Optimization of CO2 booster refrigeration cycle with flooded evaporators and parallel compressor by using the bees algorithm

Energy supply is one of the most significant issues in modern society. So,energy saving becomes important in systems used frequently in dailylife. Due to these energy saving concerns, there are numerous studies inliterature to make supermarket refrigeration systems consume lessenergy. Among these studies, CO2 booster refrigeration system withflooded evaporators and parallel compressor (BFP) seems as an energysaving and nature-friendly choice. In this study, BFP was selected as thesystem of concern and the Bees Algorithm optimization was applied toget minimum power consumption (maximum COP). Gas cooler pressure(𝑃𝑔𝑐), intermediate pressure (𝑃𝑖𝑛𝑡), and medium temperature (MT) levelevaporator outlet quality(𝑥14) were chosen as optimizationparameters. According to the optimization results, the Bees Algorithmconverged well, and these three parameters were found worthy tooptimize as they brought significant energy saving in total (up to 8.7%in comparison with constant intermediate pressure and MT evaporatoroutlet quality). As a result of this analysis, the optimal 𝑃𝑔𝑐 values werefound to be between 7600 kPa and 12000 kPa at ambient temperaturesranging from 28 to 46°C. The optimal 𝑃𝑖𝑛𝑡 values were found to bearound 3500 kPa below ambient temperature of 14 °C and around 4500kPa above this temperature. The optimal values for x14 ranged between0.62 and 0.69. Additionally, annual energy consumption (AEC) and totalequivalent emission (TEE) for 15 years were calculated for fourdifferent climate types. The highest AEC and TEE were obtained attropical climate with 728.56 MWh and over 10000 tons, respectively.The lowest AEC and TEE were found at continental conditions as380.01 MWh and almost 6000 tons of emission.