Abstract
Ambient air temperature increase, in a gas power plant, causes the intake air mass flow rate to be decreased and can have a significant reducing effect on output power and efficiency. To compensate for this reduction, at different climate conditions, various systems can be used to cool the inlet air. To predict the performance of a gas turbine at off-design conditions (by changing surrounding conditions and/or the air cooling method), modeling of the unit performance is required. Due to the high consumption of water and electricity in the conventional cooling systems, in this paper, in addition to introducing an off-design algorithm, governing equations of each cycle elements were inferenced by their characteristic curve. By developing code in MATLAB software, the effect of applying a novel convergent–divergent system on GE-F5 gas units in Yazd Zanbagh power plants was studied. The results show that in a temperature range between 14 and 50 °C, for each degree decrease in ambient air temperature, an approximately 8.99 kW increase in output power can be obtained. The main advantage of this system is the capability of its application in both dry and humid regions. In addition, the refrigerant medium is not required, which makes this system desirable to use in arid areas.
Highlights
Importance of gas turbine compressor inlet air coolingHigh electricity demand, due to the application of high electricity–consuming cooling systems in the summer season case, is a major problem for electricity suppliers
The main reason for this difference is a dependency of gas turbine power output on the ambient air temperature
The net output power of a gas turbine can decrease from 0.6% to 0.9% for each degree Celsius increase, in the compressor inlet temperature.[2]
Summary
Due to the application of high electricity–consuming cooling systems in the summer season case, is a major problem for electricity suppliers. At warmer air and lower relative humidity, the efficiency of this method will be higher.[3,4,5,6,11] Cortes and Willems[12] presented an overview of the current inlet air cooling technology, whereas an extensive review of the air cooling methods and their economic impacts on the energy market was investigated by Darmadhikari and Andrepont.[13] Bagnoli et al.[14] examined the effects of spraying water between compressor stages on the performance of a GE Frame 7EA model gas turbine; they found that almost 15% of the gas turbine power output losses are due to ambient temperature rise, compared to standard conditions. If more temperature reduction is required, for accelerating flow from very low speed to supersonic speed, a C-D system use is necessary
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