A steady-state computer simulation model of a direct-fired double-effect water-lithium bromide absorption chiller in the parallel-flow configuration was developed from first principles. Unknown model parameters such as heat transfer coefficients were determined by matching the model's calculated state points and coefficient of performance (COP) against nominal full-load operating data and COPs obtained from a manufacturer's catalogue. The model compares favourably with the manufacturer's performance ratings for varying water circuit (chilled and cooling) temperatures at full-load conditions and for chiller part-load performance. The model was used to investigate the effect of varying the water circuit flow rates with the chiller load and to optimise chiller part-load performance with respect to the distribution and flow of the weak solution.

KEYWORDS: year 1995, commercial, absorption refrigeration, calculating, controls, steady state, water, lithium bromide, performance, chillers, fluid flow, part load, optimisation