Optimization between heating load and entropy-production rate for endoreversible absorption heat-transformers

• Published in: Applied energy 2005-08, Vol.81 (4), p.434-448
• Main Authors: Sun, Fengrui, Qin, Xiaoyong, Chen, Lingen, Wu, Chih
• Format: Article
• Language: English
• Subjects: Applied sciences; COP; Devices using thermal energy; Ecological criterion; Energy; Energy. Thermal use of fuels; Entropy-production rate; Exact sciences and technology; Four-heat-reservoir absorption heat-transformer; Four-heat-reservoir absorption heat-transformer Ecological criterion COP Heating load Entropy-production rate; Furnaces; Heat transfer; Heating load; Theoretical studies. Data and constants. Metering
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2004.09.003

For an endoreversible four-heat-reservoir absorption heat-transformer cycle, for which a linear (Newtonian) heat-transfer law applies, an ecological optimization criterion is proposed for the best mode of operation of the cycle. This involves maximizing a function representing the compromise between the heating load and the entropy-production rate. The optimal relation between the ecological criterion and the COP (coefficient of performance), the maximum ecological criterion and the corresponding COP, heating load and entropy production rate, as well as the ecological criterion and entropy-production rate at the maximum heating load are derived using finite-time thermodynamics. Moreover, compared with the heating-load criterion, the effects of the cycle parameters on the ecological performance are studied by numerical examples. These show that achieving the maximum ecological criterion makes the entropy-production rate decrease by 77.0% and the COP increase by 55.4% with only 27.3% heating-load losses compared with the maximum heating-load objective. The results reflect that the ecological criterion has long-term significance for optimal design of absorption heat-transformers.