(,100032)9326620066GAS&HEATVol.26No.6Jun.2006©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.©1994-2008ChinaAcademicJournalElectronicPublishingHouse.Allrightsreserved.