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Title:
WEB-MPE WITH IMPROVED DRAIN CAPACITY
Document Type and Number:
WIPO Patent Application WO/2020/074607
Kind Code:
A1
Abstract:
Multi Port Extrusion (MPE) tubing (1) for use in heat exchangers, comprising multiple individual transport tubes (T) for fluids being separated by webs (2), each tube having a height (h), and each web having a width (w), the webs (2) being arranged to be located in a plane common with one of the outer surfaces of the tubes so that drain channels (10) are formed between adjacent tubes, each having a drain channel cross sectional area (a) formed between two adjacent tubes and an inner surface (s) of the web located between the two adjacent tubes, the MPE tubing having a drain channel space (D) defined as the volume between two tubes and the web inner surface (s), and a heat exchanger comprising said MPE, wherein the MPE is surrounded by fins undulated in the tube fluid transport direction in multiple alternating layers and where the fins are attached to the MPEs at their crests, the drain cannel cross sectional area being from 2,5 mm2 - 30 mm2, preferably between 3,25 and 6,25 mm2

Inventors:
VESTERGAARD BJØRN (DK)
Application Number:
PCT/EP2019/077404
Publication Date:
April 16, 2020
Filing Date:
October 09, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
HYDRO EXTRUDED SOLUTIONS AS (NO)
International Classes:
F28D1/053; F28D3/02; F28F1/02; F28F1/12; F28F1/16; F28F17/00
Domestic Patent References:
WO2014133394A12014-09-04
WO2014133394A12014-09-04
Foreign References:
JPH11101594A1999-04-13
Attorney, Agent or Firm:
ZACCO SWEDEN AB (SE)
Download PDF:
Claims:
CLAIMS

1. Multi Port Extrusion (MPE) tubing (1) for use in heat exchangers, comprising multiple individual transport tubes (T) for fluids being separated by webs (2), each tube having a height (h), and each web having a width (w), characterized in that the webs (2) are arranged to be located in a plane common with one of the outer surfaces of the tubes so that drain channels (10) are formed between adjacent tubes, each having a drain channel cross sectional area (a) formed between two adjacent tubes and an inner surface (s) of the web located between the two adjacent tubes, the MPE tubing having a drain channel space (D) defined as the volume between two tubes and the web inner surface (s).

2. Multi Port Extrusion (MPE) tubing (1) according to claim 1, characterized in that the drain channel cross sectional area (a) is from 2,5 mm2 - 30 mm2, preferably between 3,25 and 6,25 mm2.

3. Multi Port Extrusion (MPE) tubing (1) according to claim 1 or 2, wherein the depth (d) of the drain channel is at least 2 mm, preferably at least 3 mm.

4. Multi Port Extrusion (MPE) tube according to any of claims 1-3, wherein the web width (w) is 2-15 mm, preferably 2-10 mm, more preferably 3-5 mm.

5. Multi Port Extrusion (MPE) tube according to any of claims 1-4, wherein the webs have openings for passage of water, the openings made in the web are at least half of the web length, preferably at least ¾ of the web length.

6. Multi Port Extrusion (MPE) tube according to any of claims 1-5, wherein the web opening has a width corresponding to the distance between two adjacent tubes.

7. Heat exchanger comprising the MPE according to any of claims 1-6, wherein the MPE is surrounded by fins undulated in the tube fluid transport direction in multiple alternating layers and where the fins are attached to the MPEs at their crests, characterized in that the drain cannel cross sectional area is from 2,5 mm2 - 30 mm2, preferably between 3,25 and 6,25 mm2.

8. Heat exchanger according to claim 7, wherein the fins are attached to the MPEs by brazing or gluing.

9. Heat exchanger according to any of claims 7 or 8, wherein the undulating fins are made from continuous strip without openings/cuts. 10. Heat exchanger according to any of claims 7-9, characterized in that the heat exchanger is an evaporator.

Description:
WEB-MPE WITH IMPROVED DRAIN CAPACITY

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a Multi Port Extrusion (MPE), for use in exchangers for heat exchange or heat recovery in solutions such as refrigeration or heat pump systems, in particular a condenser or evaporator in such systems.

BACKGROUND

The present invention concerns a new design of Multi Port Extrusions, so-called MPE, used in exchangers for heat exchange or heat recovery in solutions such as refrigeration or heat pump systems, in particular a condenser or evaporator in such systems. Micro channel type heat exchangers based on multiport extruded profiles of aluminium are known where fins, also of aluminium, are provided between the extruded multiport tubes. Heat exchangers of such type are for instance known from WO2014133394.

