(Minneapolis - April 17, 2008) - To get great ideas from the drawing board to the street takes commitment, time, and lots of research and testing, which is what Thermo King has done with the alternator-powered all-electric bus HVAC system. By creating a one-piece, hermetically sealed system, Thermo King has eliminated the compressor on the engine and all of the hoses, piping, valves and fittings required to connect it to the system. Essentially, this system is sealed, charged and tested at the factory like a home refrigerator - all you have to do is plug it in and turn it on.
For an all-electric HVAC system to function, power needs to come from somewhere, so the application of this technology has been limited to electric rail cars, trolley buses and, most recently, hybrid electric buses. However, if the HVAC could have its own power supply, you could have an all-electric HVAC system on a conventional diesel engine-driven bus, and even plug it in when the bus engine isn't running.
After many years of research and development, laboratory testing, field tests and operation in refrigeration applications, Thermo King has made this concept a reality for conventional diesel engine-driven buses. Why so much testing? "You have to get it right," says Steve Johnson, bus HVAC product manager at Thermo King. "Creating electric power from an alternator or generator is not a new concept. The primary obstacle when your alternator or generator is driven by the bus engine is maintaining clean, stable voltage throughout the speed range of the engine."
So how long did it take for the unit to go from theory to practical application? The initial project began in 1999. "Actually, we've had this technology in the field on truck refrigeration systems for more than five years," says Don Nielsen, bus HVAC engineering manager at Thermo King. "There are approximately 300 systems operating worldwide."
Thermo King's first field application of this technology for bus HVAC began in June of 2004 in Prague, Czech Republic. Prague is also the home of one of Thermo King's advanced R&D centers, and having the unit operating locally made for easy monitoring by the research engineers. The bus operates an average of 18 hours a day from Kladno, a town about 60 kilometers (about 37 miles) outside Prague, into the city. This route provides a good mix of both freeway and stop-and-go driving. "The bus is driven by the same drivers everyday and in an interview with one of the drivers this past summer, he commented that the bus stayed cooler than with a conventional system and got better fuel mileage as well," reports Nenad Johanovich, European marketing manager, Thermo King. Johanovich also reports that the bus has been in revenue service for four summers, traveled more than 300,000 kilometers (more than 186,000 miles) and has operated for nearly 8,000 hours.
A second unit has been operating in Florence, Italy since May of 2005 and has operated for 5,000 hours. While these units were operating in the field, testing and development continued in Minneapolis and Prague to further refine the units. In the United States, transit authorities have been adding more hybrid-electric buses to their fleets and have shown a high level of interest in running an all-electric HVAC on conventional diesel engine buses. Thermo King began partnering with North American transit authorities and completed the first installation in July of 2007. The customer is very excited about having the electric compressor in the unit to remove parasitic loads from the engine for fuel and maintenance savings.
As the trial unit operates and produces more data, Thermo King is continuing to pursue opportunities to place this technology in US fleets. "We have already received an order for 16 units to be retrofitted as part of a mid-life bus rehab project," notes Johnson. "Our goal for this year is to not only launch this product, but to be in serial production by the fourth quarter of 2008."
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