Abstract: An off-design quasi-theoretical model of absorption chiller performance is derived by combining theoretic and experimental methods. Due to the description of measurable parameters (evaporator outlet temperature, generator inlet temperature and condenser inlet temperature) in the mathematic model, the requirement of a large number of detailed parameters could be avoided, which makes this method more practical for system analysis and comparison. An advantage of the model lies in its generality. Based on experimental data, the coefficients can be determined, so it is suitable for use. It can also be used to study and analyze the off-design general characteristics of absorption chiller. The prediction values of coefficient of performance(COP) under partial load are compared with detailed experimental data from a set of commercial chillers. The maxzimum relative standard deviation is less than 10%, The agreement between theory and actual performance data confirms that the model is valid. Typical partial load performances are summarized and it is found that for absorption chiller, when COP and cooling capacity are expressed as the ratio to their design values, the set of performance curves of 1/COP against 1/(cooling rate) for a series of absorption chillers can be integrated into a single curve in partial load, also the model can be expressed in a non-dimensionless form, which indicates that similarity exists for a set of absorption chillers.

Key words: Absorption chiller, Modeling, Similarity, Thermodynamics