Prototype design of domestic‐scale freeze‐dryer with natural working fluid‐based refrigeration system and microwave heating system.

One of the most promising food preservation methods is freeze‐drying, in which almost 100% of the water content is removed from the processed food product. As a result, processed food products do not require cooling during transportation or storage. On the other hand, the energy demand of the freeze‐drying process is relatively high. In this work, the novel freeze‐dryer for domestic application was equipped with natural working fluid‐based refrigeration system and microwave (MW) heating. The refrigeration unit was carefully analysed and optimised to maximise its performance and match the required cooling in an efficient way. In addition, the validated CFD model was used to redesign the vacuum chamber of the freeze. In consequence, a new design was proposed. As a result, the power consumption of the freeze dryer was significantly improved. The introduced changes to the refrigeration system resulted in 50% reduction of freezing time compared to the reference unit.