Vogt and Turbo Ice machines have been manufactured for decades, and as such we have a large install base of machines that utilize refrigerants that are coming under increasing pressure from the phase outs of the original Montreal Protocol, like R22. In response to these global regulatory changes, Vogt/Turbo has spent a significant amount of time and effort researching and testing alternatives to R22, seeking a solution that could be a “drop in”, or at least a safe and effective replacement. This has proven to be a significant challenge.
The challenge of replacing R22 with one of the new pure HFC refrigerants or azeotropic refrigerant blends (the R1XX or R5XX families of refrigerants), or non-azeotropic HFC blends (the R4XX family refrigerants), lies in four main areas: the working pressure of the refrigerant, which must be below the safe operating levels of the current system; the glide of the refrigerant, which must be near zero to work effectively in large industrial ice machines and falling film chillers; and the volumetric efficiency, which needs to be close to that of R22 so that the sizing of the vessels, piping, and TXV(s) in the system remains viable for service without an unacceptable reduction in capacity.
The working pressure of the refrigerant is the first issue to consider, as a safe system is of the utmost importance. Low-side refrigeration components of R22 Turbo Ice Makers and Falling Film Chillers were rated for between 150 and 200 PSI Maximum Allowable Working Pressure (MAWP), depending on the system and the era. The most common HFC alternatives to R22 in industrial systems today are R404a and R507, but unfortunately both of these working fluids require a low-side MAWP of 250psi for most applications.
Second, we considered the glide of the refrigerants available for substitution for R22. While R404a and R507 have acceptably low glides, they have already been discounted from serviceability due to their MAWP requirements. The other common R4XX family of refrigerants, including R407C, R407F, and R410, also have glides well above that of R22. These high glide refrigerants pose long term operational issues caused by fractionalization in any application, but are particularly problematic for industrial ice makers and falling film chillers. Because these refrigerants have significant temperature glides, they also segregate and fractionize in service, as both ice makes and falling film chillers have very low temperature gradients across the evaporators. This causes the higher vapor pressure constituent of the refrigerant blend to volatize preferentially and reduces the lower vapor pressure component to the role of a heat transfer fluid, rather than a working (volatile) fluid. As a result, the evaporator fluid chemistry changes over the course of time and causes both erratic operation and a reduction in capacity.
The last factor reviewed in detail was the volumetric efficiency of the alterative refrigerants. As we have already discussed, the R4XX and R5XX families of refrigerants pose challenges for use in existing R22 systems, and their generally lower volumetric efficiency adds to the challenge of using them for a replacement. Unmentioned, as yet, is R134a, a common replacement for both R22 and R12 in many air conditioning and centrifugal chiller applications. R134a has a lower working pressure than R22 and, as it is not a blend, has zero glide. The challenge R134a faces as a retrofit for Turbo Plate Ice Makers and Falling Film Chiller Systems is that it has a dramatically lower volumetric efficiency than R22. The R22 Turbo Ice Machines and Falling Film Chillers were not designed to account for this, and, while the plates themselves can function on R134a, the balance of the system (TXVs, the evaporator piping, and the plate to piping connections) will be severely undersized and reduce capacity dramatically.
Also worthy of note is that there are innumerable additional working fluids being marketed by both large and small entities specifically as “R22 Replacement Solutions”. Vogt/Turbo has reviewed several of these and has not found any to be suitable for retrofit of our R22 Ice Machines or Falling Film Chillers. These fluids were all found to have excessively high glides; further, and not mentioned above, some of these alternative refrigerants are either mildly or severely flammable, while R22 and the alternatives mentioned above are non-flammable. Vogt Turbo strongly advises against the use of any flammable refrigerants in our equipment and recommends discussing this hazard with the manufacturer and distributor of the refrigerant specifically before considering it for use.
Lastly, in all of the research that Vogt/Turbo has done, we have found that virtually all of the alterative refrigerants available have significant high-side component impacts that must also be taken into consideration when evaluating potential alternative solutions to replace R22. Most, if not all, of the potential alternatives will require the system to be fully flushed of the mineral oil used in R22 compressors and the oil type changed after this flushing. Failure to fully remove the old oil can result in significant costs related to failures of components. Some elastomeric seals may also require replacement.
In summary, while the market has a large number of solutions for R22 alterative refrigerants that are suitable for some equipment and applications, Vogt/Turbo has not found any alternative that maintains an acceptable level of safety, capacity, and reliability in the R22 Turbo Plate Ice Makers and Falling Film Chillers built in the past. Vogt/Turbo has invested significant effort into this investigation over the past 10 years, and we remain convinced that the best solution for most customers in the face of the impending R22 phase down, not to mention the rising cost of R22, will be to look at replacing their existing equipment with new systems designed to use the low GWP-HFC, HFO, or natural refrigerants that are favored by the newest amendment to the Montreal Protocol.