The coefficient of performance of a multi-temperature-level absorption heat transformer at maximum specific heating load

摘要

An endoreversible cycle model of a multi-temperature-level absorption heat transformer is set up and used to analyse the performance of the heat transformer affected by the irreversibility of finite-rate heat transfer. The key performance parameters, such as the coefficient of performance, specific heating load, temperatures of the working fluid in the heat exchangers, heat-transfer areas of the heat exchangers and so on, are optimized. Some new results which are conducive to the optimal design and operation of real heat transformer systems are obtained and several special cases are discussed in detail. Moreover, the endoreversible cycle model is generalized to become an irreversible cycle model. The important results describing the optimal performance of a multi-temperature-level absorption heat transformer affected simultaneously by the internal and external irreversibilities can be obtained simply and conveniently from the corresponding formulae of the endoreversible cycle model because of the introduction both of the equivalent temperatures and of the equivalent overall heat-transfer coefficients.