AC-02-10-1 -- Economic Assessment of Low Firing Temperature Absorption Chiller Systems PDF

The performance and economics of large (600 ton, 2110 kW) single-effect and half-effect absorption chiller systems fired with hot water were investigated. The single-effect system operates at nearly constant coefficient of performance (COP) of approximately 0.65, but capacity decreases precipitously as the temperature of the hot water entering the generator is lowered from the design value of 230°F (110°C). The half-effect cycle can maintain capacity with lower hot water firing temperatures, but it operates at significantly lower COP, which requires more energy input to the generator and heat rejection through the cooling tower, compared to the single-effect system. The purpose of this investigation was to compare the performance and economics of the single- and half-effect systems as a function of hot water firing temperatures. A detailed computer model was written for the single- and half-effect systems. The single-effect model was calibrated with data from a chiller manufacturer. The results indicate that the economics of the half-effect system become more favorable than those for the single-effect system for inlet hot water temperatures lower than approximately 200°F (93°C). However, at these operating conditions, the half-effect system is not economically competitive with electrically driven centrifugal chillers on a five-year life-cycle economic basis, even if the inlet hot water is available at no cost.

Units: Dual