ENGINEERING FOR RURAL DEVELOPMENT THERMOELECTRIC GENERATORS AS ALTERNATE ENERGY SOURCE IN HEATING SYSTEMS

Abstract. By using thermoelectric generators it is possible to develop independent electric energy source in burning and heating systems -in households and industrial heating. With this energy source it is possible to provide with electricity systems appliances, lightening and other consumers. Potential placements for generators are on furnace walls, on flue way walls, on flue pipe walls after furnace. Generators can improve efficiency of combustion, because there is amount of waste heat that leaves through flue pipe in burning process. There are no boundaries for combining elements in system as just the space for their placement. As more elements are linked in chain, as much electric energy is produced. This is one of methods to develop a cogeneration process in domestic boiler house or industrial heating, or burning systems. In research thermoelectric element current, voltage, power and efficiency are defined in different temperature differences. Keywords: thermoelectric effect, Seebeck effect, thermoelectric generator, TEG. Introduction Biomass burners and firewood furnaces are used in domestic and industrial heating and burning processes. Many of these systems require electric energy support for full performance. By applying thermoelectric generators to these heat sources it is possible to develop independent electric energy source, which start generation in the moment when there will be temperature difference on their sides. Thermoelectric generators are devices that use Seebeck effect -converting heat (temperature differences) directly into electrical energy. As the heat flows from hot side to cold side, free charge carriers -electrons or holes -in the material are also driven to the cold end. The resulting voltage is proportional to the temperature difference via the Seebeck coefficient. The thermoelectric generator will generate DC electricity as long as there is a temperature difference across the module. The more electricity will be generated when the temperature difference across the module increases, and the efficiency of converting heat energy into electric energy will also increase

ASSESSMENT OF COMBUSTION PARAMETERS OF BIOMASS MIXTURES

Abstract. Herbaceous energy crops would be the main basis for solid biofuel production in agricultural ecosystem in future. Reed canary grass is grown in recent years and is recommended for solid biofuel production. Besides that, there is a possibility to utilize for bioenergy production natural biomass of common reeds overgrowing the shorelines of Latvian more than 2000 lakes. Growing of hemp can be a good alternative source for energy producing. Peat can be used as the best additive for manufacturing of solid biofuel, because it improves the density, durability of stalk material briquettes (pellets) and avoids corrosion of boilers. Given that the peat calorific value is greater than the calorific value of straw biomass, the total calorific value of the mixture increases. In the study the experimentally obtained calorific values for different biomass mixtures are given, as well as the method of calculation for higher calorific value of biomass mixtures. Keywords: calorific value, hemp, reed, reed canary grass. Introduction According to Eurostat the renewables covered 18.3 % of the gross inland consumption in the EU 27 countries in 2009. Biomass gave almost two thirds of renewables-based energy (67.7 %). In almost all of the Baltic Sea countries the share of biomass in the gross inland energy consumption is higher than the EU average. The share of biomass as a fuel in Latvia is 29.2 %, which is the highest percentage in the enlarged EU The available modern biofuel production and combustion technologies enable effective utilization of practically all type wood and also herbaceous biomass including different types of cereals, hemp, common reeds etc. Also herbaceous biomass, for example, straw has found increasingly wider implementation as a fuel. The main resources for solid biofuel in rural areas of Latvia are wood, residues of cereal crops, peat and emergent vegetation in lakes as common reeds (Phragmites australis). By its characteristics as an energy plant, Common Reed can be compared with Reed Canary Grass, which is a field-grown grass. Reed Canary Grass has proven to be both a winter-hardy and a high-yielding energy plant (in spring harvest, 6-8 tons per hectare), which stays productive for 10-12 years. Reed Canary Grass is deemed for the energy plants best suited for Northern European conditions Growing of hemp, which is a good fibre, oil and biofuel resource, can be a good alternative source for energy producing Peat can be used as the best additive for manufacturing of solid biofuel, because it improves the density, durability of stalk material briquettes (pellets) and avoids corrosion of boilers. Previous studies showed that the addition of peat in stalk biomass increases the strength and the calorific value of fuel briquettes. The study aims to find out how the peat content affects the net calorific value, ash content and ash melting point of biomass fuels