Analysis of different arrangements of combined cooling, heating and power systems with internal combustion engine from energy, economic and environmental viewpoints

Abstract

The aim of this study is comparing different arrangements of combined cooling, heating and power systems and presenting proper configuration from energy, environment, and economic viewpoints. The arrangements include two gas engines as prime movers, heat exchangers for the use of waste heat, and electric and absorption chillers to provide cooling. For system evaluation, a mathematical model called the zero-dimensional single-zone method is used for internal combustion engine and validated by the experimental data. The engine model can evaluate power output as well as heat transfer in the engine which can be recovered for heating and cooling demands. Afterward, four different arrangements for the combined cooling, heating and power, and an arrangement for the combined cooling and power have been proposed and these total five arrangements are compared with a conventional energy supply system to provide the same energy demand of the building. The arrangements are compared at various the engine rotational speed and air to fuel equivalence ratios and some main parameters such as primary energy savings and net present value are evaluated. The results reveal that by using electric chillers for cooling as well as utilizing the waste heat of prime movers for heating, the highest reduction in primary energy consumption and carbon dioxide emissions could be achieved in the range of 31 and 36%, respectively. On the other hand, from economic viewpoint, this arrangement has higher cost of fuel consumption and a longer payback period than other arrangements of combined cooling, heating and power systems based on cooling with an absorption chiller.