The Study Of "Jnx" Structure And Its Self Cleaning Performance

Energy is indispensable in improving the quality of life and development of economy. The demand of energy in our country continues to grow and we are facing the grim problem of energy security and environmental pollution. To resolve the problem, we should not only look for new energy, but also improve the energy efficiency. As one type of the most widely used heat exchange equipments, shell-and-tube heat exchanger has the problem of inefficiency. Besides, heat transfer performance of heat exchanger will deteriorate further due to the dirt in the tube caused by some problems such as water quality. Therefore, it is imminent to develop a highly efficient technology which has the function of self-cleaning and heat transfer enhancement.In this paper, we introduced the technology of heat transfer enhancement, classified the current technology from two perspectives of active technique and passive technique, and summarized the research status. Flow field and temperature field in smooth tube and tube with "JNX" are studied in this paper. We have improved the cross section of the rotor and found that flow field and temperature field in tubes with modified rotors are improved, and both Nusselt number and friction factor increase. Besides, rotors with cut on the edge are also investigated. The comparative studies are performed using rotors with cuts of different shapes (V cut and square cut), different numbers and different sizes. The results show that heat transfer and comprehensive performance are improved caused by rotors with cut.Experimental investigations are also performed on heat transfer and friction characteristics in tubes inserted with "JNX". The influence of "JNX" mixed by different types is also studied, and it is inferred that tubes with rotors mixed by spiral slot rotors and low flow resistance rotors can enhance the heat transfer.Fouling-cleaning technology is also systematically introduced from the view of numerical simulation in this paper. Based on the research of smooth tube, the numerical simulation of fouling process in circular tube inserted with "JNX" is carried out, and the line of fouling resistance changing with time in "JNX"-nserted-tube is compared with that in smooth tube. It is found that fouling resistance in "JNX"-inserted-tube is smaller than that in smooth tube, which proves that "JNX" has self-cleaning performance.