Experimental Study on Heat Transfer and Flow of Nanofluids in Corrugated Tube
;The heat transfer and flow characteristics of nanofluids in corrugated tube were experimentally studied.The uniform and stable SiO2 nanofluids were prepared by two-step method,and the principle of enhanced heat transfer was analyzed quantitatively.The results show that under the same conditions,with the increase of nanofluid mass flow rate qm in corrugated tube,the total heat transfer coefficient K and the tube side inlet and outlet pressure loss Δp gradually increase;due to the disturbance of wall structure,the increase of corrugation height H enhances the fluid heat transfer capacity and flow resistance,while the increase of corrugation spacing S weakens the fluid heat transfer capacity and flow resistance.The comprehensive heat transfer factor η of nanofluid in corrugated tube with H of 3.5 mm,S of 25 mm and inner diameter Dt of 25mm reaches the maximum,which is 1.4 to 2.2 times that of nanofluid in smooth heat exchange tube under the same working conditions.
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