Maintenance isn’t an expense; it’s an investment that saves you thousands in the long run.
A critical failure in your absorption chiller leads to hours of downtime, costly repairs, and even worse, a spike in energy consumption. What could you have done to prevent it?
The answer is simple: Maintenance
Vamtec’s guide to mastering absorption chiller maintenance: Keep your systems running at top-level
Optimize energy efficiency: To maintain the chiller’s efficiency, it may end up consuming more energy to produce the same cooling output as initially planned. This increased energy consumption can be due to fouling, leaks, or pressure imbalances. Regular maintenance of heat exchangers, purging systems, and solution pumps ensures the system uses less energy while delivering optimal cooling results.
Extend lifespan and prevent system downtime: Preventative maintenance is key to reducing the risk of high-cost failures. Early failures and the need for expensive repairs can occur when solution pumps and vacuum pumps wear out prematurely. By identifying early signs of wear in critical components, such as diaphragm valves, you can prevent unplanned issues.
Preventing System Fatigue: Improper maintenance can increase system fatigue, leading to costly repairs that could have been avoided with simple weekly checks.
Environmental sustainability: Absorption chillers are more environmentally friendly than their compression counterparts, as they utilize waste heat and solar energy instead of electricity. It is essential to maintain proper inhibitor levels in the lithium bromide and ensure tight seals to prevent air leakage, which can cause internal corrosion in the chiller.
Regular maintenance still costs, but not as much as major repairs, including sudden emergency repairs or full system replacement. The Air-Conditioning, Heating, and Refrigeration Institute shows a well-maintained absorption chiller can operate with a much lower life cycle cost.
Key maintenance tips:
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Maintain the Purge system: The purge unit maintains the vacuum in the chiller shell by removing any air that leaks in. The purge pump needs to operation at least once a week, even if the system is not in use.
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Regular Leak-Test:Air leaks reduce system performance and reliability since absorption chillers require vacuum conditions for cooling. It’s crucial to pressure-test for air leaks as soon as possible if the system requires frequent purging. Leaks must be repaired promptly.
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Test for Tube Leaks: If the refrigerant level increases in the evaporator and the lithium bromide (LiBr) concentration decreases, it indicates a leak in the generator, evaporator, condenser, or absorber tube. The chiller should be pressure tested with nitrogen immediately to identify the faulty tubes. Faulty tubes should be replaced or plugged.
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Check for Tube Fouling or Scaling: If capacity drops, tubes need to be cleaned. The cleaning frequency depends on local water characteristics, atmospheric contamination, and operating conditions. Fouling is caused by dirt, rust, sludge, and scale. For open cooling tower systems, condenser tubes should be cleaned once a year.
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Maintain the Pumps: The absorption chiller uses a hermetically sealed canned motor pump. It is important to check the pump bearings for any wear and tear. Additionally, the internal strainer should be cleaned regularly to ensure proper internal cooling of the pump.
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Ensure Proper Conditioning of LIBR: The system needs to have sufficient lithium bromide (LIBR) concentration and inhibitor levels to prevent internal corrosion of the shell and tubes. This ensures maximum protection. The LIBR sample should be analyzed every year to ensure the inhibitor and alkalinity levels are within range.
Have you checked your purge system this week? If not, you could be compromising the entire cooling system without even realising it.
Common maintenance mistakes to avoid…
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Not Having Regular Inspections: Regular inspections are important for identifying early signs of wear, leaks, or blockages that can affect system performance.
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Insufficient Cleaning of Heat Exchangers: To prevent fouling and scaling on heat exchangers, which can hinder heat transfer. Absorption chillers rely on heat transfer for cooling.
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Ignoring Solution Concentration and Quality: Solution concentration changes over time, affecting heat transfer and overall performance. Regularly check and adjust the solution concentration. These solutions, such as lithium bromide or ammonia, are crucial for absorption chiller operation.
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Neglecting the Purge Unit: The purge unit removes non-condensable gases (NCGs) from the system. These gases can build up over time and reduce the chiller’s efficiency. Inspect and clean the purge unit regularly. Neglecting the purge unit can lead to a gradual decline in chiller performance and system pressure.
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Overlooking System Pressure Checks: Precise pressure maintenance in the generator, evaporator, absorber, and condenser is crucial for proper function. Not regularly checking system pressure can lead to inefficient operation or damage to chiller components.
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Improper Water Treatment: Absorption chillers rely on water to transfer heat and maintain temperature balance. Improper water treatment can lead to scaling, corrosion, or biological growth in the system, reducing efficiency and lifespan.
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Ignoring Manufacturer Guidelines: Not following the manufacturer’s recommended procedures for cleaning, servicing, or replacing components can result in improper repairs or neglect of critical system aspects.