Improving the efficiency of thermoelectric generators by using solar heat concentrators

In this paper, we propose a method of improving the efficiency of thermoelectric generators (TEGs) by using a lens to concentrate heat on the heat source of a TEG. Initial experiments performed using discrete components show about 60mV increase in the amount of voltage generated when using a magnifying lens. Simulation results on the proposed TEG configuration exhibit up to 16% efficiency when the input heat flux is increased to 500 times that of the sun’s heat flux. The effects of varying the thermoelement length, width, and membrane diameter on the TEG’s performance are also characterized. Lastly, plans to fabricate the device on a SOI wafer in the future are presente

Design and modelling of SOI-based solar thermoelectric generators

In this work, solar micro-thermoelectric generators are designed with a lens concentrating solar radiation onto the membrane of a thermoelectric generator (TEG). By focusing solar radiation, the input heat flux increases; leading to an increase in the temperature gradient across the device. Consequently, a significant improvement in the device efficiency can be achieved. The TEG design involves the use of the SOI wafer's device layer as the first thermoelement and aluminum as the second thermoelement. Isolation trenches are also added to the design for electrical insulation. Heat transfer simulations in COMSOL are performed to verify the viability of the proposed system and an analytical model based on energy balance and heat transfer equations is developed to investigate the performance of solar TEGs with varying geometries, lens parameters, and external conditions. It is found that efficiency is improved by increasing both the concentration factor and the absorptance of the TEG membran

Emerging technologies for learning (volume 1)

Collection of 5 articles on emerging technologies and trend

Phase metrology with multi-cycle two-colour pulses

Strong-field phenomena driven by an intense infrared (IR) laser depend on during what part of the field cycle they are initiated. By changing the sub-cycle character of the laser electric field it is possible to control such phenomena. For long pulses, sub-cycle shaping of the field can be done by adding a relatively weak, second harmonic of the driving field to the pulse. Through constructive and destructive interference, the combination of strong and weak fields can be used to change the probability of a strong-field process being initiated at any given part of the cycle. In order to control sub-cycle phenomena with optimal accuracy, it is necessary to know the phase difference of the strong and the weak fields precisely. If the weaker field is an even harmonic of the driving field, electrons ionized by the field will be asymmetrically distributed between the positive and negative directions of the combined fields. Information about the asymmetry can yield information about the phase difference. A technique to measure asymmetry for few-cycle pulses, called Stereo-ATI (Above Threshold Ionization), has been developed by [Paulus G G, et al 2003 Phys. Rev. Lett. 91]. This paper outlines an extension of this method to measure the phase difference between a strong IR and its second harmonic