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This project involves the development of a prototype electrical generator for delivering and storing small amounts of electricity. Power is generated using the thermoelectric effect. A single thermoelectric generator (TEG) is utilised to convert a small portion of the heat flowing through it to electricity. The electricity produced is used to charge a single rechargeable 3.3 Volt lithium-iron phosphate battery. This study investigates methods of delivering maximum power to the battery for a range of temperature gradients across the thermoelectric module. The paper explores load matching and maximum power point tracking techniques. It was found that, for the TEG tested, a SEPIC DC-DC converter was only beneficial for temperature gradients less than 100 ⁰C across the TEG. At a temperature gradient of 150 ⁰C, the effective resistance of the battery was close to the internal resistance of the TEG. For temperature gradients in excess of 100°C a DC-DC converter is not suggested and a simple charge protection circuit is sufficient.

The liquid motion induced by surface tension variation, termed the thermocapillary or Marangoni effect, and its contribution to boiling heat transfer has long been a very controversial issue. In the past this convection was not the subject of much attention because, under terrestrial conditions, it is superimposed by the strong buoyancy convection, which makes it difficult to obtain quantitative experimental results. The scenario under consideration in this paper may be applicable to the analysis of boiling heat transfer, specifically the bubble waiting period and, possibly, the bubble growth period. Nomenclature BoBond number C p specific heat [J·kg