Ammonia has a great affinity for water. One of the fastest and most cost-effective ways to maximize the performance of your ammonia refrigeration system is to ensure you keep water contamination to a minimum. The following technical bulletin explains why and provides cost savings estimates for an average system.
Water Contamination’s Effect on Ammonia Refrigeration Systems
Water contamination is common in most refrigeration systems. The purpose of this bulletin is to explain the efficiency losses that are experienced at different concentrations of water. The effects of the water contamination are many:
- Pressure-Temperature is impaired
- Organic acids and sludges are formed in compressor oils
- Pump operation, piping pressure drop and evaporator performance is adversely affected
Sources of water are from improperly drained systems prior to start-up, condensation during construction, lack of purging, and leaks on packing glands in the suction side of the system.
The graph at the bottom shows the saturation temperature of ammonia-water at 4 different suction pressures. You will notice that the suction temperature increases as the water content increases. Therefore, it is necessary to operate equipment at lower suction pressures to maintain temperatures.
The changes in operating conditions will lead to higher operating costs. For each degree Fahrenheit that suction temperature is lowered, compressor capacity is reduced approximately 2-½ % for high stage and 3 % for boosters.
If the average system costs $20.00 per hr. per compressor to operate there would be an additional cost of $4,380.00 per year for each high stage compressor and $5,256.00 for each booster compressor. This is based on a 1ºF increase. (All cost increases are power consumption only. This does not include labor and parts.)
To find out if your system has water contamination, Airgas Specialty Products will take a sample of your ammonia using our patented Cold Flo Sampler. To arrange your test, please contact us at (800) AMMONIA (800-266-6642) or email us here.