A Study On "Ice-making In Summer" In Huai Nan Wan Bi Shu

Records of"ice-making in summer"have appeared many times in ancient books."Ice-making in summer"recorded in these ancient books was universally regarded as primitive artificial ice-making techniques in ancient china."melting glue in winter,making ice in summer"is recorded in Huai Nan Zi, which is the famous work of Huai nan school, the specific operating method was recorded in Huai Nan Wan Bi Shu:"put some hot water in urn, seal it with new Jian, sink it in the cool water and it will become ice 3 days later". Similar records existed in every periods throughout our history. Low-temperature is necessary in ice-making procedure, while Huai Nan School , on the contrary,"put hot water in urn"making ice with hot water, it seems imaginable. Mr Hong Zhen huan considered this as"A problem to which has been paid much attention by researchers in the field of history of physics in ancient china whereas unsettled for a long time". Many scholars have studied this problem and proposed some programs, such as Hong's"air pressure influences freezing point", Li Zhi chao and Zhao Hong jun's"Joule-Thomson effect". However, this problem still remains unsettled, even it was concluded as impossible.This essay analyzed the method and procedure of ice-making recorded in Huai Nan Wan Bi Shu in depth, and creatively proposes the principle of"ice-making in summer", which is refrigeration through the quick evaporation of water under low pressure absorbs heat, and in contrast to traditional view, ice was found in Jian at the top of the urn instead of inside the urn, therefore it makes clear that three necessary conditions should be fulfilled in order to realize"making ice in summer": relative humidity is low enough (less than 26%), the volume of the urn is big enough( about 100L), temperature of air is proper( about 20℃).The feasibility of ice-making by"Heat-absorption caused by quick evaporation"was testified.Huai Nan school's"ice-making in summer"is a pure physics experiment which has nothing to do with pragmatism. It didn't appear in western world until William cullen, a chemistry professor in Edinburgh made it by evaporating ethyl ether. It's 1800 more years later than Huai Nan school's. With their wisdom, Huai nan school realized artificial ice-making in practice long before thermo-dynamics appeared, it's unfair to say that it isn't a miracle in history of science and technology in ancient china.