Integrative thermodynamic optimization of a vapor compression refrigeration system based on dynamic system responses

• Published in: Applied thermal engineering 2018-05, Vol.135, p.493-503
• Main Authors: Yang, S., Ordonez, J.C.
• Format: Article
• Language: English
• Subjects: Evaporation; Exergy; Heat exchange; Heat exchangers; Heat transfer; HVAC; Optimization; Pull-down time; Refrigeration; Space temperature; Systems design; Thermodynamic optimization; Thermodynamics; Vapor compression cycle; Vapor compression refrigeration
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2018.02.088

•We present the integrative thermodynamic optimization of a refrigeration system.•We consider COP, second law efficiency, refrigeration rate, and pull-down time.•Heat exchanger area and global heat transfer coefficients are allocated optimally.•Distinct optimal design configuration exists for each performance metric. We optimized the internal structure (heat exchanger areas) of a dynamic vapor compression refrigeration system for maximum global system performance described by the coefficient of performance (COP), refrigeration rate, second law efficiency, and pull-down time. The numerical optimization was subjected to fixed system heat transfer surface, and the relative sizes of condenser and evaporator were selected optimally via parametric sweeps. Optimization results demonstrated the existence of distinct optimal area allocation for each objective function considered herein while higher evaporator to condenser global heat transfer ratio was preferred in all cases. Maximum COP was achieved, for instance, with smaller evaporator area than maximum second law efficiency that yielded shorter pull-down time and lower refrigerated space temperature in exchange for slightly higher compressor power and total exergy destruction. In summary, this work provides insights into the selection of an optimal refrigeration system design based on its dynamic responses and physical implications.