Gas Turbine Handbook : Principles and Practices

126 Gas Turbine Handbook: Principles and Practices
estimate of the effect of inlet cooling. As expected the improvement is
greatest in hot dry weather. The addition of an evaporative cooler is
economically justified when the value of the increased output exceeds
the initial and operating costs, and appropriate climatic conditions
permit effective utilization of the equipment.
Water quality is a concern. The water must be treated to remove
contaminants such as salt, calcium, magnesium, aluminum,
etc. When wetted (100% humidity) these contaminants function as
electrolytes and can result in severe corrosion of materials. Careful
application of this system is necessary, as condensation or water carryover
can intensify compressor fouling and degrade performance.
The higher the levels of dissolved solids and salts in the water the
greater the effort must be to avoid water carryover. Besides control-
Figure 8-6. Courtesy of General Electric Company. Effect of evaporative
cooling on power output and heat rate as a function of ambient
air temperature and relative humidity.