Finite time exergoeconomic performance of an irreversible intercooled regenerative Brayton cogeneration plant

A thermodynamic model of an irreversible intercooled regenerative Brayton heat and power cogeneration plant coupled to constant temperature heat reservoirs is established in this paper using finite time thermodynamics. The intercooler and the irreversible compression and expansion losses in the low and high pressure compressors and the turbine are taken into account. The finite time exergoeconomic performance of the cogeneration plant is investigated. The analytical formulae about dimensionless profit rate and exergetic efficiency are derived. The numerical examples show that there exist two different optimal values of intercooling pressure ratio, which correspond to an optimal value of dimensionless profit rate and an optimal value of exergetic efficiency respectively for the fixed total pressure ratio. There also exist optimal total pressure ratios corresponding to maximum profit rate and maximum exergetic efficiency respectively for the variable total pressure ratio. It is also found that there exist optimal consumer side temperatures, which lead to a double maximum profit rate and a double maximum exergetic efficiency respectively.