Dynamic Modelling and Experimental Validation of a Domestic Refrigeration Cycle

Performance analysis and design optimization of refrigerators are primarily carried out by time-consuming experiments. The current study presents an alternative method of analysing refrigerators through modelling of the cooling cycle using a software called Dymola, based on an object-oriented programming language, called Modelica. The main components of a domestic refrigerator (compressor, condenser, evaporator, cabinet and capillary tube-suction-line heat exchanger) are first modelled and validated individually. The full dynamic refrigeration cycle model is created afterwards. Both the simulations and the experiments have been conducted using R600a as the refrigerant with on-and off-modes of the reciprocating, single speed compressor. To represent the dynamic cyclic behaviour of the refrigerator, an algorithm block is also included. The algorithm controls the operation using two set-point temperatures of the cabinet. Experiments have been carried out on a single door refrigerator having an interior volume of 343 litres for the validation of the one-dimensional dynamic model. Results show that the cabinet air, evaporation temperature, condensation temperature, power and energy values deviate from experimental values by less than 2°C and 2% respectively. The dynamic modelling is found to be in good agreement with the experiments in the on mode of the compressor and a promising and rapid tool to represent the transient behaviour of the refrigerator.