Design And Performance Research Of A Solar Wood Dryer With Latent Heat Storage System

There were some shortages in traditional solar drying, such as low thermal efficiency of air collector, intermittent heating and unsteady energy intensity.And the drying device with heat storage system more used concrete, natural zeolite to storage heat by the way of sensible heat, which was bulky and low thermal efficiency. Latent heat storage increasingly became the first choice because of high energy density, easy to match the operating system and easy to control. The use of technology of latent heat storage made solar wood drying have more promising future.The paper started from theoretical calculation, designed and developed a new type solar wood dryer with latent heat storage system. The performance testing was also finished. The results of research could provide theoretical guidance and reference for further research and industrial application of solar wood drying. Main conclusions were as follows:(1) Heat-pipe vacuum tubes were as air solar collectors components, fork row aluminum tube bundles with paraffin were as heat storage unit, The dryer was equipped with automatic and manual control system, and automatic data acquisition system. It could automatically operated five modes, including without action, storage heat, collector supplying heat, storage heat system supplying heat, auxiliary heater heating.(2) Collector highest exit temperature, average power, supplying heat efficiency and highest total efficiency were 64.8℃,0.572 kW,56%,70%, respectively.(3) The paraffin which phase change temperatures was between 48～54℃was chosen as PCM. Heat transfer coefficient, heat storage coefficient, average heat storage coefficient and heat storage density were 26.4 W/m2,58.8～74.4%,66.5%,54.5 MJ/m3, respectively.(4) Solar drying experiment was studied on the 35 mm thickness cunninghamia lanceolata. Solar drying spent only 99 hours from initial moisture content 72.7% to final moisture content 13.5%. Comparing with the air drying, it shortened 111 hours, raised drying rate1.12times. Comparing with conventional steam drying, energy saving rate of solar drying was 71.2%.(5) The relation between dosage of PCM in heat storage system and timber volume was deduced for the first time, namely:...