Hot Side Of Thermoelectric Generator Research Articles

Integration of thermal insulation and thermoelectric conversion embedded with phase change materials

The thermoelectric effect can convert waste heat into electricity. The present work presents an integrated system of Thermoelectric Generators (TEG) and Phase Change Materials (PCMs) for thermal insulation of high-speed vehicles, where high heat fluxes of large fluctuations make thermal protection and energy harvest challenging. A single-stage thermoelectric generator is prepared with phase-change materials embedded to absorb and convert excessive heat. The performance is evaluated experimentally and numerically, between which a reasonable agreement is observed. The maximum temperature at the outside surface is reduced by 200 K, and the temperature curves are flattered. Furthermore, two-stage and two-segment integrated systems are numerically evaluated, generating a data set of thermoelectric performance. An artificial neural network is developed for prediction and a genetic algorithm is employed for optimization. The maximum specific power can be improved to 570 W/m2 in the two-segment system, while the temperature variation at the hot side of TEG in the two-stage system can be reduced to 230 K. Finally, a discussion on the effects of PCMs parameters is performed. Overall, the present work not only demonstrates the feasibility of such an integrated system but also illustrates the whole procedure of the predictions and optimizations. This could inspire more development for advanced integrated systems for thermal management.

Design and investigation of the solar-thermoelectric energy harvesting system at asphalt pavements road

Renewable energy is the generation of power from natural resources that plays an essential part in our society and economy as it helps reduce emissions for more sustainable future. Therefore, this project aims to analyse two energy harvesting technology, photovoltaic (PV) panels and thermoelectric generators (TEG), in terms of charging and voltage generated from waste heat in a road environment. H-shape heat sinks passive cooling element at subterranean level was implemented to achieve a maximum temperature difference of 15°C for TEG. The top plate, the hot side of TEG, can obtain a maximum of 53°C with a cold side of TEG only increased to 4°C from its initial temperature. Three TEGs connected in series able to charge 5F supercapacitors within 3.5 h, while 3V rated PV solar panel, acquired 15 min to charge the supercapacitor fully. Integrated PV and TEG were evaluated regarding the connection configuration of both energy harvesters into a single system. Series connection of the integrated system takes 29 min to fully charged the supercapacitor where all the results are saved into a microSD card and easily read in Excel. This project provides new insight into the charging performance of the two combinations of energy harvesting technology.

Performance improvement of thermoelectric generator by drooping the cool side temperature with thermacool 0.3M coating

The hot side of Thermoelectric generator (TEG) receives heat from the heat source. Meanwhile, the output power and voltage depend on the temperature gradient between the hot and cold junction. Drooping the cold side temperature of TEG can increase the temperature gradient between its junction and subsequently the performance of the device. The conventional heatsinks used for heat dissipation and temperature drooping are at least twice as bulky as TEGs. Hence as an alternative, this work proposes coating of acrylic polyurethane-based heat reflective coating (Thermacool 0.3M) of 120 μm on cold side of TEG for drooping cold side temperature. To evaluate the performance of proposed system TEG (SP1848-27145) is tested in controlled temperature environment, Initially with heat sink model and later with thermacool 0.3M coating. A mathematical model has also derived for validation. The retardation in temperature of both model's cold side from 90 °C with respect to time are recorded. It is observed that after 4-minute of natural convection cooling the thermacool 0.3M coated model cool side temperature is 34 °C compared with 39 °C cool side heat sink attached model. There is a significant improvement in power, efficiency and figure of merit parameters of 0.18W, 3.8% and 0.04 respectively.

Using high-frequency ultrasonic and thermoelectric generators to enhance the performance of a photovoltaic module

In this study, 1.7 MHz ultrasonic and thermoelectric generators (TEGs) are used to cool down a photovoltaic (PV) module and improve its performance. The PV module is placed on a rectangular enclosure equipped with five ultrasonic piezoelectrics, which produce cold vapor of water inside the enclosure. The hot side of TEGs is attached to the rear surface of the PV module and their left side is cooled using water cold steam generated by ultrasonic piezoelectrics. The outcomes revealed that when the cooling system is not used, Ts,ave increases to about 62.81 °C in the steady-state condition, while by using just the TEGs and just ultrasonic (H = 1.5 cm), the Ts,ave is reached 55.4 °C and 52.3 °C, respectively. The hybrid cooling system of TEGs and ultrasonic reduced the Ts,ave to 48.1 °C and increased its output power by 25.7%. By using the proposed cooling system, considering the impact of H on the temperature uniformity of the PV module represents that H = 0.75 cm is an efficient value to achieve high power output. In addition, the electrical efficiency of the PV module at the more efficient condition boosts from 8.61% to 12.46% compared to the non-cooling system.

