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Copper Tube Information

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3mm brass tube

author:MF manufacturerstime:2022-03-12 04:13:24

Room air conditioner cleaner with smaller pipe diameter,Canify the knot More compact、Lower cost、More heat transfer efficiency、And significantly reduced Refrigerant。Environmental work R290 Extremely flammable,EU, etc. have strictly defined their perfusion,Its promotion and application depends on the study of small tube-sized heat exchanger。E.g,Put the inner threaded copper tube of an existing air conditioner7 mm Narrow 5 mm,Reduce heat exchanger 20%~40%Unequal,Refrigerant fell reduction20%, So in recent years 5 mm The tube heat exchanger has been widely used in the air conditioner。


(3mm brass tube)

3mm brass tube


0 introduction


If 5 mm Based on the heat exchanger, the tube of the heat exchanger is reduced to 3 mm,The cost of the heat exchanger will drop 20%~40%,The amount of charge will also Further decline。Therefore, the room air conditioner is adopted 3 mm Copper tube heat exchanger,Is an important development direction of the future design efficient and environmentally friendly air conditioner。

(3mm brass tube)

As the heat exchanger's copper pipe5 mm Narrow 3 mm,system The pressure drop in the cold reinforced side and the hydraulic diameter of the copper pipe5 The second party increases。 Pressure droppowing causes energy loss of refrigerant,Leading the performance of the heat exchanger drastically attenuated。Develop 3 mm A difficulty of tube heat exchangers It is necessary to significantly reduce the pressure drop on the refrigerant side.。 Two methods of reducing the refrigerant side pressure drop:


1)Light Tube replaces the traditional internal threaded tube;

2)Increase the number of flow paths。The heat exchanger uses a light pipe instead of the internal threaded tube,Will lead to internal replacement The heat coefficient and heat exchange area are reduced,Make heat transfer performance attenuation。If the performance attenuation is within a reasonable range, you can use the light pipe.,Therefore 3 mm Light pipe and strengthening tube5 mm Strengthen tube for performance Comparison。The number of flow paths in the heat exchanger increase,Will lead to cooling in the branch Differential flow reduction causes the heat transfer performance attenuation。Increase the number of change heat pipes And reduce the pipe diameter to make up this shortcomings,Therefore, it is necessary to study the matching relationship between flow path parameters and pipe diameter to design heat exchange capacity and pressure drop. Duzu's heat exchanger。

The goal of this article is to determine the room air conditioner adoption 3 mm Tube Technical idea,include 3 mm Tube type selection、Optimistic flow path Number and pipe diameter determination。


1 Technology route

(3mm brass tube)

Design room air conditioner3 mmTechnical ideas of copper tube heat exchanger include 3 Step,Copper tube type selection、Flow path parameters and copper pipe diameter External and heat exchanger performance analysis,Figure 1 Shown。


3mm brass tube

The selection method of the copper tube type is to quantify the effects of tubular type on heat exchange and voltage drop.,Find the best performance optimized。Fluctuation method for flow path parameters and pipe diameter is to synthesize flow path parameters that meet heat exchange requirements and flow path parameters that meet the pressure drop requirements.,The number of flow paths, optimal process, and corresponding pipe diameters。The performance analysis of the heat exchanger is a combination of heat exchanger size and flow path parameters,calculate Get heat transfer and voltage drop performance and cost of heat exchangers。This article is calculated when calculating heat exchange performance,use UA Measurement,Definition(1)。

(3mm brass tube)
3mm brass tube

2 Copper tube type selection

Method for determining the optimal tube type of a smaller pipe diameter copper tube heat exchanger Yes:

Adopting a wide range of broad 5.0 mm Enhanced tube 3,500 W Room air conditioner(Refrigerant R410A)Benchmark, Quantitative calculation 3.0 mm Light pipes and strengthening tubes UA、Pressure drop,as well as The temperature dropped by the pressure drop,To determine the optimal tube type。This article“Pipe diameter”And refer to the value of the pipe diameter,Such as 7 mm、5 mmand 3 mm,Both represent the outer diameter of the copper tube。This article calculation R410A The heat exchange and pressure drop association of boiling in the light pipe is 5 mm and 7 mm The experimental data of the tube is fitted。Some data verification,These correlation calculations 3 mm The average error of the heat transfer and voltage drop of the light pipe is 11%and 19%,So can be used 3 mm Tube heat exchange And pressure drop calculation。

2.1 Copper tube parameters

(3mm brass tube)

In the calculation 5mm Strengthen tube、3 mm Light pipe、3 mm The parameters of the strengthening tube are like a table 1 Shown。

(3mm brass tube)3mm brass tube(3mm brass tube)


2.2 Effect of tube type on heat exchange performance


Application of tube heat transfer coefficient in tube diameter copper tube,Calculate the above 3 Copper-tube heat exchanger UA,Figure 2 Shown。Under the same mass flow,Heat exchanger 3 mm strengthen Tube and 3 mm TubeUA Significantly greater than 5 mm Strengthen tube, This is because 3 mm Tube ratio 5 mm Tube has a larger current stream density, Make a significant increase in heat transfer coefficients。The quality flow of the refrigerant is 10g/s Time,Heat exchanger 3 mm Strengthen tube ratio 5 mm Enhanced tube UA Increase 14.5%,and 3 mm Light tube ratio 5 mm Enhanced tubeUA Increase 6.8%。The above results 3 mm The light pipe is fully achievable 5 mm Heat heat exchanger。