SUMMARYOF THE INVENTION

The global demand (regulated by HFC-gas regulation) to reduce C0 2 emissions points at low GWP (global warming potentials) refrigerants and systems with reduced refrigerant per kW cooling/ heating. The low GWP refrigerants are flammable/toxic/very high pressure and alternative solutions are strived at. The use of MPEs reduces the amount of refrigerant per kW and is thereby a suitable alternative. A problem with conventional MPEs, in particular when used in evaporators/heat pumps, is to effectively drain away any condensed water/ melted ice from the heat exchanger. Unless properly drained the heat transfer capacity of the heat exchanger is greatly reduced. The early Web-MPEs using centered webs were designed for horizontally oriented tubes placed between fins with openings cut for water drainage, a design that is complicated and expensive to make.

With the Web-MPE according to present invention it is possible to provide effective drainage of any condensed water or melted ice. This is done by controlling the web width between the tubes and the location of the web in relation to the tube outer surfaces and removing as much as needed of the web material in order to have the water drain by gravity. The present invention relates to a Multi Port Extrusion (MPE) tubing for use in heat exchangers, comprising multiple individual transport tubes for fluids being separated by webs, each tube having a height (h), and each web having a width (w). The webs are arranged to be located in a plane common with one of the outer surfaces of the tubes so that drain channels are formed between adjacent tubes, each having a drain channel cross sectional area formed between two adjacent tubes and an inner surface of the web located between the two adjacent tubes, the MPE tubing having a drain channel space defined as the volume between two tubes and the web inner surface. The drain channel cross sectional area (a) is preferably from 2,5 mm 2 - 30 mm 2 , more preferably between 3,25 and 6,25 mm 2 . The depth of the drain channel is preferably at least 2 mm, more preferably at least 3 mm. The web width (w) is preferably 2-15 mm, more preferably 2-10 mm, more preferably 3-5 mm. Advantageously, the webs have openings for passage of water, the openings made in the web are preferably at least half of the web length, more preferably at least ¾ of the web length. Preferably, the web opening has a width corresponding to the distance between two adjacent tubes. In the MPE, each individual tube is typically separated by webs, so that is has webs on both sides.

The present invention also relates to a heat exchanger comprising the MPE described above, wherein the MPE is surrounded by fins undulated in the tube fluid transport direction in multiple alternating layers and where the fins are attached to the MPEs at their crests, and the drain cannel cross sectional area is from 2,5 mm 2 - 30 mm 2 , preferably between 3,25 and 6,25 mm 2 . The fins are preferably attached to the MPEs by brazing or gluing. The undulating fins can preferably be made from continuous strip without openings/cuts. The heat exchanger is advantageously an evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, with reference being made to the enclosed schematic drawings illustrating different aspects and embodiments of the invention, given as examples only, and in which:

Figure la shows schematically a web-MPE according to the prior art

Figure lb shows schematically a vertically arranged web-MPE with attached fins according to the prior art

Figure 2a shows schematically a web-MPE according to the present invention Figure 2b shows schematically a vertically arranged web-MPE according to the invention with parts of the web removed to form a specific pattern

Figure 2c shows schematically the web-MPE in figure 2b seen in a 2-dimensional view

Figure 2d shows schematically a vertically arranged web-MPE with attached fins according to the invention

Figures 2e-2f schematically illustrate web-MPEs having different cross-sectional area of the tubes

Figure 3 schematically illustrates a heat exchanger comprising the Web-MPE according to the invention, e g an evaporator/outdoor heat pump coil

DETAILED DESCRIPTION

Today's Web-MPE extrusion has the webs placed symmetrically in the height direction of the individual tubes between every two tubes to keep the distance between the tubes, which makes the drainage openings too small to drain by gravity. The web blocks the drainage opening due to capillary forces and does not provide enough passage for the condensate water to drain by gravity when the MPEs are vertically oriented.

The present invention makes the drainage openings much bigger by locating the webs to one of the tube surfaces, so that the webs are arranged to be located in a plane common with one of the outer surfaces of the tubes. The invention allows the use of vertical Web-MPE's. The invention furthermore allows the use of serpentine fins formed from rolled sheet (used in conventional MicroChannel Heat Exchangers) without making drainage openings therein.

Figure la shows a web-MPE (A) as known in the art, comprising tubes joined by a thin webs (B), where the webs are located at the center of the tubes.

