Numerical simulation of thermal comfort in microgravity-confined space

Abstract

To investigate the thermal environment in a crewed space capsule, the velocity field, water vapor concentration field, local Nusselt number, and thermal comfort in microgravity are studied by numerical simulation. The results show that (a) gravity has an essential effect on the cabin flow field and personnel heat exchange. When the air supply velocity is less than 0.45 m/s, the average Nussert number on the body surface under normal gravity is more significant for the top air supply system. On the contrary, when the air supply velocity is higher than 0.45 m/s, the average Nussert number on the body surface under microgravity is larger. (b) In microgravity, due to the weakening of natural convection. Water vapor accumulates around the human body, increasing local relative humidity. When the relative humidity rises from 20% to 80%, the standard effective temperature rises by 1.6°C. (c) By analyzing the SET* under each working condition, we can conclude that the impact of personnel activity rate on Comfortable Environment Condition is weak under microgravity. When the air supply speed equals 0.06 m/s, indoor thermal comfort could be improved by increasing the lower temperature limit value or decreasing the upper humidity limit value of the Comfortable Environment Condition.

Keywords

• Thermal comfort
• Microgravity environment
• Standard effective temperature
• Numerical simulation