Cross flow plate heat exchangers are available as sensible only or enthalpy—two heat transfer configurations of energy recovery ventilation system. Choosing one over the other depends on the specific requirements of the HVAC application.
Sensible Only Plate Heat Exchanger (Heat only)
A sensible only plate heat exchanger is designed to transfer heat (temperature without moisture) between two air streams. It consists of plates with alternating hot and cold air channels separated by thin walls. The heat transfer occurs through conduction across the thin walls; the temperature of one air stream increases while the temperature of the other decreases.
Enthalpy Plate Heat Exchanger (Heat and Moisture)
An enthalpy plate heat exchanger, also known as a total heat exchanger, is designed to transfer both sensible and latent heat (heat and moisture) between two air streams. It includes plates with alternating hot and cold air channels, like the sensible only plate heat exchanger. However, the plates also incorporate a special membrane to facilitate the transfer of moisture between the air paths.
Advantages of Sensible Only Plate Heat Exchangers
- Less Complexity, Lower Cost: Sensible only plate heat exchangers do not require the addition of a desiccant or hygroscopic material, as the enthalpy plate heat exchangers do. This simpler design results in less complexity and a lower cost.
- Reduced Maintenance, Longer Life: Sensible only plate heat exchangers do not involve handling or maintenance of desiccant material. This reduces maintenance requirements and potentially extends the operational life of the heat exchanger.
Advantages of Enthalpy Plate Heat Exchangers
- Heat Transfer AND Humidity Control: Enthalpy plate heat exchangers transfer both sensible heat and latent heat (moisture). This enables better humidity control in HVAC systems, as the moisture from one air stream can be transferred to the other, reducing the need for additional humidification or dehumidification equipment.
- Energy Efficiency: By transferring both sensible and latent heat, enthalpy plate heat exchangers can improve the energy efficiency of HVAC system. The recovered heat and moisture from the exhaust air can be utilized to precondition the incoming air, reducing the load on heating or cooling equipment and resulting in energy savings.
If humidity control is not a significant concern, a sensible only plate heat exchanger may be sufficient and offers simplicity and lower maintenance. However, if humidity control is important or when energy efficiency is a priority, an enthalpy plate heat exchanger may be preferred due to its ability to transfer both sensible heat and moisture.