Minimizing Energy Consumption During the Cryopreservation Process of Plant Products

The article studies the energy efficiency of plant products cryopreservation and the ways to optimize the operating modes of refrigeration equipment. The aim of the work is to develop rational modes of plant products freezing in order to minimize energy costs. The tasks were solved: study of the effect of freezing conditions on the process kinetics and energy costs; effect assessment of morphological structure on the internal thermal resistance of objects; search of indirect control of the product state based on the energy characteristics of the system. The object of the study was the cryopreservation of samples with different tissue structures (blanched apple and cranberry) in the experimental stand with a static cooling system. It was found that under identical conditions (t = -15 °C), the processing time of cranberries was ~4.75 h (cryoscopic plateau - ~1.5 h); for blanched apples - ~7.2 and ~2.5 hours, respectively. Blanching reduces the effective product thermal conductivity, increasing the phase transition time. The most important result is to find the relationship between changes in the compressor duty cycle and the phase transition stage in plant products. Significant undercooling in cranberries ensures a high rate of nucleation of small crystals at low heat dissipation rates. The significance of these results lies in the development of a method for indirectly monitoring the freezing process through standard automation systems without the use of invasive sensors. This allows for the optimization of control algorithms and the reduction of unproductive energy consumption in refrigeration systems.