3mm brass tube

3mm brass tube


2.3 Influence of tube type on pressure drop performance


Use the pipe internal pressure drop coefficient to calculate the heat exchanger 5 mm Strengthen tube、3 mm Strengthen tube and 3 mm Refrigerant of the light pipe Side pressure drop,Further, the temperature difference of the refrigerant import and export。Figure 3 Place Show,Under refrigeration,Heat exchanger 3 mm Strengthen tube 3 mm Light pipe,Pressure drop、The average increase of temperature drop is28%、41%, Selecting the light pipe to effectively reduce temperature drop to improve system performance。

(3mm brass tube)3mm brass tube

3mm brass tube

Computational results for comprehensive heat transfer and voltage drop,Should be selected 3.0 mm Copper tube of the left and right light tube as a smaller pipe diameter,This is Finally 3.0 mm The internal thread of the copper tube is inconvenient for processing problems。

(3mm brass tube)

3 External calculation of heat transfer parameters and pipe diameters

(3mm brass tube)

3.1Calculation method


3.1.1 Definition of flow path parameters

“Flow path parameters”Remember(n,N),in n A support Number of copper pipes in the road,N Total number of copper tubes representing all branches。picture 4 for n from 1 receive 6 Flow path arrangement。

3mm brass tube

3.1.2 Algorithm for flow path parameters and pipe diameters

picture5 The heat exchanger design flow package of different pipe diameter copper tubes shown Include the following 5 step。


1)First1step,Relationship according to the heat exchange and pressure drop of the small tube diameter,Establish air conditioning heat exchanger heat exchange and voltage drop model,This model Input parameters(n,N),The output parameter is UA Pressure drop。Considering the range of processing,This article selection outer diameter is 2.4 mm、3.0 mm and 3.6 mm Copper tube for flow path calculation of heat exchanger。

2)First 2 step,Adjusting the input parameters of the flow path(n,N),Make The air conditioner reaches the heat exchange requirements,Get in the room air conditioner、Outer machine Equal UA String。

3)First 3 step,A group corresponding to each pipe diameter is obtained according to the requirements of the pressure drop.(n,N),Draw an equivalent line。

(3mm brass tube)4)First 4 step,Two lines corresponding to each pipe diameter,That is, in line with heat exchange requirements, etc. UA Wire and compliance with pressure drop requirements String,The intersection of these two curves represents the flow of two requirements Road parameters。

5)First 5 step,By comparing the processing feasibility of the flow path arrangement scheme of each pipe diameter,Thereby choosing a suitable pipe diameter。In the first 2 Step and 3 In the middle,In order to get all the match Required flow path parameters(n,N),Need to establish a suitable enumeration rule。This method makes n by 1 Increment、N by 1 Increment or decrement until the range,All of the can be traversed by traffic path parameters。Note the number of copper pipes in a branch n The range of values is significantly less than Copper tube N,and N The value is n Multiplex,So this article is adopted n Main variable、N Enumerate for the method of sub-variable variable。

3mm brass tube

Drawing, etc. UA The enumeration method of the line is an example,Figure5 Right side Show,Enter the light pipe diameter in turn 2.4 mm、3.0 mm and 3.6 mm, Flow path of indoor unit and outdoor machine at each pipe diameter Make enumeration,when UA Outputs the number of copper pipes in a branch during the time n Total number of copper tubes N,Finally, this group(n,N)Glossy Curve connection。Enumeration method of drawing isometric downtown is similar to this。

3.2 Calculation model


The heat exchange and voltage drop model of the heat exchanger is shown 6 Shown,It in embedded Tube heat transfer coefficient and pressure drop association with small pipe diameter tube,Self-variable is the flow path parameters of the heat exchanger(n,N),Due to variables are heat exchangers UA And the pressure drop on the refrigerant。The input parameter of the calculation model is the geometric structure and working parameters of the heat exchanger.。

3mm brass tube


(3mm brass tube)in,Geometry includes the size of the heat exchanger and fin specification, etc.,Table 2 Shown,Status parameters include imported temperatures of refrigerant,Table 3 Shown。This model is streaming according to the performance indicators of heat exchange and voltage drop Road and pipe diameter,Among them, performance indicators are based on the original5mmThe performance and working conditions of the heat exchanger,Table4Shown。

Because of a heat exchanger UA And pressure drop relies on the stream density of the refrigerant G,That is, both are each coupled.,So directly enumerate Simultaneous flow path parameters required to meet heat exchange and voltage drop require a large amount of calculation。In order to reduce the amount of calculation,This paper studies the requirements of the heat transfer and voltage drop performance, respectively.。Calculate heat transfer performance,By changing(n,N)Adjusting rigid Spend,Tube heat transfer coefficient hi Change,Further, affecting the heat exchanger UA。

