Performance of real absorption heat-transformer with a generalized heat transfer law

• Published in: Applied thermal engineering 2008-05, Vol.28 (7), p.767-776
• Main Authors: Qin, Xiaoyong, Chen, Lingen, Sun, Fengrui
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Finite-time thermodynamics; Four-temperature-level absorption heat-transformer cycle; Generalized thermodynamic optimization; Heat transfer; Heat transfer law; Irreversible cycle; Theoretical studies. Data and constants. Metering
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2007.06.017

An irreversible four-temperature-level absorption heat-transformer cycle model with a generalized heat transfer law of Q ∝ Δ( T n ) ( n ≠ 0) is established, which considers effects of heat resistance, heat leak and internal irreversibilities. The general relation between the COP (coefficient of performance) and the heating load is deduced. The fundamental optimal relation and the performance limit, the optimal temperatures of working substance, as well as the optimal heat transfer surface area distributions with linear phenomenological heat transfer law are derived. Moreover, effects of heat transfer law, heat leak, and internal irreversibilities on the performance of absorption heat-transformer are analyzed; and the performance comparison is performed for the distribution of the total heat transfer surface area is optimized or not by numerical example. The results obtained herein are useful for optimal design and performance improvement of absorption heat-transformer cycles.