Comparison of performance of copper tube and stainless steel heat exchange tube.

Stainless steel heat exchange tube: a device made of stainless steel, one of the components of a heat exchanger, placed inside the tube, used for heat exchange between the two media.

Stainless steel heat exchange tube has the following advantages:

1. The heat transfer tube adopts thin-walled tube with 0.5-0.8mm, which improves the overall heat transfer performance. Under the same heat exchange area, the overall heat transfer coefficient is 2.121-8.408% higher than that of copper tube.

2. As the material is made of SUS304 high quality stainless steel alloy steel, it has a high hardness, and the steel degree of the pipe is obviously improved. Therefore, it has a strong impact resistance and anti-vibration performance.

3. As the inner wall of the tube is smooth, the thickness of the bottom layer of its boundary layer is thinned, which not only intensifies the heat transfer, but also improves the anti-fouling performance.In order to eliminate the welding stress in the shielding gas with 1050 ℃ high temperature heat treatment.The pressure difference was used for the leak check, the pressure test was 10MPa, and the pressure was not reduced in 5 minutes.

Copper tube: also known as copper tube, a kind of nonferrous metal tube, is the seamless tube that is pressed and drawn.The copper tube has the characteristics of strong and corrosion-resistant, and it is the first choice for modern contractor to install water pipes, heating and cooling pipes in all residential commercial houses.Copper pipe is the best water supply pipe.

Advantages of copper pipe:

1. Light weight, good thermal conductivity and high temperature.Used to make heat transfer equipment (such as condenser, etc.).It is also used for the assembly of low temperature pipeline in oxygen production equipment.Copper tubes with small diameters are often used to convey pressurized liquids (such as lubricating systems, oil pressure systems, etc.) and pressure gauges used as instruments.

2. The copper pipe has a strong and corrosion-resistant property, and it is the first choice for modern contractor to install water pipes, heating and cooling pipes in all residential commercial houses.

3. The copper tube has many advantages: it is strong, it has the high strength of general metal;Again at the same time than the general metal flexible, easy to reverse, not easy to crack, is not easy to break, and have certain antifreeze bulge and impact resistant ability, so the construction of the water supply system of cupreous conduit is installed, safe and reliable to use, don't even need maintenance and maintenance.

The disadvantage of copper pipe: as far as copper tube is concerned, high price is its biggest shortcoming. It is the most expensive water pipe at present, and it will never leak after installation of welding process.The connection of copper pipe joints is mainly dependent on the process level of construction, and the construction quality is higher.

The following aspects will illustrate the differences between copper pipe and stainless steel heat exchange tube.

The performance comparison of copper pipe and stainless steel heat exchange tube is as follows:

1. The thermal conductivity of copper tube and stainless steel heat exchange tube.

Because the coefficient of thermal conductivity of copper tube for 100 w/m ℃, the coefficient of thermal conductivity of stainless steel pipe for 13 w/m ℃, this will affect the overall heat transfer coefficient, of course.However, the wall thickness of the stainless steel tube can be reduced by 0.5~0.8mm, while the copper tube is due to strength and erosion wear.

The wall thickness cannot be less than 1.2mm.

According to the formula: Rc= (1) : Rc - thermal resistance, m2k/w.Lambda - thermal conductivity, W/(m.k).

Delta - tube wall thickness, m.

The pipe material must be, when it is invariant, according to the formula (1), the smaller the delta, the smaller the Rc, the greater the heat transfer coefficient.This can reduce the difference between the overall heat transfer coefficient of the stainless steel tube and the copper tube.

Because the inner and outer wall of copper tube is rougher than stainless steel, it is easy to scale and increase the thermal resistance of copper tube, which makes the difference of the overall heat transfer coefficient of copper tube and stainless steel tube narrow.

The comparison of the performance of copper pipe and stainless steel heat exchange pipe is carried out.

