=−1.927892×10−8+5.233699×10−10∗Tfor160≤T<600−4.107885×10−13∗T2+6.694129×−16∗T3−4.447775×10−19∗T4 (6) Ii=PRi=P∗Across−sectionρres,i∗lheater In which ρre