Conference Year



Energy Recovery, Heat Pump, Turbine, Nozzle, CO2


Carbon dioxide (CO2) is being widely used as a refrigerant in HVAR&R applications due to its low Global Warming Potential (GWP). There are many aspects of CO2 systems that make it unique to other traditional refrigerants in that it has higher pressure levels and typically operates at transcritical levels. These higher pressure levels make CO2 systems ideal for installing an energy recovery expansion device that consists of a nozzle, micro-turbine and a generator. The expander functions by using a nozzle to convert the pressure of the refrigerant into a high speed jet that is directed into the impeller of the micro-turbine. The turbine impeller then spins a shaft that is coupled with a generator to generator electrical energy. This energy recovery expansion device is to replace the passive thermostatic expansion valve (TXV). Experimental testing of this device with R410A indicates that the device is more suitable for systems of higher pressure levels and with lower density refrigerants. For these reasons, the implementation of this energy recovery device in a CO2 refrigeration system for marine transportation has been investigated. The results of this paper quantifies the potential impact that this device could have in the system in terms of theoretical recoverable power. This recovered power has then been used to understand the impact on other various system parameters like COP, SEER and HSPF. This paper aims to present whether or not pursuing further experimental research on installing this energy recovery device into a CO2 system is of interest.Â