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Optimization of TEG for Human Body Powered Mobile Devices

Most of the energy leaves our bodies in the form of heat simply due to existing temperature gradients in the environment. An average human body at rest emits about 350,000 J of energy per hour, which is roughly equivalent to the energy given off by a 100-Watts incandescent light bulb [1]. As a matter of fact, the conversion of human-body-heat into electrical energy using a solid-state thermoelectric generator (TEG) sparks interest in creating wearable self-powered mobile electronics and sensors [2]. This paper develops a prototype to investigate the performance of a human-body-heat-powered mobile fan using a commercial TEG and a heat-sink structure [3]. The heat-sink is attached to the cold-side of the TEG, with a 20mm x 7mm DC motor centered by the pin fins. As body-heat from the wrist is being applied to the hot-side of the TEG via thermal conduction, a voltage is generated across the terminal of the TEG to power the DC motor, whereas the operating DC motor produces further cooling to the heat-sink through forced convection. The proposed model is calculated analytically by solving governing equations of heat transfer, numerically via ANSYS Thermo-Electric simulation, and experimentally by testing the customized model. The temperature and voltage distributions in the TEG are analyzed, and the effects of the material properties, sizing of the TEG and heat-sink structures, and thermal contact resistance at the interface between TEG and human-skin are discussed. The results obtained in this research can be utilized for optimal structural designs of wearable TEGs and for material selection to enhance the power generation for body-heat-powered mobile devices.