JP6223298B2 - Heat transfer tube for single-phase flow in tube - Google Patents

Heat transfer tube for single-phase flow in tube Download PDF

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JP6223298B2
JP6223298B2 JP2014156527A JP2014156527A JP6223298B2 JP 6223298 B2 JP6223298 B2 JP 6223298B2 JP 2014156527 A JP2014156527 A JP 2014156527A JP 2014156527 A JP2014156527 A JP 2014156527A JP 6223298 B2 JP6223298 B2 JP 6223298B2
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tube
heat transfer
fluid
pipe
corrugated
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JP2016033440A (en
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宏行 高橋
宏行 高橋
順広 井上
順広 井上
岩本 秀樹
秀樹 岩本
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Kobelco and Materials Copper Tube Ltd
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Description

本発明は、管外の流体(自然冷媒、フロン冷媒、水等)の保有熱又は管外の物体(土壌熱等の固体物質等)の保有熱若しくはソーラーパネル等の輻射熱と、管内を流れる単相流流体(水、ブライン等)とを熱交換させる管内単相流伝熱管に関し、特に、管内の流体が低流速域、即ち、低レイノルズ数Re域(Reが3000以下)で乱流が増大することなく、また、管内流体の圧力損失を実質的に増大させることなく、熱伝達率を著しく向上させて、低流速域での使用に適した管内単相流用伝熱管に関する。   The present invention relates to the heat retained by the fluid outside the tube (natural refrigerant, chlorofluorocarbon refrigerant, water, etc.), the heat retained by an object outside the tube (solid material such as soil heat), or the radiant heat from the solar panel, and the single flow that flows inside the tube. In-pipe single-phase flow heat transfer tubes that exchange heat with phase flow fluids (water, brine, etc.), especially turbulent flow increases in the low flow velocity region, that is, the low Reynolds number Re region (Re is 3000 or less). In addition, the present invention relates to a single-phase flow heat transfer tube suitable for use in a low flow rate region, with a significantly improved heat transfer rate without substantially increasing the pressure loss of the fluid in the tube.

管内単相流用伝熱管は、管外面に1本の溝を螺旋状に形成したコルゲート管であり、銅又は銅合金管からなる。この管内単相流用伝熱管の具体的な用途としては、(a)ヒートポンプ給湯器(例えば、エコキュート)に使用される水―冷媒熱交換器に使用される伝熱管、(b)ガス給湯器内にて使用される水―水の二重管式熱交換器に使用される伝熱管、(c)太陽熱温水器のソーラーパネル内に設置されている温水配管、(d)地中に埋め込んで使用する土壌熱−水熱交換器配管用伝熱管がある。これらのコルゲート管からなる伝熱管において、一部が曲げ加工されたり、また、コイル状に巻回するように曲げ加工されたものがある。   The in-tube single-phase flow heat transfer tube is a corrugated tube in which one groove is spirally formed on the outer surface of the tube, and is made of a copper or copper alloy tube. Specific uses of this single-phase flow heat transfer pipe in the pipe include (a) a heat transfer pipe used in a water-refrigerant heat exchanger used in a heat pump water heater (for example, Ecocute), and (b) in a gas water heater. Heat-transfer tubes used in water-water double-tube heat exchangers used in (c) Hot water piping installed in solar panels of solar water heaters, (d) Used embedded in the ground There is a heat transfer pipe for soil heat-water heat exchanger piping. Some heat transfer tubes made of these corrugated tubes are partially bent or bent so as to be coiled.

管内外の流体間で熱交換させる機器は、省エネ化の取り組みがなされており、熱交換器単体での高性能化を図るとともに、熱媒体の搬送動力の低減による省エネ化を図るべく、取り組まれている。熱媒体の搬送動力の低減としては、通常は、熱媒体の流体を熱交換器内に送るためにポンプが使用されているが、搬送動力の低減策として、搬送流体の流量を低減させることにより、ポンプ運転動力を低減させる方法が採用されている。   The equipment that exchanges heat between the fluid inside and outside the pipe is making efforts to save energy, and in order to improve the performance of the heat exchanger alone and reduce the heat transfer power of the heat medium, efforts are being made to save energy. ing. In order to reduce the conveyance power of the heat medium, a pump is usually used to send the fluid of the heat medium into the heat exchanger. However, as a measure for reducing the conveyance power, the flow rate of the conveyance fluid is reduced. A method of reducing pump driving power is employed.

また、熱交換器内において、長時間かけて流体を高温にさせる機器があり、その事例として代表的なものに、ヒートポンプ給湯器がある。このヒートポンプ給湯器は、水道水の給水口より直接熱交換器内に流体である水を送り込み、熱交換器内において長時間かけて流体を高温にさせるため、管内の流体の速度を低く設定していること、またこの水道水の圧力はポンプ等での搬送力に比較して低く、その結果、管内を通過する流体の速度が遅くなり、管内のレイノルズ数Reは3000以下で使用されることが多い。この低レイノルズ数領域では、管内の流体は層流域になり、層流域での熱伝達率は、乱流状態と比較して低下するため、使用する伝熱管自体の性能を向上させることにより、対応せざるを得ない。   In addition, there is a device that heats a fluid to a high temperature in a heat exchanger, and a typical example is a heat pump water heater. In this heat pump water heater, water, which is a fluid, is directly fed into the heat exchanger from the tap water supply port, and the temperature of the fluid in the pipe is set low so that the fluid becomes high temperature in the heat exchanger over a long period of time. In addition, the pressure of this tap water is lower than the conveying force of the pump etc., and as a result, the speed of the fluid passing through the pipe becomes slow, and the Reynolds number Re in the pipe should be 3000 or less. There are many. In this low Reynolds number region, the fluid in the tube becomes a laminar flow region, and the heat transfer coefficient in the laminar flow region is lower than that in the turbulent state, so this can be improved by improving the performance of the heat transfer tube used. I have to.

これらの伝熱管は、二重管式熱交換器等に加工し、更に組み立てた後に、通常、給湯機器等の機器に組み込んで使用するが、熱交換器の占有スペースを小さくすることが多く、その際に、必要に応じて、伝熱管及び熱交換器を曲げ加工して、給湯機器等の機器内に組み込まれることが多い。この曲げ加工を施した場合、曲げ部分において、渦の発生等による圧力損失が増加し、ポンプ動力増加する等の問題点が生じる。   These heat transfer tubes are processed into a double-pipe heat exchanger, etc., and further assembled, and are usually incorporated into equipment such as a hot water supply device, etc., but often occupy a small space for the heat exchanger, At that time, if necessary, the heat transfer tube and the heat exchanger are often bent and incorporated into a device such as a hot water supply device. When this bending process is performed, problems such as an increase in pressure loss due to the generation of vortices and the like, and an increase in pump power occur at the bent portion.

現状使用されている代表的な伝熱管として、平滑管、内面溝付管(特許文献1)、コルゲート管(特許文献2)、突起加工を施したコルゲート管(特許文献3)があり、コルゲート管を使用した熱交換器(特許文献4)も開示されている。   As typical heat transfer tubes used at present, there are a smooth tube, an internally grooved tube (Patent Document 1), a corrugated tube (Patent Document 2), and a corrugated tube (Patent Document 3) subjected to protrusion processing. The heat exchanger (patent document 4) using this is also disclosed.

