Exploratory Testing of Energy-Saving Characteristics of Large-Scale Freeze-Drying Equipment

The advantages of continuous freeze-drying are increasingly being emphasized, including energy saving, high production efficiency, and superior quality. In this context, an innovative continuous production process and cold trap structure for large-scale freeze-drying equipment is proposed. Built-in alternating cold traps are adopted instead of the stationary type to reduce the defrosting downtime, significantly improving the energy efficiency of the refrigeration and heat pump heating units. In the freeze-drying production of shiitake, comparisons between the built-in alternating cold traps and the stationary type indicate a reduction in energy consumption of approximately 24% for the full production process when the alternating cold traps with tube coils are used, that is, from 1937 kW·h for the stationary type to 1471 kW·h. In addition, the energy consumption for the built-in alternating cold traps with finned tube coils could be further reduced by about 8%. Finally, through the implementation of the new continuous production process and built-in alternating cold traps in industrial large-scale freeze-drying equipment, the systematic energy consumption per unit of food dehydration (kg) is reduced by approximately 40%, i.e., from 1.31 kW·h in the intermittent production process to 0.79 kW·h in the new continuous production process.