首排管径增大时顺排管束的对流换热

HEAT TRANSFER OF AN ALIGNED TUBE BANK WITH ENLARGED FIRST ROW TUBE

采用蔡升华质热比拟技术对首排管径增大时：ｓ１／ｄ＝３，ｓ２／ｄ＝１．１的顺排管束的强制对流换热进行了实验研究，管径比的范围为ｄ１／ｄ＝１．０～１．４４，Ｒｅｙｎｏｌｄｓ数的范围为３０００～１００００．通过对局部与平均换热系数的测量表明：首排管径增大时，后排管的换热与标准顺排管束相比显著增强；管径比越大，影响的排数越多；文中给出了３种管径比下的修正系数，本文的研究结果对解决现代大容量电站锅炉的对流过热器和屏式过热器的同片热偏差有着重要的意义。

The analogy between heat and mass transfer(using naphthalene sublimation techniqueto measure the mass transfer coemcient)is used to investigate the heat transfer of alignedtube bank with s1/d =3,s2/d=1.1.The tube bank studied has a nonstandard arrangement,the diameter of the first row tube(d1) is enlarged as compared with those(d)of the follow-ing rows, and the enlargement ratio d1/d has been studied up to 1. 44 and Re=3×103～1×104.Experimental results show that the heat transfer of the following rows is enhanced ascompared with the standard aligned tube bank.The larger the d1/d,the higher the heattransfer coefficients and the more the rows will be affected.Correction factors for three dif-ferent enlargement ratios are given,which are useful for the design of superheaters ofmodern large capacity boilers