Disaggregation models for the thermoeconomic diagnosis of a vapor compression refrigeration system

Abstract

The demand for chilled or frozen pre-cooked food and also for conditioned air has increased significantly in the last years. It is also well known that food refrigeration systems (blast chilling or freezing, cold storage, etc.) and air conditioners are important energy consumers in the tertiary sector. Thus, proper diagnosis techniques are important to avoid excessive energy consumption and to assure that the cooling demands will be met. In order to predict the performance of these systems under off-design conditions, mathematical models of refrigeration and air conditioning systems are presented. Besides that, four malfunctions are simulated and the equilibrium condition for each one of them is calculated. Two thermoeconomic methodologies are used to evaluate the fuel impact of each degradation. It was revealed that different values of degradations and dysfunctions were calculated even though the same fuel impact was obtained. One of the productive structures assessed presented more suitable results for the diagnosis of anomalies due to its use of fewer fictitious flows, which are known to incorrectly influence in the magnitude of exergy flows leading to improper results. Further studies regarding the structure of the malfunctions (intrinsic and induced components) are needed for more accurate diagnosis in refrigeration systems.