Pub Date : 2021-06-05DOI: 10.9734/bpi/nupsr/v4/5716d
Dumitrascu Gheorghe, F. Michel, P. Aristotel, Grigorean Stefan
This paper focuses on the finite physical dimensions thermodynamics (FPDT) based design of combined endoreversible power and refrigeration cycles (CCHP). Four operating schemes were analyzed, one for summer season and three for winter season. These basic CCHP cycles should define the reference ones, having the maximum possible energy and exergy efficiencies considering real restrictive conditions. The FPDT design is an entropic approach because it is defining and using the dependences between the reference entropy and the control operational parameters characterizing the external energy interactions of CCHP subsystems. The FPDT introduces a generalization of CCHP systems design, due to the particular influences of entropy variations of the working fluids are substituted with influences of four operational finite dimensions control parameters, i.e. two mean log temperature differences between the working fluids and external heat sources and two dimensionless thermal conductance inventories. Two useful energy interactions, power and cooling rate were used as operational restrictive conditions. It was assumed that there are consumers required for the supplied heating rates depending on the energy operating scheme. The FPDT modeling evaluates main thermodynamic and heat transfers performances. The FPDT model presented in this paper is a general one, applicable to all endoreversible trigeneration cycles. The FPDT design model of the trigeneration component endoreversible cycles emphasizes the cycle internal relationships between the operational functions and the restrictive imposed variable finite physical dimension parameters.
{"title":"Study on Endoreversible Trigeneration Cycles Design Based on Finite Physical Dimensions Thermodynamics","authors":"Dumitrascu Gheorghe, F. Michel, P. Aristotel, Grigorean Stefan","doi":"10.9734/bpi/nupsr/v4/5716d","DOIUrl":"https://doi.org/10.9734/bpi/nupsr/v4/5716d","url":null,"abstract":"This paper focuses on the finite physical dimensions thermodynamics (FPDT) based design of combined endoreversible power and refrigeration cycles (CCHP). Four operating schemes were analyzed, one for summer season and three for winter season. These basic CCHP cycles should define the reference ones, having the maximum possible energy and exergy efficiencies considering real restrictive conditions. The FPDT design is an entropic approach because it is defining and using the dependences between the reference entropy and the control operational parameters characterizing the external energy interactions of CCHP subsystems. The FPDT introduces a generalization of CCHP systems design, due to the particular influences of entropy variations of the working fluids are substituted with influences of four operational finite dimensions control parameters, i.e. two mean log temperature differences between the working fluids and external heat sources and two dimensionless thermal conductance inventories. Two useful energy interactions, power and cooling rate were used as operational restrictive conditions. It was assumed that there are consumers required for the supplied heating rates depending on the energy operating scheme. The FPDT modeling evaluates main thermodynamic and heat transfers performances. The FPDT model presented in this paper is a general one, applicable to all endoreversible trigeneration cycles. The FPDT design model of the trigeneration component endoreversible cycles emphasizes the cycle internal relationships between the operational functions and the restrictive imposed variable finite physical dimension parameters.","PeriodicalId":295943,"journal":{"name":"Newest Updates in Physical Science Research Vol. 4","volume":"694 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134126157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper develops generalizing entropic approaches of irreversible closed cycles. The mathematical models of the irreversible engines (basic, with internal regeneration of the heat, cogeneration units) and of the refrigeration cycles were applied to four possible operating irreversible trigeneration cycles. The models involve the reference entropy, the number of internal irreversibility, the thermal conductance inventory, the proper temperatures of external heat reservoirs unifying the first law of thermodynamics and the linear heat transfer law, the mean log temperature differences, and four possible operational constraints, i.e., constant heat input, constant power, constant energy efficiency and constant reference entropy. The reference entropy is always the entropy variation rate of the working fluid during the reversible heat input process. The amount of internal irreversibility allows the evaluation of the heat output via the ratio of overall internal irreversible entropy generation and the reference entropy. The operational constraints allow the replacement of the reference entropy function of the finite physical dimension parameters, i.e., mean log temperature differences, thermal conductance inventory, and the proper external heat reservoir temperatures. The paper presents initially the number of internal irreversibility and the energy efficiency equations for engine and refrigeration cycles. At the limit, i.e., endoreversibility, we can re-obtain the endoreversible energy efficiency equation. The second part develops the influences between the imposed operational constraint and the finite physical dimensions parameters for the basic irreversible cycle. The third part is applying the mathematical models to four possible standalone trigeneration cycles. It was assumed that there are the required consumers of the all useful heat delivered by the trigeneration system. The design of trigeneration system must know the ratio of refrigeration rate to power, e.g., engine shaft power or useful power delivered directly to power consumers. The final discussions and conclusions emphasize the novelties and the complexity of interconnected irreversible trigeneration systems design/optimization.
{"title":"Studies on Closed Irreversible Cycles Analysis Based on Finite Physical Dimensions Thermodynamics","authors":"G. Dumitraşcu, M. Feidt, Ș. Grigorean","doi":"10.3390/wef-06905","DOIUrl":"https://doi.org/10.3390/wef-06905","url":null,"abstract":"The paper develops generalizing entropic approaches of irreversible closed cycles. The mathematical models of the irreversible engines (basic, with internal regeneration of the heat, cogeneration units) and of the refrigeration cycles were applied to four possible operating irreversible trigeneration cycles. The models involve the reference entropy, the number of internal irreversibility, the thermal conductance inventory, the proper temperatures of external heat reservoirs unifying the first law of thermodynamics and the linear heat transfer law, the mean log temperature differences, and four possible operational constraints, i.e., constant heat input, constant power, constant energy efficiency and constant reference entropy. The reference entropy is always the entropy variation rate of the working fluid during the reversible heat input process. The amount of internal irreversibility allows the evaluation of the heat output via the ratio of overall internal irreversible entropy generation and the reference entropy. The operational constraints allow the replacement of the reference entropy function of the finite physical dimension parameters, i.e., mean log temperature differences, thermal conductance inventory, and the proper external heat reservoir temperatures. The paper presents initially the number of internal irreversibility and the energy efficiency equations for engine and refrigeration cycles. At the limit, i.e., endoreversibility, we can re-obtain the endoreversible energy efficiency equation. The second part develops the influences between the imposed operational constraint and the finite physical dimensions parameters for the basic irreversible cycle. The third part is applying the mathematical models to four possible standalone trigeneration cycles. It was assumed that there are the required consumers of the all useful heat delivered by the trigeneration system. The design of trigeneration system must know the ratio of refrigeration rate to power, e.g., engine shaft power or useful power delivered directly to power consumers. The final discussions and conclusions emphasize the novelties and the complexity of interconnected irreversible trigeneration systems design/optimization.","PeriodicalId":295943,"journal":{"name":"Newest Updates in Physical Science Research Vol. 4","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115509454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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