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

Abstract

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.