brass tubes for heat exchangers

About the heat exchanger is good with the copper pipe？Stainless steel pipe effect？

I believe that you are more confused.，I want to know about the knowledge about the heat exchanger.。Shuangxing stainless steel small knitting today，To analyze you detailed。

Comparison of properties of stainless steel heat exchange pipes and copper tubes

(brass tubes for heat exchangers)1、Stainless steel heat transfer pipe has the following advantages：

ØChange heat pipe0.5-0.8mmThin-walled pipe，Improve overall heat exchange performance，Under the same heat exchange area，The overall heat transfer coefficient is higher than the copper pipe2.121-8.408%。

Ø Due to the materialSUS304High quality stainless alloy steel，Make it high hardness，The steel level of the pipe is also significantly improved.，therefore，Strong impact resistance and vibration resistance。

(brass tubes for heat exchangers)Ø Due to the inner wall of the pipe，Make the thickness of the boundary layer of the boundary layer，Enhance heat exchange，Increased anti-scale performance。

Ø In order to eliminate welding stress，In protective gas1050℃High temperature heat treatment。

(brass tubes for heat exchangers)Ø Steel pipes are taken by pressure differences，Air pressure test10MPa，5No pressure drop in minutes。

2、Detailed comparison：

one、Thermal conductive

Due to the thermal conductivity of the copper tube100W/m℃，The thermal conductivity of the stainless steel pipe is13W/m℃，This, it is of course to affect the overall heat transfer coefficient。but，The wall thickness of the stainless steel pipe can be thinned0.5~0.8mm，Causes of copper tube due to strength and erosion wear，Its wall thickness cannot be lower than1.2mm。

According to formula：Rc= （1）

in：Rc——Heat thermal resistance，m2k/w。

λ——Thermal Conductivity，W/(m.k)。

δ——Tube wall thickness，m

(brass tubes for heat exchangers)Tube，λConstant，According to formula（1），δSmaller，RcSmaller，The greater the heat transfer coefficient。This can reduce the gap between the overall heat transfer coefficient of stainless steel pipe and the copper pipe.。

(brass tubes for heat exchangers)Since the internal and outer walls of the copper tube are more rough than stainless steel，Easy scaling，Increase the thermal resistance of the copper tube，This has reduced the gap between the total heat transfer coefficient of the copper tube and the stainless steel pipe.。

two、Convergence

Use stainless steel pipe or use copper tube，The flow rate of the pipe is turbulence。The maximum factor affecting the heat of flow is the thickness of the laminar flow layer.，Because heat transfer in the laminar flow is thermally conductive，And the water thermal conductivity is very low.。In the same way in the flow state，The thickness of the laminar flow layer depends on the roughness of the inner wall of the tube。Oxide in the inner surface of the copper tube，Its roughness is much larger than stainless steel tubes，The thickness of the laminate of the copper tube is larger than the thickness of the laminar layer of the stainless steel pipe.。This makes the stainless steel tube on the convection heat coefficient of the copper tube.。

(brass tubes for heat exchangers)Rw= (2)

(brass tubes for heat exchangers)in：Rw——Conversion heat resistance，m2k/w。

αw——Conversion coefficient，w/m2.k。

According to formula（2）αwGreater，RwSmaller。

three、Condensation

Two kinds of film condensed coagulation and bead condensation，Bead condensate is much more than film coagulation is much larger.。However, which is more unclear that the outer wall of the stainless steel tube and the outer wall of the copper tube is more unclear.，However, it can be said that most of the outer walls of the pipes are film-shaped.。The exothermic coefficient of membrane coagulation is large and the thin thickness of the film is very large.，Because the inside of the film is thermally conductive，The water film is particularly low, and the thickness of the film depends on the roughness of the outer wall of the tube.。The relationship between the outer wall of the copper tube is the relationship between the oxide layer，More than stainless steel tube。therefore，The coagulation heat dissipation coefficient of the outer wall of the stainless steel tube is larger than the coagulation heat dissipation coefficient of the outer wall of the copper tube.。

Rm= （3）

(brass tubes for heat exchangers)in：Rm——Concentrating heat resistance of outer wall，m2k/w。

αm——Condensation of the outer wall of the tube，w/m2.k。

According to formula（3），αmGreater、RmSmaller。

Four、Overall heat transfer coefficient

K= （4）

in：R——Overall thermal resistance，m2k/w。

K——Overall heat transfer coefficient，w/m2.k。

(brass tubes for heat exchangers)Depend on（4）Know：Conversion thermal resistance、The thermal resistance and condensed thermal resistance are reduced，The total heat resistance is small：Total thermal resistance is small，Overall heat transfer coefficient。

In the case of the same wall thickness，The overall heat transfer factor of the stainless steel pipe is lower than the copper tube6%。Due to the use of thin stainless steel tubes than copper tube，The overall heat transfer coefficient of the stainless steel pipe and the coagulation exothermic coefficient are larger than the copper pipe.，The overall heat transfer coefficient of the stainless steel pipe is improved。

(brass tubes for heat exchangers)