1 Schematic diagram of Regenerative Gas Turbine CycleFor a regenerative gas turbine cycle the p-v and T-s diagrams are shown in Fig 4.2.2. Fig 4.2.2 p-v and T-s plots of Regenerative gas turbine cycleFor complete regenerationT3 = T5 and T2 = T6 The efficiency of the regenerator cycle with ideal regenerator is given by:Efficiency = = = = = (Eq. 4.1)For isentropic compression and expansion,Efficiency = (Eq. 4.2)Thus, we see that the efficiency of a regenerative gas turbine cycle depends upon the turbine and the compressor inlet temperature and the pressure ratio used. For a given inlet pressure and pressure ratio the cycle efficiency increases with increase in turbine inlet temperature because more generation can be affected. The efficiency decreases with an increase in pressure ratio with a given turbine inlet temperature. This explains the regenerative gas turbine cycle in which the efficiency decreases with an increase in pressure ratio for a given turbine inlet temperature.4.2.2 Intercooled Gas Turbine CycleA regenerator does not change the work output of a gas turbine cycle. So to increase the work output two possible methods are:1. By reducing the work of compression2. By increasing the work done by the turbineIntercooling is used for decreasing the work done on the compressor. This possibility of reducing the compressor work arises from the fact that the constant pressure lines converge on T-s diagram as the temperature is reduced. So if the total compression is divided into a number of stages the total compressor work is smaller than that for a single stage compression for the same total pressure ratio.Fig. 4.2.3 shows the schematic diagram of a two-stage intercooled gas turbine.

Fig 4.2.3 Schematic diagram of Two-stage Intercooled Gas Turbine CycleFig 4.2.4 shows T-s diagram for two-stage intercooled gas turbine.

Fig 4.2.4 T-s plot of Intercooled Gas Turbine CycleThe charge from the first stage is cooled before it is led to the second stage. This process, called intercooling, reduces the inlet temperature of second stage, resulting in reduction in compression work. If the charge is cooled to its initial temperature it is called perfect intercooling. For minimum work of compression the pressure ratio for each stage should be same with charge cooled to its initial temperature between the stages.Intercooling will always increase the net work output of the cycle, and due to lower compressor outlet temperature there will be more scope for regeneration. However, for the same reason, the fuel supplied to obtain a given turbine inlet temperature will also increase. Therefore, the thermal efficiency of the intercooled cycle is less than that for a simple cycle. One more reason of loss in efficiency is that heat is supplied at lower temperature. There is also a loss of pressure in the intercooler.Intercooling is useful when the pressure ratios are high and the efficiency of the compressor is low. At low pressure ratios it is not so important and regeneration can be used to recover a substantial amount of heat from exhaust gases.4.2.3 Gas Turbine Cycle with ReheatingAnother method of increasing the specific work output of the cycle is to use reheating to increase turbine work. The gain in work output is obtained because of divergence of constant pressure lines on T-s diagram with an increase in temperature. Thus for the same expansion ratio if the exhaust from one stage is reheated in a separate combustion chamber and expanded, more output will be obtained by expansion in a single-stage. Reheating is generally done up to the upper limit of temperature T3. Usually reheating up to two stages is done. With open cycle gas turbine the limit of reheating is the oxygen which is available for combustion.Fig 4.2.5 shows schematic diagram of reheating gas turbine cycle and Fig 4.2.6 shows the corresponding T-s diagram.

Fig 4.2.5 Schematic diagram of Reheat Gas Turbine Cycle

Fig 4.2.6 T-s plot of Reheat Gas Turbine CycleThe efficiency of a reheat cycle is lower than the corresponding intercooled cycle because in case of reheat, due to limitations of turbine inlet temperature, the heat added does not affect the work output, while intercooling reduces the compressor work, the specific output of a reheat cycle is greater than that of a corresponding intercooled cycle. Efficiency of both reheat and intercooled cycle is less than that of a simple cycle while the work output is greater. 4.2.4 Gas Turbine with Regeneration, Intercooling and ReheatingBoth the methods of increasing specific output, i.e. intercooling and reheating can be used in conjunction with a generator to get high specific output and high efficiency gas turbine plant. Intercooling decreases the compressor work and because of reduced compressor outlet temperature extra heat is needed to raise the temperature to turbine inlet temperature. However, if a regenerator is used this disadvantage can be converted into an advantage in that now more regeneration is possible. Fig 4.2.7 shows a gas turbine cycle with regeneration, intercooling and reheating.

