THE APPLICATION OF THERMOSYPHON IN FIXED-BED OIL PALM DRYING

摘要

The serious problem which occurs in hot air drying process of oil palm through hot air is the bottom layer of oil palm bed is burnout while the top layer of oil palm bed is wet.The cause of this problem is a large temperature difference between the bottom and the top layer.This work studied the decrease of that temperature difference by inserting thermosyphon into oil palm bed.The temperature distribution inside oil palm bed with and without inserting thermosyphon was investigated.The water-steel thermosyphon with diameter of 38.1 millimeters was used in this work.The evaporator section with 400 millimeters was inserted into hot air flow passage, while the condenser section with 1000 millimeters was inserted in oil palm bed.The temperature of hot air was used as a heat source of hot air drying process which was 197 ℃.The oil palm bed was divided into 5 layers and 4 probes of K-type thermocouples were used to measure the temperatures of each layer.The temperatures inside the oil palm bed were recorded continuously for 11 hours.To clearer observation of the effect of inserting thermosyphon on temperature distribution of oil palm bed, the hot air was not allowed to flow through the oil palm bed i.e.heat from the hot air can be transferred to the oil palm bed by only thermosyphon.The result showed that the temperature differences between the bottom and top layer of oil palm bed decreased when thermosyphon was inserted into oil palm bed.Comparing with non-inserting bed, the temperature difference in the oil palm bed was decreased.Furthermore, the average temperature of oil palm bed was increased from 39 ℃ to 51 ℃.