An efficient biogas-base tri-generation of power, heating and cooling integrating inverted Brayton and ejector transcritical CO2 cycles: exergoeconomic evaluation

In the present work, an efficient multigeneration system is proposed to meet diverse energy requirements such as power, heating, and cooling. The system consists of a biogas-fueled gas turbine cycle as the topping cycle, and a Brayton, an inverted Brayton, and also, a transcritical carbon dioxide refrigeration cycles with an ejector expansion as the bottoming cycles Using the ejector instead of compressor results in a reduction in the power consumption. Moreover, the required power of the refrigeration cycle can meet by the inverted Brayton cycle which eliminates the need for an external power source. The thermodynamic and exergoeconomic evaluations are done for the suggested system considering the energy and exergy efficiencies and total specific cost of the system as objective functions. Also, a parametric analysis is performed to specify the effects of decision variables on the system performance. The energy and exergy efficiencies and total cost rate of the system are determined as 79%, 44. 4%, and 183. 4 /h, respectively. These values demonstrate that the energy and exergy efficiencies of the proposed system have been improved by 48. 9% and 54%, respectively, compared to the gas turbine cycle. Also, the cost of produced electricity is calculated to be 52. 84 /MWh.