内面溝付管は、管内にらせん状の突起を多数設け、管内を通流する媒体の乱流を促進させて管壁面での速度境界層及び温度境界層の形成を抑制するものである。コルゲート管は、管の内面及び外面に、深い凹凸をらせん状に、かつ小ピッチにて形成したものである。このように形成された凹凸により、管内(管外も含めて)の流体が層流域にて流れる場合でも、乱流が促進されて熱伝達異率が向上する。更に、例えば、特許文献2のコルゲート管のコルゲートピッチは、3乃至10mmであり、特許文献3のコルゲート管のコルゲートピッチは10mmである。なお、特許文献3においては、コルゲート溝の他に、突起が形成されており、この突起がコルゲート溝内に15mmのピッチで形成されているので、管内面の突出部は、10mmよりも小さくなる。そして、このコルゲート管においては、このコルゲート溝として形成された凹凸により、管内の流体が層流域にて流れる場合でも、乱流が促進されて熱伝達率が向上する。これは、管外の流体も同様である。また、内面溝部に小突起を形成したコルゲート管の場合、この形成した小突起を設けることにより、伝熱性能が向上すると共に、圧力損失が小さくなる。特許文献4に記載のコルゲート管は、管内外面に深い凹凸を螺旋状にかつ小ピッチにて形成したものである。この凹凸により、乱流を促進されて熱伝達率が向上する。   The internally grooved tube is provided with a number of spiral protrusions in the tube and promotes the turbulent flow of the medium flowing through the tube to suppress the formation of the velocity boundary layer and the temperature boundary layer on the tube wall surface. The corrugated tube is formed by forming deep irregularities in a spiral shape at a small pitch on the inner and outer surfaces of the tube. Due to the unevenness formed in this way, even when the fluid inside the pipe (including outside the pipe) flows in the laminar flow region, the turbulent flow is promoted and the heat transfer coefficient is improved. Further, for example, the corrugated pitch of the corrugated pipe of Patent Document 2 is 3 to 10 mm, and the corrugated pitch of the corrugated pipe of Patent Document 3 is 10 mm. In Patent Document 3, protrusions are formed in addition to the corrugated grooves, and the protrusions are formed at a pitch of 15 mm in the corrugated grooves, so that the protrusion on the inner surface of the tube is smaller than 10 mm. . And in this corrugated pipe, even when the fluid in the pipe flows in the laminar flow region, the turbulent flow is promoted and the heat transfer coefficient is improved by the irregularities formed as the corrugated groove. The same applies to the fluid outside the tube. Further, in the case of a corrugated tube in which small protrusions are formed in the inner surface groove portion, by providing the formed small protrusions, heat transfer performance is improved and pressure loss is reduced. The corrugated tube described in Patent Document 4 is a tube in which deep irregularities are formed spirally and at a small pitch on the inner and outer surfaces of the tube. This unevenness promotes turbulent flow and improves the heat transfer coefficient.

特開2006−242553号公報JP 2006-242553 A 特開2007−218486号公報JP 2007-218486 A WO2008/029639号公報WO2008 / 029639 特開2012−122714号公報JP 2012-122714 A

しかしながら、平滑管は、文字どおり、内面及び外面に溝等がないものであり、管表面が平滑面である。このように、流体と接触する面が平滑であると、管内に流体を流したときに、管壁面に速度境界層及び温度境界層が形成され、その境界層が流体間の熱交換を阻害する。   However, the smooth tube literally has no grooves on the inner surface and the outer surface, and the tube surface is a smooth surface. As described above, when the surface in contact with the fluid is smooth, when the fluid flows in the tube, a velocity boundary layer and a temperature boundary layer are formed on the tube wall surface, and the boundary layer inhibits heat exchange between the fluids. .

また、内面溝付管は、管内面に多数の溝を設けたことにより、伝熱管の重量が増加し、これにより使用材料が増加して、コストが増大するという問題点がある(特許文献1)。また、層流域で使用した場合、溝を多数設けたことにより溝部での流体の流動性が悪くなり、管を曲げ加工した場合に,曲げ部での渦がより多く発生しやすくなり、圧力損失が増大する。   In addition, the inner grooved tube has a problem that the weight of the heat transfer tube increases due to the provision of a large number of grooves on the inner surface of the tube, thereby increasing the material used and increasing the cost (Patent Document 1). ). In addition, when used in a laminar flow area, the fluidity of the fluid in the groove deteriorates due to the provision of a large number of grooves, and when the pipe is bent, more vortices are likely to occur in the bent part, resulting in pressure loss. Will increase.

更に、コルゲート管においては、らせん状に深い凹凸を小ピッチに形成して乱流を促進させたことにより、管内流体の圧力損失が増大する(特許文献2,3)。また、圧力損失の増大により搬送動力が増加し、また管内にスケール等の堆積物が滞留することにより、極端な場合には、管内を閉塞させてしまうという問題点がある。更に、層流域で使用した場合に、突起ピッチが小さいことにより、突起間の部分での流体の流動性が悪くなり、曲げ加工を施した場合に、曲げ部において、渦がより一層発生しやすくなり、圧力損失が増大する。   Furthermore, in the corrugated pipe, the pressure loss of the fluid in the pipe increases by forming spiral deep irregularities in a small pitch to promote turbulent flow (Patent Documents 2 and 3). In addition, there is a problem that the conveyance power increases due to an increase in pressure loss, and deposits such as scales stay in the pipe, and in an extreme case, the inside of the pipe is blocked. Furthermore, when used in a laminar flow area, the fluidity of the fluid between the projections becomes poor due to the small projection pitch, and when bending is performed, vortices are more likely to occur in the bent portion. As a result, the pressure loss increases.

更にまた、コルゲート管に突起加工を施した伝熱管においては、コルゲート突起及びコルゲート突起間の溝部に形成した小突起が高く、小突起の下流側にて流体に乱れの発生による渦が発生し、圧力損失が増大する(特許文献3)。この伝熱管で、曲げ加工を施した場合には、曲げ部での渦がより一層発生されやすくなり、圧力損失が増大する。   Furthermore, in the heat transfer tube in which the corrugated tube is subjected to protrusion processing, the small protrusion formed in the groove between the corrugated protrusion and the corrugated protrusion is high, and a vortex is generated due to the turbulence in the fluid downstream of the small protrusion, Pressure loss increases (Patent Document 3). When bending is performed with this heat transfer tube, vortices at the bent portion are more easily generated, and the pressure loss increases.

更にまた、特許文献4に記載されたコルゲート管も、螺旋状に深い凹凸を小ピッチで形成したことにより、突起間の部分での流体の流動性が悪くなり、曲げ加工を施した場合に曲げ部で渦がより一層発生しやすくなり、圧力損失が増大する。   Furthermore, the corrugated tube described in Patent Document 4 is also bent when a bending process is performed because the fluidity of the fluid between the protrusions deteriorates due to the formation of spiral deep irregularities at a small pitch. Vortices are more likely to occur at the part, and the pressure loss increases.

本発明はかかる問題点に鑑みてなされたものであって、管内の流体の流速が低流速域で、乱流を促進することなく、また、管内流体の圧力損失の増大を抑制しつつ、熱伝達率を著しく向上させることができる管内単相流用伝熱管を提供することを目的とする。   The present invention has been made in view of such a problem, and the flow velocity of the fluid in the pipe is a low flow velocity range, without promoting turbulence, and while suppressing the increase in pressure loss of the fluid in the pipe, It is an object of the present invention to provide a heat transfer tube for a single-phase flow in a tube that can significantly improve the transfer rate.

本発明に係る管内単相流用伝熱管は、管外面に溝が螺旋状に形成され、前記溝に対応して管内面に突起が形成され、前記管内面の前記突起間に前記突起先端よりもDcだけ深い凹部が形成されたコルゲート管を半径Rcoilで円形コイル状に曲げ加工されたものからなり、
管内に単相流流体をレイノズル数3000以下で流し、この単相流流体と、管外の流体、物質又は輻射熱との間で、熱交換を行う管内単相流用伝熱管において、
管外径ODが6乃至20mm、管内径IDが5乃至19mmであり、
前記溝の管軸方向におけるピッチPcが、15乃至25mmであり、
前記曲げの半径Rcoilが48乃至82mmであることを特徴とする。
この単相流用伝熱管は、銅又は銅合金製であることが好ましい。
In the heat transfer tube for single-phase flow in a tube according to the present invention, a groove is formed in a spiral shape on the outer surface of the tube, and a protrusion is formed on the inner surface of the tube corresponding to the groove. A corrugated tube in which a concave portion deeper than Dc is formed by bending a circular coil with a radius Rcoil ,
In a heat transfer tube for a single-phase flow in a pipe that flows a single-phase flow fluid in a pipe with a lay nozzle number of 3000 or less and performs heat exchange between the single-phase flow fluid and a fluid, substance, or radiant heat outside the pipe.
The tube outer diameter OD is 6 to 20 mm, the tube inner diameter ID is 5 to 19 mm,
The pitch Pc in the tube axis direction of the groove is 15 to 25 mm,
The bending radius Rcoil is 48 to 82 mm.
The single-phase flow heat transfer tube is preferably made of copper or a copper alloy.

この管内単相流用伝熱管において、前記管内面の前記凹部の深さDcは、Dc/IDが、0.051乃至0.097を満たすものであることが好ましい。 In this in-tube single-phase flow heat transfer tube, it is preferable that the depth Dc of the recess on the inner surface of the tube satisfies Dc / ID of 0.051 to 0.097.

