Selection and Sizing of Prime Movers in Combined Heat and Power Systems

Abstract

Combined heat and power (CHP) is a technology with significant economical and environmental benefits. Proper sizing and operational strategy of CHP systems must take into account the time dependent character of electrical and thermal load requirements. Furthermore the CHP systems should be able to operate at off-design points with variable power and heat outputs. In this paper, the selection of type and combination of prime movers, their nominal powers and planning their operational strategy is performed. Three prime movers namely diesel engine, gas engine and gas turbine have been used to provide the required power and heat loads. Ambient conditions, and time dependent electrical/heat load curves are assumed to be the known variables, and thermal efficiency, engine exhaust gas temperatures, exhaust and fuel mass flow rate at partial load are estimated using relations obtained for prime movers mentioned in this paper. The presented approach successfully estimated the most economical combination of prime movers for a selected district heating plant.