Performance investigation of a multi-ejector R744 heat pump.

Paper published in poster form during the conference. Carbon dioxide (CO2, R744) is a natural refrigerant which is emerging as a potential substitute for Hydrofluorocarbons (HFCs) and FCs nowadays because of its eco-friendliness, non-flammability, high volumetric capacity and good heat transfer properties. The demand for domestic water heating is growing rapidly in India for applications like dairies, hotels, hospitals etc. Trans-critical R744 system with heat recovery seems to be appropriate for such application. The drawbacks of lower efficiency and the demand mismatch can be improved by incorporating ejectors; while, the mismatch is addressed by suitable control and standby gas cooler respectively. The paper presents an experimental evaluation of an R744 multi-ejector based system with heat recovery for hot water production. The effect of high ambient temperature (36-46°C) on the overall performance of the system and heat recovery is also evaluated. It is observed that the COP of the multi-ejector R744 system with heat recovery for domestic production at high ambient context is high. Also, the opportunity of maximum heat available for recovery is encouraging to accept this technology for high ambient context.