JPH0444192B2

JPH0444192B2 -

Info

Publication number: JPH0444192B2
Application number: JP13423484A
Authority: JP
Inventors: Fumitoshi Nishiwaki; Mitsuhiro Ikoma; Tomoaki Ando; Masaaki Adachi
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1984-06-28
Filing date: 1984-06-28
Publication date: 1992-07-20
Also published as: JPS6115088A

Description

【発明の詳細な説明】産業上の利用分野本発明は空気調和機の蒸発器などのように流体
の沸騰、蒸発を伴う熱交換器に使用する伝熱管に
関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat exchanger tube used in a heat exchanger that involves boiling and evaporation of a fluid, such as an evaporator for an air conditioner.

従来例の構成とその問題点従来、空気調和機および冷凍機の蒸発器におい
て、冷媒側の熱伝達は良好な沸騰熱伝達であるた
め、この熱抵抗をあまり考慮する必要はなかつ
た。しかしながら、最近たとえば高性能フインの
開発によつて、空気側の熱伝達が著しく改善され
管外側の熱抵抗が減少したことなどのために、蒸
発伝熱管内の冷媒の熱抵抗も考慮する必要が生
じ、蒸発器の小形高性能化をはかるためには、管
外の伝熱促進とともに、管内の冷媒側の伝熱促進
を行う必要が生じてきた。Conventional Structure and Problems Conventionally, in the evaporators of air conditioners and refrigerators, the heat transfer on the refrigerant side is good boiling heat transfer, so there is no need to take this thermal resistance into consideration much. However, recently, for example, with the development of high-performance fins, heat transfer on the air side has been significantly improved and thermal resistance on the outside of the tube has been reduced, so it is necessary to consider the thermal resistance of the refrigerant inside the evaporative heat transfer tube. Therefore, in order to make the evaporator smaller and more efficient, it has become necessary to promote heat transfer outside the tube as well as on the refrigerant side within the tube.

第１図ａ，ｂはそれぞれ従来の沸騰用伝熱促進
管の縦断面図および横断面図であり、第２図は第
１図ａの拡大図である。この沸騰用伝熱管は、線
径および線間のすき間が一様なスクリーンメツシ
ユ２を、伝熱管１の内壁面に沿うように挿入し熱
的に密着させたものである。 FIGS. 1a and 1b are a longitudinal sectional view and a transverse sectional view, respectively, of a conventional boiling heat transfer accelerator tube, and FIG. 2 is an enlarged view of FIG. 1a. In this boiling heat exchanger tube, a screen mesh 2 having a uniform wire diameter and a uniform gap between the wires is inserted along the inner wall surface of the heat exchanger tube 1 and thermally adhered thereto.

このような構成のために、伝熱面上にスクリー
ンメツシユ２によつて、その素線間に多くの微小
なくぼみ３が形成され、この微小なくぼみ３が沸
騰熱伝達に対して有効な沸騰核となり、沸騰熱伝
達が促進された。しかしながら、伝熱量が増加す
るに伴い、伝熱面で蒸発しスクリーンメツシユ２
の素線間から管中央部の主流部へ流出（矢印４の
方向）する蒸気の流量が増加するために、その蒸
気の流れと対向してスクリーンメツシユ２の素線
間から伝熱管１内壁面に主流部の液体が流入（矢
印５の方向）しにくくなる。このように、素線間
のすき間が一様に細かいスクリーンメツシユ２を
伝熱面上に設置したのでは、高熱流束時に伝熱面
がドライアウトしやすいという欠点があつた。し
かし、スクリーンメツシユ２の素線間のすき間を
大きくすれば、伝熱面上にスクリーンメツシユ２
によつて形成される素線間のくぼみ３が大きくな
り、そのくぼみは沸騰熱伝達に対して有効なくぼ
みではなくなる。 Due to this configuration, many minute depressions 3 are formed between the wires by the screen mesh 2 on the heat transfer surface, and these minute depressions 3 are effective for boiling heat transfer. It became a boiling nucleus and the boiling heat transfer was promoted. However, as the amount of heat transfer increases, it evaporates on the heat transfer surface and the screen mesh 2
Since the flow rate of steam flowing out from between the wires of the screen mesh 2 to the main stream at the center of the tube (in the direction of arrow 4) increases, the flow of steam from between the wires of the screen mesh 2 to the inside of the heat exchanger tube 1 increases, opposite to the flow of steam. It becomes difficult for the liquid in the main stream to flow into the wall surface (in the direction of arrow 5). In this way, when the screen mesh 2 with uniformly narrow gaps between the strands was installed on the heat transfer surface, there was a drawback that the heat transfer surface was prone to dry out during high heat flux. However, if the gap between the wires of the screen mesh 2 is increased, the screen mesh 2 will be placed on the heat transfer surface.
The depressions 3 between the strands formed by this increase, and the depressions are no longer effective for boiling heat transfer.

