A study on heat transfer enhancement in the radial direction of gas flow for thermoelectric power generation
A study on heat transfer enhancement in the radial direction of gas flow for thermoelectric power generation
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DOI：
10.1016/j.applthermaleng.2016.03.063
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发表时间：
2016-06
影响因子：
6.4
通讯作者：
Xin-Zhu Wang;Bo Li;Yuying Yan;Sheng Liu;Jun Li
中科院分区：
文献类型：
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作者：
Xin-Zhu Wang;Bo Li;Yuying Yan;Sheng Liu;Jun Li
温差发电系统的性能主要取决于热电腿的热端温度和腿的热端和冷端之间的温差。为了保持TEG模块在最佳条件下工作，需要保持通过TEG的超过10 W/cm 2的高热通量。由于通常在400 °C至800 °C范围内的高温下气流至排气管壁表面的低传热系数，进入TEG热交换器的实际热通量受到显著限制，导致TEG转化的效率相对较低。在本研究中，提出了一种有效的解决方案，以加强在径向方向上的气体流到TEG的热传递的高温热管垂直浸入到排气流的装置。类似地，常规热管径向地插入同心冷却剂套中，以便增强TEG模块的冷侧处的热传递性能。总的来说，TEG组件被配置为紧凑且可扩展的热管热交换器。模拟结果表明，对于正常的发动机冷却剂回路，TEG的热侧温度可以达到并保持高达300 °C，而TEG的冷侧温度可以保持在约85 °C。结果还表明，TEG系统越靠近管道中的热源，预期的发电效果越好。此外，在更高的发动机速度下可以预期更好的热电发电。通过在催化转化器和消声器之间安装TEG热交换器，可以在450 W和5000 rpm下实现热电热交换器中的最佳功率输出。如果TEG热交换器邻近催化转化器的出口，则对于单个子管线，6000 rpm时的最佳模拟性能为705 W。因此，由于现有的排气管是双管道系统，因此可以实现1410 W的总发电量。
The performance of thermoelectric generation (TEG) systems is significantly dependent on the hot side temperature of thermoelectric legs and the temperature difference between the hot side and cold side of the legs. To keep the TEG module working at an optimal condition, a high heat flux over 10 W/cm2through the TEG needs to be maintained. Due to the low heat transfer coefficient of the gas flow to the exhaust pipe wall surface, typically at a high temperature ranging from 400 °C to 800 °C, the actual heat flux into the TEG heat exchanger is limited significantly, resulting in relatively low efficiency of the TEG conversion. In the present study, an effective solution for enhancing the heat transfer of gas flow in the radial direction to the TEG is proposed by means of immersing high temperature heat pipes perpendicularly into the exhaust flow. Similarly, conventional heat pipes are radially inserted into a concentric coolant jacket in order to enhance heat transfer performance at the cold side of TEG modules. Overall, the TEG assembly is configured as a compact and scalable heat pipe heat exchanger. The simulation results show that the hot side temperature of the TEG can reach and be maintained as high as 300 °C while the cold side temperature of the TEG can be maintained at approximately 85 °C for a normal engine coolant loop. The results also show that the closer to the heat source in the pipeline the TEG system is located, the better the power generation that is expected. Moreover, better thermoelectric generation can be expected at a higher engine speed. By installing the TEG heat exchanger between catalytic converter and muffler, the best power output in the thermoelectric heat exchanger can be achieved at 450 W and 5000 rpm. If the TEG heat exchanger is adjacent to the outlet of a catalytic converter, the best-simulated performance at 6000 rpm is 705 W for a single sub pipeline. Therefore, a total power generation of 1410 W is achievable since the existing exhaust pipe is a dual pipeline system.