Exergetic performance optimisation of an endoreversible intercooled regenerated Brayton cogeneration plant. Part 1: thermodynamic model and parametric analysis

摘要

An endoreversible intercooled regenerative Brayton cogeneration plant model coupled to constant-temperature heat reservoirs is established in Part 1 of this article. On the basis of the exergetic analysis, the performance of the plant is investigated using finite-time thermodynamics. Analytical formulae about dimensionless exergy output rate and exergy efficiency are deduced. The two cases with fixed and variable total pressure ratios are discussed, and the intercooling pressure ratio and the total pressure ratio are optimised. The effects of the effectiveness of intercooler and regenerator, and the ratio of the hot-side heat reservoir temperature to environment temperature on the general and optimal performances of the cycle are analysed by detailed numerical examples. The relations between dimensionless exergy output rate and exergy efficiency are discussed and the characteristics are loop-shaped. At last, it is found that there exist two different optimal consumer-side temperatures, respectively, which lead to a double-maximum dimensionless exergy output rate and a double-maximum exergy efficiency. The exergy output rate and exergy efficiency of the model cycle are optimised by optimal allocation of the heat conductance of the heat exchangers in Part 2 of this article.