Experimental and numerical investigation of thermal environment of the child trapped in a parked vehicle

Pediatric vehicular hyperthermia (PVH) has aroused wide public concern recently. High temperatures in closed vehicles with full sun exposure and no ventilation in summer seriously endanger children's lives. Aiming at this practical problem, this study first took the temperature of child’s core body as a standard, and divided the hyperthermia into three stages: un-compensable heating (Tc > 37ºC), heat stroke (Tc > 40ºC) and critical thermal maximum (Tc > 42ºC). On this basis, two weeks of outdoor parking experiments during 10:00-18:00, using an equivalent size dummy were conducted to explore the influence of ambient temperature and solar irradiation on cabin temperature, humidity, and child’s core body temperature. According to the experimental results, at an ambient temperature of 32.4ºC, the child in the cabin developed un-compensable heating within 72min, suffered heat stroke within 129min, and reached the critical thermal maximum within 151min. Considering the limitations of the experiment, a numerical study was conducted to analyze the effects of ambient temperature, solar irradiation, and window radiation characteristics on cabin temperature and flow fields comprehensively. Simulation results were in good agreement with the experiments: even at low ambient temperature Ta = 23ºC or weak solar irradiation (ts = 18:00) condition, the temperature in a closed compartment could reach the "hazardous" level. This study can provide guidance for public to increase security and prevention awareness, and promote the development of relevant policies and technologies.