LOW CHARGE REFRIGERATION SYSTEMS : THERMODYNAMIC APPROACH AND MAIN GOALS

摘要

Refrigeration systems implies usually vapour compression machines. Typically the machine is composed of four main components : the compressor, the valve and two main heat exchangers (HEX): evaporator and condenser. The studies done until now appear to focus on charge limitation relative to these main components, and more precisely of compact HEX. Recently a paper [1] gave an important insight on the fact that the machine operating characteristic could be drastically affected by using non appropriate mixed refrigerant charges. We know that even with pure refrigerant, the design of low refrigerant charge systems could be strongly dependent on connexions and auxiliaries, as well as on oil-refrigerant interactions. Moreover a competition could exist with other alternatives, with more friendly refrigerating fluids (sorption systems), or systems without fluids. We intent to propose a review of some criterions that could be useful in order to compare the various alternatives of machines. The main purpose of the paper is directed in direction of energy efficiency, environment and economy. A new criterion EC ecological cost is developed, in conjunction with entropy analysis and refrigerant mass charge. Two examples are given relative to local design or global appraisal of the HEX (evaporator and condenser).