Design, thermal performance evaluation, and economic analysis of a new solar air dryer suitable for high latitude regions

Seasonal solar energy in high-latitude regions has great potential for development, particularly in the field of drying agricultural products using solar-air dryers. However, the intermittency of solar energy and geographical conditions at high latitudes significantly reduce the heat-collection performance, drying efficiency, and economic benefits of typical solar air dryers (Type 1). Therefore, in order to improve the aforementioned indicators of solar air dryers, this study comprehensively considered the geographical conditions of high latitudes, seasonal sunshine conditions, and thermal characteristics of phase change materials (PCM) to design a new solar air dryer model (Type 2) suitable for high latitudes. A new model was constructed, and a mushroom-drying experiment was conducted. A comparison and analysis of the thermal performance and economic indicators demonstrated that the Type 2 PCM layer stored 3.453 x 105 J of heat energy after only 2.3 h, which was conducive to ensuring the continuous drying ability of the drying box at night. The average daily heat collection efficiency of Type 2 was 19.88 % lower than that of Type 1, indicating that the Type 2 dryer exhibited a good thermal peak transfer capacity, which transferred the heat energy of the solar day to the night. The drying time of the Type 2 dryer was 31.11 h, which was 5.15 h less than that of the Type 1 dryer, indicating that the Type 2 dryer had a higher drying rate. The Type 2 dryer exhibited a cost recovery period of 0.22 years, a daily profit of 29.95 USB, and a total profit of 26,658.69 USB over its life cycle, which was 3987.68 USB higher than Type 1. This demonstrates that the Type 2 dryer has better economic benefits, which greatly enhances the market competitiveness of the product.