When adjusting to satisfaction UA Time,Output flow path parameters (n,N),Get a collection A。Considering the pressure drop characteristics,By changing Number of copper pipes in a branch n Total number of copper tubes N,Can change quality Flow density and pipe length,Friction pressure drop affecting the flow of gas phase in the tube,To adjust the value of the total pressure drop in the tube。When the pressure drop meets the requirements,Output flow path parameters(n,N),Get a collection B。gather A Collection B The intersection is the final flow path parameter of the heat exchanger。

3.3 Calculation results


3.3.1 Fluctuation results of flow path parameters


picture9middle,WaitUALine represents all just to reach heat exchange requirements Flow parameter collection,Isometric downtown represents the collection of flow path parameters that meet the pressure drop indicator。The intersection coordinates of the two lines corresponding to the same pipe diameter represent flow paths that meet the heat exchange and pressure drop in the pipe diameter.。


3mm brass tube

Round the coordinate value,Copper tube corresponding to different pipe diameters The flow path parameters of the unit are shown in the table 5。Compare the number of copper pipes for each branch n Discover,The greater the pipe diameter n Greater;Number of compared total copper tubes N send now,Number of copper tubes of the inner machine N almost the same,The number of copper pipes of the outer machine Decrease with the increase of the pipe diameter。The reason is that the larger the pipe diameter,Heat exchanger UA The smaller, the smaller the internal pressure drop coefficient,Need to reduce N Increasing n To reduce the number of branches N/n,Thus improve the branch Traffic,Finally keep it UA And the pressure drop on the refrigerant。

3.3.2 Pipeline search results


Figure 4 The flow path layout map,when n An even time,Advancer、Exports are in the same side of the tube;when n Be odd,Enter、 Exports are on the height of the heat exchanger。Design a heat exchanger,Be as best as possible Make n An even number,This is conducive to manufacturing、Processing and maintenance。In the table 3 Copper tube of a pipe diameter is used to design a heat exchanger,only 3.0 mm Light Tube n An even number,Therefore, the tube diameter should be 3.0 mm。

3mm brass tube(3mm brass tube)


4 Performance analysis of heat exchangers


4.1 Heat and pressure drop performance


Due to determination of flow path parameters,right n and N The value is round,Therefore, the actual heat exchange capacity and voltage drop characteristics need to be recalculated.。surface 6 The results of the performance test results of the new design heat exchanger and the design Ask for comparison。use 3.0 mm Smaller tube diameter heat transfer Instrumental UA Deviation with the original plan indicator 5%Within。


use 3.0 mm The heat exchanger of the light pipe is increased by the number of flow paths. Flow reduction,Therefore, ratio 5.0 mm Strengthened heat exchanger Lower pressure。The deviation of the pressure drop and the set value is 50%Within,But the absolute value of the pressure drop is still within a reasonable range.。Comprehensive,3.0 mm The heat exchange and voltage drop performance of the heat exchanger meets the requirements。

3mm brass tube

4.2 cost analysis


use 3.0 mm Alternate 5.0mm Strengthening tube for air conditioning Heat Exchanger,Calculate the material quality of copper tube and aluminum fins, respectively。design The amount of air conditioner heat exchanger material before and after 10,as illustrated,use 3.0 mm The copper tube heat exchanger is reduced by the amount of copper of prototypes.57.2%,Aluminum2.2%。According to the brass unit price35Yuan/kg、The single price of aluminum is12Yuan/kg calculate,use 3.0 mm Alternate 5.0 mmIntensive pipe for air conditioner heat exchanger,The material cost of the heat exchanger drops 31%。

3mm brass tube

4.3 Process feasibility analysis


Existing typical light pipe is known for the outer diameter of 3 mm~6 mm。3.0 mm Hydraulic expansion can be used when the mold is used to heat exchanger。Insert a dedicated core bar into the inside of the heat transfer tube,use OSplit or liquid bag seal back,Import high pressure liquid to expand the heat transfer tube。The advantage is that the wall Even by force、Residual stress、Chip。The disadvantage is that the process is Strength of the core rod、Stability and manufacturing requirements are high。This article is designed 3 mm Air conditioner's inner machine and outer machine The number is 10 and 12,More 5 mm The number of support of the heat exchanger increases significantly。

The dispenser for more flow paths still needs to be studied.,need Starting from the principle of average,Structural design and verification。

5 Summarize

This article proposes a room air conditioner adoption 3 mm Copper tube design Think,Through the case verification 3 mm Alternate 5 mm Strengthen tube Feasibility of design methods。Designed 3 mm Heat exchanger and original 5 mm Heat exchanger,Heat heat transfer performance 5.7%~15.4%、Press Fall down 43.2%、Copper is lowered in the heat exchanger 57.2%、 Aluminum is added 2.2%,Application prospects。


3mm brass tube

Copyright Notice:Zhao Dingqiang, author of this article、Ren Jing、Ding Guoliang;Editing the refrigeration air conditioner heat exchanger。

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