The use of phase change material for the control of the food storage temperature

Each product has a specific optimal storage temperature since a too high or too low temperature can adversely affect the quality and/or safety of the food. This project focus on the use of Phase Change materials (PCMs) for cold storage both in insulated boxes and in refrigerating equipment. 
Applying PCM in the food chain provides less temperature variations and better energy management. To achieve these benefits many factors should be considered: insulating material, PCM (type, quantity and position), load characteristics, operating conditions. There are many experimental and theoretical analyses but given the multiplicity of factors to be considered additional study is necessary to find the most appropriate PCM type for each application. Belman-Flores et al., (Int J Refrig 2015) considered the employment of PCMs to achieve considerable energy savings in domestic refrigerators and highlighted their utilisation for internal temperature control. Veerakumar and Sreekumar, (Int J Refrig 2016) concluded that PCMs are becoming essential in cold storage.

The state of art analysis reveals the benefits of PCMs on food storage and refrigeration on product temperature control, longer off periods and lower energy consumption of the refrigeration systems. In this project we intend to study the effect of PCM in insulated boxes and in refrigerating equipment through numerical investigations.

• Insulated box: a numerical model will be developed to optimize the design (material and thickness of the box, type and thickness of insulating material, type of PCM, position and usage). Once the box has been correctly designed, numerical tests will be carried varying the operating conditions.
• Refrigerating equipment: a numerical model will be used to select the optimal PCM material (the melting temperature affects the temperature distribution inside the refrigerator) and its position. Subsequently, different control settings (varying the ambient temperature and food mass conditions) will be numerically analysed.

Following the numerical analyzes that will be conducted both on the insulated box and on the refrigerating equipment with the use of PCM several advantages will emerge. In the follow the expected results.

• Insulated box: an insulated box equipped with a fan will be developed. This type of box would allow airflow by forced convection inside the box, and the temperature would thus be more homogeneous. A rechargeable battery should supply enough power to the fan to assure continuous fan running along the supply chain. The use of PCM in the box will maintain low temperature and reduce temperature fluctuation during food transport.
• The expected benefits in the use of PCM in refrigerating equipment will be: an improvement of product conservation conditions since the introduction of PCM will reduce the fluctuations of the product temperature during the refrigerator operation; a better temperature distribution within the cabinet; the extend of the OFF time of the compressor and the reduction in its switching frequency; a reduction of the energy consumption of the refrigerator.