An Evaluation of Internal Combustion Engines as the Prime Movers in CHP Systems

Abstract

Abstract: Optimum selection of prime movers in combined heat and power (CHP) systems is of crucial importance due to the fact that inappropriate choices reduce the benefits of CHP systems considerably. In the selection procedure the performance characteristics of prime movers as well as economic parameters should be considered. The aim of this paper is to present a thermo-economic approach to selecting the optimum nominal power and planning the operational strategy of internal combustion engines in a medium scale combined heat and power system is presented using the Net Annual Cost (NAC) criterion. Three modes of operation have been considered, namely one-way connection (OWC) mode, two-way connection (TWC) mode, and heat demand following (HDF) mode. The proposed method has been used for a case study. It has been observed that the optimum nominal powers in the case of using gas engines are 3.3 MW, 3.2 MW, and 1.2 MW and in the case of using diesel engines are 3.4 MW, 3.4 MW, and 1.4 MW for TWC, OWC, and HDF modes respectively. The proposed method may be also used for other types of prime movers as well as various sizes of combined heat and power systems.