Disaggregation models for the thermoeconomic diagnosis of a vapor compression refrigeration system. (15th February 2020)

• Record Type: Journal Article
• Authors: Mendes, Tiago; Venturini, Osvaldo José; da Silva, Julio Augusto Mendes; Orozco, Dimas José Rúa; Pirani, Marcelo José
• Is Part Of: Energy. Volume 193(2020)
• Publication Date: 2020-02-15
• Subjects: Computer modelling -- Refrigeration system -- Energy consumption -- Exergy splitting -- Thermoeconomic diagnosis; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2019.116731
• Languages: English
• ISSNs: 0360-5442

Abstract

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. Highlights: The definition of productive flows for dissipative components is necessary to define their function. Two disaggregation levels were used to define the products for dissipative components. Different productive structures lead to diverse malfunctions values, but they do not affect the fuel impact. The UFS Model is the most suitable for diagnosis assessments in the refrigeration system. The benefits arising from eliminating malfunctions can be assessed independent of the methodology.