Abstract:

Objective The upper torso is the part of the human body with the highest heat output, and the temperature changes in cold and hot environments greatly affect the thermal balance of the human body. In response to the design issue of the cold and hot regulation zone in the integrated refrigeration and heating clothing, this study explores the degree of cold and hot demand for various parts of the upper torso affected by the cold and hot environments of the human body using skin temperature as a key indicator.

Method The skin temperature of different zones of the upper torso of young men was measured in cold and hot environments in four different movement states, including sitting, standing, walking, and brisk walking. The distribution of human organs and the distribution of human sweating were adopted to divide the upper torso skin zone, and contact temperature sensors was adopted to continuously monitor the skin temperature. The changes in skin temperature of each part were analyzed to judge the cold and hot conditions of local areas, and cluster analysis was employed to classify the skin temperature changes.

Results By comparing the local temperature with the average skin temperature in the same environment and comparing the local skin temperature under the same movement state, it was seen that the distribution pattern of skin temperature in the upper torso of the human body in cold environments was studied and it showed that the average skin temperature of the human body demonstrated an overall decreasing tendency, with particularly significant changes in all four states. But the skin temperature of each part of the upper torso was decreasing and then increasing. During the sitting state, skin temperature in most zones was decreased significantly, and at this state, the temperature of side chest and back shoulder was generally significantly lower than the average skin temperature of the human body. At any states, the temperature of the side chest and back shoulder was at a lower level compared to other torso zones, which was lower than the thermal comfort temperature of the human body. Except for some zones close to the core organs of the human body, the skin temperature was relatively high and changes were relatively small. As the cooling time was increased, especially during the brisk walking state, the temperature change was decreased and the cold sensation gradually weakened. The distribution pattern of skin temperature in the upper torso of the human body under thermal environment showed that the overall skin temperature in various parts of the upper torso was similar to the average skin temperature of the human body, both of which was increased as experimental time got longer. The maximum temperate increase was observed at the sitting state, with temperature at the front shoulder, back shoulder, and middle back significantly becoming higher than the average skin temperature of the human body. At the same state, the temperature of all parts was generally higher, with the front and back shoulder being higher in any state and higher than the temperature of human thermal comfort. And the results obtained in the same environment and at movement state were consistent with the classification results obtained through cluster analysis. In addition, through comparison, it was found that the influence of the environment on skin temperature in various parts was much greater than that of the movement state. Therefore, it was necessary to focus on considering the impact of the environment on the local skin temperature of the human body.

Conclusion For the design of the cold and hot regulation zone in heating clothing, combined with the cold and hot situation in local zones of the human body and the results of cluster analysis, a heating device is adopted to focus on heating the side chest and back shoulder of the first level heating zone, so as to achieve local heat adjustment. For the design of the cold and hot regulation zone in refrigeration clothing, the refrigeration device is adopted to focus on cooling the front and back shoulders of the first level cooling zone. However, when designing the cold and hot temperature adjustment zone for clothing with both heating and cooling functions, it is necessary to comprehensively consider the degree of cold and hot demand in the side chest, front and back shoulders, and other zones.

Key words: skin temperature, movement state, division of upper torso shin zone, human thermal comfort, functional clothing