A dynamic model of the human/cooling system/clothing/environment system.

摘要

The human body compensates well for moderate climatic heat stress, but artificial environments often block or overwhelm physiological defense mechanism. Personal protective equipment (PPE) is one of sources of heat stress. It protects individual from chemical, physical, or biological hazards, but the high thermal insulation and low vapor permeability of PPE may also lead to substantial heat stress. Personal cooling is widely used to alleviate heat stress, especially for those situations where ambient environmental cooling is not economically viable or feasible.; It is important to predict the physiological responses of a person wearing PPE with personal cooling to make sure that the individual is free of heat stress, as well as any additional discomfort that may occur.; A thermal model was developed to improve human body thermal comfort prediction. The system researched includes human body, personal cooling system, clothing and environment. An existing model of thermoregulation is taken as a starting point. Changes and additions are made to provide better prediction. Thermal resistance networks for the cooling system are built up; additionally a combined model of heat and mass transfer from cooling garment through clothing to environment is developed and incorporated into the personal cooling model and thermoregulatory model. The control volume method is employed to carry out the numerical calculation. An example simulation is presented for extra-vehicular activities on Mars.; The simulation results agree well with available experimental data, though a small discrepancy between simulation results and experimental data is observed during the beginning of the cooling process. Compared with a water cooling lumped model, the thermal model provides a much better prediction. For water cooling, parametric study shows that the cooling water inlet temperature and liner thermal resistance have great effects on the maximum exposure time; PPE resistance and cooling water flow rate do not have much impact on the maximum exposure time. For air cooling, cooling air flow rate, inlet temperature, relative humidity and liner resistance have great effects on the maximum exposure time.