CN111336841A - A wrap-around microchannel heat exchanger - Google Patents

Abstract

The invention discloses a surrounding type microchannel heat exchanger. The shell of the invention is connected with a liquid inlet pipe and a liquid outlet pipe of a fluid I and a liquid inlet pipe and a liquid outlet pipe of a fluid II. The heat exchanger core comprises a plurality of micro-channel heat exchange units; every microchannel heat exchange unit structure is the same, all includes two collector tubes and many microchannel heat exchange tubes, and two collector tubes are inserted respectively at the both ends of many microchannel heat exchange tubes. The microchannel heat exchange units are divided into two groups, wherein the microchannel heat exchange tubes of one group of microchannel heat exchange units are longitudinally arranged, the microchannel heat exchange tubes of the other group of microchannel heat exchange units are transversely arranged, the microchannel heat exchange units in one group and the microchannel heat exchange units in the other group are arranged in a staggered mode, and all the microchannel heat exchange units are arranged in parallel. The invention provides a heat exchange unit with a plurality of micro-channels arranged in a staggered manner, which has higher heat exchange efficiency, can discharge more micro-channel heat exchange tubes in the same space and enhances the heat exchange effect.

Description

A wrap-around microchannel heat exchanger

technical field

The invention belongs to the technical field of heat exchangers, and relates to a stacked microchannel heat exchanger, which can be widely used in all heat exchangers with liquid-liquid and liquid-phase change liquid heat exchange.

Background technique

After the oil crisis in the 1970s, energy-saving technologies and new energy development have become the focus of research around the world. Commercial and industrial air conditioning systems typically employ liquid-to-liquid heat exchangers, the most common of which are plate and shell and tube heat exchangers. Because the plate heat exchanger is affected by its structure, the length of the sealing line is too long, and it cannot withstand high pressure, and the brazing form is not easy to clean. Due to the large diameter of the pipe, the heat exchange area per unit volume of the shell and tube heat exchanger is smaller than that of the microchannel heat exchanger. Miniaturized and miniaturized plate heat exchangers are not suitable for large-energy heat exchange requirements. High energy, high heat flux density, high flexibility, easy maintenance, compact structure, light weight and high efficiency heat exchangers are the current research directions of heat exchangers. Therefore, a wrap-around metal circular tube heat exchanger has the advantages of compact structure, high heat exchange efficiency per unit volume and unit weight, and can be widely used in liquid-liquid heat exchange applications.

The Chinese patent document with the patent publication number CN203336996U discloses a micro-micro-channel metal circular tube liquid-cooled heat exchanger, wherein the heat exchange mechanism is formed by connecting the refrigerant inlet tube and the outlet tube through the micro-channel metal circular tube, and The inner diameter of the micro-micro-channel metal circular tube is between 0.1 and 0.4 mm, and the entire heat exchange mechanism is arranged in the cooling liquid container. In addition, the invention uses the micro-channel metal circular tube as the main heat exchange mechanism, and the liquid flowing outside the tube mainly cools or heats the fluid in the tube. Because of the large pressure drop, this structure is not conducive to the flow in the high-velocity pipe.

SUMMARY OF THE INVENTION

The purpose of the present invention is to address the deficiencies of the prior art, and to provide a stacked micro-channel heat exchanger, which has a compact structure, is energy-saving and material-saving, has high heat exchange efficiency per unit weight, and can reduce refrigerant charge. fluence.

The invention comprises a casing, which is connected with a fluid I liquid inlet pipe, a fluid I liquid outlet pipe, a fluid II liquid inlet pipe, and a fluid II liquid outlet pipe. The fluid I liquid inlet pipe and the fluid I liquid outlet pipe are connected to the inner space of the shell and are arranged on two opposite sides of the shell; the shell is provided with a heat exchanger core, the fluid II liquid inlet pipe and the fluid II liquid outlet pipe Connect to the inlet and outlet of the heat exchanger core respectively.

The heat exchanger core body includes a plurality of microchannel heat exchange units; each microchannel heat exchange unit has the same structure and includes two liquid collecting tubes and a plurality of microchannel heat exchange tubes.

