New heat exchangers for high efficiency CO2 plants.

CO2 refrigeration systems are now in widespread use in many applications, especially in the retail sector. In fact CO2 is an excellent, environmentally-friendly refrigerant which requires very efficient heat exchangers to reach high performance. LU-VE recently made developments with the aim of further improving the design of the finned heat exchanger, using also new technology with a very compact heat transfer matrix with tube diameter of only 5mm. The new heat exchanger configuration is designed both for gas coolers and unit coolers. The paper describes the activity of designing and testing the new geometry inside the CO2 test plant of the company. The new geometry provides an excellent balance between performance and reduced quantity of refrigerant in the circuit. A further development was made in the heat pump sector, in particular for supermarket applications. The decision to integrate the refrigeration and heating systems in these buildings is becoming increasingly common. However, in order to guarantee a sufficient quantity of heat to warm the supermarket even on the coldest days, with temperature below -10°C, an additional evaporator, positioned outside, must be added. This involves a special machine for which LU-VE has developed innovative technologies, capable of achieving very high levels of heat transfer efficiency, as described in this article.