発明の目的本発明は上記従来の欠点を解消するものであ
り、高熱流束時にでも管内壁面近傍に沸騰熱伝達
に有効な気泡核を安定化し、しかもドライアウト
しにくい伝熱面を有する伝熱性能の優れた沸騰用
伝熱管を提供することを目的とする。Purpose of the Invention The present invention solves the above-mentioned conventional drawbacks, and provides a heat transfer surface that stabilizes bubble nuclei that are effective for boiling heat transfer near the inner wall surface of the tube even during high heat flux, and has a heat transfer surface that is difficult to dry out. The purpose is to provide a boiling heat exchanger tube with excellent performance.

発明の構成本発明の沸騰用伝熱管は、素線間のすき間が小
さく密な素線の部分と素線間のすき間が大きく疎
な素線の部分を同一層内に有するスクリーンメツ
シユを、伝熱管内壁面に沿うように挿入し、熱的
に密着させたものである。Structure of the Invention The boiling heat exchanger tube of the present invention includes a screen mesh having a dense wire portion with small gaps between the wires and a sparse wire portion with large gaps between the wires in the same layer. It is inserted along the inner wall surface of the heat exchanger tube and is in close thermal contact with it.

実施例の説明以下本発明の一実施例を図面とともに説明す
る。DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

第３図ａ，ｂはそれぞれ本発明の一実施例の沸
騰用伝熱管の縦断面図および横断面図であり、第
４図は第３図ａの拡大図である。 FIGS. 3a and 3b are a longitudinal cross-sectional view and a cross-sectional view, respectively, of a boiling heat exchanger tube according to an embodiment of the present invention, and FIG. 4 is an enlarged view of FIG. 3a.

スクリーンメツシユ７は一様な線径の素線で構
成され、その縦線、横線ともに素線間のすき間が
小さく密な織り方の部分が素線間のすき間が大き
く疎な織り方の部分と交互になるように織られて
いる。このスクリーンメツシユ７を伝熱管６の中
にその内壁面に沿うように一層だけ挿入し、その
後、内壁面と熱的に接触させることにより本発明
の沸騰用伝熱管を形成する。 The screen mesh 7 is composed of strands of uniform wire diameter, and the vertical and horizontal lines have a densely woven area with small gaps between the strands and a sparsely woven area with large gaps between the strands. It is woven in such a way that it alternates with This screen mesh 7 is inserted into the heat transfer tube 6 along its inner wall surface in only one layer, and then brought into thermal contact with the inner wall surface to form the boiling heat transfer tube of the present invention.

なお、スクリーンメツシユ７と伝熱管６の内壁
面との接触状態をより良くし、その間の熱抵抗を
減少させるために、伝熱管６の内壁面にあらかじ
めロウ材を塗布しておき、スクリーンメツシユ７
を伝熱管６内に挿入後、伝熱管６を加熱してロウ
付けしてもよい。 Note that in order to improve the contact between the screen mesh 7 and the inner wall surface of the heat transfer tube 6 and reduce the thermal resistance therebetween, brazing metal is applied to the inner wall surface of the heat transfer tube 6 in advance, and the screen mesh is Tsushiyu 7
After inserting into the heat exchanger tube 6, the heat exchanger tube 6 may be heated and brazed.

