The novel use of Phase Change Materials (PCM) in refrigerated display cabinets for energy conservations
Lead University: Brunel University London
Dr Yunting Ge, Professor Savvas Tassou, Falah Alzuwaid
Collaboration: work presented in this research was carried out with financial support from the Department of Environment, Food and Rural Affairs (DEFRA: AFM280)
Each day the world's attention increases on how to minimize the energy consumption in order to reduce energy cost and carbon emissions as well as conserve the energy resources we have. Open-type vertical refrigerated display cabinets are part of refrigeration equipment and systems that considered as the largest consumer sectors for electric energy. One technique that has been used to improve the efficiency of such refrigeration equipment is to employ thermal energy storage inside. This approach will lead to improve the overall efficiency and also reduce the required cooling load of the equipment. This research project details the effect of phase change materials (PCMs) integration on the thermal performance of an open type multi-deck display cabinet in terms of energy savings, food product temperature improvements, cabinet air temperature and comparisons with conventional units. The experimental part included a series of tests that were carried out to determine that effect of incorporation of PCM through two types of display cabinets. Two integration procedures of PCM-HEs with different PCM types were employed for each cabinet depending on its design. The theoretical study involves a 2D CFD model established for the Norpe display cabinet. The model is used to investigate the effect of adding PCM-HE on the energy consumption of display cabinet, thermal performance and cabinet air temperatures in similar method and same test conditions.
- The simulation and test results indicated that the response of the cabinet with PCM was positive in minimizing the power consumption, product and cabinet air temperatures when the cabinet was off and improving thermal performance.
- It was found that with PCM the energy saving potentials of the cabinet significantly improved experimentally and theoretically, to around 5% and 6.4 % respectively at climate class 3 conditions (25ºC and 60% RH).
- In terms of cabinet air temperatures, both test and model results showed considerable benefit from reductions of maximum temperatures and temperature range.
- The whole variation range of product temperatures has become more moderate after modification signifying more uniformity in product temperatures. Also, adding PCM showed an increase in the whole average of product temperatures.
- The defrost intervals were the most affected factors for the modified cabinet. They were increased experimentally and theoretically by approximately 70% and 98% respectively compared to those with the basic cabinet. Simulation results also showed an increase by about 50% in compressor off intervals.
The PCM radiators and their position inside the cabinet