The Heat Transfer Characteristics of a 16 kW Steam Driven Double Effect Absorption Chiller

A 16 kW (4.6 refrigerant tons) steam driven, double effect, parallel flow absorption chiller has been designed, manufactured, and installed in the Intelligent Workplace (IW) of Carnegie Mellon University (CMU). This chiller is driven by 6 bar saturated steam and uses a 57% LiBr-H₂O sorbent. It is the smallest absorption chiller available in the existing market. The absorption chiller consists of five major and four minor heat transfer components. The manufacturer of the chiller has provided information on detailed configuration and dimensions of these components to support the calculation of their heat transfer areas, A’s, and the estimation of overall heat transfer coefficients, U’s. A steady state computational performance model for the chiller has been developed based on the applicable scientific and engineering principles. The model has been used to calculate all chiller internal working conditions and to analyze the experimental data over a wide range of operating conditions. Heat transfer coefficients inside and outside of the tubes making up the chiller’s heat transfer components have been estimated by published empirical correlations. The product of the overall heat transfer coefficient and the surface contact area, UA’s, for the 5 major heat transfer components have been estimated using the chiller model and measured performance data. Significant variations, 30%, in this parameter are observed under partial load, reduced flow conditions. Deviations between the experimental measurements and the model solutions have been analyzed to evaluate the model accuracy. At design operating conditions, the overall deviation is about 6%.