A.銅 B.巖棉 C.玻璃棉 D.軟木
A.πrm2 B.2πrm2 C.2πrm2L D.2πrmL
A.雷諾準數(shù)Re B.相對粗糙度ε/d C.管長l D.流體導(dǎo)熱系數(shù)λ