Heat Flux Source Research Articles

Unsteady Temperature Distribution in a Sphere Subjected to Time-Dependent Surface Heat Flux and Internal Heat Source

General expressions are derived for the three-dimensional unsteady heating of a solid sphere under the influence of a variable internal heat source and an arbitrary initial temperature distribution when the entire surface is subjected to a variable heat flux. Both the volume heat source and the surface heat flux are prescribed in terms of arbitrary functions of space and time. Various forms of solutions are noted. These expressions, not available hitherto, contain the solutions of many special problems of technological importance. The results presented in two recent studies on the arbitrary heating of spheres are shown to be special cases of the general sphere problem treated here and the errors appearing in these studies are corrected. Other special cases are also discussed.

Thermo-electric generator

Thermal management and energy crisis have been two major problems in this 21st century. Engine exhaust has tremendous amount of energy which can be recovered by waste heat recovery systems. The thermoelectric concept is seen as a perfect solution for recovering waste heat from engine exhaust and converts in to electric energy. Since the use of semiconductor materials for thermoelectric applications, there has been a huge quest for improving its figure of merits (ZT) to make it commercially viable. This synopsis report presents the simulation and experimental validation study on the transient behavior of a proposed combined exhaust heat recovery device and thermoelectric power generation system. The proposed system consists of waste heat recovery that provides a heat flux source for thermoelectric generators. In this research, thermoelectric generator device are consist of two major part, first one is exhaust recovery device and second one is thermoelectric generation system. In the first phase of study, optimize the waste heat recovery system design, performed cfd analysis and get heat and temperature data then cfd model coupled with thermoelectric model, find out the thermoelectric effect on particular devices. This paper presents of numerical simulation for several the thermoelectric materials. Numerical simulation is carried out by using a finite element package ANSYS.

Thermionic energy converter : Hernqvist, K. G.; Kanefsky, M.; Norman, F. H., RCA Rev.19(2): 244–258, June 1958. Illus.

We present a comprehensive analysis of a dual, micro-gap thermionic-thermoelectric hybrid energy converter by developing a detailed theoretical model of the system. The space-charge and near-field effects in thermionic conversion and the temperature-dependent effects in thermoelectric conversion are considered while studying the energy flow through the cascade system. The temperatures and energy exchange channels in the different parts of the system are quantified using a self-consistent iterative algorithm considering the energy balance condition. The model is deployed to simulate the hybrid system performance when energized by a constant heat flux source which could, for example, be concentrated solar irradiance. The effect of solar radiation intensity on the combined system efficiency, and the dependence of the thermoelectric generator performance on the waste heat released from the thermionic top stage, are illustrated with several examples. Based on these analyses, a performance optimization of the hybrid system is carried out. The findings presented in this work offer useful insights into the hybrid generator operation. Moreover, the model developed can be used as a design tool for the practical implementation of such a hybrid system, or for extracting material- and device-related parameters from experimental data.