本発明においては、コルゲート管を構成する溝のピッチ(コルゲートピッチ)が、15乃至25mmと、従来よりも長い。そして、管外面の前記溝により管内面には突起が形成されるが、この突起間に形成された凹部の長さが長くなる。そうすると、低レイノルズ数の領域では、流速が遅く、層流状態となるが、この低流速の場合に、溝のピッチを大きくすると、管内を流れる単相流流体の主流(管中央部を通る流体)と、前記凹部内で対流している単相流流体の副流とが合流しやすくなり、伝熱性能が向上する。このため、低レイノルズ数領域でも、高い伝熱性能を達成できる。また、低レイノルズ数領域であるから、管内流体の圧力損失は十分に小さい。   In the present invention, the pitch of the grooves constituting the corrugated pipe (corrugated pitch) is 15 to 25 mm, which is longer than before. Then, a projection is formed on the inner surface of the tube by the groove on the outer surface of the tube, but the length of the recess formed between the projections becomes longer. Then, in the low Reynolds number region, the flow velocity is slow and the flow is laminar. However, when the groove pitch is increased at this low flow velocity, the main flow of the single-phase flow fluid flowing in the pipe (the fluid passing through the center of the pipe) ) And the substream of the single-phase fluid that is convection in the concave portion are easily merged, and the heat transfer performance is improved. For this reason, high heat transfer performance can be achieved even in a low Reynolds number region. Moreover, since it is a low Reynolds number region, the pressure loss of the fluid in the pipe is sufficiently small.

(a)は、本発明の実施形態に係るコルゲート管からなる管内単相流用伝熱管を曲げた状態を示す左側面図、(b)は同じくその正面図である。(A) is a left view which shows the state which bent the heat exchanger tube for single phase flow which consists of a corrugated tube which concerns on embodiment of this invention, (b) is the front view similarly. 本発明の実施形態のコルゲート管を示す縦断面図である。It is a longitudinal section showing a corrugated pipe of an embodiment of the present invention. (a)、(b)は流速が遅い場合の流体の流れを示す模式図である。(A), (b) is a schematic diagram which shows the flow of the fluid when a flow velocity is slow. (a)、(b)は流速が速い場合の流体の流れを示す模式図である。(A), (b) is a schematic diagram which shows the flow of the fluid in case a flow velocity is quick. 本発明の実施形態に係るコルゲート管を平面上で左方に曲げた際に、管内を流れる流体の主流が基点(衝突点、コルゲート加工の突起3の側面)から流動する流れを示す平面図である。FIG. 6 is a plan view showing a flow in which the main flow of the fluid flowing in the pipe flows from the base point (collision point, side surface of the corrugated projection 3) when the corrugated pipe according to the embodiment of the present invention is bent leftward on the plane. is there. 曲げ加工の形態を、楕円形にしたコイルの模式図である。It is the schematic diagram of the coil which made the bending form the ellipse. 曲げ加工の形態を、半円周の部分を、直線部分で連結したコイルの模式図である。It is a schematic diagram of the coil which connected the form of the bending process in the semicircular part by the linear part. 熱伝達係数及び摩擦係数等を測定する試験装置を示す図である。It is a figure which shows the test apparatus which measures a heat transfer coefficient, a friction coefficient, etc. 本発明の実施形態に係るコルゲート管を、二重管式熱交換器に組み込んだ際の管端部での構造を示す模式図である。It is a schematic diagram which shows the structure in the pipe | tube end part at the time of incorporating the corrugated pipe | tube which concerns on embodiment of this invention in a double pipe type heat exchanger.

以下、本発明の実施形態について、添付の図面を参照して具体的に説明する。図1(a)は、本発明の実施形態に係るコルゲート管からなる管内単相流用伝熱管を示す左側面図、図1(b)は同じくその正面図である。図2は、本実施形態のコルゲート管の縦断面図である。コルゲート管1は、平滑管の外面に、先端が先鋭な工具を押し当て、この状態で、例えば、管を回転させつつ管軸方向に移動させる等して、工具により1本の螺旋の溝2を管外面に形成することにより、コルゲート溝2を形成したものである。管内面には、管外面に溝2を形成することにより、突起3が形成され、更に、管内面には、この突起3間に、凹部4が形成される。なお、図2において、ODは管外径、IDは管内径、管肉厚はδ、コルゲート溝ピッチはPc、コルゲート溝の深さはDcで示す。また、コルゲート溝2は、1本の螺旋状の条により形成されているので、コルゲート溝2のねじれ角は、管の外径OD、コルゲート溝2のピッチPc、及び条数が決まれば、一義的に決まる。なお、コルゲート管の材質は、銅、銅合金、アルミニウム、アルミニウム合金、鉄、ステンレス、チタン等の熱が伝導する金属材料からなり、特に、銅又は銅合金のような熱伝導率が良好なものであれば、なお好適である。   Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. Fig.1 (a) is a left view which shows the heat-transfer pipe | tube for single phase flow which consists of a corrugated pipe | tube which concerns on embodiment of this invention, FIG.1 (b) is the front view similarly. FIG. 2 is a longitudinal sectional view of the corrugated tube of the present embodiment. In the corrugated tube 1, a tool with a sharp tip is pressed against the outer surface of the smooth tube, and in this state, for example, the tube is moved in the direction of the tube axis while rotating the tube. Is formed on the outer surface of the tube to form the corrugated groove 2. Protrusions 3 are formed on the inner surface of the tube by forming grooves 2 on the outer surface of the tube. Further, recesses 4 are formed between the protrusions 3 on the inner surface of the tube. In FIG. 2, OD is the tube outer diameter, ID is the tube inner diameter, tube thickness is δ, corrugated groove pitch is Pc, and corrugated groove depth is Dc. Further, since the corrugated groove 2 is formed by one spiral strip, the twist angle of the corrugated groove 2 is unambiguous if the outer diameter OD of the tube, the pitch Pc of the corrugated groove 2 and the number of strips are determined. Is determined. The material of the corrugated tube is made of a metal material that conducts heat, such as copper, copper alloy, aluminum, aluminum alloy, iron, stainless steel, titanium, etc., and particularly has good thermal conductivity such as copper or copper alloy. If so, it is still preferable.

本発明の実施形態においては、コルゲート管1は、例えば、図1に示すように、コイル状に曲げ加工されて、コイル10として、熱交換器内に組み込まれる。コルゲート管1を前述の如くして製造した直後はコルゲート管1は直管状をなしており、その後、コルゲート管1の両管端部を除いて、コルゲート管1をコイル状に曲げ加工することにより、コルゲート管1のコイル10を得る。なお、コルゲート加工と、曲げ加工とは、連続的に行っても良いし、コルゲート加工の後、直管状で出荷し、別の工場で曲げ加工しても良い。なお、このコルゲート管1の中心線によるコイル10の曲げ半径をRcoilとする。また、このコイル10のピッチをPcoilとする。   In the embodiment of the present invention, for example, as shown in FIG. 1, the corrugated tube 1 is bent into a coil shape and incorporated as a coil 10 in a heat exchanger. Immediately after the corrugated tube 1 is manufactured as described above, the corrugated tube 1 has a straight tube shape, and thereafter the corrugated tube 1 is bent into a coil shape except for both ends of the corrugated tube 1. The coil 10 of the corrugated tube 1 is obtained. The corrugating process and the bending process may be performed continuously, or after the corrugating process, the corrugated process may be shipped in a straight tube and bent at another factory. The bending radius of the coil 10 along the center line of the corrugated tube 1 is Rcoil. The pitch of the coil 10 is Pcoil.

なお、コルゲート管1の曲げ加工の形態は、図1に示すコイル状のものに限らない。例えば、図6に示すように、曲げ加工の形態を、楕円形にした楕円コイル11としても良いし、図7に示すように、曲げ加工の形態を、半円周の部分を、直線部分で連結したような形状のコイル12としても良い。このコイルの形状は、種々のものが考えられる。図6に示す楕円形状のコイル11の場合は、その小径を曲げ半径Rcoilとする。また、図7に示すコイル12の場合は、半円部分の半径をRcoilとする。   The form of bending of the corrugated tube 1 is not limited to the coil shape shown in FIG. For example, as shown in FIG. 6, the bending process may be an ellipse coil 11 having an elliptical shape, and as shown in FIG. 7, the bending process may be performed on a semicircular portion with a straight line portion. It is good also as the coil 12 of the shape which connected. Various shapes of the coil are conceivable. In the case of the elliptical coil 11 shown in FIG. 6, the small diameter is set as a bending radius Rcoil. In the case of the coil 12 shown in FIG. 7, the radius of the semicircular portion is Rcoil.

