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据估计,现在全世界每年所消耗的矿产燃料相当于史前每二百万年地球所储存的。当今燃料的供应,便成了尖锐的问题。很多人从事研究寻找出路,美国在1978年所拨研究费为39亿美元,超过32亿美元的空间研究费用。目前在工业发达的国家里,空气调节(包括采暖)所消耗的能源量占能源总耗量的比例很大,每年平均以4～5％的速度在增长着。所以,空气调节上的节能问题也十分重要。节约能量方法很多,其中主要的方式为废热回收。若仅靠热交换的方式进行回收,则在温度差很小的情况下(在空调上大都属这种情况),效率是不高的。这是由于; 热量的传递,不仅遵循热力学第一准则,即能
It is estimated that the mineral fuels consumed by the world each year are equivalent to what the Earth stored every two million years ago. The supply of fuel today has become a sharp problem. Many people engaged in research to find a way out. The United States allocated 3.9 billion U.S. dollars in research fees in 1978, which exceeded the space research cost of 3.2 billion U.S. dollars. At present, in industrially advanced countries, the amount of energy consumed by air conditioning (including heating) accounts for a large proportion of total energy consumption, which is growing at an average rate of 4 to 5% per year. Therefore, the issue of energy conservation in air conditioning is also very important. There are many ways to save energy, the main one being waste heat recovery. If only the heat exchange method is used for recovery, in the case where the temperature difference is very small (this is mostly the case in air conditioners), the efficiency is not high. This is due to the fact that heat transfer not only follows the first thermodynamic criteria, ie