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This paper evaluates the optimum coolant temperature considering the exergy loss in a shell and tube condenser in which vapor is at its saturated temperature. First, exergy loss was formulated mathematically and then presented as a function of operating temperatures and optimum coolant and steam mass flow rates. The optimization problem was defined by full condensation of vapor in a condenser and solved by a sequential quadratic programming method. The optimization results were obtained for an industrial condenser for two condensate temperatures of 46°C and 54°C. When the upstream steam mass flow rate increased, the optimum coolant temperature and the exergy efficiency decreased, and the exergy loss also increased simultaneously. The results showed higher values for the higher condensate temperature of 54°C compared with that for 46°C. For instance, if the condensate temperature increases from 46°C to 54°C, the coolant temperature will be increased from 16.76°C to 25.17°C. In addition, by assuming the ambient temperature of 15°C, the exergy loss will be decreased from 172.5 to 164.6 kW. A linear relationship was also shown between the exergy efficiency and the dimensionless temperature, which is presented as a ratio of the temperature difference rate between inlet cooling water and ambient temperatures to the temperature difference rate of condensate and ambient temperatures. 相似文献
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This study deals with the energetic and exergetic performance assessment of a combined heat and power system with micro gas turbine (MGTCHP). Quantitative energy and exergy balance for each component and the whole MGTCHP system was considered, while energy and exergy consumption within the system were determined. The performance characteristics of this MGTCHP system were evaluated using energy and exergy analyses methods. The energetic and exergetic efficiencies of the MGTCHP system are calculated as 75.99% with 254.55 kW (as 99.15 kW—electrical and 155.40 kW—hot water@363.15 K) and 35.80% with 123.61 kW (as 99.15 kW—electrical and 24.46 kW—hot water@363.15 K), respectively. The maximum energy loss and exergy consumption occur at 44.03 kW in the stack gas and 129.61 kW in the combustion chamber, respectively. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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The influence of operating conditions such as reheat, intercooling, ambient temperature and pressure ratio are analyzed from a second law perspective on the performance of a natural gas‐fired gas turbine cogeneration system. The effect of these operating parameters on carbon dioxide emissions is also discussed. The second law efficiency of gas turbine cogeneration system increases markedly with reheat option. Higher pressure ratios lead to decreased second law cogeneration efficiency but this effect can be reduced with a higher level of reheat option. The effect of intercooling on second law efficiency is strongly related to pressure ratio with higher pressure ratios significantly decreasing efficiency. The second law efficiency is not so sensitive to the environment temperature for levels of reheat or intercooling greater than 50%. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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This study deals with the exergetic performance assessment of a combined heat and power (CHP) system installed in Eskisehir city of Turkey. Quantitative exergy balance for each component and the whole CHP system was considered, while exergy consumptions in the system were determined. The performance characteristics of this CHP system were evaluated using exergy analysis method. The exergetic efficiency of the CHP system was accounted for 38.16% with 49 880 kW as electrical products. The exergy consumption occurred in this system amounted to 80 833.67 kW. The ways of improving the exergy efficiency of this system were also analysed. As a result of these, a simple way of increasing the exergy efficiency of the available CHP system was suggested that the valves‐I–III and the MPSC could be replaced by a 3500 kW‐intermediate pressure steam turbine (IPST). If the IPST is installed to the CHP system (called the modified CHP (MCHP) system), the exergetic efficiency of the MCHP system is calculated to be 40.75% with 53 269.53 kW as electrical products. The exergy consumption is found to be 77 444.14 kW in the MCHP system. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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We have developed a simple model of a micro gas turbine system operating at high ambient temperatures and characterized its performance with a view to integrating this system with thermally activated cooling technologies. To develop and validate this model, we used experimental data from the micro gas turbine test facility of the CREVER research centre. The microturbine components were modelled and the thermodynamic properties of air and combustion gases were estimated using a commercial process simulator. Important information such as net output power, microturbine fuel consumption and exhaust gas mass flow rate can be obtained with the empirical correlations we have developed in this study. This information can be useful for design exhaust gas fired absorption chillers. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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对某供热厂的燃气轮机热电联供系统进行了研究,将燃煤分产和燃气分产进行了全方面的比较,其性能评价对合理应用CHP有重要作用。在热电分产的节能性方面,以燃气-蒸汽联合循环电厂和燃气锅炉作为比较的基准线,全年平均节能率为8.9%;在运行经济性方面,燃气轮机系统与燃煤锅炉分产相比,每年节省46万元,与燃气锅炉分产相比,每年节省182万元,且节省费用随着电价的增加而增加,随着气价的增加而减少。另外,与燃煤锅炉分产相比时,还随着煤价的增加而增加;在排放物方面,燃气轮机联供系统与燃煤分产和燃气分产对比,NOx减排量并不显著,而其余排放物有明显地减少。燃气轮机系统与燃煤以及燃气锅炉相比具有一定的优越性,在设计合理的情况下具有良好的前景。 相似文献