図3及び図4は、溝ピッチPcと、管内部の単相流流体の流れとの関係を示す模式図である。図3は、流速が遅い(レイノルズ数Reが小さい)場合、図4は、流速が速い(レイノルズ数Reが大きい)場合を示す。なお、図3及び図4は、図2に示すコルゲート管の形状を模式的に示したものであり、実際には、これらの図に示すような角形の溝は形成されない。図4に示すように、流速が速い場合は、流体間の剪断力が大きく、図4(a)に示すように、溝ピッチPcが小さい場合でも、凹部4内の流体が凹部4内で十分に対流が形成され、拡散されて、主流と合流するため、伝熱効率が高い。一方、コルゲート溝のピッチPcが大きいと、図4(b)に示すように、主流からの流体が凹部4内に入り込み、凹部4内を流れるため、凹部4の両隅部でのみ対流拡散が生じることになり、凹部4の全体で流体の対流拡散が生じることがないので、伝熱効率が低下する。   3 and 4 are schematic views showing the relationship between the groove pitch Pc and the flow of the single-phase fluid inside the pipe. FIG. 3 shows a case where the flow velocity is slow (Reynolds number Re is small), and FIG. 4 shows a case where the flow velocity is fast (Reynolds number Re is large). 3 and 4 schematically show the shape of the corrugated tube shown in FIG. 2, and in reality, a square groove as shown in these drawings is not formed. As shown in FIG. 4, when the flow velocity is high, the shear force between the fluids is large, and as shown in FIG. 4A, the fluid in the recesses 4 is sufficient in the recesses 4 even when the groove pitch Pc is small. The heat transfer efficiency is high because convection is formed, diffused, and merges with the mainstream. On the other hand, when the pitch Pc of the corrugated groove is large, as shown in FIG. 4B, the fluid from the main flow enters the concave portion 4 and flows through the concave portion 4, so that convection diffusion occurs only at both corners of the concave portion 4. As a result, the convection diffusion of the fluid does not occur in the entire concave portion 4, so that the heat transfer efficiency is lowered.

これに対し、管内部の単相流流体の流速が遅い場合は、図3に示すように、管内の主流と、凹部4内の副流(対流)との間の剪断力が小さい。このため、図3(a)に示すように、コルゲート溝ピッチPcが小さい場合は、副流は、凹部4内で弱い対流を形成するが、この対流(副流)は主流と合流せず、凹部4内に留まりやすい。このため、流速が遅く、コルゲート溝ピッチPcが小さい場合は、伝熱効率が低い。   On the other hand, when the flow velocity of the single-phase fluid inside the tube is low, the shear force between the main flow in the tube and the side flow (convection) in the recess 4 is small as shown in FIG. For this reason, as shown in FIG. 3A, when the corrugated groove pitch Pc is small, the side flow forms a weak convection in the recess 4, but this convection (side flow) does not merge with the main flow, It tends to stay in the recess 4. For this reason, when the flow velocity is slow and the corrugated groove pitch Pc is small, the heat transfer efficiency is low.

一方、図3(b)に示すように、管内の単相流流体の流速が小さい場合でも、コルゲート溝ピッチPcが大きい場合は、凹部4内の流体と主流とが接触する部分の面積が十分に大きいため、主流による剪断力が小さくても、凹部4内で対流した流体が主流と合流するため、伝熱効率が高い。   On the other hand, as shown in FIG. 3B, even when the flow velocity of the single-phase flow fluid in the pipe is small, if the corrugated groove pitch Pc is large, the area of the portion where the fluid in the recess 4 is in contact with the main flow is sufficient. Therefore, even if the shearing force due to the main flow is small, the convection fluid in the recess 4 merges with the main flow, so the heat transfer efficiency is high.

このように、本発明者等は、低レイノルズ数の流速が遅い場合には,コルゲート溝ピッチPcが大きい方が、伝熱効率が高いことを見出し、本発明を完成されたものである。そして、本発明は、単相流流体が低レイノルズ数で流速が遅い条件下でも、コルゲート溝ピッチPcを15mm以上とすることにより、乱流を促進させることなく、伝熱効率を高めることができることを、後述のごとく実証したものである。また、本発明においては、乱流が促進されないので、管内流体の圧力損失が増大して搬送動力が増加するようなことがなく、管内にスケール等の堆積物が滞留し、管内を閉塞させてしまこともない。   Thus, the present inventors have found that the heat transfer efficiency is higher when the corrugated groove pitch Pc is larger when the flow rate of the low Reynolds number is slow, and the present invention has been completed. And this invention can improve heat-transfer efficiency, without promoting a turbulent flow by making corrugated groove pitch Pc 15 mm or more also on the conditions where a single phase flow fluid is a low Reynolds number and slow flow velocity. This has been demonstrated as described later. Further, in the present invention, since turbulent flow is not promoted, pressure loss of the fluid in the pipe does not increase and the conveyance power does not increase, and deposits such as scales stay in the pipe and block the inside of the pipe. There is nothing to do.

本実施形態においては、コルゲート管1からなる伝熱管が半径Rcoilのコイル状に曲げ加工される。図5は、コルゲート管1が平面視で左方に曲げ加工された状態を示す。このようにコルゲート管1を曲げ加工すると、図5に示すように、その内部を通流する流体は、コルゲート管1の曲げ部に流入する際において、コルゲート管1の中心を流れる流体(以下、主流という)がそのまま直進して流入し、曲げ加工部に形成されているコルゲート加工の突起3の側面に主流が衝突する。衝突した主流は、コルゲート加工の突起3が螺旋状に形成されているため、突起3間の凹部4の下流側面壁近傍に沿って上流側と下流側に分離して流れていく。即ち、図5の一点鎖線にて示す主流は、流体の通流方向の上流側で熱交換されながら、下流側に流れていく。そして、この主流が曲げ加工部において、コルゲート管の突起3に衝突すると、衝突した点である基点(衝突点)において、分流する。その後、分流した流体は上流側と下流側に旋回して流れる。   In the present embodiment, the heat transfer tube made of the corrugated tube 1 is bent into a coil shape having a radius Rcoil. FIG. 5 shows a state in which the corrugated tube 1 is bent leftward in a plan view. When the corrugated tube 1 is bent in this manner, as shown in FIG. 5, the fluid flowing through the corrugated tube 1 flows through the center of the corrugated tube 1 when flowing into the bent portion of the corrugated tube 1 (hereinafter, referred to as “corrugated tube”). The mainstream) travels straight and flows in as it is, and the mainstream collides with the side surface of the corrugated projection 3 formed in the bent portion. Since the corrugated projection 3 is formed in a spiral shape, the main stream that has collided flows separately on the upstream side and the downstream side along the vicinity of the downstream side wall of the recess 4 between the projections 3. That is, the main flow shown by the one-dot chain line in FIG. 5 flows downstream while heat exchange is performed on the upstream side in the fluid flow direction. And when this main stream collides with the corrugated pipe projection 3 in the bending portion, it is diverted at the base point (collision point) that is the collision point. Thereafter, the diverted fluid swirls and flows upstream and downstream.

この分流した流体は、層流状態で(流れが乱れずに)管内面に形成された突起3間の凹部4の下流側に沿って、一部は上流側に戻りながら旋回して流れ、残部は下流側に旋回して流れて行く。その後、凹部4の下流側で旋回する流れが,凹部4にて形成された対流(副流)に合流して副流との伝熱性能が向上する。その後、更に図3(b)に示すように、凹部4内に位置する流体が、管中心部の主流と接触し、凹部4の部分で対流が生じ、この対流流体と主流とが合流して、より一層伝熱性能が向上する。   This diverted fluid flows in a laminar flow state (without disturbing the flow) along the downstream side of the concave portion 4 between the protrusions 3 formed on the inner surface of the pipe, and a part of the fluid flows while returning to the upstream side. Turns and flows downstream. Thereafter, the flow swirling on the downstream side of the recess 4 merges with the convection (substream) formed in the recess 4 to improve the heat transfer performance with the substream. Thereafter, as shown in FIG. 3 (b), the fluid located in the recess 4 comes into contact with the main flow at the center of the tube, and convection is generated in the recess 4, and the convection fluid and the main flow merge. The heat transfer performance is further improved.

