A cross flow heat exchanger has fluids moving perpendicular to each other, with one fluid flowing across tubes while the other flows through them. This configuration is common in air conditioning and refrigeration systems where air passes across finned tubes containing refrigerant or chilled water. The perpendicular arrangement creates moderate heat transfer efficiency compared to other designs.
Technical Details
Cross flow exchangers typically achieve effectiveness ratings between 0.50 and 0.80, depending on the number of transfer units (NTU). The design uses either unmixed or mixed flow configurations. Unmixed flow provides better temperature uniformity but slightly lower efficiency, while mixed flow increases contact time and heat transfer rates. Most residential air handlers employ cross flow designs with aluminum fins and copper tubes.
Applications in HVAC
Cross flow heat exchangers are standard in air conditioning evaporator and condenser coils. They work effectively in package units, split systems, and commercial rooftop equipment. The configuration handles air-side fouling well, making maintenance simpler than counter flow alternatives. Fin pitch typically ranges from 8 to 20 fins per inch depending on the application and indoor air quality.
Practical Significance
This design balances cost efficiency with performance, making it economical for residential and light commercial applications. The perpendicular flow arrangement simplifies installation in constrained spaces within air handlers and outdoor condensing units.