# Design and Research of Thermoelectric Generator Simulation System for Boiler Flue Gas Waste Heat
## 3 Experimental Research on TEG Simulation System
### Design of cold end module  
In order to maintain a stable temperature difference, it is necessary to dissipate heat from the cold end in time. There are three heat dissipation modes for the cold end module: fan heat dissipation, natural air heat dissipation, and water cooling heat dissipation. The fan heat dissipation method is to connect a heat dissipation plate with many sides on the aluminum alloy deflector, and then take away the heat conducted to the heat dissipation plate through the fan. The cooling effect is related to the area, the gap between plates and the wind speed. The natural air cooling method requires no other equipment and uses aluminum alloy deflector at the cold end to dissipate heat. Due to the relatively small thermal conductivity of air and thermal radiation, the heat dissipation method is less effective. With the extension of time, the temperature of the cold end will rise quickly and affect the efficiency. Water cooling heat dissipation is to connect the tap water into the aluminum alloy deflector, and the tap water flows in from one end of the aluminum deflector and then out from the other. This cooling method can keep the water temperature relatively stable and does not pollute the water. The output hot water can be used for industrial or domestic water. Figure 4: Schematic diagram of TEG experimental device. Typical water cooling heat dissipation deflectors employ a relatively slender hollow design, featuring an inlet and outlet for water at opposite ends, resulting in a suboptimal heat transfer efficiency. In this paper, the structure of the aluminum alloy deflector is optimized, and the optimized design of the aluminum alloy deflector is shown in Figure 5. The fins inside the deflector are dense, and the heat exchange effect is very good, which can ensure the uniformity of temperature on the deflector. The surface of the deflector is very smooth and has almost zero contact with the thermoelectric plate. The deflector's inlet and outlet are outfitted with chamfered steps that facilitate installation and prevent the water pipe from detaching after being tightened. Through the analysis of the above three cooling methods, water cooling heat dissipation method is the best, and natural air heat dissipation method is the worst. This paper intends to choose a water cooling heat dissipation method with tap water in the aluminum deflector, and the output hot water can also be used twice to improve energy utilization efficiency. (2) Design of hot end module  
As shown in Figure 6, the hot end module is composed of aluminum alloy deflector, PT100 thermocouple, Delici relay, industrial electric heating rod, temperature sensor (Mico sensor), heat resistant silicone tube, peristaltic pump and oil tank, etc. In order to ensure the uniformity of temperature distribution at the hot end, the hot end aluminum deflector adopts the same internal structure as the water cooling deflector. The fins inside the deflector are dense, which can improve the heat exchange effect. The use of double-headed peristaltic pumps solves the problem of hot oil and water flow. (3) Composition of TEG module  
The TEG module designed is composed of multiple thermoelectric plates in series, which is made of semiconductor material Bi2 Te3. This material works best at temperatures below 230 \({}^{\circ}\)C and is the most commonly used material for commercial TEG applications [28]. It has a large Seebeck coefficient and high thermal conductivity, with a ZT value of about 1 in commercial preparations. The uniformity of temperature distribution on the hot and cold ends of the TEG module affects the output power, where a reasonable installation position and good contact will affect the temperature distribution [29]. It is especially important to  
Figure 5: Internal structure diagram of aluminum alloy guide plate. Figure 6: Schematic diagram of hot end module. increase the temperature uniformity on the hot and cold ends of the module as much as possible.