一方、図5に示すように、直管部から曲げ加工部分に遷移する領域と異なり、図1に示す円筒コイルのように連続して曲げ加工した部分においては、主流が遠心力により外周側に主流が移動していき、曲げ外周側の管内面の突起3に主流が衝突して管上部及び管下部に分流される。その後、凹部4の下流側で旋回する流れが、凹部4にて形成した対流(副流)に合流して、副流との伝熱性能が向上する。その後、更に凹部4内に位置する流体が、管中心部の主流と接触し、凹部4の部分で対流が生じ、この対流流体と主流とが合流して、より一層伝熱性能が向上する。   On the other hand, as shown in FIG. 5, unlike the region where the straight pipe portion transitions to the bent portion, the mainstream moves to the outer peripheral side by centrifugal force in the continuously bent portion such as the cylindrical coil shown in FIG. 1. The main flow moves, and the main flow collides with the protrusion 3 on the inner surface of the bending outer peripheral side and is divided into the upper part and the lower part of the pipe. Thereafter, the flow swirling on the downstream side of the concave portion 4 merges with the convection (secondary flow) formed in the concave portion 4, and the heat transfer performance with the secondary flow is improved. Thereafter, the fluid located in the recess 4 further comes into contact with the main flow at the center of the tube, and convection occurs at the portion of the recess 4, and the convection fluid and the main flow merge to further improve the heat transfer performance.

本実施形態においては、コルゲート管1からなる伝熱管が半径Rcoilのコイル状に曲げ加工される。このようにコルゲート管1を曲げ加工すると、図5に示すように、その内部を通流する冷媒は、コルゲート管1の曲げ部において、コルゲート加工の突起3に衝突して、その一部が上流側に戻ってくる。即ち、コルゲート管1の中心を流れる流体(以下、主流という)は、流体の通流方向の上流側で熱交換されながら下流側に流れていく。そして、この主流が曲げ加工部において、コルゲート管の管壁に衝突すると、衝突した点を基点(衝突点)にして、管上部及び管下部に分流される、この分流した流体は、層流状態で(流れが乱れずに)管内面に形成された突起3間の凹部3に沿って、一部は上流側に戻りながら旋回して流れ、残部は下流側に旋回して流れて行く。その後、凹部3内に位置する流体が、管中心部の主流と接触し、凹部4の部分で対流が生じ、この対流流体と主流とが合流して、より伝熱性能が向上する。   In the present embodiment, the heat transfer tube made of the corrugated tube 1 is bent into a coil shape having a radius Rcoil. When the corrugated pipe 1 is bent in this manner, as shown in FIG. 5, the coolant flowing through the corrugated pipe 1 collides with the corrugated protrusion 3 at the bent portion of the corrugated pipe 1, and a part of the refrigerant flows upstream. Come back to the side. That is, the fluid flowing in the center of the corrugated pipe 1 (hereinafter referred to as main flow) flows downstream while heat exchange is performed on the upstream side in the fluid flow direction. And when this main stream collides with the corrugated pipe wall in the bending part, it is divided into the upper part of the pipe and the lower part of the pipe with the point of collision as the base point (collision point). (Without turbulent flow), along the recess 3 between the projections 3 formed on the inner surface of the pipe, a part of the swirl flows while returning to the upstream side, and the remaining part swirls and flows downstream. Thereafter, the fluid located in the recess 3 comes into contact with the main flow at the center of the tube, and convection occurs at the portion of the recess 4, and the convection fluid and the main flow merge to further improve the heat transfer performance.

次に、本発明のコルゲート管からなる単相流用伝熱管の構成について説明する。   Next, the structure of the single-phase flow heat transfer tube composed of the corrugated tube of the present invention will be described.

「伝熱管の管外径OD:6乃至20mm、管内径ID:5乃至19mm」
先ず、例えば、伝熱管の外径ODは、6乃至20mm、内径IDは、5乃至19mmである。管内には、水及びブライン等の単相流流体が流れる。一方、管外の熱媒体は、本発明の伝熱管を使用する分野により異なる。本発明の伝熱管の使用分野が、ヒートポンプ給湯器のように水−冷媒熱交換器の場合には、管外面に自然冷媒又はフロン冷媒が流れ、使用分野が、ガス給湯器のように水−水熱交換器に使用される二重管式熱交換器の場合は、管外にも水等の単相流体が流れる。また、他の技術分野においても、例えば、太陽熱温水器のソーラーパネルの温水配管に本発明の伝熱管を使用する場合は、輻射線等の電磁波が管外面に吸収されて生じる輻射熱が伝熱管に作用する。また、本発明の伝熱管を地中に埋め込んで、土壌と管外面とが接触する水−土壌熱交換器の分野に伝熱管を使用する場合は、土壌に蓄積された熱と管外面との間で熱交換が生じる。
“Tube outer diameter OD of heat transfer tube: 6 to 20 mm, tube inner diameter ID: 5 to 19 mm”
First, for example, the outer diameter OD of the heat transfer tube is 6 to 20 mm, and the inner diameter ID is 5 to 19 mm. A single-phase fluid such as water and brine flows in the pipe. On the other hand, the heat medium outside the tube varies depending on the field in which the heat transfer tube of the present invention is used. When the field of use of the heat transfer tube of the present invention is a water-refrigerant heat exchanger such as a heat pump water heater, natural refrigerant or CFC refrigerant flows on the outer surface of the pipe, and the field of use is water- In the case of a double tube heat exchanger used for a water heat exchanger, a single-phase fluid such as water also flows outside the tube. Also, in other technical fields, for example, when the heat transfer pipe of the present invention is used for the hot water pipe of a solar panel of a solar water heater, radiant heat generated by absorption of electromagnetic waves such as radiation rays on the outer surface of the pipe is generated in the heat transfer pipe. Works. In addition, when the heat transfer tube of the present invention is embedded in the ground and the heat transfer tube is used in the field of a water-soil heat exchanger where the soil and the outer surface of the tube are in contact, the heat accumulated in the soil and the outer surface of the tube Heat exchange occurs between them.

このようにして、これらの管内の流体と管外の流体又は物質との間で、熱交換をする。このような用途に使用される単相流用伝熱管としては、外径及び内径が、例えば、上記範囲である。また、本発明は、管内を流れる単相流流体のレイノルズ数Reは3000以下であることが好ましい。好ましくは、この管内を流れる単相流流体のレイノルズ数Reは2000以下である。本発明の伝熱管は、このような低レイノルズ数の流体に適している。   In this way, heat exchange is performed between the fluid in these tubes and the fluid or material outside the tubes. As a single-phase flow heat transfer tube used for such applications, the outer diameter and inner diameter are, for example, in the above range. In the present invention, the Reynolds number Re of the single-phase flow fluid flowing in the pipe is preferably 3000 or less. Preferably, the Reynolds number Re of the single-phase flow fluid flowing in the pipe is 2000 or less. The heat transfer tube of the present invention is suitable for such a low Reynolds number fluid.

「コルゲート溝ピッチPc:15乃至25mm」
コルゲート溝ピッチPcは、15乃至25mmである。コルゲート溝ピッチPcを上記範囲にすることにより、衝突点で流体が凹部4に分流して旋回する際、凹部4内への流体の流入が促進され、流体が乱流促進されずに、流体通流方向の上流側及び下流側に旋回しやすくなる。更には、凹部4内の流体と、管中心部の主流とが接触する面積が大きくなり、凹部4内で対流した流体が、主流と合流しやすくなり、伝熱性能が向上する。
“Corrugated groove pitch Pc: 15 to 25 mm”
The corrugated groove pitch Pc is 15 to 25 mm. By setting the corrugated groove pitch Pc to the above range, when the fluid is diverted into the recess 4 at the collision point and swirled, the inflow of the fluid into the recess 4 is promoted, and the fluid is not promoted and the fluid flow is not promoted. It becomes easy to swivel upstream and downstream in the flow direction. Furthermore, the area in which the fluid in the recess 4 and the main flow at the center of the tube come into contact with each other is increased, and the convection fluid in the recess 4 can easily merge with the main flow, thereby improving the heat transfer performance.

