The Experimental Study Of Heat Transfer Enhancement Of Single-flow Convection

The single-phase water is taken as a medium, and the experimental study of heat transfer characteristics of three different geometric dimensions flat tubes (the value of h_i/D_i is 0.286,0.45 and 0.557 respectively) is conducted in the horizontal casing pipes. And the experimental study of tube flow resistance is also finished under the cold condition. While the analysis of the characteristic and the influencing factor of flat tube heat transfer and flow resistance is carried on at the same time.Experimental results and analysis show that the flat tube and circular tube with the same perimeter have the same Reynolds number under the same water volume flow, however total heat transfer and tube heat transfer coefficient of the three flat tubes are higher than that of the circular tube, and the heat transfer degree is stronger when the value of h_i/D_i is smaller. Namely, the circular tube is more flat, the heat transfer is strengthened obviously. The flat tube heat transfer coefficient is circular's 1.2～2.43 times in the experimental scope. It can be concluded that the flat tube has better performance of heat transfer. The heat transfer performance of horizontally and vertically laid flat tube in the casing pipe is studied and compared, and the experimental result indicates that the vertical one gains the advantage over the other.The flow resistance experiment is carried on in the flat tube under the different Reynolds number conditions, which values are 90～8000 and 10000～60000 respectively. Experimental results show that three flat tube resistances are similar under the same flow in laminar region, and the flat tube flow resistance is bigger when the value of h_i/D_i is smaller under the same flow in turbulent region. The flat tube resistance coefficient is circular's 1.18～5.39 times in the experimental scope. Based on the experimental data of the experimental results, this paper also obtains the reunification of the experimental correlation of heat transfer and flow resistance in the tube.