Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 57 1 2025 03 21 Study the Effect of Water Injection Upstream of the ‎Compressor of a Gas Microturbine Engine on the Off-design Performance Study the Effect of Water Injection Upstream of the ‎Compressor of a Gas Microturbine Engine on the Off-design Performance 89 104 5744 10.22060/mej.2025.23641.7790 FA Fatemeh Rahmani Aerospace Engineering Department, Amirkabir University of Technology, Tehran, Iran Abulghasem Mesgarpur Tusi Aerospace Engineering Department, Amirkabir University of Technology, Tehran, Iran Hosein Khaleghi Aerospace Engineering Department, Amirkabir University of Technology, Tehran, Iran Journal Article 2024 10 27 One of the disadvantages of microturbines, which are used as combined heat and power units, ‎is the constant ‎ratio of thermal power to electrical power at each operating point. A method that has ‎recently been employed to ‎address this issue and enable a variable thermal-to-electrical power ratio ‎at any rotational speed is water injection ‎into the microturbine. In this study, the Turbec T100 ‎microturbine has been investigated. Initially, the ‎performance of the Turbec T100 was simulated and ‎validated against experimental results. Subsequently, by ‎adding a heat recovery steam generator after ‎the compressor and converting the Turbec T100 into a wet ‎microturbine, the simulation code was ‎upgraded, and the off-design performance of the wet microturbine was ‎simulated. The results ‎indicate that, with water injection, the electrical power and efficiency increase at all ‎rotational speeds, ‎while the thermal power and efficiency decrease. The maximum steam injection rate into the ‎engine ‎at 67,940.67 rpm is 0.03769 kg/s, which leads to a 33% increase in electrical power and a 62% decrease ‎in ‎thermal power. Therefore, by injecting different amounts of steam at each speed, it is possible to ‎achieve a ‎variable electrical-to-thermal power ratio. One of the disadvantages of microturbines, which are used as combined heat and power units, ‎is the constant ‎ratio of thermal power to electrical power at each operating point. A method that has ‎recently been employed to ‎address this issue and enable a variable thermal-to-electrical power ratio ‎at any rotational speed is water injection ‎into the microturbine. In this study, the Turbec T100 ‎microturbine has been investigated. Initially, the ‎performance of the Turbec T100 was simulated and ‎validated against experimental results. Subsequently, by ‎adding a heat recovery steam generator after ‎the compressor and converting the Turbec T100 into a wet ‎microturbine, the simulation code was ‎upgraded, and the off-design performance of the wet microturbine was ‎simulated. The results ‎indicate that, with water injection, the electrical power and efficiency increase at all ‎rotational speeds, ‎while the thermal power and efficiency decrease. The maximum steam injection rate into the ‎engine ‎at 67,940.67 rpm is 0.03769 kg/s, which leads to a 33% increase in electrical power and a 62% decrease ‎in ‎thermal power. Therefore, by injecting different amounts of steam at each speed, it is possible to ‎achieve a ‎variable electrical-to-thermal power ratio. https://mej.aut.ac.ir/article_5744_78631a4bb5303be54fa1cfdcb958c00a.pdf