Estudo e avaliação de um sistema de refrigeração industrial: estimativa de carga térmica e capacidade frigorífica

Abstract

The present work was developed in parallel to the author 's internship activities in a dairy factory and it’s objective was study the refrigeration system in operation, evaluating temperature variations in the refrigerated spaces. It was also intended estimating the thermal load of the tunnel by forced-air cooling to base the system’s sizing so that the thermal demand is met. Therefore data collection and monitoring of the system parameters were performed In loco between May and September 2018. It is a vapor compression refrigeration system that operates with Freon R-22 and Ammonia fluids and needs to meet the demand of three refrigerated environments: the storage and expedition chambers (cold room and antechamber) with temperatures of interest in the 0 to 10ºC and 0 to 15º ranges, respectively; and the tunnel by forced-air cooling used for pre-cooling a type of yogurt which is hot packaged and temperature of interest in the range of -5 to 10 ° C. The system was not designed for the current production condition so the thermal load for the cooling tunnel was estimated since it was observed that it does not meet the production demand and this has impacted the quality indicators of the factory. Data were analyzed by ANOVA and Tukey's test at 95% significance level. Thus it was possible verify that the current operation and maintenance conditions negatively impact the efficiency of the system even though the cold room meets the production demand, since it works with 40 to 60% of its capacity. In addition the precooling time adopted (1.5 hours) is not sufficient to reach the temperature range of interest for yogurt (0 to 10ºC) requiring at least 4.5 hours considering the current system conditions. At the end the refrigerated capacity was estimated in 66,587 kW and opportunities for improvement were observed for the secondary packages that are being improved and can contribute with a better cooling effect by increasing the convective thermal exchange between the cold air and the products of interest.