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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

10An electrical generator has been integrated with a locally produced, biomass-fed clay cooking stove in rural Malawi. The 11 generator produces small amounts of electricity based on the thermoelectric effect. Five demonstrator stoves were 12 deployed into a rural community in the Balaka district for up to 6 months. This study investigates the power generation 13 performance of the devices over the first 80 days of the field trial. It was determined that the users were able to charge 14 mobile phones, lights and radios from the generator stoves. The power generating performance of the stoves deteriorated 15 slightly over the 80 day period. The was due to the effects of thermal cycling on the generator system as a whole which 16 caused eventual drying out of the thermal paste and a loosening of the clamping nuts which reduces clamping pressure 17 and power output. One stove failed due to a mechanical problem. It was found that the power produced significantly 18 exceeded the power consumed in most cases, which indicates an over-supply. It appears that 3 W·h is sufficient to meet 19 the average daily electrical power requirements for the participants in this study. The data obtained from the field trial 20 has been used to inform a redesign of the device for a second field trial.

A novel off-grid electricity-producing device has been designed for integration with biomass-fuelled improved cooking stoves commonly in use in the developing world. The device operates on the thermoelectric principle whereby small amounts of electricity can be produced in response to a temperature difference across a thermoelectric generator, or TEG. The energy produced by the integrated generator can be used for direct charging or stored in a rechargeable lithium-ironphosphate (LiFePo4) battery. The generator is equipped with a standard USB output which allows the user to charge a variety of 5 Volt appliances. Five technology demonstrator electricity generating stoves have been integrated with locally produced clay cooking stoves in the Balaka district of Malawi, Africa. This study details the results from an 80-day field trial of the devices. The data reveals that the stoves are in use for a greater time than was anticipated. The data also indicates that the generators perform adequately in the field and provide the user with the ability to charge LED lights and mobile phones from the generator stoves every day if necessary.

5A measurement system has been designed to characterize the radiant energy efficiency of infrared heating 6 elements. The system also allows for measurement of the radiant heat flux distribution emitted from radiant heater 7 assemblies. To facilitate these, a 6-axis robotic arm is fitted with a Schmidt-Boelter radiant heat flux gauge. A 8 LabVIEW interface operates the robot and positions the sensor in the desired location and subsequently acquires 9 the desired radiant heat flux measurement. To illustrate the functionality of the measurement system and 10 methodology, radiant heat flux distributions and efficiency calculations are performed for a commercially 11 available ceramic heater element for two cases. In the first, a spherical surface is traced around the entire heater 12 assembly and the total radiant power and net radiant efficiency is computed. In the second, 50 cm x 50 cm vertical 13 planes are traced parallel to the front face of the heater assembly at distances between 10 cm and 50 cm and the 14 in-plane power and efficiencies computed. The results indicate that the radiant efficiencies are strongly dependant 15 on the input power to the element and, for the in-plane efficiencies, depend on the distance from the heater.