Simultaneous industrial waste heat recovery and power generation using heat pipe assisted thermoelectric generator
Creators: name: Remeli, Muhammad Fairuz
Publisher: name: RMIT University
Year: 2024

description: In most of the process industry, more than two third of the energy used is lost to the environment as waste heat. The current energy conversion systems are not sufficiently efficient to avoid this thermal energy leakage. With the broad concern about recent rises in the price of oil, society has turned attention to technologies which can reduce fossil fuel consumption and minimise the greenhouse effect. The reuse of industrial waste heat can save money and represents an efficient energy practice for industry. However, most industrial waste heat is of low-grade and at low temperature. This type of waste heat is difficult to recover or to use with a conventional heat engine, for example a steam turbine in a power plant. It is highly desirable for researchers to design a heat transfer device which works passively in order that minimal temperature drop can be achieved when recovering low-temperature waste heat.<br><br>There are many types of heat recovery system readily available in the market including the convective-type recuperator, heat wheel, and economizer. Most of these systems need auxiliary forces such as using a pump or compressor to move the heat transfer fluid in their operation. Consequently these systems require additional electrical energy input and frequent maintenance. However, the heat pipe offers a simple solution to these problems because it is a passive heat transfer device. The heat pipe has a compact design, is light in weight and has no moving parts. A heat pipe allows its working fluid to evaporate at low temperature under vacuum pressure. This use of heat pipes can minimise the temperature drop during heat transfer processes and can increase heat recovery effectiveness.<br><br>A thermoelectric generator (TEG) is a solid state energy converter which allows the direct conversion of waste heat into electrical power using the Seebeck effect. As with the heat pipe, the TEG operates without moving parts, vibration or noise and is very reliable. It is capable of generating power even with low-temperature difference between the heat source and sink which is highly desirable for the low-grade waste heat case. Although the TEG is known for having low thermal-to-electrical conversion efficiency, many recent studies have been conducted to design more advanced and high-performance TEGs by improving their material properties. The TEG is ideal for waste heat recovery because its operating cost is negligible compared to the TEG module cost as the energy input into the TEG is free. An important part of TEG power generation is optimisation of the heat transfer system to reduce the overall cost-per-watt of the energy production.<br><br>The aim of this research work was to develop a passive heat transfer and heat to work conversion system for simultaneous heat recovery and power generation. This system is designated as a heat pipe thermoelectric generator (HP-TEG). The basic concept of the system consists of thermoelectric generators (TEGs) sandwiched between two heat pipes, one connected to the hot side of the TEG, and the other connected to the cold side of the TEG.<br><br>The thesis presents a detailed design process, a theoretical model, experimental analysis, and cost-benefit analysis for an actual system. The proposed system has the potential to simultaneously recover waste heat and produce electrical power in an entirely passive system without any auxiliary forces. <br><br>