A single stage absorption refrigeration system dynamic mathematical modeling, adjustment and experimental validation

• A dimensionless dynamic absorption refrigeration mathematical model is introduced.
• The model was adjusted and experimentally validated with two measured data sets.
• Numerical and experimental results are in qualitative and quantitative agreement.
• Fast and accurate model with potential for design, control and optimization.

In this paper, a dimensionless dynamic mathematical model is proposed, in order to analyze the response of single stage absorption refrigeration systems according to operating and geometric parameters. Suitable control volumes are defined in order to obtain the system dynamic response. Mass accumulation in the components is neglected, and the system is divided in two regions: i) the absorbent/refrigerant solution in the thermal compressor, and ii) pure refrigerant in the condenser, expansion valve and evaporator. The temperatures at each control volume are calculated in time with a system of ordinary differential equations (ODEs) for the refrigerant side, and with a system of non-linear algebraic equations for the absorbent/refrigerant solution side of the refrigerator. The model equations are based on conservation of mass and energy principles, and simple functions to evaluate the thermodynamic properties of the ammonia–water system. Two sets of experimental data from an absorption refrigeration prototype were used to carry out model adjustment (set 1), followed by experimental validation (set 2), which showed good qualitative and quantitative agreement, within the experimental uncertainties. Dynamic simulations were conducted to assess the adequacy of model assumptions. Since accuracy and low computational time were obtained, it is reasonable to expect that the mathematical model could be used as a reliable design, control and optimization tool for absorption refrigeration systems.