Types of Airflow Patterns in HVAC Heat Exchangers

January 17, 2019
Air conditioning unit for repair

Heating, ventilation, and air-conditioning units now make an integral part of all properties. Most people assume that it only takes connecting the wires to a power source to get their air conditioning up and optimally running. Hence, they consider professional installation a waste of money. With their DIY installation, however, they realize that their units are not delivering optimally heated or cooled air. This is because there is more to an HVAC installation service handled by some experts in Knoxville than wire connections and controls. One of the elements that will determine how your system works is its heat exchanger’s airflow pattern. This denotes the direction of a tube fluid’s flow in relation to the shell fluid. Here are the primary HVAC airflow patterns:


In a counterflow, hot fluid enters the heat exchanger from one end and cold fluid from the opposite end. This way, the fluids run in opposite rather than similar directions. This direction of flow allows maximum temperature exchange between the fluids and generates a consistent temperature throughout the exchanger. Counterflow heat exchangers are the most common ones used primarily because of their high efficiency due to the maximum heat transfer between incoming and outgoing air.

Parallel Flow

This is also called a concurrent flow. The fluids in the shell and tube of the heat exchanger flow in one direction. This type of flow is usually used for double-pipe heat exchangers. Compared to other airflow patterns, the parallel flow has a more uniform exchanger wall temperature. Its heat exchange rate is hence not as high as in other patterns. As such, you will need a bigger surface area for the installation of an HVAC unit with a parallel flow pattern to maximize heat exchange. The dramatic temperature variation at the inlets of points with this airflow pattern might cause thermal stress and consequently vibrations in your system, which might prematurely damage your unit.


Man inspecting the HVAC air ventThis type of HVAC airflow is designed such that two fluids in different states will run perpendicularly to each other. The tube or shell fluid might be a liquid while the one in the opposite pipe will be a gas. This pattern is generally used in steam condensers where a liquid will be changed into a gas at the end of its flow.

Combined Flow

In large-scale HVAC systems, the airflow patterns mentioned above are all used in varying degrees. This way, the systems will conform to your available budget and floor space and deliver your property’s ideal temperature. Some systems, for instance, will combine crossflow and counterflow patterns to maximize heat transfer while minimizing the floor space their system takes.

Proper knowledge of the flow patterns mentioned above will not only enable you to make the right choice of an HVAC system but also quickly identify its malfunction. With the best airflow pattern choice to meet your property’s air conditioning and expert installation, the need for repairs of your system will be minimal. As such, hiring a professional to install your HVAC unit will save you cash in expensive future repairs and ensure the unit works at its best.

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