Gas Turbine Handbook : Principles and Practices

130 Gas Turbine Handbook: Principles and Practices
CHILLERS
Chillers, unlike evaporative coolers, are not limited by the
ambient wet bulb temperature. The power increase achievable is
limited by the machine, the capacity of the chilling device to produce
coolant, and the ability of the coils to transfer heat.
Cooling initially follows a line of constant humidity ratio (Specific
Humidity). As saturation is approached, water begins to condense
from the air. Further heat transfer cools the condensate and air, and
causes more condensation (Figure 8-5 and 8-7). Because of the relative
high heat of vaporization of water, most of the cooling energy in
this regime goes to condensation and little to further temperature
reduction. Therefore, since little benefit is achieved as the cooled
temperature approaches the dew line, chillers should be designed to
avoid forming excessive condensate.
Figure 8-7. Courtesy of Baltimore Aircoil Company. This gas turbine
inlet air conditioner combines three steps of air conditioning: Air
Pre-Cooling, Air Chilling, and Air Reheat.
References
1. "GE Gas Turbine Performance Characteristics,” Reference No. GER-
3567C, by F.J. Brooks, GE Industrial & Power Systems, Schenectady,
NY, August 1992.
2. Gas Turbine and Combined Cycle Capacity Enhancement, Second Interim
Report, EPRI TR-104612, January 1995.