Mj Swain

Measurement and prediction of air movement through doorways in refrigerated rooms

Reducing the amount of air infiltration through the doorways of food storage rooms would improve temperature control and the overall economics of food storage. In the UK a joint government/industry supported LINK project has been set up to look at methods of reducing air infiltration. The project is combining direct experimental measurement with computational fluid dynamics (CFD) modelling. A CFD model of air movement through a doorway has been developed and verified against conventional and laser Doppler anemometry (LDA) measurements. The CFD model has been shown to be generally accurate, however, there are areas where the accuracy is less than perfect. For example the CFD model predicted the shape of the vertical profile accurately, although it under-predicted the maximum velocity by 0.1 m s−1 and it predicted the height at which the airflow changed direction to be 40 mm lower than was measured by the LDA.

Experimental verification of analytical and CFD predictions of infiltration through cold store entrances

Measurements of infiltration through different size entrances of a cold store at two different cold store temperatures were taken and compared against established analytical models and computational fluid dynamics (CFD) models. The analytical and CFD models generally tended to over predict the infiltration. The analytical model developed by Gosney et al. [Proc. Inst. Refrig. 72 (1975) 31] provided the closest comparison with the various experiments. The CFD models were more accurate than the fundamental analytical models but less accurate than those based on a semi-empirical approach. For the experimental configurations examined, CFD offered no real advantage over these empirical analytical models. If the conditions were such that the infiltration rate changed with time or if door protection devices (e.g. air curtains) were used, CFD would become much more advantageous in predicting infiltration.