Abstract
Compression refrigeration systems are very widely used to provide cooling to sub-ambient processes. The power demand of the cycle depends strongly on the temperature at which cooling is required, the temperature at which the refrigerant is condensed, as well as the type of refrigerant being used. At lower temperatures (typically lower than -40 °C), complex refrigeration schemes, such as cascaded refrigeration cycles, may be needed, increasing the complexity of the models used to predict the power requirements for a given cooling demand. This work proposes a simple model for predicting the power consumption of such complex cycles, based on regression of more rigorous process simulation models.
A simple linear refrigeration model which relates the actual power demand of a refrigeration cycle to the ideal performance (i.e. the Carnot cycle) is developed. The model predicts the power demand prior to design of the refrigeration scheme given the condensing and evaporation temperatures of the refrigerant. The model predictions are shown to be in good agreement with those of more accurate simulation models. Case studies demonstrate the validity of the refrigeration model. The predicted power demand is shown to be within 10 % of that of Branan (2005). The simplicity of the model enables its use for optimizing the design conditions of a complex refrigeration cycle and/or the associated processing conditions.
