Influence Of Design And Technics Parameter On Heat Transfer Performance Of The Copper Auto Radiator

The radiator is a critical part in the automotive engine cooling system.It is the heat exchanger between inner coolant and outer air of the automotive engine.With the development of automotive engine and the increase of the engine power, the requirements for the radiator is becoming higher and higher.Now specialists pay more and more attention on the study of cooling system especially the radiator.The advantages of auto copper radiator are good heat performance, easy operation and maintenance and good corrosion resistance. In recent years,with the increasing demanding on the heat performance,studies on the heat transfer performance of auto copper radiator are more and more.The design and technics parameter of auto copper radiator is the important influent factor for heat capability.In this thesis,first I introduce the structure and work principle of the ribbon-tubular radiator and the calculation way of air-side area.Then I analysis the way to increase the heat performance.Finally I study the effect of the design and technics parameters on the heat performance based on test data.The influent parameter: air side area of radiator,fin material and thickness,fin pitch,fin louver distance,fin louver angle,core thickness,tube dimension , liquid and air differential temperature,etc.Both face area and air side area affect the heat performance.The increase of heat performance is proportional to the face area. Arranged in a certain space,increasing the face area is the effective way to improve the heat performance. On the other hand, increasing the air side area or decreasing the pin pitch also can improve the heat capability.But when it gets to a certain degree, increase of the standard capacity becomes slowly.The standard capacity of pure copper radiator is 40% higher than that of 70% copper radiator .So the decrease of copper content affect the heat performance heavily.At the certain parameters,decreasing copper content is not recommended.When changing the distance of fin louver from 1.5mm to 1.0mm, the heat performance increases by 13% and the air side pressure drop increases by 10%, So reducing the louver distance is a good way to improve the heat performance.When changing the fin louver angle from 25°to 35°,the heat performance increases by 3% and the air side pressure drop increasesby 5%.So increasing the fin louver angle can't improve the heat performance effectively.Changing the row of tubes from 3 to 4,the air side area increases by 36%,but the heat performance only increases by 17%.So increasing the row of tubes is not a good way to improve the heat performance of radiator.Changing the dimension tube from 16×2 to 14×2.5, the standard capacity decreases by 4% and the air side pressure drops are about the same.It is to say that effect of tube dimension on heat performance is not obviously. So changing the tube dimension is not a good way to improve the heat performance.Based on the tests, the main designing parameters that affect the heat performance are determined as the following: fin pitch and fin louver distance.Based on the orthogonal test, the main technics parameters are determined as the following:blowy pressure,the fist area temperature in the brazing oven, ,tube manufacture temperature,the second area temperature in the brazing oven and the chain speed. The brazing rate and heat performance decrease along with the rising of blowy pressure. The max brazing rate be present at 0.08MPa.The brazing rate and heat performance decrease along with the rising of the first area temperature in brazing oven. The max brazing rate be present at 260℃.The brazing rate and heat transfer performance fluctuate along with the rising of tube manufacture temperature. The max brazing rate be present at 360℃.The brazing rate and heat performance decrease along with the rising of the second area temperature in brazing oven. The max brazing rate be present at 300℃.The brazing rate and heat performance fluctuate along with the rising of chain speed. The max brazing rate be present in 4HZ.The first rank technics parameters are the following: blowy pressure:0.08MPa, the first area temperature in the brazing oven:260℃,the tube manufacture temperature: 360℃,the secong area temperature in the brazing oven:300℃,the chain speed:4HZ.