Wearable Thermoelectric Generator with Copper Foam as the Heat Sink for Body Heat Harvesting
ABSTRACT
Wearable thermoelectric generator (TEG) is an attractive technology to enable self-powered electronics and sensors for healthcare and the Internet of Things through its ability to convert body heat into electricity. However, the actual inner temperature gradient in the thermoelectric legs is relatively small when a TEG is worn on the body, which leads to a low voltage and power generation. To enhance the output performance, the structural design of a wearable TEG with copper foam as the heat sink is proposed. A thermal resistance model was developed to investigate the effects of using copper foam heat sink on the heat transfer and performance of the TEG. In addition, for comparison, the inner temperature gradients and open-circuit voltages of the TEGs with and without plate-fin heat sink were analyzed. Then, these different TEGs were fabricated and tested using an experimental setup. The results showed that TEGs with heat sinks could generate greater open-circuit voltage and output power values, while the TEG with copper-foam heat sink achieved highest power-to-weight ratio. Finally, a wearable TEG with copper-foam heat sink was connected to a step-up circuit and worn on the wrist to power a miniaturized accelerometer for body motion detection. The results demonstrated that the wearable TEG with the copper-foam heat sink design provided a potential pathway for the realization of electronics powered by harvesting human body heat.
EXISTING SYSTEM
Wearable electronics and sensors for health monitoring are becoming increasingly popular as their functionality continues to grow. Wearable thermoelectric generators (TEGs) are attracting interest due to their ability to self- power these electronic devices or sensors by harvesting human body heat. For wearable TEGs, a flexible thermal interface layer (TIL) is used underneath the TEG for wearing on the human body. The large thermal resistance induced at the interface between the skin and the TEG currently limits improvements in the performance of wearable TEGs and needs to be evaluated. This paper develops a numerical model to investigate the performance of wearable TEGs on the curved human wrist. The TEG and bottom TIL are meshed using rectangular grids and the body-fitted coordinate (BFC) transformation, respectively. Using the finite volume method (FVM), the proposed model is calculated, and the temperature and voltage distributions in the TEG and bottom TIL are analyzed. The effects of the radii of curvature of the curved surface, the material properties, and the thicknesses of the TIL are investigated both numerically and experimentally. The results obtained in this research can be utilized for optimal structural designs for wearable TEGs and for material selection of the TIL to enhance the power generation for self-powered electronics
PROPOSED SYSTEM :
This paper presented a novel wearable TEG with copper foam as a heat sink to power the electronics needed for body motion detection. A thermal resistance model was developed to investigate the effects of different heat sinks on the inner temperature gradient and output voltage generation. The performances of TEGs without a heat sink, and with copper-foam and plate-fin heat sinks, were predicted and validated by experimental characterization. The copper-foam heat sink design could reduce the thermal resistance at the cold side, which increased the temperature difference and output voltage generation. Furthermore, the TEG with the copper-foam heat sink had the highest power-to-weight ratio, with a value of 30.73 μWg-1 at ΔT = 45 K. Thus, it would be suitable for body wearing and heat harvesting applications. Body wearing experiments demonstrated that a miniaturized accelerometer could successfully be powered by the wearable TEG for static and dynamic three-axis acceleration measurements under different movement conditions.
To enhance the output performance, the structural design of a wearable TEG with copper foam as the heat sink is proposed. A thermal resistance model was developed to investigate the effects of using copper foam heat sink on the heat transfer and performance of the TEG.
CONCLUSION :
This paper presented a novel wearable TEG with copper foam as a heat sink to power the electronics needed for body motion detection. A thermal resistance model was developed to investigate the effects of different heat sinks on the inner temperature gradient and output voltage generation. The performances of TEGs without a heat sink, and with copper-foam and plate-fin heat sinks, were predicted and validated by experimental characterization. The copper-foam heat sink design could reduce the thermal resistance at the cold side, which increased the temperature difference and output voltage generation. Furthermore, the TEG with the copper-foam heat sink had the highest power-to-weight ratio, with a value of 30.73 μWg-1 at ΔT = 45 K. Thus, it would be suitable for body wearing and heat harvesting applications. Body wearing experiments demonstrated that a miniaturized accelerometer could successfully be powered by the wearable TEG for static and dynamic three-axis acceleration measurements under different movement conditions.
The results obtained in this research open up opportunities for specific body motion detection applications based on the harvesting of body heat and using the proper design for a wearable TEG. The parameters’ effect of copper-foam heat sink on the heat transfer coefficient will be further investigated by experiments, and more applications of this wearable TEG with copper-foam will be conducted in future work