Optimization of environment control system for narrow sleeping space in underground shelters

Abstract

As one of the main functions of urban underground spaces, underground shelter can be utilized for prevention/mitigation of disasters. In underground shelter, narrow sleeping spaces are recommended due to cost-effective and space-saving charcteristics. However, it is challenging to create a satisfied indoor environment with narrow sleeping spaces because of the limited space, high density of occupants and complex physical fields. In this study, an environmental control system was proposed for narrow sleeping spaces with multiple occupants, and numerical simulations were adopted in design and optimization process. Firstly, a numerical strategy (including turbulence modeling, meshing method and experimental validation) was proposed for the environment control system. Secondly, the validated numerical model was adopted to investigate the influences of key design parameters (such as inlet air velocity, temperature, air supply angle and airflow pattern) on indoor environment and energy consumption of narrow sleeping spaces with airflow pattern of “Up-supply and Down-return”. Thirdly, the CFD-GA (Genetic Algorithm) method was utilized to optimize multiple design parameters of the environment control system. The optimal results indicated that all of the indexes (predicted percentage dissatisfied [PPD], percentage dissatisfied of draft sensation [PD] and carbon dioxide [CO2] concentration) satisfied the requirement of standards, and its energy consumption was much lower than other design conditions. Compared to the “Up-supply and Down-return” airflow pattern, the “Down-supply and Up-return” airflow pattern produced higher PD values and caused stronger draft sensation. Overall, the numerical strategy and CFD-GA optimization method is able to provide proper design of indoor environment control for the underground narrow sleeping space, from the perspectives of thermal comfort, air quality and energy saving.