Organic Rankine cycle (ORC) coupled with biomass combustion boiler is an appealing and promising technology for small scale combined heat and power (CHP) plants. The aim of this paper is to investigate thermodynamic analysis and economic assessment of biomass-fired ORC CHP system, especially from the perspective of pinch point location. The thermoeconomic model of bioenergy cogeneration system has been developed, in which the pressurized boiler hot water is worked as heat source for ORCs and the condensation heat can be fully utilized to supply domestic hot water. Results show that pinch point location from vaporization start point to preheating start point is observed with increasing boiler hot water temperature or decreasing evaporation temperature in evaporator. The pinch point location has slight influence on thermodynamic performance, while it has significant effect on economic assessment in this bioenergy system. The same optimal boiler hot water temperature with the specific evaporation temperature can be achieved in terms of total investment (INVtot), dynamic payback period (DPP) and profit ratio of investment (PRI).
Keywords biomass, organic Rankine cycle, combined heat and power, thermo-economic, pinch point