This paper contains a mathematical model to predict the transient behavior of a laboratory-scale refrigerating system consisting of a single-cylinder reciprocating compressor, a shell-and-tube condenser, a thermostatic expansion valve, and a dry evaporator.All the components were modeled, and basic equations for them were derived from the physical laws of mass and energy conservation. By timewise integration of the equations, the model permits digital computer simulation of steady state as well as transient behavior of the system.Results of the simulation were compared with experimental results, and the validity of the model was confirmed.