Research and development of combustion engine for micro - cogeneration unit

The paper deals with research and development of original small-size internal combustion engine Lombardini LGW 702. This engine was optimised for application in micro-cogeneration unit (MCU), equipped with variable-speed generator and electronic converter. The electronically controlled combustion engine in MCU works in a regime depending on the load of the generator. It has the lowest possible number of revolutions and minimum possible fuel consumption. The generator combines directly with the crankshaft of the engine. To reach stable parameters of the network, the power electronics controls and processes the variable frequency of the generator. A combustion engine powered by natural gas can utilise also a blend of natural gas and hydrogen and other alternative fuels produced from renewable sources of energy, e.g. synthesis gases. A comparison of engine parameters was made, namely parameters of engines powered by the above-mentioned alternative fuels, such as syngas, coke-oven gas, landfill gas, sewer gas, Hythane and natural gas. A new three-phase variable-speed generator and converter for micro-cogeneration unit were developed. The rated electric power of MCU is 4 kW. The power overload is 80%, compared to rated power. In the case of natural gas, the best electric efficiency is 25%, the thermal efficiency is 65% and the total efficiency of MCU is more than 90%.