T100 Micro Gas Turbine Converted to Full Humid Air Operation: A Thermodynamic Performance Analysis

Waste heat recovery has become more and more important for the profitability of small-scale Combined Heat and Power (CHP) plants like micro Gas Turbines (mGTs). Adding a saturation tower to the mGT unit is such a waste heat recovery route. The cycle includes the saturation tower after the compressor to humidify the compressed air. Simulations show that this cycle, known as the micro Humid Air Turbine (mHAT), increases mGT electric efficiency by 7% relatively (2% absolute), improving the general economic performance. The mHAT concept with saturation tower was however never tested experimentally. To show the potential of the cycle, the Turbec T100 mGT of the University of Brussels was converted into a mHAT cycle by adding a spray saturation tower to the system. In this paper, we present the results of several water injection tests in the T100 mGT at part and nearly nominal load. The water injection experiments resulted in stable mGT operation at reduced rotational speed and pressure ratio and increased electric efficiency. Experimental results showed a reduced fuel mass flow rate by 4.3% and a relative electric efficiency increase of 4.8% for the different experiments. In addition, the impact of the water on the other turbine parameters has been studied.