Nanofibrous electrocatalyst including nanofibrous continuous network of graphitic nanofibers having embedded catalytically active metal moieties

Present study demonstrates a waste heat recovery from the proton exchange membrane fuel cell (PEMFC) using thermally coupled thermoelectric generator (TEG) and metal hydride (MH) cylinder. In TEG system, cooling of cold side is very crucial that significantly affects its power output. Therefore, a strategy is proposed in which PEMFC, TEG and MH are thermally coupled for efficient waste heat recovery from the PEMFC. A mathematical model is developed for the theoretical prediction of the dynamic performance of the proposed system. The proposed strategy is compared with different cases of cold side cooling of TEG such as: 1. natural cooling 2. fan cooling. An experimental study is performed with1 kW PEMFC and 5000 L MH cylinder. An air duct is designed to extract the heat loss from the PEMFC which is utilized at the hot side of TEG while cold side is mounted on MH cylinder. Results show that PEMFC heat loss increases with increase in the operationg load, therefore TEG power output also increases. Maximum temperature difference ≈3.2 °C is achieved between hot and cold sides of TEG. It is observed that TEG modules coupled with MH can be an efficient strategy for waste heat recovery from the PEMFC.

Dynamic modeling and experimental analysis of waste heat recovery from the proton exchange membrane fuel cell using thermoelectric generator

Present study demonstrates a waste heat recovery from the proton exchange membrane fuel cell (PEMFC) using thermally coupled thermoelectric generator (TEG) and metal hydride (MH) cylinder. In TEG system, cooling of cold side is very crucial that significantly affects its power output. Therefore, a strategy is proposed in which PEMFC, TEG and MH are thermally coupled for efficient waste heat recovery from the PEMFC. A mathematical model is developed for the theoretical prediction of the dynamic performance of the proposed system. The proposed strategy is compared with different cases of cold side cooling of TEG such as: 1. natural cooling 2. fan cooling. An experimental study is performed with1 kW PEMFC and 5000 L MH cylinder. An air duct is designed to extract the heat loss from the PEMFC which is utilized at the hot side of TEG while cold side is mounted on MH cylinder. Results show that PEMFC heat loss increases with increase in the operationg load, therefore TEG power output also increases. Maximum temperature difference ≈3.2 °C is achieved between hot and cold sides of TEG. It is observed that TEG modules coupled with MH can be an efficient strategy for waste heat recovery from the PEMFC.

Experimental study on waste heat recovery system of an internal combustion engine using thermoelectric technology

Internal combustion engines do not effectively convert energy from the chemical reaction into useful energy, notably mechanical energy. In fact, majority of the energy are converted into heat energy, and dissipated into environment which does not fully contribute to the performance of internal combustion engine. This results in lower overall efficiency of the engine. The heat released into the environment can be converted into useful electrical energy by using thermoelectric generator (TEG). TEG consists of cold side and hot side and works based on the principle of Seebeck effect. The hot side of TEG is exposed to hot surfaces of the exhaust, and the cold side is cooled with fan cooled heat sink. The function of heat sink is to increase the temperature differences across the TEG. The conversion of waste heat into electricity by TEG in an automobile can be a good case study to replace the alternator for battery charging and increase the overall efficiency of the Internal Combustion (IC) engine. In this study, eight pieces of TEG with dimensions of 40 mm x 40 mm each were attached to a square heat exchanger. This heat exchanger was connected to the exhaust pipe of the engine. The temperature recorded in the exhaust was more than 150 °C. Thermocuples were embedded on the hot side and cold side of the thermoelectric generators to evaluate the temperature differences across the TEGs. The output of the TEGs were obtained at idle and half-throttled engine conditions. An electronic load was applied to obtain the voltage, current and the power output from the TEGs system. The TEGs were tested individually, all connected in series and parallel connections. The maximum output voltage was recorded for the series connections at 5.8 V with an average hot side temperature of 48 ° C across TEGs. Maximum power output obtained when all the TEGs connected in series was at 2.3 W.

