Abstract
Since environmental problems are getting to be very serious in these days, we have to provide for the protection of the environment as soon as possible. As a result of the Montreal Protocol and the Kyoto Protocol, utilization of CFCs and HFCs are restricted to phase out and to cut down respectively. Therefore, an interest is growing to apply a cryocooler to the non CFCs' and non HFCs' refrigeration system, which will be a candidate for alternatives of the traditional vapor compression refrigeration system. In particular, a helium gas is one of the promising refrigerants for its zero ODP (Ozone Depletion Potential) and zero GWP (Global Warming Potential) characteristics. In this paper, some kinds of heat exchanger have been discussed to compare the characteristics among various kinds of refrigeration system. And in addition, a Stirling cycle refrigeration system, such as pulse tube refrigeration, is focused to concretize the value of it and at the same time a checking up the feature of a pulse tube refrigerator is done. To make further reference to the performance of pulse tube refrigeration, a numerical calculation has been done. As a result of it, a velocity distribution in section varies greatly owing to the operating condition. Especially, near the solid wall, the definition of the thickness of boundary layer is difficult and that thickness acts on the refrigeration performance. Finally to improve or develop the Stirling cycle refrigeration system, some comments are made.