No more hot air
04 May 2011
Delphi's HVAC technology increases efficiency, cuts fuel costs and increases range.
Traditional air conditioning systems account for up to 5% of a vehicle's fuel usage each year. When added up, that is about 28 gallons each year – a significant number considering rising fuel prices and the current movement to make vehicles more environmentally friendly.
At Delphi Automotive, thermal experts work to develop technologies that will help reduce the amount of fuel used by the heating, ventilation and air conditioning (HVAC) system in the vehicle.
From electronically-controlled compressors to heat exchangers, Delphi technologies can reduce fuel usage by the HVAC system by 50% and help increase the range of hybrid and electric vehicles.
"Fuel economy is top of mind for many drivers, particularly during times of soaring fuel prices, and Delphi is offering technologies that can ease the impact at the pump," said James Bertrand, President, Delphi Thermal Systems. "A vehicle equipped with Delphi's air conditioning technology can save a driver an average 5 to 15 gallons of fuel each year in the US. Assuming 10 gallons are saved by every vehicle it would add up to an annual savings of more than 2.3 billion gallons of fuel each year in the US."
At the centre of these savings is an energy-efficient air conditioning system with high efficiency components, including Series Reheat Reduction (SRHR) and Air Inlet Mixture (AIM) control. When the outside air temperature is moderate, traditional cooling systems over-cool, dehumidify, and then reheat the ambient air. Providing a more efficient solution to fuel usage, Delphi's Series Reheat Reduction optimises average compressor capacity to more closely match the reduced cooling demand. Compressor work is minimised by controlling the compressor displacement and eliminating ‘over cooling’ of the air at low to moderate ambient temperatures.
When outside air is at a relatively high temperature, however, Delphi's Air Inlet Mixture (AIM) control feature cuts required compressor power while maintaining comfort. Cool, dehumidified passenger compartment air is re-used and combined with less outside air. AIM provides energy savings while providing fresh air to vehicle occupants and maintaining comfort.
Cycling Pneumatic Variable Displacement Compressor
Delphi was the first company to introduce a variable compressor into production. This technology is typically about 30% more fuel efficient than a fixed displacement compressor and has been used extensively since its introduction. Delphi has now combined the benefits of the pneumatic displacement compressor with SRHR and created one of the most cost-effective solutions for energy efficiency. The system improves compressor-related fuel efficiently by up to an additional 22%.
Electronically-controlled variable compressor
Considered to be the most fuel efficient compressor technology on the market, Delphi's externally-controlled variable compressor can adjust displacement or capacity to meet the varying needs of the powertrain and passenger compartment comfort. It can be precisely calibrated to achieve outstanding drivability and energy efficiency.
Pulse Width Modulator (PWM) Blower motor controller
Delphi's Pulse Width Modulator (PWM) blower motor speed controller offers increased HVAC performance and efficiency. This highly efficient electrical component reduces HVAC-related power consumption leading to increased fuel economy or battery charge life.
"Delphi's new PWM blower controller helps the entire HVAC system to operate more efficiently. It regulates the amount of power the HVAC blower motor needs to satisfy a given condition eliminating the wasted or dissipated energy typical of resistors or linear power devices," said Kevin Herlan, Chief Engineer, Global HVAC Systems, Delphi Thermal. "This allows the system to meet passenger comfort needs without wasting precious electrical energy."
Heat Exchangers
HVAC system efficiency increases with the use of more efficient heat exchangers. Delphi's new heat exchanger families are all leaders in energy efficiency and mass and space utilisation. The 38 and 50mm tube and centre evaporators have been added to a family of products that already includes high-performance, high-efficient 47mm and 58mm multi-tank designs. A new single pass heater core, in both 20mm and 28mm sizes, have also been added to a portfolio that currently includes 28 and 35mm cross counter flow and 28 and 32mm 2-pass products. Finally, Delphi's condenser family, which is available with folded or fabricated tube technology, includes the industry's thinnest condenser at just 12mm deep.
Spot Cooling and Heating
The passenger compartment is normally occupied by a single passenger; the driver. Instead of keeping the entire passenger compartment at a comfortable temperature under all weather conditions, significant energy saving can be achieved with the concept of ‘Spot Cooling and Heating’ for comfort maintenance.
With this technology, heating or cooling energy is directly delivered to key body parts of the occupant to achieve comfort. Delphi has developed an industry leading heated and cooled seat technology by integrating traditional HVAC airflow with the advanced thermoelectric technology. Work on spot heating and cooling continues to advance using Delphi's Virtual Thermal Comfort Engineering software.
Phase Change materials (PCMs)
One of the characteristics of a hybrid vehicle is that its engine can shut-off at any time during a drive cycle, such as while waiting at a stop sign or red light, which increases fuel efficiency and reduces emissions. Conventional vehicles use an air conditioning compressor that is belt-driven by the engine. When the engine shuts off, so does the air conditioning system. To help keep passengers comfortable when this happens, Delphi has developed a Phase Change Material (PCM) storage system.
This thermal storage system enables a hybrid or electric vehicle to store excess thermal energy while the engine is running efficiently and then releases this energy during engine-off idle stops or when the vehicle is running inefficiently. This means the air conditioning system is turned off but the vehicle is still comfortable. Similar technology is used in warehouses where PCM material is charged in the evening (when the electric rate is low) and then used to cool the interior of a building during the day when the rate is higher.
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