(Minneapolis - October 6, 2008) - As of January 1, 2010, R-22 refrigerant cannot be used in new equipment, and the most logical replacement choice is R-407C, which was designed specifically to replace R-22.
We've known that this date was coming since 1992, when the Montreal Protocol was amended to establish a phase-out schedule for HCFCs, explained Steve Johnson, product manager at Thermo King. "In 1992, Thermo King was already testing R-22 replacements and chose to use R-407C. This choice was based on the facts that 1) the chemical producers said it was a direct replacement for R-22, 2) successful performance testing in Thermo King equipment was completed, and 3) certain segments of the bus industry would always require a high-performance refrigerant. The transit air conditioning application, in particular, can benefit from the properties of R-407C as it did with R-22. With a need for high capacity at low rpms, coupled with a need for efficient use of energy and quick recovery times from door openings, R- 407C is ideally suited to transit applications."
The modern era of refrigeration began in the 1930s, with the development of CFCs and HCFCs. Dr. Thomas Midgley developed many chemicals, two of which showed particular promise as refrigerants. These were R-12, which soon became the mainstay of refrigeration, and R-22, which became the primary fluid for air-conditioning. R-22 was seen to have higher efficiency at air conditioning temperatures than R- 12, and could also provide more capacity in a given system. The refrigerant R-12 was used in Transit applications until the advent of the Houston Pull-down performance test. "This test required that the temperature inside a 110 degrees F bus be reduced down to 70 degrees F in 30 minutes at engine idle (with an outside ambient temperature of 110 degrees F)," explained Johnson. "In those days, HVAC suppliers needed R-22 to pass this test."
The environmental pressure resulting from the discovery of the ozone hole and the signing of the Montreal Protocol in 1987 lead to the phase-out of R-12 and the scheduled phase out of R-22 by 2010 in the U.S. Replacement products that did not harm the ozone layer were developed: R-134a to replace R-12 and R- 407C to replace R-22. However, because R-22 could potentially damage the ozone layer, many transit users switched to R-134a to demonstrate environmental responsibility. There were other R-22 users that did not make the switch: Some to maintain consistency in their fleets and others because of R-22's superior capacity and efficiency. Since 1994, Thermo King has been advising R-22 users that when the time came to switch refrigerants, R-407C would be the logical choice. And since 1994, many R-22 users have switched to R-407C.
R-407C: The Clear Choice
Since 1993, Thermo King has put R-407C to the test, and in each and every situation R-407C has proven itself to be more efficient than R-134a and equal to R-22 in performance. "R-407C is the industry replacement for R-22," explains Johnson. "We now have 15 years of experience with R-407C. As a solutions provider, we always offer our customers choices. Through the first eight months of this year, nearly 40 percent of our production has been R-22 or R-407C. When trying to help customers understand the efficiency difference between the two refrigerants, I often ask why we don't see R-134a in home central air conditioning systems. We don't because it would cost more to run, and the same reasoning is true for any application. In heavy duty transit, a system equipped with R-407C is smaller, has 20-35 percent more capacity and requires less energy to operate. We're confident in offering it to our customers."
R-407C: Replaces R-22, Offers Greater Efficiency than R-134a
When compared to R-134a, R-407C is clearly the more efficient choice. Data from DuPont suggests that R- 407C is around 15 percent more efficient than R-134a, when used in a correctly designed and balanced system. When applied to a system where the compressor sees widely varying rpms due to vehicle speed, the benefit of R-407C grows to around 20 percent. These results are borne out in theoretical and practical work done by Thermo King. As the world's largest manufacturer of mobile temperature control systems and the leading supplier of R-407C systems for bus and coach applications, Thermo King has extensive experience in the use and application of R-407C. Typically, a fuel savings of around 1.3 gallons per 100 miles is seen by changing from an R-134a bus airconditioning system to a correctly specified R-407C system. The chart "Chlorine-Free R-22 Replacements" illustrates the key differences between R-134a and R-407C.
Comparing Energy Efficiency
Because of the pressure difference between R-134a and R-407C, it's generally agreed that R-407C takes more horsepower from the engine when the engine is turning the compressor. However, R-407C provides more BTU per hour of cooling for each horsepower used. To be meaningful, any comparison must be based on the same amount of cooling. For example: An R-134a system would use less fuel if it was only providing 65,000 BTU per hour when compared to an R-407C system that was delivering 90,000 BTU per hour at the same conditions. The chart titled "R-134a vs. R-407C for the Same Capacity" shows, using actual test data, how different the operating conditions must be to get 60,000 BTU per hour in the same system. So, how do you get an R-134a system to deliver the same capacity at all operating conditions as the R-407C system? For starters, the system must be larger and it must have a compressor at least 600cc in size.
Early China Testing Verifies Efficiency of R-407C
The rest of the developed world started to ban the use of R-22 as early as 1994, and not all R-22 users switched to R-134a. In 2002, China's Guangzhou City Bus company believed that R-407C provided the best cooling because it used more horsepower from the engine when the compressor was running, but wanted to know if it consumed more fuel than R-134a. In cooperation with Thermo King, Guangzhou City Bus conducted a test using one Thermo King Citi RT unit running R-407C against two competitor units using R-134a. The buses were from the same body builder and ran the same routes with the same loads. Test results showed that Thermo King's unit saved approximately 2.1 gallons of fuel for every 100 miles compared to one competitor's unit and about 2.9 gallons compared to the second competitor. "Our fuel test proves the efficiency of R-407C," says Guangzhou bus technical manager Kong Jun Liang. "The bottom line is that R-407C is about 35 percent more efficient than R-134a."
The R-22 Replacement: A Truly Green Technology
The Global Warming impact of any refrigerant is a function of two things. First, there is the direct global warming potential of the gas. This occurs only when a leak arises. Many climatologists believe the most important contributor to global warming is the so-called indirect global warming, caused by the consumption of fossil fuels like those used to drive the A/C system. The use of fossil fuels produces carbon dioxide (CO2). This indirect global warming occurs every time the unit operates. More efficient systems use less fuel, so they produce less CO2 for reduced global warming.
Adding the direct global warming to the indirect global warming produces what is known as the Total Equivalent Warming Impact (TEWI). Using the standard refrigerant loss factors as set out in the British Refrigeration Association (BRA) TEWI Calculation Guidelines (2000 edition), assuming a system operating lifetime of 10 years, the data clearly shows that R-407C has a 1 percent lower environmental impact than R-134a. These results are illustrated by Thermo King field data in many parts of the world.
Thermo King Corporation, a business unit of diversified industrial firm Ingersoll-Rand Company Limited, was founded in 1938 and manufactures transport temperature control systems for a variety of mobile applications, including trailers, truck bodies, buses, shipboard containers and railway cars. The company operates 10 manufacturing facilities and 17 parts distribution centers worldwide. Sales and service is provided by a global dealer network of 865 independently owned companies in 75 countries. For more information, access the Thermo King web site at www.thermoking.com.
Thermo King Corporation, a business unit of diversified industrial firm Ingersoll Rand Company Limited, was founded in 1938 and manufactures transport temperature control systems for a variety of mobile applications, including trailers, truck bodies, buses, shipboard containers and railway cars. The company operates 10 manufacturing facilities and 17 parts distribution centers worldwide. Sales and service is provided by a global dealer network of 865 independently owned companies in 75 countries.
Mike O'Brien, Thermo King Corporation