| Tubular oil cooler is widely used in all kinds of vehicles.Because of more expensive of cooper and the requirement of “lightweight,environmental protection and optimization cost”,the replacement of cooper tubular oil cooler with aluminum tubular oil cooler is development trend in automobile industry.In this paper,the production process of aluminum tubular oil cooler was studied and optimized,as well as its mechanical properties and heat transfer performance,by combining theoretical analysis,finite element analysis and a serious of experiment tests.In the first part(chapter 2),the heating process of high-frequency induction heating was studied,and the electromagnetic-thermal coupling analysis was carried out on the base of the nonlinear physical properties of the material.The results showed that the relative error of temperature between the simulation and test results was less than 4%.By studying the eddy current distribution and volume loss distribution on the aluminum tubular oil cooler,it was found that the eddy current agreed well with the projection law of the coil,and the pipe end and the flange from the nearest part of the coil is prone to erosion.Compared with the heating effect of the new conical coil and the plane coil,it is found that the plane coil is easy to cause the pipe end erosion and the conical coil is easy to cause the flange erosion.The effect of taper and current on the heating effect of the coil was studied and the results showed that the optimum taper was 56.9° corresponding to the 3.35 turns coil structure being C3-3.35.As this coil was applied,the welding time was 15.5 s without the occurrence of erosion.Based on the C3-3.35 coil,the structure of the magnetic conductor was further studied.Because of its large back-end magnetic inductance line collection area line collection area and small front-end area of the magnetic conductor,the energy was concentrated as much as possible near the solder for likeduckbill magnetizer.Thus,the heating effect of aluminum tubular oil cooler was the best as the like-duckbill magnetizer was applied.The distance between the magnetizer and the flange had a great influence on the welding effect.Finally,the optimal distance is 4 mm,which had good temperature distribution and production efficiency.The welding time was reduced from the initial 22.3 s to 6.5 s.In the second part(chapter 3),the overall thermodynamic performance of the aluminum tubular oil cooler was analyzed by Computational Fluid Dynamics(CFD)simulation.Firstly,the local structure was simulated under certain conditions to record the temperature difference and pressure drop data.Then the finned region was simplified to the porous medium,and the equivalent drag coefficient and equivalent porosity were obtained which were the same as the pressure drop and temperature difference of the local structure.The above parameters were substituted into the whole porous medium model for simulation and compared with the test data.It was found that the relative error of heat transfer and pressure drop was within-5%.For example,the oil flow rate of 84 g/s,the heat transfer performance of aluminum tubular oil cooler was 16.1% higher than that of cooper tubular oil cooler,and the pressure drop by 47.3%at the same time.The third part(chapter 4)analyzed the mechanical properties of aluminum tubular oil cooler.The test value of static pressure strength was between 6.18-6.65 MPa.In addition,the appearance of the aluminum tubular oil cooler kept intact as it was tested at high pressure pulse1.5 MPa for 10000 times.The results showed that the aluminum tubular oil cooler meet the standard for application. |
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