Global Journal of Researches in Engineering, A: Mechanical & Mechanics, Volume 22 Issue 1

b) Capstone micro-turbine Microturbines have advantages over modern internal combustion engines, such as their high-power density, less moving parts and comparatively low emissions. They can be fuelled by liquid and gaseous fuels - fossil or renewable. Microturbine capacities are generally between 30 to 350 kW. The Capstone 330 MTG, made available by the company Supernova Energy Services, installed in Alsabana was subjected to service setting works, as it was new. Photographs in figure 1 allow to illustrate the general view of the MTG located at the test site. Figure 1: Location of the MTG at the Alsabana Campus test site The Model 330 MTG is a compact low emission solid-state controlled power generator, based on a 30 kW Capstone micro-turbine. The latter is designed for 30 kW output, uses power electronics to convert the high- frequency output of the generator to three-phase 480 volts voltages, at 50-60 Hz current frequency. The high- frequency AC current of the generator is converted to the 50-60 Hz AC current, after being processed through an inverter and a DC converter. Table 2 lists the rated capabilities of each microturbine based on available literature. Table 2: Technical performance data of the Capstone 330 microturbine for different fuels [7]* Fuel type GNC (55 psig) GLP (55 psig) Diesel (5 psig) Mean time to repair 20,000 h 20,000 h 20,000 h Nominal full power 30 kW net (+/- 1 kW) 30 kW net (+/- 1 kW) 29 kW net (+/- 1 kW) Peak efficiency (LHV**) 27% (+/- 2%) 27% (+/- 2%) 26% (+/- 2%) Fuel consumption*** 18,7 lb/h, 8,5 kg/h 19,0 lb/h, 8,6 kg/h 21,9 lb/h, 10,0 kg/h Methane based fuel flow (Metan-HHV) 440,000 kJ/h (420,000 Btu/h) Methane based energy of exhaust gases 305,000 kJ/h (290,000 Btu/hr) Exhaust gases temperature 500°F, 261°C 500°F, 261°C 500°F, 261°C Output voltage 250-700 VDC 250-700 VDC 250-700 VDC * Source: Capstone Turbine Corporation Since Capstone Microturbines use lean premix combustion system to achieve low emissions levels at a full power range, they require operating at high air-fuel ratio; injectors control the air-fuel ratio. The MTG is instrumented to record operational parameters (of which, temperatures, pressures, fuel usage, turbine speed, internal voltages/currents, and status are of importance for the undertaken study). The average readings of two thermocouples indicates the Turbine Exit Temperature (TET); a compressor inlet thermistor is installed to measure the air temperature at the inlet of the compressor wheel; the air flow, Wair, (in pounds per hour) and the amount of energy needed in the combustion chamber required to regulate fuel flow in the combustion chamber, W energy (in Btu/sec), are calculated based on engine speed. Such data are available with a computer or modem connected to an RS-232 port on the microturbine. A schematic drawing of the built-in instrumentation supported by the microturbine generator is presented in figure 2. Global Journal of Researches in Engineering (A ) Volume XxXII Issue I Version I 19 Year 2022 © 2022 Global Journals Performance of a Capstone Gas Turbine based Power Plant Working on High Butane LPG