Investigating the interactive effects of different functional parameters of a heating, cooling and power cycle based on DOE method

Abstract

Cogeneration systems reduce fuel consumption and environmental pollutants. Optimizing these systems and operating existing equipment under optimal conditions further enhances fuel savings and pollution reduction. This study aims to investigate the interaction effects of functional parameters to identify the optimal operating conditions for all components. A new cogeneration system based on the methane-burning Brayton cycle, Kalina cycle, lithium-bromide cooling cycle, and a heating unit is designed. System performance is evaluated in terms of energy, exergy, and exergoeconomics. A parametric study identifies the optimal range of functional conditions with linear output changes, and the DOE method with fractional factorial design examines component interactions and their effects on system outputs. The most significant factors are the equivalence ratio and isentropic efficiency of compressors and the gas turbine, with their upper limits maximizing first and second-law efficiencies and the utilization factor. Analyzed using FORTRAN and Minitab, the system delivers 0.8 MW power, 0.4 MW cooling, and 1.2 MW heating, with energy and power costs of $16.53 and $51.19 per MWh. Multi-objective optimization improves exergy efficiency, reduces the total cost rate by 8.16 % to $110.76/hr, and lowers LCOP and cooling costs by 11.73 % and 4.15 %, respectively.