Reduced order modeling for multi-circuit fin-and-tube heat exchangers with multiple identical circuit types

• Published in: International journal of refrigeration 2019-10, Vol.106, p.236-247
• Main Authors: Sarfraz, Omer, Bach, Christian K., Bradshaw, Craig R.
• Format: Article
• Language: English
• Subjects: Air conditioners; Air conditioning; Algorithms; Circuits; Circuits identiques; Coils; Computer simulation; Fin discretized model; Fin-and-tube heat exchanger model; Heat exchangers; Heat transfer; HVAC; Identical circuits; Modèle discrétisé d’ailette; Modèle d’échangeur de chaleur à tube à ailettes; Modèle segment par segment; Modélisation de l’ordre réduit; Reduced order modeling; Reduced order models; Reduction; Segment-by-segment model; Simulation; Symmetry; Tube heat exchangers; Tubes; Ventilation
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2019.06.015

•The multi-circuit heat exchangers with identical circuits are commonly used.•An identical circuitry algorithm to identify identical circuits developed.•The algorithm is incorporated in Xfin and FD heat exchanger models.•The simulation time was reduced by more than 50%. Fin-and-tube heat exchangers are widely used in vapor compression systems for the heating, ventilation, and air-conditioning applications. There are numerous fin-and-tube heat exchanger models described in literature with some considering techniques to reduce the overall simulation time. A technique that can help reduce the simulation time in fin-and-tube heat exchangers is the reduction in the identical circuits by leveraging symmetry that typically exists in fin-and-tube heat exchangers. An algorithm is developed in this paper that finds the identical circuits in the heat exchanger to allow a user to leverage this symmetry. A parametric study is conducted by simulating different number of identical circuits in a multi-circuit heat exchanger using 2 different i.e. detailed and reduced order segment-by-segment models that can account for cross-fin conduction between the neighboring tubes of the heat exchanger. The capacity and simulation time for different number of simulated circuits is compared to when all circuits are simulated in a multi-circuit heat exchanger. The result show that the inclusion of reduced number of identical circuits instead of all circuits resulted in more than 70% reduction in simulation time for both the models with less than 3% difference in capacity. The simulation of only 5 out of 23 identical circuits in an air-to-water coil using reduced order model resulted in less than 1% of the simulation time and less than 3% difference in capacity relative to the detailed segment-by-segment model with all circuits simulated.