Study On Heat Transfer And Pressure Drop Characteristics Of Pulsating Fluid Flow In Corrugated Tube

Since the oil crisis broke out in the1970s, the situation of energy shortage is becomingmore and more serious. In order to alleviate energy shortages, heat transfer enhancementhas been the research focus of scholars at home and abroad. Corrugated pipe and pulsatingflow as two different methods of enhancing heat transfer have been studied separately, andthe use of those two methods at the same time is rarely been reported. In this paper, theheat transfer and pressure drop characteristics of corrugated pipe with pulsating flow in itwere numerically and experimentally studied, and the possibility of the effect of compoundheat transfer enhancement when corrugated pipe and pulsating flow were used togetherwas been discussed.In the part of numerical simulation, the heat transfer and pressure drop characteristicsof corrugated pipe with constant wall temperature and pulsating flow in it wereinvestigated by applying Fluent. In the simulation, the mean velocity of inlet ranged from0.03m/s to0.05m/s in the laminar case while changed from1m/s to2m/s in the turbulentcase. The frequency changed from2Hz to10Hz, and magnitude ranged from0.2to1. Theinfluence of pulsating frequency and amplitude of pulsating flow on the heat transfer andpressure drop characteristics were been discussed. The causes for heat transferenhancement were analyzed.According to the evaluation criteria （K_p/K_s）^3.5-（Δp_p/Δp_s）, the performance ofcorrugated tube was evaluated by the reference of numerical result. The results are asfollows:When the flow is laminar, the pulsating flow with lower frequency and higheramplitude can either enhance heat transfer or increase the pressure drop. The former has amore obvious effect than the last on corrugated tube. This ensures the corrugated tube agood performance. The pulsating flow with the frequency of2Hz and amplitude of1ensures the best performance to corrugated tube. The effect of compound heat transferenhancement can be realized by using corrugated tube and pulsating flow together.When the flow is turbulent, pulsating flow can’t ensure a good performance forcorrugated tube, it even worse that. Because the heat exchange is very good when thesteady flow is turbulent, the pulsating flow has a very limited effect on it. At the same time, pulsating flow increase the presser drop, which offset the effect of heat transferenhancement.In the part of experimental study, an experiment was designed to test the realperformance of heat transfer of turbulent pulsating flow in a corrugated tube. The meanvelocity of inlet ranged from1m/s to2m/s，the frequency changed from0.5Hz to3.5Hz,and magnitude fixed on0.01. The results show that compared with steady flow, pulsatingflow can either enhance or weak heat transfer. It depends on the velocity and frequency ofthe pulsating flow.