Harvesting Waste Heat Energy from Automobile Engine Exhaust Using Teg with Heat Pipes

This research investigates how the heat from car exhaust pipe line can be recovered as power using passive Thermo electric generator (TEG) using heat pipes. In this research the heat pipes are place on the cold side of TEG to remove the rising temperature and hot side of TEG is placed on the circumference of exhaust pipe line of car engine. The heat pipes with and without nano-fluids were placed on cold side of TEGs to investigate heat removal from increasing temperature and too maintain constant temperature on cold side. On the basis of results from 3D finite element simulations and experiments in the setup, the heat flow, voltage, and current were measured. The method presented in this paper gives detailed insight into how TEG modules perform in general, and also enables prediction of potential improvement in module performance by using different nano-fluids as coolants and Preliminary results were obtained. The results of Finite Element Analysis are analogous with the experimental results of TEG with water filled heat pipes with minimal possible errors. Therefore, the performance of nano-fluids in heat pipes are numerically evaluated and proposal are made for the enhancement of Module power outputs in Harnessing exhaust heat energy.

Modeling and fabricating a prototype of a thermoelectric generator system of heat energy recovery from hot exhaust gases and evaluating the effects of important system parameters

The heat lost through smokestacks has an adequate energy recovery capacity. A new and effective method of recovering this energy is the use of thermoelectric generators, which directly convert thermal energy to electricity. Some of the advantages of thermoelectric generators include their environmental friendliness and also their lack of moving or rotating parts, which makes them operate without noise and extends their service life. This paper deals with the general modeling of a thermoelectric generator system, including the modeling of the cooling system for the cold side of thermoelectric generator, system of heat transfer from smokestack to the hot side of thermoelectric generator and also the modeling of the thermoelectric modules themselves. In continuation, for validating the obtained equations, an experimental prototype of this thermoelectric generator is fabricated and the empirical results including the nominal voltage, current and power of the manufactured system are compared with the theoretical results. This comparison shows the validity of the presented modeling and the good agreement between the theoretical and practical results, especially at low temperatures. Based on the calculations, the highest error was 4.6 percent for a temperature difference of lower than 100 °C. Additionally, for the same temperature difference, the highest theoretical and practical output powers for this module were 3.4 W and 2.8 W, respectively. Considering the matching of these results, the effects of some important parameters on the output power of the considered thermoelectric generator are also investigated, and the significant influence of the thermal conduction coefficient of thermoelectric modules is demonstrated.

Experimental investigation of thermoelectric generator (TEG) with PCM module

In the paper, the results of experimental investigation of thermoelectric generator (TEG) are presented. The model of TEG was designed for the use of solar radiation as a heat source. An important feature of the design under study is the method of cooling of thermoelectric modules. Phase change material (PCM) absorbs heat during its melting, thus stabilizing temperature of the cool side of TEG. Basic performance characteristics, i.e. voltage and current generated vs. time, were measured during tests conducted for different electrical configurations of the unit, and for different heat fluxes on hot side of TEG. Temperature distributions in PCM container during the operation of TEG were also recorded. The reverse operation of TEG, i.e. when heat earlier accumulated in PCM is utilized, was tested as well. The results confirmed the potential of the application of phase change materials as a cooling/heating media in TEGs.

Theoretical and experimental estimation of limiting input heat flux for thermoelectric power generators with passive cooling

This paper focuses on theoretical and experimental analysis used to establish the limiting heat flux for passively cooled thermoelectric generators (TEG). 2 commercially available TEG’s further referred as type A and type B with different allowable hot side temperatures (150°C and 250°C respectively) were investigated in this research. The thermal resistance of TEG was experimentally verified against the manufacturer’s specifications and used for theoretical analysis in this paper. A theoretical model is presented to determine the maximum theoretical heat flux capacity of both the TEG’s. The conventional methods are used for cooling of TEG’s and actual limiting heat flux is experimentally established for various cold end cooling configurations namely bare plate, finned block and heat pipe with finned condenser. Experiments were performed on an indoor setup and outdoor setup to validate the results from the theoretical model. The outdoor test setup consist of a fresnel lens solar concentrator with manual two axis solar tracking system for varying the heat flux, whereas the indoor setup uses electric heating elements to vary the heat flux and a low speed wind tunnel blows the ambient air past the device to simulate the outdoor breezes. It was observed that bare plate cooling can achieve a maximum heat flux of 18,125W/m2 for type A and 31,195W/m2 for type B at ambient wind speed of 5m/s while maintaining respective allowable temperature over the hot side of TEG’s. Fin geometry was optimised for the finned block cooling by using the fin length and fin gap optimisation model presented in this paper. It was observed that an optimum finned block cooling arrangement can reach a maximum heat flux of 26,067W/m2 for type A and 52,251W/m2 for type B TEG at ambient wind speed of 5m/s of ambient wind speed. The heat pipe with finned condenser used for cooling can reach 40,375W/m2 for type A TEG and 76,781W/m2 for type B TEG.