Using a stainless steel tube or copper tube, the flow velocity in the tube is turbulent.The biggest factor that affects convective exothermic heat is the thickness of laminar layer, because the heat transfer in the bottom layer is heat conduction, while the thermal conductivity of water is very low.In the case of the same flow state, the thickness of the laminar layer depends on the roughness of the inner wall.The surface of the copper tube is coated with oxide, and its roughness is much larger than that of the stainless steel tube. The thickness of the laminar layer of the copper tube is larger than that of the laminar layer of the stainless steel tube.The convective exothermic coefficient of stainless steel tube is larger than that of copper tube.

Rw = (2)

Among them: Rw - thermal resistance to exile, m2k/w.W - convective exothermic coefficient, w/m2. K.?According to the formula (2), the larger the alpha w, the smaller the Rw.

3. The condensation heat release coefficient of copper tube and stainless steel heat exchange tube.

There are two kinds of condensation exothermic coefficient, such as membrane condensation and bead condensation, and the heat coefficient of bead condensation is much larger than that of membrane condensation.However, the outer wall of the stainless steel tube and the outer wall of the copper tube are more unclear, but it can be said that most of the outer wall of the pipe is membrane condensation.The heat transfer coefficient of membrane condensation has a great relationship with the thin film thickness, because the heat conduction is inside the film, the thermal conductivity of the water film is very low and the thickness of the film depends on the roughness of the outer wall.The outer wall of the copper tube is much rougher than the stainless steel tube due to the oxide layer.Therefore, the condensation heat coefficient of the outer wall of the stainless steel tube is larger than that of the outer wall of the copper tube.

The Rm = (3)

Where: Rm -- the condensation heat resistance of the outer wall of the tube, m2k/w, the condensation exothermic coefficient of the outer wall, w/m2. K.According to formula (3), the larger the alpha m, the smaller the Rm.

The overall heat transfer coefficient of copper tube and stainless steel heat exchange tube.

K = (4)

Where: R - total thermal resistance, m2k/w.K - overall heat transfer coefficient, w/m2. K.

It can be known from (4) that the convective thermal resistance, thermal resistance and condensation heat resistance decrease, but the total thermal resistance decreases: the total thermal resistance decreases, and the overall heat transfer coefficient increases.

Under the same wall thickness, the overall heat transfer coefficient of the stainless steel tube is 6% lower than that of copper tube.The overall heat transfer coefficient of the stainless steel tube is larger than that of copper tube, and the overall heat transfer coefficient of the stainless steel tube is improved.

Comparison table of heat exchange performance of

 copper tube and stainless steel tube.

Name	specification (mm)	Texture	total heat transfer coefficient (W/m squared. K)
Copper tube	1	hsn70-ia	3682.423869.
Stainless steel tube	1	AI304	3460.327347.
Stainless steel tube	0.7	AI304	3760.628476.
Stainless steel tube	0.8	AI304	872.686729.

 

5. The long-term economic performance of copper tube and stainless steel heat exchange tube.

As the running time increases, the oxide layer of copper tube will become thicker and thicker, and the heat transfer effect will become worse and worse.Stainless steel is not oxidized or oxidized very slowly.Therefore, if the heat exchanger of the stainless steel tube and the heat exchanger of the copper tube are put into operation at the same time, the longer the operation time, the economical efficiency of the stainless steel tube heat exchanger will be better and better than that of the copper tube heat exchanger.At the same time, the adsorption capacity of the copper tube to the cooling water is much stronger than that of the stainless steel pipe, which greatly reduces the economical efficiency of the equipment.

Comparison of safety performance of copper tube and stainless steel heat exchange tube.

 

Engineering characteristics of copper tube and stainless steel heat exchange tube.

Copper tube and stainless steel tube heat exchange engineering property sheet.

Tube	Copper tube		stainless steel tube
Density t/m³	8.4	&＜8.9	8
Yield strengthMpa	120＜	140	280-350
Tensile strengthMpa
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