Te industry, on a world-wide scale, is now in the process of
deciding what will be the replacement for the R134a refriger- ant, which is being phased out in Europe primarily because of its global warming potential. In the U.S., Honeywell and DuPont are jointly developing a refrigerant named R1234yf, while in Europe, an alternative called R-744 is being tested.
Incorporating the Design and New Trends Over the last several years, air conditioning units have become
more integrated into the design of the school bus, with some third party providers working with OEMs to complete the installation while the vehicle is still on the assembly line. Following the trends of the transit industry, the placement of the system, or a part of it, has moved to the roof of the bus. Tis can vary from the condens- er-only section to a complete rooftop air conditioning system. “Future designs, now in initial production, will include all-
electric air conditioning systems,” said David Oberdorff, North America bus product and marketing manager for Carrier. Others in the A/C industry agree that an all-electric system will
become the standard system, for a number of reasons. “Reliability and performance of these systems are unmatched,”
said Scott Imamura, vice president of sales for SUTRAK. “Tey have significantly less items to maintain and utilize the most ef- ficient hermetic scroll compressors on the market.”
74437_4494_7x4.875_STN1 1/30/08 7:25 PM Page 1
Tis “next generation” is already being deployed in transit
buses and are fully electric systems that are self contained with no external refrigerant runs and hermetically sealed scroll com- pressors, according to Imamura, who added that for the system to work on hybrid school buses, the accessory power must be 208-460 three-phase 50-60Hz. “As with most advances in hybrid bus developments, the ini-
tial offerings will not have electric HVAC because of the limited amount of power available,” agreed Steve Johnson, Termo King’s director of bus product management. “All-electric HVAC systems for buses are available now and can be configured to work on school buses when the industry is ready.” Advancements in compressor technology could also add to
the efficiency of the entire A/C cycle, according to Cheyne Rau- ber, sales and marketing manager for Rifled Air Conditioning. Basically, the compressor needs oil for its moving parts, which robs the system of heat transfer. “Advances in compressor design that need no oil in the A/C
loop will greatly enhance the systems of the future,” said Rauber. “Newer refrigerants that are now being tested will probably be incorporated in the next generation of air conditioners. n
Visit
www.stnonline.com/product-info to learn more about A/C parts and service.
For reliable air conditioning, turn to the people with advanced degrees. Carrier offers the most extensive line of split and rooftop AC units to optimize system performance on any school bus, small to large. And they’re all backed by expert support. Maybe that’s why more school buses in North America cool with Carrier. Call Carrier Transport AC, 1.800.673.2431. Or visit our Web site. For AC that’s an A+.
www.transportaircon.carrier.com
38 School Transportation News Magazine April 2010 ©2008 Carrier Corporation
A member of the United Technologies Corporation Family. Stock symbol UTX. CM-2 Condenser
IW-1 Evaporator
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