Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
Global environmental and energy concerns have prompted the heating, ventilating, air-conditioning and refrigeration (HVAC&R) industry to re-visit the use of natural refrigerants. Nearly all natural refrigerants have superior transport properties as compared to synthetic refrigerants; however, the drawback with natural refrigerants has been their toxicity and flammability with an exception of carbon dioxide. In order to overcome this hurdle it is essential that enhanced surface methods be developed and introduced to reduce the refrigerant charge in a system. Halocarbon industry has expended enormous amount of time and money in developing ultra-high efficiency heat exchangers. This experience and knowledge is available and could be applied in developing efficient exchangers for natural refrigerant applications. This paper presents an over view of the status of natural refrigerants and the trends in development of compact and low-charge systems.