The purpose of this work is to investigate the benefits of some different ambient air conditioning methods for reducing the gas turbine intake air temperature in order to enhance the gas turbine power. As a reference case the combined heat and power plant of the campus area of the Technische Universita¨t Mu¨nchen in Garching is considered, which is equipped with an Allison KH501 Cheng Cycle gas turbine. Three novel technical possibilities of ambient air cooling and power augmentation are shown in detail (desiccant dehumidification and evaporative cooling, absorption chiller unit with air cooler, evaporative cooling at increased inlet air pressure). Based on site ambient conditions and measured yearly load lines for heat and electrical power connected with actual cost functions, the potential economic savings are worked out for the different technical modifications using ambient air cooling for power augmentation of the gas turbine plant. The economic operation lines for power and heat, supplied by the modified gas turbine plant, are calculated by a cost optimization system. The results are compared based on investment costs and economic savings by the extended annual electrical and thermal power production of the modified gas turbine plant.

A new gas turbine cogeneration plant based on the Cheng cycle was installed to supply electricity and heat for the Technische Universität München’s campus site at Garching. To utilize fully the Cheng cycle flexibility, an optimizing system was developed which controls the mode of operation continuously and adapts the point of operation without manual interface. Only with such a system it is possible to exploit the full economic potential of the system. The paper presents the technical framework and some aspects of the control strategy used to minimize the costs based on three years of operating experience.