The liquid collecting pipe is a straight metal pipe with a semicircular section, including a flat pipe wall and an arc surface pipe wall. A plurality of through holes are arranged in a matrix, and both ends of the plurality of micro-channel heat exchange tubes are respectively inserted into the plurality of through holes on the flat tube walls of the two liquid collectors, and are sealed and fixed by welding.

The two liquid collecting tubes constituting each microchannel heat exchange unit are closed at one end and open at the other end, and the open ends of the two liquid collecting tubes are arranged diagonally; the microchannel heat exchange tubes are thin-walled metal circular tubes with open ends at both ends. , the distance between the cores of two adjacent microchannel heat exchange tubes is 1.5-2.5D, and D is the outer diameter of the microchannel heat exchange tubes.

The microchannel heat exchange units are divided into two groups, wherein the microchannel heat exchange tubes of one group of microchannel heat exchange units are arranged longitudinally, and the microchannel heat exchange tubes of the other group of microchannel heat exchange units are arranged horizontally. The heat exchange units are arranged staggered with the microchannel heat exchange units in another group, and all the microchannel heat exchange units are arranged in parallel.

The open ends of the liquid collectors on all sides of the microchannel heat exchange units constituting a group are communicated through the liquid inlet pipeline, one end of the liquid inlet pipeline is closed, and the other end is open; all the open ends of the liquid collectors on the other side Connected through the liquid outlet pipeline, one end of the liquid outlet pipeline is closed, and the other end is open; that is, each group of microchannel heat exchange units is connected in parallel, and the open ends of the liquid inlet pipelines of the two groups of microchannel heat exchange units after parallel connection are connected, and the The fluid II inlet pipe is connected; the open ends of the liquid outlet pipes of the two groups of microchannel heat exchange units after parallel connection are connected, and the fluid II outlet pipe is connected.

Further, the outer diameter of the micro-channel heat exchange tube is D=0.5-2mm, and the inner diameter d=0.3-1.8mm.

The invention proposes to displace a plurality of micro-channel heat exchange units, so that the heat exchange efficiency is higher and the overall volume of the heat exchanger is saved. The invention can discharge more micro-channel heat exchange tubes in the same space, increase the heat exchange area and enhance the heat exchange effect. The invention has the advantages of simple structure, light weight, small volume, less material usage, and obvious improvement of heat exchange performance.

Description of drawings

Fig. 1 is the structural representation of the present invention;

Fig. 2 is the schematic diagram of the microchannel heat exchange unit in Fig. 1;

3 is a sectional view of a single microchannel heat exchange unit A-A in FIG. 2;

FIG. 4 is a cross-sectional view of a single microchannel heat exchange unit B-B in FIG. 2 .

Detailed ways

The present invention will be further described below with reference to the accompanying drawings.

As shown in Figure 1, a microchannel liquid-cooled heat exchanger includes a shell 1, and the shell 1 is connected with a fluid I liquid inlet pipe 1-1, a fluid I liquid outlet pipe 1-2 and a fluid II liquid inlet pipe 1 -3. Fluid II outlet pipe 1-4, fluid I inlet pipe 1-1 and fluid I outlet pipe 1-2 are connected to the inner space of shell 1, and are respectively arranged on two opposite sides of shell 1. The shell 1 is provided with a heat exchanger core body, and the fluid II liquid inlet pipe 1-3 and the fluid II liquid outlet pipe 1-4 are respectively connected to the inlet and outlet of the heat exchanger core body.

As shown in Figures 1, 2, 3, and 4, the heat exchanger core includes a plurality of microchannel heat exchange units 2, and each microchannel heat exchange unit 2 has the same structure, including two liquid collection pipes 2-1 and a plurality of Root microchannel heat exchange tube 2-2. The liquid collecting pipe 2-1 is a straight metal pipe with a semicircular section, including a flat pipe wall and an arc surface pipe wall. There are through holes on the top, and a plurality of through holes are arranged in a matrix. Seal and secure.

