The Effect Of Hot Air On Paddy Drying And Germinating Rate

China is a big country with huge populations. The demand by economic development led to the decrease of farming land and thereby reduced crop yield year by year. On the other hand, annual grain loss due to various reasons is huge. Hence, it is acute importance to avoid the harvested grain loss. An effective measure is to extend grain drying machines. As drying machines are extended, the problem of drying machine operation appears. Attention not only should be paid on the quality of the dried grain, but also on economic energy consumption and reduced loss. Thus selection of reasonable drying technique and suitable drying parameters is an important guarantee for a better drying quality.The experiment was conducted during a real drying process. Using our own drying machine, we measured some drying parameters and experimented on the drying machines. The aim of this work is to learn the relationships between various parameters in drying procedure, so as to provide constructive opinion for the future improvement work.Results showed that grain water content steadily decrease with the time elapse, showing a decreasing trends. High water content grain lose water in a higher rate, having a steady rate, and when reaching a certain water content, turning into a decreased water losing rate. A linear relationship is noticed between drying time elapse and grain water content, a regression formula of M = at + b is suitable for expressing such a relationship.During the drying process, temperature of grain do not surge after an initial stage of pre-heating period, it fluctuates around a value but with a little degree. In general, higher drying temperature results into higher grain temperature. So that the control of grain temperature can be realized by the adjustment of the temperature of hot air.Average grain temperature increases as the temperature of the hot air increases, so is average drying rate.As the hot air temperature increases, the germinating rate is obviously impaired. When grain temperature is raised above 34C, seed germinating rate is clearly reduced. On the same drying conditions, the batch with longer drying period will have a lower germinating rate compared with the shorter drying period. A higher drying rate results into more reduced germinating rate. A higher initial water content relates to more reduced germinating rate. Onthe same hot air temperatures, reduced drying quantities relates to increased grain temperatures and higher drying rates, resulting into higher loss of germinating.In the drying process the hot air temperature should be properly adjusted. Depending on the drying conditions in the real practice, regulation of hot air temperature should be performed, so that no negative effect happens on paddy seed quality and the working efficiency of drying machine is increased, avoiding energy loss is reached.