Exergetic Analysis of a Novel Solar Cooling System for Combined Cycle Power Plants

Calise, Francesco; Libertini, Luigi; Vicidomini, Maria

doi:10.3390/e18100356

Cited by 13 publications

(4 citation statements)

References 62 publications

(83 reference statements)

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“…However, in publications [3][4][5][6][7][8][9][10], the exergy efficiency of plants is estimated only by the values of their total exergy. Other studies use exergy efficiency to assess the exergy effectiveness of plants.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

Comparative analysis of the exergy efficiency of methods for protecting gas exhaust ducts of boiler plants

Fialko

Stepanova

Navrodska

et al. 2021

EEJET

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This paper reports the results of studying the exergy effectiveness of thermal methods for anti-corrosion protection of the gas-draining tracts of boiler plants. These include the method of mixing heated air into flue gases, the method of passing part of the hot gases of the boiler through the bypass chimney, and a flue gas drying method. The research involved the devised comprehensive procedure based on an exergy approach. The dependences of exergy loss Elos and the heat- exergy criterion ε on the following parameters of thermal methods have been established: the amount of heated air N mixed into flue gases, the proportion of bypassed flue gases K, and the amount of dried flue gases R. A comparative analysis of the effectiveness of heat recovery systems when applying the methods considered has been performed. It has been established that for the method of mixing, Elos and ε at ambient temperature ten=10 °C demonstrate the lowest values, that is, the efficiency of the system, in this case, is the highest. The most effective, when implementing the bypass method, is the heat recovery system at ten=10 °C. Under the method of drying, at all values of the amount of dried flue gases, the loss of exergy is the lowest at ten=0 °C. As regards the heat- exergy criterion, at values R≤20 %, the lowest values of ε are observed at ten=10 °C. At R>20 %, the lowest values of ε are at ten=0 °C. Thus, the efficiency of the system when implementing the method of drying is the highest at ten=0 °C and at the amount of dried air of R>20 %. The study reported here would provide the necessary information for designing optimal heat recovery schemes. The development of this study is to establish the relationship between the exergy and environmental efficiency of thermal protection methods in order to further reduce toxic emissions.

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Section: Literature Review and Problem Statementmentioning

confidence: 99%

Comparative analysis of the exergy efficiency of methods for protecting gas exhaust ducts of boiler plants

Fialko

Stepanova

Navrodska

et al. 2021

EEJET

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“…Такі системи повинні відповідати умовам термодинамічної оборотності процесів, що протікають в їхніх елементах. Тому важливим аспектом вказаних досліджень є дослідження ексергетичної ефективності окремих елементів установок і виявлення елементів, які характеризуються великими втратами ексергії [1][2][3][4][5][6][7][8][9][10]. Робота [1] присвячена ексергетичному та ексерго-економічному аналізу елементів високотемпературної електростанції з комбінованим циклом.…”

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Localization of exergy losses in the exhaust gases heat-recovery exchanger of gas-fired heat plants

Fialko¹,

Stepanova²,

Navrodska³

et al. 2020

Energy and automation

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The problem of increasing the thermodynamic efficiency of power plants can be solved only by using a complex approach using methods based on modern methods of exergy analysis in combination with methods of heat transfer theory, theory of linear systems, structural-variant methods, multi-level optimization methods, etc. The analysis of the possibility of applying the discrete-modular principle and the corresponding complex method for analyzing the efficiency of the exhaust gases heat-recovery exchanger of a cogeneration unit heat engine is performed in the paper. The aim of the work is to analyze the localization of exergy losses, their differentiation, and the establishment of the relative contribution of various types of losses to the general exergy losses in the exhaust gases heat-recovery exchanger of a cogeneration unit heat engine. The structural features of the heat-recovery exchanger and the exergy properties that reflect the essence of exergy methods: universality and additivity, made it possible to use the discrete-modular principle and a complex method based on exergy-dissipative functions for efficiency analysis. The advantage of this method is the ability to analyze the localization of exergy losses in separate modules of the heat-recovery exchanger and to differentiate the exergy losses associated with nonequilibrium heat transfer between the heat-transfer agents and the wall, heat conduction and the movement of heat-transfer agents. Using the chosen complex method, the analysis of the localization of exergy losses in the heat-recovery exchanger was carried out and the exergy-dissipative functions of each of the eight modules of the heat-recovery exchanger were calculated. Differentiation of exergy losses was carried out and the relative contribution of exergy losses associated with the processes of heat transfer from flue gases to the wall, from wall to water, in heat conduction processes, as well as exergy losses associated with the movement of heat-transfer agents, in the general exergy losses was analyzed. To determine the exergy losses due to nonequilibrium heat transfer between the heat-transfer agents and the motion of the heat-transfer agents, the differential exergy equations, the equations for the heat flow densities between the heat-transfer agents and the wall, the equation for the heat flow density due to heat conduction through the wall and the equations of motion are used. It has been established that the localization of maximum exergy losses in all modules of the heat-recovery exchanger is associated with losses due to heat transfer from flue gases to the wall.

