Heat transfer and pressure drop characteristics in a circular tube with mesh cylinder inserts

Abstract

Heat transfer performance and pressure drop tests were conducted on a circular tube with mesh cylinder inserts. These inserts with different open area rate, 30, 60, and 120 pores per inch (PPI) were tested at Reynolds numbers between 4000 and 18,000. Tap water was used as the working fluid. A high heat transfer coefficient was obtained by using mesh cylinder inserts. The friction factor increases with increases in PPI. Optimal results were obtained for PPI=60. Heat transfer rates and friction factors were enhanced by 2.3–2.6 and 3.4–3.7 times, respectively, to those in the plain tube. Performance evaluation criterion (PEC) values were approximately 1.48–1.7. Numerical method is also employed to analyze the enhancement. The results show that the reason for the heat transfer enhancement is attributed to two factors. One is attributed to the velocity increase at the inlet. Another owes to the high turbulent intensity generated by inserting the mesh issue. Two factors work together to achieve a high heat transfer rate. Compared with other inserts, mesh cylinder inserts can transfer more heat for the same pumping power.