Abstract:

In the passive improvement of heat transfer technology, the use of inserts in tubes is a very common and practical technique. Inserting a central inclined rod in a heat exchanger tube can realize multilongitudinal vortex flow, similar to the optimized flow field in the tube, and effectively improve the heat exchange performance of the heat exchanger tube while retaining a small increase in flow resistance. In this study, a heat exchanger tube with an inserted central inclined rod is examined based on the numerical simulation method. The influence of the number, pitch, and diameter of inclined rods on the heat transfer performance and resistance characteristics is investigated. Results show that the heat transfer tube with the inserted central inclined rod achieves considerably better heat transfer performance than the smooth tube. The Nusselt number of the heat transfer tube with the inserted central inclined rod increases within a certain range with an increasing number of inclined rods, and the pressure drop increases with the number of inclined rods. When the number of inclined rods is three, the comprehensive heat transfer performance of the heat transfer tube with the inserted central inclined rod is better. The Nusselt number and pressure drop decrease with increasing pitch of the inclined rod. When the pitch of the inclined rod is 20 mm, the comprehensive heat transfer performance of the heat transfer tube with the inserted central inclined rod is better. The Nusselt number and pressure drop increase with the inclined rod diameter. When the inclined rod diameter is 2.0 mm, the comprehensive heat transfer performance of the heat exchange tube with the inserted central inclined rod is better.

Key words: :central inclined rod, pitch of inclined rod, number of inclined rod, diameter of inclined rod, numerical simulation