Experimental investigation on heat transfer and flow resistance characteristics of spirally fluted tubes

A comparative experimental investigation was carried out for heat transfer and resistance characteristics of smooth tube and 9 spirally fluted tubes with various structural parameters. The results show that the heat transfer and flow resistance performances of spirally fluted tubes are better than smooth tube. The heat transfer coefficient of the spirally fluted tubes are as 2.46~3.08 times as the smooth tube's. The flow resistance coefficient of the fluted tubes are as 2.1~7 times as the plain tube. The correlations with relatively high precision have been obtained regarding heat transfer coefficient and resistance factor of the mentioned fluted tubes by adopting a multivariable linear regression method. This paper also analyzes the main influence factors of heat transfer and flow characteristics of spirally fluted tubes and points out that using small pitch and groove depth can obtain better heat transfer effect.