Selecting A Primary Refrigerant

The objective of the primary refrigerant is to safely and efficiently remove the heat from the secondary coolant. There are several factors that must be taken into consideration when selecting a refrigerant. Budget for construction, the cost of electricity, building design, availability of trained operators and technicians, and local codes and regulations.

Over the years Ammonia and R-22 have been by far the most common refrigerants employed in the ice rink industry. With the future phase out of R-22 new alternatives are starting to appear on the market. The following is a brief description of some of the pros and cons of the regularly used refrigerants.

Ammonia

For energy efficiency and equipment first cost, ammonia is still by far the best choice. Ammonia has a significantly higher heat transfer coefficient then any of the other refrigerants. This can be exploited in two ways. Selecting a smaller chiller and condenser can reduce first costs. Alternatively you can select components with the same heat transfer surface area and increase the total system efficiency by operating at lower discharge pressures and higher suction pressures. The higher BTU per pound of mass flow reduces the size of piping and valves. Ammonia's better thermodynamic properties reduce the cost of electrical consumption. An ammonia system requires less refrigerant than any of the alternatives and the cost of ammonia per pound is approximately 1/5th of the other refrigerants.

Some facilities can not use of ammonia for various code reasons. Due to its pungent odor and higher toxicity, special precautions must be taken in plant room and equipment design. The strong odor makes detection and leak prevention much easier than with the alternatives.

Ammonia systems are built with much higher construction standards than the alternative refrigerants, which results in a higher quality, longer lasting industrial grade system. With the recent improvements in compressor seals, limited charge chillers, leak proof valves and ammonia detection equipment we feel that ammonia is still by far the best choice for an ice rink application.

R-22

Next to ammonia, R-22 is still the most efficient alternative. However, due to the .05 ozone depletion factor R-22 is slated for total phase-out out over the next 20 to 30 years. R-22 still is very reasonably priced in comparison to some of the new alternatives. Compressor sizing is slightly larger than ammonia and the required horsepower per ton of refrigerant is approximately 8% higher. R-22 is still used in many new installations. Where possible we suggest using components, piping, and valves so you leave the door open for an ammonia conversion if required.

AZ-50

AZ-50 has been used successfully as an alternative to R-22 since the mid 1990's. It is approximately 12% less efficient than R-22 on a reciprocating compressor application. This efficiency loss can be greatly reduced through some creative sub-cooling techniques. The mass flow of AZ-50 is greater, requiring larger line sizes and valves than R-22. The compressor size must be approximately 10% larger for the same refrigeration effect. AZ-50 requires the use of Polyolester oil, which is quite expensive. Discharge temperatures are significantly lower than R-22 or ammonia, which eliminates the need for any oil cooling. The lower operating temperatures reduces equipment room exhaust fan run time. The cost of refrigerant is approximately double that of R-22. This price difference will reduce as R-22 phases out.

R-134a

Recently R-134a has been used in a number of facilities. It is more expensive than R-22 and about 12% less efficient than R-22 on reciprocating compressor applications (20% less efficient than ammonia). The volume flow rate of R-134a is much higher than R-22, AZ-50 and ammonia, which means that the compressors must be approximately 60% larger to do the same job. This translates into higher first costs and maintenance costs.

<<previous tip

next tip >>

Tips Menu