Study on the Impact of Solar Chimneys on Thermal Comfort and Energy Efficiency in Portable Toilets

Lanzhou Jiaotong University, Lanzhou, Gansu, 730070 China

^* Corresponding author: wangtp@mail.lzjtu.cn

Abstract

To address the issues of energy consumption, ventilation, and pollutant accumulation in mobile toilets, this paper proposes an optimisation strategy for human thermal comfort and energy conservation based on solar materials and the chimney effect. Through a heat-collecting wall-mounted vent system, CFD simulation and pollutant dispersion models are used to quantify its performance. The results show that: under extreme low temperatures of -10°C, the optimised mobile toilet achieves a maximum indoor temperature difference of 5.93°C, with the thermal comfort zone expanded by 40%, a 50% reduction in temperature gradient, and significant improvements in PMV-PPD indices during the transitional season and summer. In winter, the average PPD decreased by 58%, and in summer, the PPD reduction reached 10%. Compared to traditional models, annual ventilation energy consumption was reduced by 74.5%, thermal comfort-related energy consumption decreased by 67.2%, and the overall energy savings rate reached 58.5%. This approach holds significant reference value for improving the thermal environment of mobile toilets and advancing the achievement of carbon peaking goals. While the study lacks field experiment, the CFD models were rigorously benchmarked against established solar chimney studies^5,6,11 with grid independence verification.