Experimental study and modelling of air distribution systems and temperature control for chilled food factories in a scaled test facility

In this paper, an investigation on different air distribution systems at the required conditions of an actual chilled food processing factory is presented. A scaled test facility has been set-up for the analysis of air distribution systems and their energy consumption at different conditions. A three-dimensional CFD model of the scaled test room was also developed, validated and used to investigate the most appropriate air distribution approaches to create temperature stratification in the space. Initial experiments focused on the study of an air distribution via fabric duct which is the current configuration used in an actual chilled food processing facility. Measured temperatures were found to vary between 6.7 ºC and 11.3 ºC. CFD Modelling of the air distribution system employing the SST-k-ω turbulence equation was also conducted. Results showed that the predicted temperatures and velocities were in good agreement with respect to the data measured from the scaled experimental test facility. The CFD model was then used to evaluate the performance of (a) air distribution via displacement ventilation with one horizontal diffuser, (b) air distribution with displacement ventilation system with two 1-way supply diffusers, (c) air distribution system with a half fabric duct at a medium level, and (d) air distribution system via slot diffusers at medium level. Results from the different approaches investigated showed that the half fabric duct located at medium level provided a wider temperature gradient (from 7 ºC to 14 ºC). The most significant stratification was observed between head level and the ceiling level. It was also identified that the air distribution system via half fabric duct at a medium level provided a more homogeneous air flow over the entire production zone. The level of temperature stratification provided, air flow homogeneity and ease of implementation in a real factory situation provides a good solution for achieving thermal stratification and energy savings in a chilled food factory without compromising the thermal environment.