コルゲート溝ピッチPcが15mmより小さくなると、衝突点で流体が凹部4に分流して旋回する際、凹部4内への流体の流入が阻害され、分流流体が乱流促進されて、圧力損失が増大すると共に、凹部4内での対流が阻害されて、伝熱性能が低下する。また、コルゲートピッチPcが25mmよりも大きくなると、衝突点で流体が凹部4に分流して旋回する際、凹部4内への流体の流入が容易になるが、旋回流が弱くなって凹部4での対流が阻害され、凹部4内の流体と管中心部の主流との合流が促進されず、伝熱性能が低下する。従って、コルゲート溝ピッチPcは、15乃至25mmとする。   When the corrugated groove pitch Pc is smaller than 15 mm, when the fluid diverts into the recess 4 at the collision point and turns, the inflow of the fluid into the recess 4 is inhibited, the turbulent flow is promoted, and the pressure loss increases. At the same time, the convection in the recess 4 is hindered and the heat transfer performance is reduced. Further, when the corrugated pitch Pc is larger than 25 mm, when the fluid diverts into the recess 4 at the collision point and turns, the fluid can easily flow into the recess 4, but the swirl flow becomes weak and the recess 4 The convection is hindered, the merging of the fluid in the recess 4 and the main flow at the center of the tube is not promoted, and the heat transfer performance is reduced. Accordingly, the corrugated groove pitch Pc is set to 15 to 25 mm.

「曲げ半径Rcoil:48乃至82mm」
コイル10の曲げ半径Rcoilが48mmより小さくなると、伝熱管内を通流する流体が、伝熱管内面の衝突点から分流して旋回する際に、流体に作用する遠心力が強くなりすぎると共に、突起3間の凹部4内の流体が管壁から離脱して、主流が乱れ、管壁と主流との合流が阻害されて、伝熱性能が阻害され、圧力損失が増大する。また、コイル10の曲げ半径が82mmを超えると、衝突点から分流して旋回する際に、流体に作用する遠心力が弱くなる。このことにより、圧力損失は低下するものの、衝突点で分流した流体が上流側及び下流側へ流れる際の流動性が低下するため、伝熱性能が低下する。従って、曲げ加工の曲げ半径Rcoilは、48乃至82mmとする。
"Bending radius Rcoil: 48 to 82mm"
When the bending radius Rcoil of the coil 10 is smaller than 48 mm, the centrifugal force acting on the fluid becomes too strong when the fluid flowing through the heat transfer tube is swung from the collision point on the inner surface of the heat transfer tube, and the protrusion The fluid in the recess 4 between the three is separated from the tube wall, the main flow is disturbed, the merge of the tube wall and the main flow is inhibited, the heat transfer performance is inhibited, and the pressure loss increases. Further, when the bending radius of the coil 10 exceeds 82 mm, the centrifugal force acting on the fluid is weakened when turning and turning from the collision point. As a result, although the pressure loss is reduced, the fluidity when the fluid diverted at the collision point flows to the upstream side and the downstream side is lowered, so that the heat transfer performance is lowered. Therefore, the bending radius Rcoil for bending is set to 48 to 82 mm.

「Dc/ID:0.051乃至0.097」
コルゲート溝2の深さ(管内面の凹部4の深さ)をDcとすると、Dc/IDを0.051乃至0.097とすることにより、衝突点で流体が凹部4に分流して旋回する際、凹部4内の流体が乱流促進されずに、上流側及び下流側に旋回しやすくなる。これにより,凹部4内での対流が阻害されにくくなり、管中心部の主流と、凹部4内で対流した流体との接触及び合流が促進され、伝熱性能が促進される。
“Dc / ID: 0.051 to 0.097”
When the depth of the corrugated groove 2 (the depth of the concave portion 4 on the inner surface of the pipe) is Dc, the fluid is diverted to the concave portion 4 and swirls by setting Dc / ID to 0.051 to 0.097. At this time, the fluid in the recess 4 is not easily promoted for turbulent flow, but is easily swirled upstream and downstream. This makes it difficult for the convection in the recess 4 to be hindered, promotes contact and merging of the main flow in the tube center and the fluid convected in the recess 4, and promotes heat transfer performance.

Dc/IDが0.051よりも小さい場合、衝突点で流体が凹部4に分流して旋回する際、凹部4内の流体が、凹部4内より主流側に流れやすくなり、管中心部の主流と凹部4内の流体との間の対流が阻害されて、伝熱性能が低下する。また、Dc/IDが0.097より大きい場合は、衝突点で流体が凹部4に分流して旋回する際、凹部4内の流体が乱流促進されずに、上流側及び下流側に流れやすくなるものの、溝深さDcが深くなることにより曲げ部での管中心部の主流流体が乱流促進されて圧力損失が増大する。従って、Dc/IDは0.051乃至0.097とする。   When Dc / ID is smaller than 0.051, the fluid in the recess 4 easily flows from the inside of the recess 4 to the mainstream side when the fluid diverts to the recess 4 at the collision point and turns. And the convection between the fluid in the recess 4 are hindered and the heat transfer performance is reduced. Further, when Dc / ID is larger than 0.097, when the fluid diverts into the recess 4 at the collision point and turns, the fluid in the recess 4 does not promote turbulent flow and easily flows upstream and downstream. However, as the groove depth Dc becomes deeper, the main flow fluid at the center of the tube at the bent portion is promoted for turbulence, and the pressure loss increases. Therefore, Dc / ID is set to 0.051 to 0.097.

「溝ねじれ角βc:40°以上」
コルゲート溝2は、1本の螺旋状の条により形成されている。この場合、溝ねじれ角βcは、管の外径OD、コルゲート溝のピッチPc、及び条数が決まれば一義的に決まるので、溝ねじれ角βcは、管外径OD及びコルゲート溝ピッチPcにより決まる。例えば、この溝ねじれ角βcは、実施例に記載のように、54°等種々の値をとることができる。また、伝熱管1の肉厚δは、例えば、実施例に記載のように、0.613mm等、種々の値をとることができる。
“Groove twist angle βc: 40 ° or more”
The corrugated groove 2 is formed by a single spiral strip. In this case, the groove twist angle βc is uniquely determined if the outer diameter OD of the tube, the pitch Pc of the corrugated groove, and the number of strips are determined. Therefore, the groove twist angle βc is determined by the tube outer diameter OD and the corrugated groove pitch Pc. . For example, the groove twist angle βc can take various values such as 54 ° as described in the embodiment. Further, the thickness δ of the heat transfer tube 1 can take various values such as 0.613 mm as described in the examples.

なお、本発明においては、管軸方向にみて、凹部4内に管軸と平行な平坦部を形成することができる。これにより、管内を流れる単相流流体の乱流化を抑制することができると共に、衝突点を基点に、管上部及び管下部の凹部4内に分流された流体が、旋回して流れやすくなり、凹部4内の流体と、管中心部の主流とが接触する面において、凹部4内で対流している副流と、主流とが、より一層合流しやすくなり、伝熱性能が向上する。この平坦部の管軸方向の長さLfは、コルゲート溝のピッチPcの0.40乃至0.80倍とすることが好ましい。即ち、Lfは0.40Pc乃至0.80Pcとすることが好ましい。   In the present invention, a flat portion parallel to the tube axis can be formed in the recess 4 in the tube axis direction. As a result, the turbulent flow of the single-phase fluid flowing in the pipe can be suppressed, and the fluid diverted into the concave portion 4 in the upper part of the pipe and the lower part of the pipe can be swirled and flow easily from the collision point. In the surface where the fluid in the recess 4 and the main flow at the center of the tube come into contact, the substream and the main flow that are convective in the recess 4 are more easily merged, and the heat transfer performance is improved. The length Lf of the flat portion in the tube axis direction is preferably 0.40 to 0.80 times the pitch Pc of the corrugated groove. That is, Lf is preferably 0.40 Pc to 0.80 Pc.

