An air-to-air plate heat exchanger (PHE) is a device that transfers heat between two air streams without mixing them, using a series of thin, closely spaced metal plates. It’s commonly used for energy recovery in HVAC systems, improving efficiency by preheating or precooling incoming air with exhaust air.

Key Features:

• Construction: Alternating plates create separate channels for the two air streams, with heat transferring through the plates due to temperature differences.
• Types:
  • Cross-flow: Air streams flow perpendicularly, simpler design.
  • Counter-flow: Air streams flow in opposite directions, higher efficiency.
• Efficiency: Typically 50-80% heat recovery efficiency, depending on design and airflow.
• Materials: Plates are often aluminum, stainless steel, or polymers, balancing cost, durability, and thermal conductivity.
• Applications: Ventilation systems, industrial processes, data centers, and residential HVAC for energy savings.

Benefits:

• Reduces energy costs by recovering heat.
• Maintains indoor air quality by preventing air mixing.
• Compact and scalable design.

Limitations:

• Potential for frost buildup in cold climates.
• Pressure drop across the exchanger may require additional fan power.
• Maintenance needed to prevent fouling or clogging from dust/particulates.