Advantage of CO₂ heat pump chiller for the application in Indian hotels

Hotels in India conventionally use diesel-fired hot water generators to meet hot water demands at 46°C.
These are inefficient and also release high emissions. This study focuses on the energy saving and emission
reduction potentials of a CO₂ heat pump chiller system for such an application. An ejector-based system of
50 kW heating capacity is proposed for a typical hotel having a hot water demand of 40 m3
/day with a 5 m3
thermal storage tank (TST). The heat pump produces the hot water at 68°C which is stored in the proposed
TST. As per the demand, the hot water from the TST will be supplied to two existing 5 m3 hot water supply
tanks (one for rooms and the other for the kitchen) after being mixed with cold water to reach the required
temperature (46°C). The system also supplements up to 3.2% of the cooling demand of the hotel by
contributing chilled water at 7°C. The proposed system reduces the operating cost and CO₂ emissions to
approximately 10 and 30%, respectively of the existing set-up. Return on investment is found to be less than
2 years.
Keywords: Ejector, R744, Transcritical, DHW, Thermal storage, Energy savings