また、本発明の実施形態の伝熱管を、用途に応じて、例えば、二重管式熱交換器に加工して使用する場合は、平滑管の管内に本実施形態の伝熱管を挿入して、二重管構造にする。二重管式熱交換器の場合、本実施形態の伝熱管を平滑管の管内に挿入し、図6又は図7に示すコイル状等で使用する場合、この挿入された状態で管を曲げ加工することにより、コイル状に曲げ、所望のコイル形態に加工する。その際に、本実施形態の伝熱管の曲げ半径がRcoilになるように、曲げ加工の程度を適宜調整する。図9は、二重管式熱交換器の外管として使用する平滑管30の管内に、本実施形態の伝熱管31が挿入された管端部の状態を示している。この二重管は、曲げ加工された後に、その管端部には、例えば、T継手32(図9に破線にて示す)等を差し込み、平滑管30とT継手32との差込部分及び伝熱管31とT継手32とをろう付け等で接合することにより、T継手が取り付けられる。なお、T継手32の上方に分岐して延びる部分は、熱交換器への組込み時に応じてその方向を適宜決めて組み付け、流体の出入口配管と接続される。なお、本実施形態の伝熱管を二酸化炭素冷媒を使用した給湯器で使用する場合、本実施形態のコルゲート管1の外周面に、二酸化炭素冷媒を通流させるための細管を螺旋状に巻回する。   In addition, when the heat transfer tube of the embodiment of the present invention is used after being processed into, for example, a double tube heat exchanger, the heat transfer tube of the present embodiment is inserted into a smooth tube. , Make a double tube structure. In the case of a double tube heat exchanger, when the heat transfer tube of this embodiment is inserted into a smooth tube and used in the form of a coil as shown in FIG. 6 or FIG. 7, the tube is bent in this inserted state. By doing so, it is bent into a coil shape and processed into a desired coil shape. At that time, the degree of bending is appropriately adjusted so that the bending radius of the heat transfer tube of the present embodiment is Rcoil. FIG. 9 shows a state of the tube end portion in which the heat transfer tube 31 of the present embodiment is inserted into the tube of the smooth tube 30 used as the outer tube of the double tube heat exchanger. After this double pipe is bent, for example, a T joint 32 (shown by a broken line in FIG. 9) or the like is inserted into the pipe end portion, and the insertion portion between the smooth pipe 30 and the T joint 32 and The T joint is attached by joining the heat transfer tube 31 and the T joint 32 by brazing or the like. In addition, the portion branched and extending above the T joint 32 is assembled by appropriately determining the direction in accordance with the time of incorporation into the heat exchanger, and connected to the fluid inlet / outlet piping. In addition, when using the heat exchanger tube of this embodiment with the water heater using a carbon dioxide refrigerant, the thin tube for making a carbon dioxide refrigerant flow around the outer peripheral surface of the corrugated pipe 1 of this embodiment is helically wound. To do.

以下、本発明の効果を実証するために、本発明の範囲に入る実施例と、本発明の範囲から外れる比較例とについて説明する。   Hereinafter, in order to demonstrate the effects of the present invention, examples that fall within the scope of the present invention and comparative examples that fall outside the scope of the present invention will be described.

まず、単相流流体の伝熱性能の試験方法について説明する。図8はこの試験装置を示す模式図である。本試験装置においては、加熱側及び給湯側の双方に水を媒体として使用した。熱交換槽13内には加熱水が貯留されており、この加熱水は、加熱水タンク21から、配管22aを介して供給され、配管22bを介して、加熱水タンク21に戻される。熱交換槽13内には、伝熱管15が水平に配置されており、この伝熱管15内には、給湯水タンク11から、給湯水が、配管12aを介して供給され、伝熱管15を通流した後、配管12bを介して、給湯水タンク11に返戻される。加熱水タンク21は、加熱水の温度が、恒温循環装置24により、一定温度(32℃,37℃又は42℃)になるように、制御される。また、給湯水タンク11は、給湯水の温度が、恒温循環装置18により、20℃に一定に制御される。   First, a test method for heat transfer performance of a single-phase flow fluid will be described. FIG. 8 is a schematic diagram showing this test apparatus. In this test apparatus, water was used as a medium on both the heating side and the hot water supply side. Heated water is stored in the heat exchange tank 13, and this heated water is supplied from the heated water tank 21 via the pipe 22a and returned to the heated water tank 21 via the pipe 22b. A heat transfer pipe 15 is horizontally disposed in the heat exchange tank 13. Hot water is supplied from the hot water tank 11 through the pipe 12 a into the heat transfer pipe 15, and passes through the heat transfer pipe 15. After flowing, it is returned to the hot water tank 11 through the pipe 12b. The temperature of the heated water tank 21 is controlled by the constant temperature circulation device 24 so that the temperature of the heated water becomes a constant temperature (32 ° C., 37 ° C. or 42 ° C.). In the hot water tank 11, the temperature of the hot water is controlled to be constant at 20 ° C. by the constant temperature circulation device 18.

給湯水は混合器20a、20bを介して、伝熱管15に出入りするが、この伝熱管15への給湯水の出入口温度は、この伝熱管の出入口に設置した混合器20a、20bにおいて、白金測温抵抗体を使用して、測定することができる。給湯水の流量は、バルブ25により、一定流量になるように、段階的に調節する。また、熱交換槽13内の伝熱管15の平均温度は、温度変化に伴う電気抵抗値の変化により測定することができる。そして、この伝熱管15の出入口に設置した圧力タップの圧力を配管16により差圧変換器17に導き、差圧変換器17を、1kPa、10kPa,50kPa,又は200kPaに切り替えて測定する。なお、熱交換槽13内は撹拌器14により撹拌され、給湯水タンク11内は撹拌器19により撹拌され、加熱水タンク21内は撹拌器23により加熱されて、水の温度の均一化が図られている。伝熱管15は、図1に示す形状を有するコイルであり、コイル巻き数nは5.5である。曲げ加工は、所定のコイル直径に合わせた曲げ加工治具を製作し、この曲げ加工治具を使用して直管状コルゲート管をコイルに曲げ加工した。   The hot water enters and exits the heat transfer tube 15 through the mixers 20a and 20b, and the temperature of the hot water supply to and from the heat transfer tube 15 is measured by the platinum in the mixers 20a and 20b installed at the entrance and exit of the heat transfer tube. It can be measured using a temperature resistor. The flow rate of the hot water supply is adjusted stepwise by the valve 25 so as to be a constant flow rate. Moreover, the average temperature of the heat exchanger tube 15 in the heat exchange tank 13 can be measured by a change in electric resistance value accompanying a temperature change. And the pressure of the pressure tap installed in the entrance / exit of this heat exchanger tube 15 is guide | induced to the differential pressure converter 17 by the piping 16, and the differential pressure converter 17 is switched and measured to 1 kPa, 10 kPa, 50 kPa, or 200 kPa. The heat exchange tank 13 is agitated by a stirrer 14, the hot water tank 11 is agitated by a stirrer 19, and the heated water tank 21 is heated by a stirrer 23 so that the temperature of the water is made uniform. It has been. The heat transfer tube 15 is a coil having the shape shown in FIG. 1, and the number n of coil turns is 5.5. For bending, a bending jig matched to a predetermined coil diameter was manufactured, and a straight corrugated pipe was bent into a coil using the bending jig.

冷却水の熱交換量Qsは、給湯水流量をW、定圧比熱をcp、給湯出口温度をTsout、給湯入口温度をTsinとして、下記数式1により求めることができる。また、熱伝達係数αiは、熱流束をqi、電圧降下により求めた管平均温度をTwi、管の熱伝導を考慮して修正した管内壁面温度をTwm、給湯水の出入口温度の算術平均温度をTsnとして、下記数式2により求めることができる。但し、qi、Twi、Tsnは、夫々下記数式3,4,5により求めることができる。なお、Lは有効伝熱長さ,diは最大内径、doは外径、λは銅の熱伝達率、δは肉厚を表す。そして、管内ヌッセルト数Nui及びレイノルズ数Reは、下記数式6及び数式7により求まる。但し、ρは給湯水の密度、viは給湯水の流速、μは給湯水の粘性である。そして、ΔPを圧力損失、xを試験区間の長さとして、摩擦係数fiは下記数式8により求まる。   The heat exchange amount Qs of the cooling water can be obtained by the following formula 1, where the hot water flow rate is W, the constant pressure specific heat is cp, the hot water outlet temperature is Tsout, and the hot water inlet temperature is Tsin. The heat transfer coefficient αi is the heat flux qi, the tube average temperature obtained by voltage drop Twi, the tube wall surface temperature corrected in consideration of the heat conduction of the tube Twm, and the arithmetic average temperature of the hot water inlet / outlet temperature. As Tsn, it can obtain | require by following Numerical formula 2. However, qi, Twi, and Tsn can be obtained by the following mathematical formulas 3, 4, and 5, respectively. L is the effective heat transfer length, di is the maximum inner diameter, do is the outer diameter, λ is the heat transfer coefficient of copper, and δ is the thickness. The in-pipe Nusselt number Nui and the Reynolds number Re are obtained by the following formulas 6 and 7. However, ρ is the density of hot water, vi is the flow rate of hot water, and μ is the viscosity of hot water. Then, ΔP is the pressure loss, x is the length of the test section, and the friction coefficient fi is obtained by the following formula 8.