このような構成であるために次のような作用と
効果を生じる。 This configuration produces the following functions and effects.

スクリーンメツシユ７は伝熱管６の内壁面と熱
的に密着しているために伝熱面として機能し、伝
熱に対する有効面積が増加する。このために伝熱
量が増大する。 Since the screen mesh 7 is in close thermal contact with the inner wall surface of the heat transfer tube 6, it functions as a heat transfer surface, increasing the effective area for heat transfer. This increases the amount of heat transfer.

また、流体の表面張力に応じてスクリーンメツ
シユ７の素線の織り方の密な部分を構成する素線
の線径と線のすき間を適切に選ぶことにより、沸
騰熱伝達に対して有効な多数の活性な沸騰核（く
ぼみ８）を形成することができる。このような活
性な沸騰核は、その壁温が降下しても液体で満た
されることはなく常に気泡核を有しているため
に、安定した伝熱促進効果が得られる。このよう
に沸騰熱伝達を促進するためには伝熱面上に活性
な沸騰核を形勢することが重要である。そのため
には、伝熱面上に熱的に接した一層のスクリーン
メツシユで十分である。一方、流体の表面張力に
応じてスクリーンメツシユ７の素線の織り方の疎
な部分を構成する素線の線径と線のすき間を適切
に選ぶことにより、管内の主流部の液体が織り方
の疎な素線間のすき間９から伝熱管６内壁面上に
流入（矢印１０の方向）することが可能となる。
たとえ伝熱量が増加し、スクリーンメツシユ７か
らの蒸発量が増加した場合でも、スクリーンメツ
シユ７の織り方の密な素線部の活性な沸騰核８か
ら蒸気が主流部へ流出（矢印１１の方向）し、主
流部の液体が織り方の疎な素線部のすき間９から
伝熱管６内壁面上に流入（矢印１０の方向）し、
そしてその液体はスクリーンメツシユ７と伝熱管
６の内壁面のすき間を通して活性な沸騰核８に供
給される。このように伝熱面上の沸騰核８に供給
される液体の流れと沸騰核８から流出する蒸気の
流れが対向しないために、高熱流束時においても
伝熱面がドライアウトしにくい。 In addition, by appropriately selecting the wire diameter and the gap between the wires that make up the dense weave of the wires in the screen mesh 7 according to the surface tension of the fluid, effective boiling heat transfer can be achieved. A large number of active boiling nuclei (indentations 8) can be formed. Such active boiling nuclei do not become filled with liquid even if the wall temperature drops and always have bubble nuclei, so that a stable heat transfer promoting effect can be obtained. In order to promote boiling heat transfer in this manner, it is important to form active boiling nuclei on the heat transfer surface. For this purpose, a single layer of screen mesh in thermal contact with the heat transfer surface is sufficient. On the other hand, by appropriately selecting the wire diameter and the gap between the wires that constitute the sparsely woven portion of the screen mesh 7 according to the surface tension of the fluid, the liquid in the main flow part of the pipe can be woven. It becomes possible to flow onto the inner wall surface of the heat exchanger tube 6 (in the direction of arrow 10) through the gap 9 between the sparse strands.
Even if the amount of heat transfer increases and the amount of evaporation from the screen mesh 7 increases, steam flows out from the active boiling nuclei 8 in the densely woven strands of the screen mesh 7 to the mainstream (arrow 11 ), and the liquid in the main stream flows onto the inner wall surface of the heat exchanger tube 6 from the gap 9 in the loosely woven strands (in the direction of the arrow 10),
The liquid is then supplied to the active boiling nuclei 8 through the gap between the screen mesh 7 and the inner wall surface of the heat transfer tube 6. In this way, since the flow of liquid supplied to the boiling core 8 on the heat transfer surface and the flow of steam flowing out from the boiling core 8 do not oppose each other, the heat transfer surface is unlikely to dry out even during high heat flux.

さらに、伝熱管６内に挿入したスクリーンメツ
シユ７表面の凹凸のために壁面近傍の流れが乱さ
れ、乱流促進効果が生じて、管内熱伝達は向上す
る。 Furthermore, the unevenness of the surface of the screen mesh 7 inserted into the heat transfer tube 6 disturbs the flow near the wall surface, creating a turbulent flow promotion effect and improving heat transfer within the tube.

