Many facilities have R-22 Chillers that have years of reliable, efficient service ahead of them.
But when operating with this refrigerant, they are equipment that is subject to international disposal due to depleting the ozone layer. Many are now looking to upgrade their equipment with an alternative refrigerant that is readily available, cost-effective, and environmentally preferred throughout the life of the chiller.
What are the options for Chillers with R-22 that are still in use?
- Certainly, it is always desirable to replace an old R-22 cooler with a newer, more efficient cooler, but it is not always practical from a budget point of view.
- For small tonnage chillers loaded with R-22, the most likely alternative for a retrofit is the HFC refrigerant, R-407C.
- Although there is a moderate penalty of 5 to 10 percent for capacity and efficiency, R-407C has been available for many years for low-capacity chillers.
- It is worth noting that R-407C is a mixed refrigerant, but for small tonnage chillers with DX-style evaporators, this will not affect performance, and no significant equipment modifications would be necessary.
- While alternative refrigerants can generally be used to upgrade older generation refrigerants with similar pressures, the upgrade comes at the expense of reduced capacity and efficiency.
- If for example you have a 100 TRF chiller and the particular application requires all those 100 TRF to maintain the design temperature, then a reduction in capacity would not be acceptable. The thermodynamic properties will determine what the refrigerant mass flow rate will be in a given application.
- The capacity of the thermostatic expansion valve is based on the physical dimensions of the valve pin and port, the system conditions, and the thermodynamic properties of the refrigerant. If the mass flow requirement of the replacement refrigerant is significantly higher than the mass flow requirement for R-22, then the existing R-22 TEV would have insufficient capacity for the replacement refrigerant.
- With R-407A and R-407C with mass flow rates similar to R-22, the original selection of R-22 TEV is well suited for application with both refrigerants.
- Other refrigerants have a higher mass flow requirement than R-22, resulting in the original R-22 TEV being smaller for each.
- The most notable capacity deficiency is with R-434A. Additionally, the manufacturer of R-434A states that its refrigerant requires a TEV element that is compatible with R-502 (R-404A).
- R-404A shows good capacity compared to R-22. However, with a 42% higher mass flow requirement, a TEV replacement will be required. Plus, it has a nine percent reduction in efficiency.
- R-417A is shown to have a good mass flow requirement compared to R-22, which means that a TEV replacement will not be required. But a 14% loss of capacity probably wouldn’t be the best option.
- R-407C shows a slight increase in capacity compared to R-22, a very close mass flow requirement compared to R-22, and a lower drop efficiency of three percent. What’s more.
- The R-407C has been off-patent for several years. It is widely distributed and reasonably priced. As such, the industry has viewed R-407C as the most common replacement for R-22 in comfort cooling applications.
- Systems that do not work properly with R-22 will not work properly after refrigerant conversion. Elastomer seals tend to leak after conversion because R-22 has the most aggressive swelling influence on elastomer seals, so after conversion, the seal will effectively shrink.
- To avoid any potential leakage after conversion, it is recommended to replace all elastomer seals.
- All TEV in the system should be checked for the proper superheat setting and adjusted as necessary.
- It must be remembered that the temperature at the outlet of the valve will be lower than the evaporation temperature of the last particles of liquid that are boiling, this is due to sliding For existing R-22 screw and centrifugal chillers, R-134a is often the best upgrade option.
- While this will lead to a reduction in capacity, which can go up to 35 percent, modifications often result in a more efficient package.
Where to learn all about chillers?
We have prepared a complete training in chilled water installations with chillers.
