Liquid Overfeed (Liquid Circulation) System Evaporator Explained

In the realm of HVAC systems, understanding various refrigerant feeding methods is crucial for optimizing performance and efficiency. One such method is the liquid overfeed system, also known as the liquid circulation system. In this blog, we will delve into the workings of this evaporator feed system, focusing on its mechanism, benefits, and applications.

What is a Liquid Overfeed System?

A liquid overfeed system is an evaporator feeding technique where refrigerant liquid is first flashed to a saturated suction pressure and temperature within an accumulator. This liquid is then propelled by a mechanical pump or by the vapor pressure of the refrigerant towards the evaporators.

How Does It Work?

The process begins as the refrigerant enters the accumulator, where it experiences flashing. During this stage, part of the refrigerant transitions from liquid to vapor due to pressure drop, achieving the necessary temperature and saturation. From here, liquid refrigerant is circulated to the evaporators at a rate higher than the evaporation rate, ensuring that every section of the evaporator surface remains wet. This promotes maximum heat transfer and enhances system efficiency.

Benefits of Liquid Overfeed Systems

• Improved Heat Transfer: By maintaining a constant wet surface on the evaporator, these systems enhance the overall heat exchange process, which leads to better cooling efficiency.
• Reduced Risk of Flooding: Unlike conventional systems, which might struggle with liquid refrigerant returning to the compressor, the overfeed system keeps liquid circulating, reducing the risk of flooding.
• Energy Savings: Enhanced heat transfer and reduced compressor workload contribute to lower energy consumption, which can significantly decrease operational costs.
• Flexibility in Design: This system can adapt to varying load conditions, making it suitable for a variety of industrial and commercial applications.

Applications

Liquid overfeed systems are particularly effective in large refrigeration systems, such as those used in food processing, cold storage, and industrial cooling applications. Their ability to maintain wet evaporator surfaces makes them ideal for environments where consistent cooling is critical.

Conclusion

The liquid overfeed (liquid circulation) system presents a robust solution for HVAC professionals seeking to optimize evaporator efficiency. With improved heat transfer capabilities and flexibility for various applications, this system plays a vital role in modern refrigeration and cooling processes. Understanding and implementing this technique can lead to better system performance, reduced energy consumption, and overall enhanced operational longevity.