Simulation of the performance of thermal energy storage systems for the cold chain in developing countries

Approximately 10% of all electricity consumption worldwide is used for cooling, and this number is expected to increase rapidly as the world’s population grows [1]. The increasing need for cooling in food storage facilities is directly related to the rising temperature trend worldwide. But one of the means of turning this temperature increase into an opportunity is solar cooling, which has many environmental advantages, such as lowering the need for the main grid and cutting down on greenhouse gas emissions. This thesis provides a case study of a solar photovoltaic (PV) powered refrigerated container (25m×40m×5m) with integrated Thermal Energy Storage (TES) which gives a great opportunity to minimize the need for grid electricity while yet keeping perishable foods at constant temperature in Venice, Italy. TRNSYS software has been used to run a dynamic simulation of the case study system. The system consists of a container, vapour compression chiller, PV panel and TES. To calculate the cooling load of the container, the stratification of the walls, heat gains and the dimensions of the container are added to TRNBuild. After connecting the container, chiller, and PV to the weather data, and fixing the inlet and outlet temperatures of the chiller, the mass flow rate of the refrigerant was calculated and sent back to the system as input. To determine how much solar energy is needed to fulfil the electricity demand of the chiller, different PV areas are simulated. One of the main focal points of this thesis is how much electricity we save with different capacities of TES and areas of PV panels. The results show that the total amount of electricity saved during the year varies considerably depending on the season. Minimum savings occur in winter because of the chiller’s low power consumption and the TES’s near-constant charging level, while in summer PV panels cannot fully cover the demand of the chiller even using with high capacities TES, so saved energy percentages are also lower in summer months. On the other hand, increasing TES size capacity and reducing PV areas can have a positive impact both economically and in terms of energy.