The two liquid collecting pipes 2-1 constituting each microchannel heat exchange unit 2 are closed at one end and open at the other end, and the open ends of the two liquid collecting pipes are arranged diagonally. The micro-channel heat exchange tube 2-2 is a thin-walled metal circular tube with both ends open. The distance between the cores of two adjacent micro-channel heat-exchange tubes is 1.5-2.5D, and the outer diameter of the micro-channel heat-exchange tube is D=0.5-2mm , inner diameter d=0.3～1.8mm.

As shown in FIG. 2 , the microchannel heat exchange units 2 are divided into two groups (in this embodiment, each group includes four microchannel heat exchange units), wherein the microchannel heat exchange tubes 2-2 of one group of microchannel heat exchange units 2 are longitudinally Arrangement (that is, the liquid collector tubes 2-1 are arranged horizontally), the microchannel heat exchange tubes 2-2 of the other group of microchannel heat exchange units 2 are arranged horizontally (that is, the liquid collector tubes 2-1 are arranged vertically), and the microchannel heat exchange tubes 2-2 of the other group of microchannel heat exchange units The channel heat exchange units 2 are arranged alternately with the microchannel heat exchange units 2 in another group, and all the microchannel heat exchange units 2 are arranged in parallel. The liquid collector tubes 2-1 are placed in dislocation, and the microchannel heat exchange tubes 2-2 are neatly stacked in parallel, which saves space and facilitates arranging the inlet and outlet liquid outlets on one surface. The microchannel heat exchange tubes 2-2 of two adjacent microchannel heat exchange units 2 are arranged in a staggered manner to prevent the liquid outside the tube wall from rapidly flowing in one direction, which can effectively improve the heat exchange rate.

The open ends of the liquid collection pipes 2-1 on all sides of the microchannel heat exchange unit 2 constituting a group are communicated through the liquid inlet pipeline, one end of the liquid inlet pipeline is closed, and the other end is open; all the liquid collection pipes on the other side The open end of the pipe 2-1 is connected through the liquid outlet pipeline, one end of the liquid outlet pipeline is closed, and the other end is open; that is, each group of microchannel heat exchange units 2 are connected in parallel; The open ends of the pipelines are connected and connected to the fluid II liquid inlet pipes 1-3; the open ends of the liquid outlet pipes of the two groups of parallel microchannel heat exchange units are connected and connected to the fluid II liquid outlet pipes 1-4.

The following takes a single microchannel heat exchange unit with a length of 460mm, a width of 200mm and a height of 14mm as an example to analyze the performance of the stacked microchannel heat exchanger.

The microchannel heat exchange tube is 0.38mm stainless steel microchannel round tube, each row has 100 microchannel round tubes, a total of 4 rows. Under the standard condition of R410A as the refrigerant, tap water at 20°C is used as the cooling liquid outside the microchannel (ie, fluid I), the inlet temperature is 79°C, and the outlet temperature of the refrigerant is 22°C through experimental tests. The cooling water flow rate is 700kg/h, and the refrigerant working medium (ie, fluid II) flow rate is 152.8kg/h. The heat transfer resistance on the water side is first calculated, and the Reynolds number Re _D on the water side is calculated: Re _D =ρ _water ·Vel _water ·D _out /μ _water .

Therefore, the corresponding Nusselt number is expressed as:

The thermal resistance on the water side is:

The Reynolds number on the R410A side is:

Ignoring the thermal resistance of the stainless steel tube, the thermal resistance is smaller due to its thinner wall thickness.

The thermal resistance on the refrigerant side is:

Calculate the heat transfer using the e-NTU heat transfer unit number method:

Calculation of heat exchange efficiency of heat exchanger:

Calculation of the heat exchange (maximum heat exchange) of the microchannel unit body:

It is calculated that the heat transfer performance of the condenser can reach 8083W, the convective heat transfer coefficient of the water side is as high as 1744W/m ² -K, and the convective heat transfer coefficient of the working fluid in the microchannel is 70W/m ² -K. The total heat exchange efficiency of the heat exchanger reaches 82.46%, and its core weight is only about 0.4kg.

