Condensers: Mineral Deposits

 Mineral Deposits in Condensers:

• Impact: Severely reduce heat transfer and system efficiency.
• Diagnosis: Measure the condensing temperature of the refrigerant and the leaving water temperature.
  • Condenser Approach Temperature: The difference between these two measurements.
  • Indicator: If the approach temperature exceeds 10°F, mineral buildup is likely present, requiring cleaning.
  • Note: For larger industrial water-cooled condensers (e.g., water chillers), an approach temperature greater than 2°F may indicate the need for cleaning.

Mineral Buildup Location:

• Formation: Typically starts where hot gas enters and warm condenser water leaves.

Example:

• Tube and Tube Condenser:
  • Discharge vapor enters at the top, liquid exits at the bottom.
  • Water enters at the bottom and exits at the top.
  • Observation: Mineral deposits tend to accumulate more towards the top, where hot gas and water interact.

Shell and Tube Water-Cooled Condensers:

• Usage: Common in commercial and larger industrial systems.
• Design:
  • The shell acts as a condenser and liquid receiver.
  • Straight water tubes pass through the shell.
  • Water boxes or marine boxes distribute water to each tube.
• Example:
  • Hot gas enters at the top, condensed refrigerant exits at the bottom.
  • Water flows through the tubes, condensing the refrigerant as it passes across them.

Cleaning Process:

• Mechanical Cleaning:
  • Use brushes or power brushes to clean condenser tubes.
  • Not always effective, especially in tube-in-tube coaxial coils with twists and turns.
• Acid Cleaning:
  • Steps:
    1. Disconnect existing water lines.
    2. Connect acid pump lines to the condenser.
    3. Prepare a diluted acid solution.
    4. Circulate the solution through the condenser using the acid pump.
    5. Preferably, circulate the solution counter to the normal water flow direction for better descaling.
    6. Flush the acid and reconnect the original water lines.
  • Safety: Use gloves, eye goggles, ensure proper ventilation, and follow instructions for acid dilution and handling.

Illustration of Cleaning Process:

• Setup: Acid solution and pump connected to the condenser.
• Operation: The acid solution is circulated through the condenser to dissolve scale and mineral deposits.
• Adjustment: Pry open the water regulating valve during cleaning by raising the spring with a screwdriver to force the valve open.