Experimental Investigation on the use of PCM in a Pistachio solar dryer by the Evacuated Heat Pipe solar Collector

One of the most important application of solar energy is its utilization in solar dryers in which the agricultural products will maintain for long-term storage. Pistachio is one of the most important non - petroleum exports in Iran. Due to the importance of the drying method in preserving quality properties produced from the pistachio nut by using renewable energy sources, an indirect solar dryer with a vacuum heat pipe solar collector with 62.53 % efficiency was designed and fabricated with application of the paraffin as a phase change material with 55 ° C melting point. The dried product was compared with the dried hazelnut pistachio in terms of shape and good quality. Parameters such as the dryer chamber temperature, inlet and outlet temperature of the collector, humidity inside the dryer chamber and ambient humidity, solar radiation intensity, the moisture reduction curve for two cases was measured. Performance of the dryer was compared with PCM and without using PCM. The results were shown that utilization of phase change material improved the performance and efficiency of the dryer and increase the capability of drying process, around 2 hours after sunset.