The volume ratio of the high pressure working fluid and the low pressure working fluid in the plate heat exchanger is usually 1, the volume ratio between the high pressure and the low pressure in the shell and tube heat exchanger is usually less than 1, and the high pressure working fluid and the low pressure working fluid in the stacked microchannel heat exchanger The volume ratio varies from 0.1 to 0.03. The heat exchange of the same volume and the same working conditions is 10 times that of the plate heat exchanger and 10 to 30 times that of the shell and tube heat exchanger, which is more conducive to the application of deep and complete heat exchange.

Claims (2)

1. A folding type microchannel heat exchanger comprises a shell (1), wherein a fluid I inlet pipe (1-1), a fluid I outlet pipe (1-2), a fluid II inlet pipe (1-3) and a fluid II outlet pipe (1-4) are connected to the shell (1); the method is characterized in that:

the fluid I inlet pipe (1-1) and the fluid I outlet pipe (1-2) are connected with the inner space of the shell (1) and are respectively arranged on two opposite side surfaces of the shell (1); a heat exchanger core is arranged in the shell (1), and a fluid inlet pipe (1-3) and a fluid outlet pipe (1-4) of the fluid II are respectively connected with an inlet and an outlet of the heat exchanger core;

the heat exchanger core comprises a plurality of micro-channel heat exchange units (2); each micro-channel heat exchange unit (2) has the same structure and comprises two liquid collecting pipes (2-1) and a plurality of micro-channel heat exchange pipes (2-2);

the liquid collecting pipes (2-1) are linear metal pipes with semicircular sections and comprise plane pipe walls and cambered surface pipe walls, the plane pipe walls of the two liquid collecting pipes (2-1) are arranged oppositely, through holes are formed in the plane pipe walls of the liquid collecting pipes (2-1), a plurality of through holes are arranged in a matrix mode, and two ends of a plurality of micro-channel heat exchange pipes (2-2) are inserted into the through holes in the plane pipe walls of the two liquid collecting pipes (2-1) respectively and are sealed and fixed through welding;

one end of each of the two liquid collecting pipes (2-1) forming each micro-channel heat exchange unit (2) is closed, the other end of each of the two liquid collecting pipes is open, and the open ends of the two liquid collecting pipes are arranged diagonally; the microchannel heat exchange tubes (2-2) are thin-wall metal round tubes with two open ends, the tube core distance of two adjacent microchannel heat exchange tubes is 1.5-2.5D, and D is the outer diameter of each microchannel heat exchange tube;

the microchannel heat exchange units are divided into two groups, wherein the microchannel heat exchange tubes (2-2) of one group of microchannel heat exchange units are longitudinally arranged, the microchannel heat exchange tubes (2-2) of the other group of microchannel heat exchange units are transversely arranged, the microchannel heat exchange units (2) in one group and the microchannel heat exchange units (2) in the other group are arranged in a staggered mode, and all the microchannel heat exchange units (2) are arranged in parallel;

the open ends of the liquid collecting pipes (2-1) at all sides in the micro-channel heat exchange units (2) forming one group are communicated through a liquid inlet pipeline, one end of the liquid inlet pipeline is closed, and the other end of the liquid inlet pipeline is open; the open ends of all the liquid collecting pipes (2-1) on the other side are communicated through liquid outlet pipes, one ends of the liquid outlet pipes are closed, and the other ends of the liquid outlet pipes are open; each group of micro-channel heat exchange units (2) are connected in parallel, and the open ends of the liquid inlet pipelines of the two groups of micro-channel heat exchange units which are connected in parallel are communicated and connected with a liquid inlet pipe (1-3) of a fluid II; the open ends of the liquid outlet pipelines of the two groups of micro-channel heat exchange units which are connected in parallel are communicated and connected with liquid outlet pipes (1-4) of the fluid II.

2. The stacked microchannel heat exchanger of claim 1, wherein: the outer diameter D of the microchannel heat exchange tube is 0.5-2 mm, and the inner diameter D is 0.3-1.8 mm.

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