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A compact thermoelectric energy harvester is developed to harvest the thermal energy from the hot surface of the gas turbine, providing continuous and reliable power for the sensing and monitoring system in the gas turbine. An experimental prototype is built and the performances of the energy harvester with different electrical load resistances and source temperatures are characterized. A mathematical iterative method, taking account of Thompson Effect, line spacing gap heat leakage, material property variations, and thermal resistance of the ceramic covering layer, is used to analyze the performance of the segmented thermoelectric generator (TEG) module with good accuracy. Based on this model, the temperature profiles and heat fluxes along the thermo-elements, efficiency, and heat leakage through the filling gap material are analyzed. The prototype, with a source temperature of 325 °C, has a voltage output of 2.4 V and power output of 0.92 W, which is more than enough to power a sensor node in the gas turbine. A higher power output can be expected with some improvement on the prototype design. [ABSTRACT FROM AUTHOR]

Thermoelectric generator is a device taking advantage of the temperature difference in thermoelectric material to generate electric power, where the higher the temperature difference of the hot-cold ends, the higher the efficiency will be. However, higher temperature or higher heat flux upon the hot end will cause strong thermal stress which will negatively influence the lifecycle of the thermoelectric module. This phenomenon is very common in industrial applications but seldom has research work been reported. In this paper, numerical analysis on the thermodynamics and thermal stress performance of the thermoelectric module has been performed, considering the variation on the thickness of materials; the influence of high heat flux on thermal efficiency, power output, and thermal stress has been examined. It is found that under high heat flux imposing upon the hot end, the thermal stress is so strong that it has a decisive effect on the life expectation of the device. To improve the module’s working condition, different geometrical configurations are tested and the optimum sizes are achieved. Besides, the side effects on the efficiency, power output, and open circuit voltage output of the thermoelectric module are taken into consideration. [ABSTRACT FROM AUTHOR]

A thermoelectric energy harvester composed of two thermoelectric modules, a wicked copper-water heat pipe, and finned heat sinks has been designed, modeled, and tested. The harvester is proposed to power sensor nodes on heating/cooling, steam, or exhaust pipes like these in power stations, chemical plants and vehicle systems. A model to analyze the heat transfer and thermoelectric performance of the energy harvesting system has been developed and validated against experiments. The results show that the model predicts the system power output and temperature response with reasonable accuracy. The model developed in this paper can be adapted for use with general heat sink, heat pipe, and thermoelectric systems. The design, incorporating a heat pipe and two 1.1″ by 1.1″ Bi 2 Te 3 modules generates 2.25 W ± 0.13 W power output with a temperature difference of 128 °C ± 1.12 °C and source temperature of 246 °C ± 1.9 °C, which is more than enough to operate wireless sensors or some actuators. The use of a heat pipe in this design increased the power output by 6 times over conventional designs. Based on the model, further improvement of the power output and energy harvesting efficiency of the system has been suggested by optimizing the number of thermoelectric modules. [ABSTRACT FROM AUTHOR]

• A three-dimensional numerical model based on the finite element method has been developed. • A multi-factor roadmap for the design of wearable micro-TEGs is proposed. • A micro-TEG module is fabricated to verify the theoretical roadmap. • The maximum power density reached 1.79 μW/cm2 for the micro-TEG module worn on the wrist. To further meet the requirement of the Internet of Things (IoT), more and more sensors need to be integrated inside wearable devices. Wearable TEGs directly convert the heat flow generated by the temperature difference between a human body and the environment into electricity, thus acting as a permanent energy supply for sensor systems. In this work, considering the body's thermoregulation function in the wearing scenario, a three-dimensional numerical model based on the finite element method has been developed to systematically study the power generation performance of micro-TEGs. The multi-factor design involves the packing density (p d), leg width (w), leg height (l) and convective heat transfer coefficient (h) at the cold side of the generator. On this basis, we have proposed a multi-factor roadmap for the design of wearable micro-TEGs with the required power density and open circuit voltage. The theoretical roadmap modeling was verified by fabricating a micro-TEG module of 20 × 20 mm2, with w = 0.5 mm, l = 1.38 mm, and the leg density of p d = 33 legs/cm2. When worn on the wrist (T core = 37 ℃, T air = 22 ℃), a steady voltage output of ∼ 21.0 mV was generated and the corresponding maximum power density reached 1.79 μW/cm2. [ABSTRACT FROM AUTHOR]

A solar chimney power plant (SCPP) is not only a solar thermal application system to achieve output power, but also a device extracting freshwater from the humid air. In this article, we proposed a SCPP with collector being replaced by black tubes around the chimney to warm water and air. The overall performance of SCPP was analyzed by using a one-dimensional compressible fluid transfer model to calculate the system characteristic parameters, such as chimney inlet air velocity, the condensation level, amount of condensed water, output power, and efficiency. It was found that increasing the chimney inlet air temperature is an efficient way to increase chimney inlet air velocity and wind turbine output power. The operating conditions, such as air temperature and air relative humidity, have significant influence on the condensation level. For water generation, chimney height is the most decisive factor, the mass flow rate of condensed water decreases with increasing wind turbine pressure drop. To achieve the optimum peak output power by wind turbine, we should set the pressure drop factor as about 0.7. In addition, increasing chimney height is also an efficient way to improve the SCPP efficiency. Under ideal conditions, the system total efficiency of a SCPP with a height of 3000 m can be up to nearly 7%. [ABSTRACT FROM AUTHOR]

In order to improve the performance and maximize the efficiency of energy conversion of thermoelectric generator (TEG), a mathematical model to predict the maximum energy conversion efficiency of TEG is developed. Then, a new compact thermoelectric generator (C-TEG) and a dimensional optimized TEG (DO-TEG) are proposed in this article. The compact thermoelectric generator is designed via logical intersection angle selection and layout, thus to improve the electric performance per unit volume. Finally, we compared the output electric performance of C-TEG and traditional thermoelectric generator (T-TEG) and that of DO-TEG under design and off-design conditions via numerical simulations. The results indicate that C-TEG has an excellent electric performance whose voltage, power, and efficiency decrease slightly whereas the output voltage, work, and efficiency compared with that of T-TEG have been significantly improved, with the amplitude increasing with the increase of resistant value of external loads. [ABSTRACT FROM AUTHOR]