AIR-TO-AIR Heat Exchanger Types

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Maximizing Efficiency: The Power of Modern Heat Exchangers

Did you know that innovative heat exchangers can significantly reduce energy consumption and operating costs? From plate exchangers optimizing airflow, to rotary wheels capturing both heat and moisture, and liquid-coupled systems excelling in industrial settings – each solution is designed to recover energy and improve sustainability.

Explore how these technologies can transform your HVAC systems or industrial processes. Efficiency isn’t just smart – it’s essential. Let’s make energy savings the new standard!

Introduction to Air-to-Air Heat Exchangers

An air-to-air heat exchanger is a device that transfers heat between two separate air streams without mixing them. It is commonly used for ventilation and energy recovery in buildings and industrial processes—in particular, within Air Handling Units (AHUs).

The heat exchanger allows warm, stale air from inside to transfer heat to cooler, fresh incoming air (or vice versa), improving energy efficiency while maintaining air quality.

What Are the Most Common Exchanger Types?

So what are the most common exchanger types? Let’s discover them together.

Air-to-Air Heat Exchangers

1. Plate Heat Exchangers

Plate heat exchangers, as the name implies, use a series of plates to transfer heat between two airflows. The most common type is the cross-flow exchanger, where air moves through perpendicular channels within the plates. Heat is efficiently transferred from the outgoing warm air to the incoming cool air, reducing the strain on heating and cooling systems.

Airflow Configuration Matrix

  • Outside Air: Incoming fresh air entering the system.
  • Supply Air: Conditioned air delivered to the indoor space.
  • Extract Air: Stale air drawn out from the indoor environment.
  • Exhaust Air: Stale air expelled completely out of the building.
Plate Heat Exchangers diagram

2. Rotary Heat Exchangers

Rotary heat exchangers, also known as heat wheels, provide efficient heat recovery by rotating a heat-absorbing wheel between the supply and exhaust airflows. These devices transfer both sensible heat (related to temperature) and latent heat (associated with moisture).

There are three main types of rotary heat exchangers:

  • Condensation type: Recovers moisture only during the colder seasons.
  • Enthalpy type: Recovers moisture during both cold and transitional seasons.
  • Sorption type: Provides year-round moisture recovery.

Condensation heat wheels are the most widely used due to their lower cost and simplicity, as they do not require additional equipment for proper functioning.

Airflow Configuration Matrix

  • Outside Air: Fresh outdoor air entering the rotary system.
  • Supply Air: Conditioned air sent directly into the building.
  • Return Air: Warm or stale air drawn from rooms back into the system.
  • Exhaust Air: Used air pushed out of the building.
Rotary Heat Exchangers diagram

3. Run Around Heat Exchangers

A liquid-coupled heat recovery system uses two separate tube-fin coils: one positioned in the supply air stream and the other in the exhaust air stream. These coils are connected by a liquid circuit, typically filled with a glycol-water mixture, which transfers heat from the exhaust air to the supply air.

These systems are particularly efficient for recovering heat from high-temperature exhaust air, making them ideal for industrial applications. Additionally, they allow for greater flexibility in space planning, as the supply and exhaust sections can be located at a distance from each other.

Airflow Configuration Matrix

  • Outside Air: Incoming outdoor air passing through the first coil.
  • Supply Air: Conditioned fresh air entering the indoor space.
  • Extract Air: Internal stale air drawn into the recovery system.
  • Exhaust Air: Spent air safely discharged into the atmosphere.