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Human local and total heat losses in different temperature
Lijuan Wang1, Hui Yin1, Yuhui Di1
1College of Environmental and Chemical Engineering, Xi'an Polytechnic University, Xi'an 710048, China.
Physiology & Behavior
|February 17, 2016
Summary
Investigating operative temperature effects on human body heat loss reveals distinct patterns. Radiation and convection decrease with rising temperatures, while sweat evaporation increases, informing thermal comfort and HVAC design.
Area of Science:
- Environmental Science
- Human Physiology
- Building Science
Background:
- Understanding human thermal regulation is crucial for designing comfortable and energy-efficient indoor environments.
- Operative temperature significantly influences the body's heat exchange processes.
- Previous research has established general trends in whole-body heat loss, but detailed local variations require further investigation.
Purpose of the Study:
- To analyze local and total heat losses from ten body parts across various operative temperatures (23-37°C).
- To investigate the relationship between operative temperature, local heat loss distribution, and thermal sensation.
- To derive a formula for convection and radiation heat loss ratios for improved thermal comfort and HVAC design.
Main Methods:
- Quantitative analysis of convection, radiation, evaporation, respiration, conduction, and diffusion heat losses.
- Measurement and comparison of heat losses across ten specific body regions (head, neck, chest, abdomen, upper arm, forearm, hand, thigh, leg, foot).
- Experimental setup involving controlled operative temperatures of 23, 28, 33, and 37°C.
Main Results:
- Local heat loss is influenced by body part area (thigh highest for radiation/convection) and sweat gland distribution (chest highest for evaporation).
- Total local heat loss varies with temperature: thigh, leg, and chest at low temps; chest, abdomen, thigh, and head at high temps.
- Whole-body analysis shows decreasing radiation/convection and increasing evaporation with rising operative temperature; conduction, respiration, and diffusion remain relatively constant.
Conclusions:
- Local and whole-body heat loss patterns are significantly affected by operative temperature, providing insights for clothing and building design.
- The derived formula for convection and radiation heat loss ratios can enhance thermal comfort evaluations.
- Findings are valuable for optimizing heating, ventilation, and air conditioning (HVAC) systems and promoting energy efficiency.
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