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燃气轮机是21世纪乃至更长时间内能源高效转换与洁净利用系统的核心动力装备.介绍了燃气轮机的发展现状及其在热电联产工程中的应用,简述了联合循环和简单循环燃气轮机电厂的基本组合方式,并列举了目前应用在热电联产工程中的几种主要的燃气轮机.阐述了燃气轮机相对于常规火电机组的优点,分析了影响燃气轮机在热电联产工程中推广的因素,并对我国燃气轮机的发展前景进行了展望. 相似文献
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Factors such as low capital cost, good match of power and heat requirements and proven reliability can sometimes lead an end user into purchasing gas turbines for use in a modern cogeneration plant. The steam‐injected gas turbine is an attractive electrical generating technology for mitigating the impacts of rising energy prices. According to such mentioned above this paper is to provide results of an optimization study on cogeneration power cycle, which works by gas turbine with recuperator and injection steam added to the combustor of the gas turbine. The performance characteristics of the cycle based on energy and exergy concepts and based upon practical performance constraints were investigated. The effect of the recuperator on the cycle was greatly clarified. Results also show that the output power of a gas turbine increases when steam is injected. When extra steam has to be generated in order to be able to inject steam and at the same time to provide for a given heat demand, power generating efficiency increases but cogeneration efficiency decreases with the increasing of injected steam. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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壳管式海水换热器污垢状况的火用评价方法研究 总被引：3，自引：0，他引：3
分析了壳管式海水换热器管程结垢后换热强度及流动压降变化对换热器火用损失的影响,提出了一种利用(火用)损失系数评价换热器污垢状况的方法.该方法比通过检测污垢热阻评价换热器污垢状况的方法更全面,更简捷. 相似文献
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结垢是影响城市原生污水换热器热工性能的主要原因.以壳管式污水换热器为例,在分析了污垢对换热器性能影响的基础之上,提出了换热器由于传热温差和流动阻力引起的不可逆有效能损失的计算方法,以及污水换热器不可避免(火用)损失的定义及计算方法.分析结果为污水换热器的工程应用和科学研究提供了理论基础. 相似文献
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针对中型抽汽供热机组应用较多,但却面临大容量两用机组挑战的问题,通过研究中型抽汽供热机组的特点和影响热力发电厂节能的因素,客观地评价其优缺点,得出其应用条件和范围。 相似文献
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Most natural gas (NG) producers in the Persian Gulf face increasing challenges in meeting their domestic gas demands and therefore seek to reduce their NG consumption. Concurrently, the on‐site power generation and cooling capacities of local NG processing facilities are constrained by extreme climatic conditions. A combined cooling and power scheme based on gas turbine (GT) waste heat‐powered absorption refrigeration is techno‐economically assessed to reduce the NG consumption of a major gas processing plant in the Persian Gulf. The scheme utilizes double‐effect water‐lithium bromide absorption refrigeration activated by steam generated from GT exhaust gas waste heat to provide both GT compressor inlet air and process gas cooling. Based on a thermodynamic analysis, recovery of 150 MW of GT waste heat is found to enhance the plant cooling capacity by 195 MW, thereby permitting elimination of a 32.6 MW GT and existing cooling equipment. On‐site power generation is enhanced by 196 GWh annually through GT compressor inlet air cooling, with energy efficiency (i.e., 64%) improved by 35% using cogeneration relative to the existing power generation plant. The overall net annual operating expenditure savings contributed by the combined cooling and power system are of $US13 million to 34 million based on present and projected local utility prices, with an economic payback period estimated at 2 to 5 years. These savings translate to approximately 94 to 241 MMSCM of NG per year, highlighting the potential of absorption refrigeration to both enhance the power generation and cooling capacity of hydrocarbon processing plants exposed to harsh environmental conditions and to realize substantial primary energy savings. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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The analysis of a subcritical Rankine cycle with superheating, operating between a constant flowrate low‐temperature heat source and a fixed temperature sink, according to the principles of classical and finite size thermodynamics, is presented. The results show the existence of two optimum evaporation pressures: one minimizes the total thermal conductance of the two heat exchangers, whereas the other maximizes the net power output. A comparison of such results for five working fluids leads to the selection of R141b for a system generating 10% of a reference power which depends on the specified source and sink characteristics; for the conditions under consideration this reference power is 6861 kW. The results for this particular system show that the minimum total thermal conductance of the two heat exchangers is 1581 kW K?1; the corresponding thermal efficiency is 12.6% and the total exergy losses are 13.8% of the source's exergy. Slightly more than 50% of the exergy destruction occurs in the vapor generator. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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论“热电联产”型燃气—蒸汽联合循环的特性 总被引：3，自引：0，他引：3
探讨了“热电联产”型燃气－蒸汽联合循环中热电联产的各种组合方案及其特性,剖析了燃气轮机热电联产系统特性图的物理含义,提出了热电联产型联合循环装置的各种组合方案。 相似文献
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利用汽轮机抽汽作为吸收式制冷驱动热源的联产制冷，将供电、制冷有机结合在一起，不仅满足制冷要求也改善联产机组效率。通过引入抽汽yong增益概念，揭示了汽轮机抽汽特性规律，在此基础上从联产制冷目的yong效率角度比较了几种制冷方式，分析了汽轮机抽汽参数和相对内效率等因素对联产制冷能效性能影响规律，抽汽的yong增益比是联产制冷yong效率影响起决定作用的因素，所得结论对联产制冷吸收机的合理选用匹配提供有益的指导。 相似文献