First R407H retrofit bears fruit
USA: Daikin has completed its first US retrofit of its new lower GWP refrigerant, Creard R407H, in the refrigeration system of a cold storage warehouse.
Creard R407H was used to replace R22 in the refrigeration system in the warehouse in upstate New York.
R407H is a zeotropic blend of R32/R125/R134a and is designed as a R404A/R507 drop-in and as a R22 retrofit replacement in refrigeration systems with limited modifications. It is an A1 refrigerant with a GWP of 1495 under the IPCC Fourth Assessment Report AR4.
The 240,000 bushel (8.4 million litres), 12-room refrigerated fruit storage facility, has one major loading season and performs continuous storage and delivery throughout the year.
System components at the warehouse include four 50hp Bitzer 6F.2 open-drive reciprocating compressors mounted on a Hillphoenix rack, an Evapco water-cooled condenser, 24 Kramer and six Colmac evaporators; with two evaporators per storage room and six for the loading areas/overflow storage. The storage temperature target between 30°F to 34°F (-1ºC to +1ºC).
According to Daikin, the customer had a number of requirements when it came to selecting a replacement refrigerant for their system’s existing R22. It needed to be of low GWP, a close efficiency match to R22 and to be similar in temperature, pressure, and mass flow in order to maintain the same equipment and piping. It also had to be a proven match in material compatibility with R22 components, to avoid future leaks, and to be cost-effective.
Daikin partnered with mechanical contractor Van Ernst Refrigeration of East Rochester, New York, for the retrofit.
To prepare the system, the contractor began the retrofit process early with the complete replacement of mineral oil with POE oil. The oil was changed out over a period of two months during regular system check-ups, which included several oil changes.
The final retrofit took place over the course of four days directly prior to the harvest season.
The system was pumped down and all R22, a total charge of 3,200lb (1,450kg), was recovered. Van Ernst’s engineers replaced all Schrader cores and caps, filter-drier cores, and other rubber seals. A deep vacuum was pulled on the system over night, and the R407H refrigerant was added the next day.
Superheat was checked on system startup. Evaporator distribution was found to be similar to R22, and most of the system’s TXVs required only minor adjustments (closing). The compressor discharge pressure was higher than with R22, and this required some adjustments to the system controller’s programming.
Following the retrofit, the system is said to have performed as expected. There is said to have been a 2-4psi pressure rise at the evaporator and a 7-20psi pressure rise at the compressor exit depending on outdoor ambient. Discharge temperatures fell 30°F to 40°F (-1ºC to 4.5ºC) depending on outdoor ambient.
“The thing that I am happiest about was that we only had to make very small expansion valve adjustments, and coil distribution was perfect,” said Van Ernst sales engineer Chris Harland.
“I would like to use R407H for new construction work, now that refrigerants R404A/R507A are getting tricky,” he said. “We have used R407A in gas defrost condensing units up to 200,000 Btus, but getting good evaporator distribution is tougher than with R507A, and given the GWP number of R407A I’d prefer to move on to R407H for new equipment.”