A novel approach combining thermosiphon and phase change materials (PCM) for cold energy storage in cooling systems: A proof of concept

Abstract

A novel approach combining thermal energy storage (TES) and a thermosiphon was investigated for cold storage. The use of TES units for cooling systems has been studied for many years, as they are well suited for short-term energy storage. A cold latent heat accumulator was designed to replace the function of any vapour compression cycle in the event of electrical failure without using any electrical device but rather the thermosiphon principle. A laboratory prototype of a thermosiphon combined with the cold accumulator was developed using a paraffin mixture as a phase change material (PCM). The accumulator was connected to the vapour compression system of a closed display cabinet. An experimental study was carried out by simulating 1.5 h compressor shutdowns with and without the accumulator. The thermosiphon loop effectively transferred 97 % of the stored energy to the display cabinet. The air and product temperatures in the cabinet, the behaviour of the compressor during restart, and the charging and discharging processes of the accumulator were analysed. The results showed that shutting down the compressor with the cold accumulator significantly reduces the increase of air and product temperatures compared to shutting down without the accumulator. The air temperature in the rear duct was maintained within the acceptable temperature range for 72 min with the accumulator, compared to 3 min without. A default in the design of the accumulator was observed during the charging phase, as some areas of the accumulator never reached 80 % of charge. This new approach extends demand-side management and renewable energies to all end users of vapour compression machines.