Experimental Investigations and Numerical Analyses of an Annular Typed Micro Gas Turbine using Low-heating Value Fuel
|關鍵字:||低熱值燃料;環型微渦輪引擎;Low-heating Value Fuel;Annular Typed Micro Gas Turbine|
本論文包含三個部份，第一部分，本論文透過實驗分析，了解低熱值燃料應用於擁有環型燃燒室之微渦輪引擎所能產生的效能。首先為微渦輪引擎架設相關的驅動與感測裝置來完成研究用測試平台。研究中使用不同比例的CO2混合甲烷做為實驗用的低熱值燃料，透過量測得到的數據來分析與評估此引擎的效能。實驗結果顯示，微渦輪引擎最低可使用60% 甲烷含量的燃料來運轉，而使用90% 甲烷燃料時，發電量在85,000轉時達到170W，且70% 甲烷燃料可在60,000轉達到70W。當使用60% 甲烷燃料時，微渦輪引擎所能產生之動力相當的低。微渦輪引擎的布雷登循環效率與發電效率可透過實驗數據的計算得知，最高分別是23% 與10%。
The utilization of renewable energy and development of new energy sources are the present governmental energy policy to cope with the more and more stringent shortage of fossil fuels and environmental regulations for carbon dioxide reduction in the new century. This dissertation examines the practicability of low-heating value (LHV) fuel on an annular micro gas turbine (MGT) through experimental evaluations and numerical simulations. The MGT used in this study is MW-54, whose original fuel is liquid (Jet A1). Its fuel supply system was re-designed to use biogas fuel with LHV. There are three parts in this dissertation. In the first part, experiments were completed to evaluate the combustion efficiency of an annular MGT while applying the LHV fuel. The corresponding sensors and actuators for the MGT were established to form our test stand. The methane was mixed with different ratio of CO2 to be our LHV fuel. The measured data indicating the engine performance were analyzed and evaluated. Experimental results showed that the presented MGT system operated successfully under each tested condition when the minimum heating value of the simulated fuel was approximately 60% of pure methane. The power output was around 170W at 85,000 RPM as 90% CH4 with 10% CO2 was used and 70W at 60,000 RPM as 70% CH4 with 30% CO2 was used. When a critical limit of 60% CH4 was used, the power output was extremely low. Furthermore, the best theoretical Brayton cycle efficiency and electric efficiency of the MGT were calculated as 23% and 10%, respectively. Following the experiments, the corresponding simulations, aided by the commercial code CFD-ACE+, were carried out to investigate the cooling effect in a perforated combustion chamber and combustion behavior in an annular MGT when using LHV gas. The investigation was conducted to realize the characteristics of the flow, combustion, heat transfer, chemical reaction, and their interactions in an annular MGT. The results confirmed that the cool air flows through dilution holes on combustor liners were functioning fully and there were no hot spots occurred in the liners. In addition, the exhaust temperatures of combustion chamber were lower than 1073K when MGT was operated under different conditions. Finally, the system identification of MGT was completed for future studies. The model identification process is prerequisite for controller design research in the near future. The measured data helped us identify the parameters of dynamic model in numerical simulation. This dissertation presents a novel distributed power supply system that can utilize renewable biogas. The completed micro biogas power supply system is small, low cost, easy to maintain and suited to household use.
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