Proposal and optimization of a novel biomass-based tri-generation system using energy, exergy and exergoeconomic analyses and design of experiments method

Abstract

A novel trigeneration system of cooling, heating and power based on biomass is designed in current study. This system consists of five parts: biomass gasification subsystem, steam turbine subsystem (Rankin cycle), gas turbine subsystem (Brayton cycle), Kalina subsystem and ejector refrigeration subsystem. Energy, exergy and exergy-economic analysis were performed on the whole system and the effects of different key parameters on energy efficiency and exergy and economic factors are investigated. The designed cycle has been qualitatively optimized using DOE method and the interaction effects of parameters on cycle performance has been investigated. The results show that the highest exergy destruction is related to the combustion chamber with 56.14 %. Also, the lowest exergy destruction is assigned to the separator of the Kalina cycle with a nearly zero value. The highest investment, operating and maintenance costs are related to air compressor, gas turbine and steam generator, respectively. The results of parametric analysis showed that with increasing the mixing ratio of natural gas to syngas the thermal and exergy efficiencies, the rate of total system cost and the unit cost of power generation increase. Also, with increasing gasification temperature, the thermal and exergy efficiencies of this system vary slightly and can be considered constant, but the total cost of system increases. The results of DOE analysis showed that among the main effects of the parameters, the isentropic efficiency of the gas turbine and the temperature of the air entering the combustion chamber have the greatest effect on the system efficiency, and the GMR has the greatest effect on the LCOE of the system, and among the interaction effects of the parameters, the interaction between the temperature of the air entering the combustion chamber has the greatest effect on the system efficiency and LCOE.