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“…The test results showed that the north-facing room had an average temperature over 17 • C while the south-facing room was over 20 • C, which illustrated that a good heating effect was achieved. Although a relatively high system COP was shown with a good heating effect for the solar heating system under the simultaneous charging and discharging operation mode, further recommendations were proposed for the mass flow rates of the solar collecting cycles and control stagey of the fan coil unit (FCU).in Lhasa is promising, as it can contribute to the improvement in indoor thermal comfort, energy consumption reduction and more environmental friendliness [1][2][3].Solar energy is one of the most promising renewable energy sources since it suitably meets sustainable development objectives and it can be exploited worldwide [4][5][6][7][8][9]. Buker et al [10] reviewed the solar thermal applications in buildings, addressed the important issues related to architectural barriers, system design and installation and revealed the trend of solar thermal technologies required in the future.…”

mentioning

confidence: 99%

“…Solar energy is one of the most promising renewable energy sources since it suitably meets sustainable development objectives and it can be exploited worldwide [4][5][6][7][8][9]. Buker et al [10] reviewed the solar thermal applications in buildings, addressed the important issues related to architectural barriers, system design and installation and revealed the trend of solar thermal technologies required in the future.…”

mentioning

confidence: 99%

Numerical and Experimental Study on a Solar Water Heating System in Lhasa

2017

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Lhasa is a "solar city" with high altitude, located in a cold zone in China. Due to the lack of mineral energy sources and the fragility of its ecological environment, solar heating technology is the first choice to satisfy the demand of indoor thermal comfort for building heating. In this study, an accurate solar heating system in Lhasa was investigated under the simultaneous charging and discharging operation mode. Based on the solar heating system, a numerical calculation method of the tank temperature distribution under the simultaneous charging and discharging operation mode was proposed and validated by experiments. This numerical method offers a correlation between the output water temperatures of the tank and the input water temperatures of the tank, which can be used to optimize the thermal performance of the solar heating system in future studies. To evaluate the system performance under the simultaneous charging and discharging operation mode, the transient coefficient of performance (COP) of the heating system was calculated based on the experimental measurements. The calculated results showed that the system COP reached an average number of 3.0, which was nearly equal to that of gas-boiler heating system and much higher than that of electrical heating systems. A north-facing room and a south-facing room were both selected to test whether the room temperatures met the heating requirements. The test results showed that the north-facing room had an average temperature over 17 • C while the south-facing room was over 20 • C, which illustrated that a good heating effect was achieved. Although a relatively high system COP was shown with a good heating effect for the solar heating system under the simultaneous charging and discharging operation mode, further recommendations were proposed for the mass flow rates of the solar collecting cycles and control stagey of the fan coil unit (FCU).

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Exergetic Analysis of a Novel Solar Cooling System for Combined Cycle Power Plants

Cited by 13 publications

References 62 publications

Comparative analysis of the exergy efficiency of methods for protecting gas exhaust ducts of boiler plants

Comparative analysis of the exergy efficiency of methods for protecting gas exhaust ducts of boiler plants

Localization of exergy losses in the exhaust gases heat-recovery exchanger of gas-fired heat plants

Numerical and Experimental Study on a Solar Water Heating System in Lhasa

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