Study on a ventilating vest with thermoelectric cooling to improve thermal comfort and cognitive ability

Abstract

Hot waves happened more often in summer due to the global climate change, which leads to hot indoor environment when air conditioning systems are absent. To improve individual thermal comfort in warm/hot indoor environment, a ventilating vest with thermoelectric cooling (TEC) was proposed. The design of TEC module and ventilating vest was introduced. The measured cooling capacity of cooling vest was about 25 W, including both sensible and latent heat. The effect of cooling vest on thermal comfort and cognitive ability was tested in the 29 °C, 31 °C and 33 °C environments. 18 male subjects were recruited to participant in the experiments. Subjective questionnaires including thermal sensation vote, thermal comfort vote, thermal acceptance vote, sweat feeling vote, and cold stimuli sensation vote were collected. Three cognitive tests were conducted including the Stroop test, typing test and number remember test. Physiological parameters including skin temperature, core temperature, local skin heat flux and heart rate variability (HRV) were measured. Results showed that continuous exposure to hot environment made the subjects felt hotter, more uncomfortable, more unbearable and sweatier. With the use of ventilating vest, all these subjective votes were improved significantly. With the ventilating vest, the skin temperatures of chest and back decreased a little, the decline was more significant in 33 °C. The mean skin temperature kept increasing during hot exposure, while the vest stopped the further increasing and reduced it slightly. When cooling vest was used, the core temperature was decreased by 0.05 °C, 0.3 °C, and 0.5 °C in the three temperature conditions, while the local skin heat flux increased approximately 4.8 % to 33.3 %. With the use of ventilating vest, the HRV indices of SDNN (Standard Deviation of Normal to Normal Intervals) and RMSSD (Root Mean Square of Successive Differences) were increased, while the LF/HF (Low Frequency to High Frequency Ratio) was decreased. Subjects’ cognitive performance in the three tests were also improved significantly when the vest was used.