How Does a Plate Heat Exchanger Work in a Heat Pump?

Plate heat exchangers (often abbreviated as PHX) are key components of many heating systems, including air-source heat pumps. They play a crucial role in the performance and reliability of heating, cooling, and domestic hot water systems.

But how exactly do they work inside a heat pump? In this article, we’ll explore the inner workings of the plate heat exchanger in a heat pump and how this critical component improves overall system performance.

Understanding Plate Heat Exchangers (PHX)

A plate heat exchanger is a compact device consisting of multiple thin, corrugated metal plates arranged in parallel. These plates are aligned and clamped together to form separate channels for the flow of hot and cold fluids. The fluids (refrigerant and water) do not mix; instead, heat is transferred across the plate surfaces.

Due to the large surface area of ​​the plates, plate heat exchangers achieve extremely high heat transfer efficiency within a compact design, making them ideal for use in modern heat pumps.

How a Plate Heat Exchanger Works in a Heat Pump

In a heat pump, the plate heat exchanger serves as an efficient transfer point between the refrigerant circuit and the water circuit. Here’s how it works step by step:

1. Absorbing Heat
   • The refrigerant absorbs heat energy from the air (or ground/water, depending on the type of heat pump).
   • The refrigerant is then compressed, increasing its temperature.
2. Heat Transfer Through Plates
   • The hot refrigerant passes through one side of the plate heat exchanger.
   • On the opposite side, cooler water (from the heating system or storage tank) flows in the counter direction.
   • As the refrigerant flows through the plates, it heats the metal. Heat from the metal plate is transferred through the thin plate walls to the cooler water.
3. Heating Water or Space
   • The heat carried by the refrigerant raises the temperature of the water.
   • This heated water is then circulated through radiators, underfloor heating, or hot water tanks.
4. Cooling Mode (Reverse Process)
   • In cooling mode, the process is reversed. The plate heat exchanger allows the refrigerant to absorb heat from the indoor water system and release it outside, cooling the space efficiently.

Benefits of Plate Heat Exchangers in Heat Pumps

• Efficiency – The plate’s large surface area maximizes heat transfer while minimizing energy loss. This makes it an ideal choice for improving heat pump efficiency.
• Compact Size – Its small size allows for easy integration into heat pumps, further reducing overall space. This makes the heat pump suitable for both residential and commercial applications.
• Flexibility – It can effectively perform both heating and cooling functions, making it ideal for trigeneration heat pumps.
• Durability – The high-quality stainless steel plates are corrosion-resistant and suitable for long-term use.
• Low Maintenance – Compared to other heat exchangers, PHEs have fewer moving parts, requiring minimal maintenance.

Why It Matters for Heat Pump Performance

The efficiency of the plate heat exchanger directly impacts the Coefficient of Performance (COP) of a heat pump. A well-designed PHE ensures:

• Faster heat transfer
• Reduced energy consumption
• Stable water outlet temperatures
• Improved system reliability

In short, the plate heat exchanger is the “bridge” that makes the heat pump system both efficient and practical for real-world heating and cooling applications.

Conclusion

So, how does a plate heat exchanger work in a heat pump? It enables efficient heat transfer between the refrigerant and water circuits, ensuring optimal performance in both heating and cooling modes.

JNOD air-source heat pumps use Danfoss plate heat exchangers. If you’re considering a heat pump for your home or business, be sure to focus on the quality of the plate heat exchanger, as it’s at the heart of its energy efficiency.