Experimental recirculating carbon dioxide refrigeration unit

Turkey farming and meat processing are fast-developing areas of the Russian food industry. However, their development requires more advanced methods of meat storage and freezing. Traditional methods of air cooling often fail to preserve the original meat texture and nutritional value. This paper introduces a new refrigeration unit with CO2 as a refrigerant. CO2 snow and gas come in direct contact with turkey carcasses, thus accelerating the cooling process and improving the meat quality. CO2 recirculation makes the refrigeration unit an economical solution to environmental issues. The refrigeration unit included a conveyor system, a vacuum chamber, and a CO2 circulation system. The research featured grade 1 turkey carcasses of 2.7 ± 0.1 kg frozen at different temperatures (–30, –50, and –70°C) and CO2 flux rates (0–5 m/s). The share of CO2 in the gas mix was ≥ 50%. The temperature and heat flux density were measured using thermocouples and heat flux probes. As the temperature dropped from –30 to –70°C, the freezing time decreased from 48 to 33 min and to 29 min when the experiment involved enforced convection. The amount of CO2 consumed increased from 7.5 to 13.5 kg without convection and from 6.5 to 12.0 kg with enforced convection. Compared to traditional methods, CO2 provided uniform freezing and reduced mechanical damage to the meat structure. The newly developed refrigeration unit with recirculated CO2 demonstrated high efficiency in freezing turkey meat while reducing CO2 consumption and providing uniform cooling of the carcass. It demonstrated could prospects for industrial use, which opens up new opportunities for further research and freezing process optimization.