Abstract:

Objective Due to the increasing frequency and intensity of extreme hot weather, the indoor working environment temperature is high without using air conditioning, which will cause low work efficiency, physical discomfort and other problems. However, the cooling effect of conventional ventilation garment in high temperature environment is poor, and Fan-phase change material hybrid cooling clothing is not suitable for long working scenarios. In order to avoid high temperature hazards, improve the thermal comfort of the human body in high temperature environment, and reduce the building energy consumption, a pipeline thermoelectric refrigeration ventilation garment is developed.

Method Six subjects were selected to conduct human experiment in an environment with temperature of 35 ℃, relative humidity of 70%, and wind speed of (0.4±0.1) m/s. Objective physiological parameters (skin temperature, core temperature and heart rate) and subjective scores (thermal sensation, thermal comfort, wet sensation) were collected during the test to evaluate the comfort of the thermoelectric refrigeration ventilation garment. Thermal manikin experiment was carried out under the conditions of temperature (35±0.5) ℃, relative humidity (40±0.5)%, and wind speed (0.4±0.1) m/s to explore the cooling performance and energy saving potential of the thermoelectric refrigeration ventilation garment.

Results The results of the human dress test showed that the average skin temperature and back skin temperature of test group subjects were significantly lower than control group. The average skin temperature and back skin temperature decreased by 0.4 ℃ and 0.71 ℃, respectively, which showed that the thermoelectric refrigeration ventilation garment can have a cooling effect, and the back area was more obvious for direct ventilation. The ear canal temperature of test group subjects was significantly lower than control group, indicating that wearing the thermoelectric refrigeration ventilation garment will reduce the core temperature to some extent and reduce the risk of heat stress in high temperature and high humidity environment. No significant difference appeared in the heart rate, and the mean heart rate in both groups increased slowly over time and stabilized after 20 min. The scores of thermal sensation, thermal comfort and wet sensation were significantly lower than those of control group, which shows that wearing thermoelectric refrigeration ventilation garment can effectively alleviate the thermal sensation brought by the high temperature environment, promote the increase of sweat, reduce human sweating, inhibit the rise of the wet sensation of the subjects, and improve the thermal comfort of human body. Through the thermal manikin test, the thermoelectric refrigeration ventilation garment can provide relatively stable cooling effect for the human body. The average cooling power is 36.56 W, the cooling power of unit weight is 13.9 W/kg, and the cooling coefficient is 0.64. The proposed thermoelectric refrigeration ventilation garment has good cooling performance. In addition, under the premise of not affecting the cooling effect, wearing thermoelectric refrigeration ventilation garment can expand the indoor ambient temperature setting point by 2.4 ℃.

Conclusion The thermoelectric refrigeration ventilation garment enhances the heat dissipation of the human body by strengthening the two modes of convection and evaporation, which reduces the human skin temperature and core temperature, improves the heat sensation, wet sensation and thermal comfort of the human body, improves the dress comfort of the human body, and saves building energy. In the future research, semiconductors with greater power refrigeration sheet and air supply fan can be adopted to increase the coverage of the ventilation pipes, and to improve the cooling effect of the ventilation garment. At the same time, on the premise of ensuring that the cooling effect of ventilation service is not affected, the refrigeration device and ventilation pipe with lighter weight are selected to improve the portability of the ventilation service.

Key words: thermoelectric cooling, ventilation clothing, dress comfort, cooling performance, energy saving potential