Keywords: Brayton refrigeration cycle, endoreversible cycle, exergy based ecological optimisation, finite-time thermodynamics, exergy loss, entropy generation, cooling load, heat exchanger
Exergy-based ecological optimisation for an endoreversible Brayton refrigeration cycle
The optimal exergy-based ecological performance of an endoreversible Brayton refrigeration cycle with the loss of heat-resistance is derived by taking into account an exergy-based ecological optimisation criterion as the objective function, which consists of maximising a function representing the best compromise between the exergy output rate and exergy loss rate (entropy generation rate and environment temperature product) of the refrigeration cycle. The expressions of the optimal cooling load, entropy generation rate and exergy-based ecological function of the cycle are derived by optimising the allocation of a fixed total heat exchanger inventory. The exergy-based ecologically optimum isentropic temperature ratio, coefficient of performance (COP), cooling load and entropy generation rate at maximum exergy-based ecological function point are also presented. Moreover, numerical examples are given to show that the effects of the temperature ratio of two reservoirs, the total heat exchanger inventory, and the temperature ratio between heat sink and surroundings on the optimal performance of the cycle.