Modeling Particle Deposition on HVAC Heat Exchangers

TitleModeling Particle Deposition on HVAC Heat Exchangers
Publication TypeConference Paper
Year of Publication2002
AuthorsSiegel, Jeffrey A, William W Nazaroff
Conference NameIndoor Air 2002, June 30 - July 5, 2002
Conference LocationMonterey, California
KeywordsExperiments, fouling, Heat exchangers, hvac, modeling

Fouling of fin-and-tube heat exchangers by particle deposition leads to diminished effectiveness in supplying ventilation and air conditioning. This paper explores mechanisms that cause particle deposition on heat exchanger surfaces. We present a model that accounts for impaction, diffusion, gravitational settling, and turbulence. Simulation results suggest that some submicron particles deposit in the heat exchanger core, but do not cause significant performance impacts. Particles between 1 and 10 µm deposit with probabilities ranging from 1 - 20 % with fin edge impaction representing the dominant mechanism. Particles larger than 10 µm deposit by impaction on refrigerant tubes, gravitational settling on fin corrugations, and mechanisms associated with turbulent airflow. The model results agree reasonably well with experimental data, but the deposition of larger particles at high velocities is underpredicted. Geometric factors, such as discontinuities in the fins, are hypothesized to be responsible for the discrepancy.

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