Fig 4.2.7 Schematic diagram of Gas turbine cycle with Regeneration, Intercooling and reheatingThus, a combination of regeneration, intercooling and reheating can improve the performance of the plant. Fig 4.2.7 shows a T-s diagram for a gas turbine cycle with regeneration, intercooling and reheating. Combustion in gas turbines typically occurs at four times the amount of air needed for complete combustion to avoid excessive temperatures. Therefore, the exhaust gases are rich in oxygen, and reheating can be accomplished by simply spraying additional fuel into the exhaust gases between two expansion states.The working fluid leaves the compressor at a lower temperature and the turbine at a higher temperature, when intercooling and reheating are utilized. This makes regeneration more attractive since a greater potential for regeneration exits. Also, the gases leaving the compressor can be heated to a higher temperature before they enter the combustion chamber because of the higher temperature of the turbine exhaust. The gas enters the first stage of the compressor and is compressed isentropically to an intermediate pressure and cooled at constant pressure. It is then compressed in the second stage isentropically to the final pressure. The gas now enters the regenerator, where it is heated at a constant pressure. In an ideal regenerator, the gas will leave the regenerator at the temperature of the turbine exhaust. The gas enters the first stage of the turbine and expands isentropically where it enters the reheater. It is reheated at constant pressure, where it enters the second stage of the turbine. The gas exits the turbine and enters the regenerator, where it is cooled at a constant pressure. The cycle is completed by cooling the gas to the initial state (or purging the exhaust gases). Fig 4.2.8 shows T-s plot for Gas Turbine cycle with Regeneration, Intercooling and reheating.

Fig 4.2.8 T-s plot of Gas Turbine Cycle with regeneration, intercooling and reheating

Chapter 5RESULT AND CONCLUSION

The demand of energy in the developing regions of the world has witnessed pronounced increase in recent past years. Much of the growth in new electricity demand is expected to come from countries of the developing world. Therefore, it is important to find new technologies for power generation that have high efficiency and specific power output, low emissions of pollutants, low investment, and low operating and maintenance cost. Industrial gas turbines are thus one of the well established technologies for power generation. 5.1 Summary of Improvements in Basic Gas Turbine Cycle with various ModificationsTable 5.1 shows the general trends of effect of various modifications on work output and efficiency of the cycle.MODIFICATIONS EFFECT ON WORK OUTPUTEFFECT ON EFFICIENCY

RegenerationNo changeIncrease

IntercoolingIncreaseDecrease

ReheatingIncreaseDecrease

Regeneration, Intercooling and ReheatingIncreaseIncrease

Table 5.1 Improvements in Basic Cycle by various ModificationsThis comparison is general in nature and not exact because of interdependence of many parameters, for example, the compressor and turbine efficiencies depend upon the pressure ratio and the losses in combustion chamber and pipelines etc., depend upon pressure ratio and the temperature of combustion. The efficiency of the basic cycle with regeneration at first, increases but after certain pressure ratio it starts falling. And ultimately it falls to a level where regeneration is useless because at that point the temperature of air is equal to the temperature of hot gases. Any further increase in pressure ratio will result in heat flow from air to hot gases.

Chapter 6BIBLIOGRAPHY1. Mottram, A.W.T.: The gas turbine-recent improvement and their effect on the range of applications, 8th World Energy Conf. Bicharest, 1971.2. Polisuchuk, V. L. and Chernys hev, P. S.: The present position and the future of gas turbine power plant construction, Thermal energy, Vol. 13, No. 5, 1966, p. 1.3. Speippel, C.: The development of the Industrial Gas Turbine Proc I.M.E. Vol. 80, Pt. 1, p. 217.4. Bowden, A. T.: The gas turbine with special reference to Industrial applications, Jr. Roy. Soc. Arts, March 1947.5. Gasparovic, N. and Hellemans J. G., Gas Turbine with heat exchanger and water injection in the compressed air, Proc. I.M.E. 1970-71, Vol. 1856. On the theory of Brayton Cycles, ASME Paper No. 70, GT 130, 1970.7. Hafer, A. A., Cycle Arrangements and Exhaust Heat recovery for small Gas Turbine Units, Sym. on the Role of the Small Gas Turbine, Dept. Mech. Engg. Polytechnic Inst. Of Brooklyn, USA, Oct. 1955.8. Johnson, J.E., Regenerator Heat Exchangers for Gas Turbines, A.R.C.R. and M. No. 2630, 19529. Foster-Pegg, R. W., Gas Turbine Heat Recovery Boiler Thermodynamics, and Evaluations, ASME paper 69, GT-116.10. Stewart, J. C., Techniques for evaluating Gas Turbine heat Recovery applications, paper presented at ASME spring meeting, San Francisco, California, paper no. 72, GT-103.

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