Common Issues of Brazed Plate Heat Exchangers in Refrigeration Systems
Brazed Plate Heat Exchangers (BPHEs) are widely used in refrigeration systems as evaporators, condensers, economizers, and desuperheaters due to their compact structure, high heat transfer coefficient, and low refrigerant charge requirement.
However, improper design, unstable operating conditions, or poor fluid quality can lead to performance degradation or even premature failure.
Below are the most common issues encountered in refrigeration applications.
Freezing is one of the most frequent problems in BPHE evaporator applications.
It occurs when the local refrigerant temperature drops below the freezing point of the secondary fluid (typically water or a glycol solution). Ice formation inside the narrow plate channels can:
Block flow passages
Increase pressure drop
Reduce heat transfer efficiency
Cause permanent plate deformation or cracking
Because BPHEs have small channel gaps and high turbulence, freezing damage can happen rapidly if flow is insufficient.
Maintain adequate secondary-side flow to avoid stagnation
Install low-temperature cut-off and flow interlocks
Use glycol solutions instead of pure water in low-temperature systems
Ensure correct refrigerant superheat control
Corrosion may occur when incompatible fluids or contaminants are present in the system.
Common causes include:
High chloride content in water
Poor water treatment
Low pH (acidic conditions)
Ammonia exposure in copper-brazed units
In copper-brazed BPHEs, ammonia or acidic fluids can severely attack brazing joints. Over time, corrosion may lead to:
Pinhole leakage
Cross-contamination between circuits
Sudden system pressure loss
Regularly monitor water quality and maintain proper pH levels
Limit chloride concentration according to material specifications
Select 316L stainless steel plates when appropriate
Use nickel-brazed or fully stainless steel units for aggressive environments
Avoid ammonia with copper-brazed exchangers
Deposits of scale, oil, or particulate matter increase thermal resistance and reduce efficiency.
In refrigeration systems, fouling is often caused by:
Poor water filtration
High hardness levels
Oil return issues from compressors
System contamination during installation
Consequences include:
Reduced capacity
Higher compressor workload
Increased energy consumption
Install proper filtration systems
Control water hardness and treatment chemistry
Use effective oil separators
Perform periodic chemical cleaning (CIP) where applicable
Frequent system cycling (start/stop operation) or large pressure and temperature fluctuations can cause thermal fatigue.
Over time, repeated expansion and contraction may result in:
Micro-cracks in brazed joints
Fatigue at plate edges
Reduced mechanical strength
This risk is higher in systems with:
High pressure differentials
Rapid defrost cycles
Poor control strategies
Minimize frequent on/off cycling
Use soft-start or pressure ramping control
Implement stable temperature control strategies
Consider parallel exchanger configurations in high-load applications
Over long-term operation, contaminants such as compressor oil, welding residue, or debris may accumulate in plate channels.
Because BPHE channels are narrow, even small particles can:
Restrict flow area
Increase pressure drop
Reduce thermal performance
Install high-efficiency oil separators
Use strainers and fine filters
Thoroughly flush piping before commissioning
Maintain regular service intervals
Brazed Plate Heat Exchangers offer high efficiency, compactness, and low maintenance requirements in refrigeration systems.
However, long-term reliability depends on:
Preventing freezing
Controlling corrosion
Managing water quality
Minimizing oil contamination
Reducing thermal and pressure stress
Proper design, correct material selection, and disciplined maintenance significantly extend service life and ensure stable system performance.
BPHEs have very narrow channels and high turbulence. While this improves heat transfer efficiency, it also makes them more vulnerable to localized freezing if flow drops or control fails.
No. Ammonia reacts with copper and will quickly damage copper-brazed joints. For ammonia systems, nickel-brazed or fully stainless steel welded plate exchangers should be used.
Pinhole leaks are usually caused by corrosion (chlorides, low pH, chemical attack) or long-term fatigue stress at brazed joints.
Maintain constant secondary-side flow
Use glycol instead of pure water
Install low-temperature safety controls
Ensure proper refrigerant superheat
Yes, especially in water-cooled systems. While they are often considered “maintenance-free,” fouling can still occur. Water treatment and filtration are critical.
With proper design, clean fluids, and stable operation, service life commonly exceeds 8–15 years. Poor water quality or frequent cycling can significantly shorten lifespan
