A Study on Designing and Manufacturing a Set of Intermediate Testing Equipment for Drying Agricultural Products with Geothermal Energy

According to drying theory and experimental results, the paper has given the principle how to determine original design parameters for hot air type drier. The method of thermodynamic calculation for the drier has also been given. This method needn't to calculate the exhaust thermal loss. Thus, it makes the calculatin process to be simplified. According to this design idea, a set of intermediate testing hot air type drying equipment has been designed and manufactured. The thermal source of the equipment is 60- 70℃ geothermal water. The drier has a batch capacity of 200kg raw material. The maximum drying rate is above 30kgw / h when moisture content of the raw material is higher than 90% and the average thermal efficiency of 53% has been obtained in the whole drying period.The result of drying experiment indicated that in practical process, drying constant-rate period exists only in the condition that the moisture content of raw material is higher than 90% and a great deal of surface combined-moisture exists.