なお、上記実施例のスクリーンメツシユ７で
は、一様な線径の素線で、しかも縦線と横線が一
様な織り方であつたが、線径および織り方が一様
でなくても上記と同様な効果が得られる。また、
上記実施例では内面が平滑な管を用いたが、例え
ば管の内面にらせん状の溝を形成したものあるい
は凹凸を形成したものを用いても上記と同様な効
果が得られる。 In addition, in the screen mesh 7 of the above embodiment, the wires have a uniform wire diameter and the vertical lines and horizontal lines are woven in a uniform manner. However, even if the wire diameter and the weave are not uniform, The same effect as above can be obtained. Also,
Although a tube with a smooth inner surface is used in the above embodiment, the same effect as described above can be obtained by using a tube with a spiral groove or an uneven surface, for example.

発明の効果以上のように本発明の沸騰用伝熱管は、素線間
のすき間が小さく密な素線の織り方の部分と素線
間のすき間が大きく疎な素線の織り方の部分を同
一層内に有するスクリーンメツシユを伝熱管内壁
面に沿うように挿入し熱的に密着させたものであ
るからスクリーンメツシユ素線間のすき間が小さく
密な素線の織り方の部分に、多数の活性な沸騰
核を形成し、管内壁面近傍に沸騰熱伝達に有効
な気泡核を安定化できる。Effects of the Invention As described above, the boiling heat exchanger tube of the present invention has a part where the strands are woven tightly with small gaps between the strands and a part where the strands are woven sparsely with a large gap between the strands. Since the screen mesh in the same layer is inserted along the inner wall surface of the heat transfer tube and thermally adhered to it, the screen mesh has small gaps between the wires and is densely woven. A large number of active boiling nuclei are formed, and bubble nuclei effective for boiling heat transfer can be stabilized near the inner wall surface of the tube.

伝熱面上の沸騰核への液体の供給路と沸騰核
からの蒸気の流出路を分離することができ、高
熱流束時にでも伝熱面がドライアウトしにく
い。 The liquid supply path to the boiling core on the heat transfer surface and the vapor outlet path from the boiling core can be separated, making it difficult for the heat transfer surface to dry out even during high heat flux.

以上のように、本発明は沸騰用伝熱管の伝熱性
能を著しく改善することが可能で、その実用的効
果は大なるものがある。 As described above, the present invention can significantly improve the heat transfer performance of boiling heat transfer tubes, and has great practical effects.

【図面の簡単な説明】[Brief explanation of drawings]

第１図ａ，ｂはそれぞれ従来の伝熱管の縦断面
図および横断面図、第２図は第１図ａの要部拡大
図、第３図ａ，ｂはそれぞれ本発明の一実施例の
沸騰用伝熱管の縦断面図および横断面図、第４図
は第３図ａの要部拡大図である。６……伝熱管、７……スクリーンメツシユ、８
……沸騰核。 Figures 1a and b are longitudinal and cross-sectional views, respectively, of a conventional heat exchanger tube, Figure 2 is an enlarged view of the main part of Figure 1a, and Figures 3a and b are respectively of an embodiment of the present invention. A vertical cross-sectional view and a cross-sectional view of the boiling heat exchanger tube, and FIG. 4 is an enlarged view of the main part of FIG. 3a. 6... Heat exchanger tube, 7... Screen mesh, 8
...boiling nucleus.

Claims

【特許請求の範囲】[Claims]

１素線間のすき間が小さく密な素線の部分と素
線間のすき間が大きく疎な素線の部分を同一層内
に有するスクリーンメツシユを伝熱管内壁面に沿
うように挿入し、熱的に密着させた沸騰用伝熱
管。1. Insert a screen mesh that has dense wire parts with small gaps between wires and sparse wire parts with large gaps between wires in the same layer along the inner wall surface of the heat exchanger tube. Boiling heat exchanger tubes that are closely connected to each other.