In Figure lb, showing a cross section through the Web-MPE in figure la at the location Al-Al in Fig. la. Fins (C), shown partially in the figure, are surrounding the vertically oriented MPE (A) and are attached to the Web-MPE extrusions at their crests. As can be seen from the figure, the webs (B) are partially removed so that only a small section (Bl) remains in the middle of the tube width, i.e. in the central part of the MPE. A heat exchanger of this type is normally composed of a number of MPE extrusions, with alternating layers of fins and extrusions, depending on the size and the desired heat exchange capacity of the heat exchanger. Water (W) that has condensed between the tubes and the fins is collected and blocked from exit due to the capillary action from the surfaces of the tubes and the fins, restricting the water to travel to the bottom of the MPE. In addition, if the web opening (i.e. where the material has been removed from the web) is too small, water condensed on the opposite side of the web-MPE will not be able to pass through the web and drain in the channel between the tubes on the other side. Surface tension will make the water stay in the areas where the fins are attached and stop the draining.

Figs. 2a-2d schematically illustrates Multi Port Extrusion (MPE) tubing (1) according to the invention. As seen in Fig. 2a, the MPE comprises multiple individual transport tubes (T) for fluids having inner and outer surfaces, the tubes having a width (d) and a height (h), the tubes being separated by a web (2). The web (2) is arranged to be located in a plane common with one of the outer surfaces of the tubes, so as to form a surface flush with one of the tube outer surfaces and forming an outer flat surface, so that a drain channel space (D), defined as the volume between two tubes and the web inner surface (s), i.e. the volume between the individual tubes of the MPE and the web, is large enough for the condensed water to drain by gravity.

The MPE tubing of the invention as shown in figure 2b has a drain channel area (D) defined by the width (w) of the web, i.e. the tube distance and the drain channel depth (d). The drain channel depth (d), i.e. the height of the individual tube minus the web thickness should preferably be at least 2 mm, more preferably at least 3 mm, in order for any condensed water to drain by gravity. The width (w) of the web, i.e. the distance between two tubes, is preferably at least 2 mm, preferably at least 3 mm and not more than 15 mm, preferably not more than 10 mm.

To maximize the drainage effect the cross sectional area of the drain channel between the web and the fin (d x w) is preferably from 2,5 mm 2 - 30 mm 2 , more preferably between 3,25 and 6,25 mm 2 .

The tubes do not necessarily need to be square, they can also be rectangular, hexagonal, round or of any geometrical shape, as schematically exemplified in Figs. 2e and 2f. The depth of the drain channel will then be defined as the tube height, and the width of the web as the average distance between the two tubes.

Accordingly, the MPE has a substantially flat side formed the webs and one of the outer surfaces of the tubes. In order to allow water condensed on the flat side of the MPE to be able to pass through the MPE openings can be provided in the webs. In the example shown in figures 2b and 2c, the web (2) has openings creating a specific web pattern where the openings have a length L o , which is preferably as long as possible for effective drainage, while keeping the web length (L w ) long enough to give support the tubes and form a flat MPE. The openings in the web can be made by for example roll punching, stamping, machining or by other means.

Figure 2d showing a cross section through the Web-MPE in figure 2a at the location Tl-Tl in Fig. 2a shows how water is only blocked by the webs to a limited extent where only parts of the webs (21) are remaining so that the drainage capacity is significantly improved when the drain channel is made larger. Fins (3), shown partially in the figure, are surrounding the vertically oriented MPE (1) and are attached to the extrusions at their crests by means of brazing or gluing.

Fig. 3 shows an evaporator/outdoor heat pump coil comprising Web-MPEs (1) according to the invention where the MPEs are joined to fins (3), the fins being undulated in the in the tube fluid transport direction and attached to the tube outer surfaces by brazing or gluing. Heat exchangers of this type can be provided with two headers, one inlet header and one outlet header. Fig. 3 shows only one header (4).

The Web-MPE also provides additional flexibility regarding formability (bending and twisting) of the profiles so that the tubes at the ends may be gathered and inserted into the header opening (5), provided therefor.

Preferably, the openings (cuts) in the web have a width which is at least half of the web width, i.e. if the web width is 2 mm the web opening is at least 1 mm, preferably at least ¾ of the web length. Most preferably the width of the web opening corresponds to the distance between two adjacent tubes in order to provide adequate draining of any condensate. The invention as defined in the claims is not limited to the example as described above and shown in the figures. Thus, the heat exchanger can be used, not only as condenser or evaporator in a refrigeration system, but in any system where heat is exchanged or recovered by means of air or other fluid.

The invention shall not be considered limited to the illustrated embodiments, but can be modified and altered in many ways, as realized by a person skilled in the art, without departing from the scope defined in the appended claims.