Moving the CO2 'equator' from the northern Mediterranean to Malaysia without ejectors.

Abstract

The current state of development of air cooled Two Stage (booster) Trans Critical CO2 Refrigerating Systems (2STCCO2RS) recognises the very low COPs in even mild climates. Attempts are made to recover some of the excess energy by the use of ejectors to be able to use 2STCCO2RS in warmer climates. COP improvements of 6 – 30% have been reported when using ejectors, but even then, resulting COPs are quite low. This is demonstrated. This has led to an industry consensus that the so called ‘CO2 equator’ runs at latitudes of about 40 degrees North and higher. This paper deals with the design of an efficient Multi Function (MF) 2STCCO2RS for a -30°C 40,000 m3 high rise cold store West of Kuala Lumpur where the average annual temperature is 27°C and the 1% Ambient Design condition of 33°C Dry Bulb, 28°C Wet Bulb. The MF2STCCO2RS with parallel compression provides all low and medium temperature refrigeration, and office AC as well as sanitary hot water and warm glycol for defrost. An evaporative condenser/gas cooler ensures CO2 gas cooler exit temperatures not exceeding 31°C at 80 bar at 28°C Wet Bulb, which is very efficient.