Non-CFC Air Conditioning for Transit Buses

Ahmad A. Pesaran, Yves O. Parent, Desikan Bharathan

Research output: Contribution to conferencePaperpeer-review

3 Scopus Citations


In the United Sates, more than 80% of transit city buses are air conditioned. Vapor compression refrigeration systems are standard for air conditioning buses and account for up to 25% of fuel consumption in the cooling season. Vapor compression devices use chlorofluorocarbons (CFCs), chemicals that contributes to Earths's ozone depletion and to global warming. Currently, evaporative cooling is an economical alternative to CFC vapor compression refrigeration for air conditioning buses. It does not use CFCs but is restricted in use to arid climates. This limitation can be eliminated by dehumidifying the supply air using desiccants. We studied desiccant systems for cooling transit buses and found that the use of a desiccant-assisted evaporative cooling system is feasible and can deliver the required cooling. The weight and the size of the desiccant system, though larger than vapor compression systems, can be easily accommodated within a bus. Fuel consumption for running desiccant systems was about 70% less than CFC refrigeration systems, resulting in payback periods of less than 2.5 years under most circumstances. This preliminary study indicated that desiccant systems combined with evaporative cooling is a CFC-free option to vapor compression refrigeration for air conditioning of transit buses. The concept is ready to be tested in a full prototype scale in a commercial bus.

Original languageAmerican English
Number of pages12
StatePublished - 1992
EventInternational Truck and Bus Meeting and Exposition - Toledo, OH, United States
Duration: 16 Nov 199219 Nov 1992


ConferenceInternational Truck and Bus Meeting and Exposition
Country/TerritoryUnited States
CityToledo, OH

Bibliographical note

Prepared for the International Truck & Bus Meeting and Exposition, 16-19 November 1992, Toledo, Ohio

NREL Publication Number

  • NREL/TP-432-4882


  • advanced cooling system
  • dehumidification
  • transportation


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