Small-scale CHP-Ejector Cooling system

Combined heat and power (CHP) systems can make savings in primary energy consumption of up to 40% when compared with conventional forms of electricity- and heat-only supply. However, their environmental and economic benefits depend to a large extent on the load patterns, on the sizing and operation of the units, and on the possibility of net metering and grid connection. To reduce the effect of thermal load fluctuation and maintain the operation of the system throughout the heating season, the excess heat generated can be used to drive a cooling cycle, a system commonly known as Tri-generation. This paper presents an investigation of a tri-generation system using two Senertec DACHS CHP units of 5.5kWe and 12.5kWt and an ejector cooling system. The CHP units will be used to supply part of the electrical and base thermal load of the SRB in the School of the Built Environment, University of Nottingham. It is estimated that the building would require a peak electrical and heat load of 50kWe and 200kWt respectively. An ejector cycle has been chosen for the cooling system as it is relatively cheap and can use low-grade heat from the CHP unit.