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本発明の第1実施例として、伝熱管の形状寸法の相違による圧力損失及び熱伝達係数についての影響について説明する。各試験伝熱管の形状寸法を下記表1乃至表3に示す。また、各試験伝熱管のヌッセルト数及び摩擦係数を、下記表4乃至表6に示す。   As the first embodiment of the present invention, the influence on the pressure loss and the heat transfer coefficient due to the difference in the shape and size of the heat transfer tubes will be described. The shape dimensions of each test heat transfer tube are shown in Tables 1 to 3 below. The Nusselt number and the friction coefficient of each test heat transfer tube are shown in Tables 4 to 6 below.

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Figure 0006223298
Figure 0006223298

上記表1〜表3において、基準1は平滑管である。また、基準2は直管状のコルゲート管である。実施例1〜9は、本発明の請求項3の範囲に入る実施例であり、実施例10〜12は、本発明の請求項1のみを満たす実施例である。比較例1〜7は、本発明の範囲から外れるコルゲート管コイルである。実施例1〜12及び比較例1〜7は、図1に示す形状を有するコイル状伝熱管であり、図2に示す形状のコルゲート管を使用した伝熱管である。なお、条数は1である。また、表4〜表6において、Nui比は、管内ヌッセルト数Nuiを示し、基準1の平滑管に対する比で示した。また、fi比は、摩擦係数であり、流体の流動抵抗を示し、圧力損失の大きさを示す特性である。このfi比も、基準1の平滑管に対する比で示した。更に、管内ヌッセルト数Nui比及び摩擦係数fi比のいずれも、(1)、(2)、(3)は、夫々、レイノルズ数Reが3000、2000、1000の場合の特性である。つまり、例えば、レイノルズ数Reが3000のときの管内ヌッセルト数の平滑管(基準1)に対する比はNui比(1)であり、同じく摩擦抵抗の平滑管(基準1)に対する比はfi比(1)である。管内ヌッセルト数Nuiが大きい程、伝熱性能が高く、摩擦係数fiが小さい程、圧力損失が小さく、伝熱管として優れている。   In Tables 1 to 3, the reference 1 is a smooth tube. Reference 2 is a straight tubular corrugated tube. Examples 1 to 9 are examples that fall within the scope of claim 3 of the present invention, and examples 10 to 12 are examples that satisfy only claim 1 of the present invention. Comparative Examples 1 to 7 are corrugated tube coils that are out of the scope of the present invention. Examples 1 to 12 and Comparative Examples 1 to 7 are coiled heat transfer tubes having the shape shown in FIG. 1, and are heat transfer tubes using corrugated tubes having the shape shown in FIG. 2. The number of strips is 1. In Tables 4 to 6, the Nui ratio represents the in-pipe Nusselt number Nui, and is expressed as a ratio with respect to the standard 1 smooth tube. The fi ratio is a coefficient of friction, which indicates the flow resistance of the fluid and is a characteristic indicating the magnitude of pressure loss. This fi ratio is also shown as the ratio to the standard 1 smooth tube. Furthermore, in the pipe Nusselt number Nui ratio and the friction coefficient fi ratio, (1), (2), and (3) are characteristics when the Reynolds number Re is 3000, 2000, and 1000, respectively. That is, for example, when the Reynolds number Re is 3000, the ratio of the in-tube Nusselt number to the smooth tube (reference 1) is the Nui ratio (1), and the ratio of the frictional resistance to the smooth tube (reference 1) is the fi ratio (1). ). The larger the Nusselt number Nui in the tube, the higher the heat transfer performance, and the smaller the friction coefficient fi, the smaller the pressure loss and the better the heat transfer tube.

本発明の比較例2〜7は、管内ヌッセルト数Nui(1)が1.76〜1.81であるのに対し、本願請求項1のみを満たす実施例10〜12は、管内ヌッセルト数Nui(1)が1.88〜2.02、本願請求項3も満たす実施例1〜9は、管内ヌッセルト数Nui(1)が1.99〜2.02である。従って、本発明の実施例1〜12は、比較例2〜7よりも伝熱性能が向上しており、更に、請求項3を満たす実施例1〜9は、請求項1のみを満たす実施例10〜12よりも管内ヌッセルト数の下限値が高く、伝熱性能が高いことが示されている。一方、圧力損失(摩擦係数(1))は、本発明の比較例2〜7が2.87〜3.41、実施例10〜12が2.98〜3.07、実施例1〜9が2.98〜3.02である。従って、本発明の実施例1〜12は、比較例2〜7と、圧力損失は同等レベルであるいえる。よって、本発明の実施例1〜12は比較例2〜7と圧力損失は同程度であるのに対し、伝熱性能が比較例2〜7よりも著しく高い。一方,比較例1は、管内ヌッセルト数(1)が2.83と高く、実施例1〜12よりも伝熱性能が優れているが、比較例1の摩擦抵抗(圧力損失)は、fi比(1)が6.52であり、本発明の実施例(fi比(1)の最大値3.07)よりも極めて高く、比較例1の伝熱管は、使用しにくいことがいえる。他のNui(2)及びfi(2)並びにNui(3)及びfi(3)も同様である。   In Comparative Examples 2 to 7 of the present invention, the in-tube Nusselt number Nui (1) is 1.76 to 1.81, whereas Examples 10 to 12 satisfying only Claim 1 of the present invention are in-pipe Nusselt number Nui ( In Examples 1 to 9 where 1) satisfies 1.88 to 2.02 and Claim 3 of the present application, the in-pipe Nusselt number Nui (1) is 1.99 to 2.02. Therefore, Examples 1-12 of this invention have improved heat-transfer performance rather than Comparative Examples 2-7, Furthermore, Examples 1-9 which satisfy | fill Claim 3 are Examples which satisfy only Claim 1. The lower limit of the tube Nusselt number is higher than 10 to 12, indicating that the heat transfer performance is high. On the other hand, the pressure loss (coefficient of friction (1)) is 2.87 to 3.41 in Comparative Examples 2 to 7 of the present invention, 2.98 to 3.07 in Examples 10 to 12, and in Examples 1 to 9. 2.98 to 3.02. Therefore, it can be said that Examples 1-12 of this invention are comparable with Comparative Examples 2-7 in a pressure loss. Therefore, Examples 1-12 of the present invention have the same pressure loss as Comparative Examples 2-7, while the heat transfer performance is significantly higher than Comparative Examples 2-7. On the other hand, the comparative example 1 has a high Nusselt number (1) in the pipe of 2.83 and is superior in heat transfer performance to Examples 1 to 12, but the frictional resistance (pressure loss) of Comparative Example 1 is fi ratio. (1) is 6.52, which is much higher than the example of the present invention (maximum value of fi ratio (1) 3.07), and it can be said that the heat transfer tube of Comparative Example 1 is difficult to use. The same applies to the other Nui (2) and fi (2) and Nui (3) and fi (3).

一方、基準2の直管状コルゲート管は、実施例1のコイル状コルゲート管に対し、基準2が直管、実施例1が曲げ半径Rcoilが60mmのコイルであること以外は、他の形状因子が同一であるが、両者を対比すると、実施例1は基準2よりも伝熱性能が高く、曲げ部を有することにより、管内を通流する冷媒が突起3にて衝突して分流することによる伝熱性能の向上が得られている。しかしながら、曲げ部を有することにより、実施例1は基準2よりも圧力損失が高い。しかしながら、基準2と比較例1〜7との対比から、伝熱性能の差が小さく、比較例1〜7は、伝熱性能が直管コルゲート管と同程度で、伝熱性能の向上が得られていないことがわかる。   On the other hand, the straight tubular corrugated pipe of the reference 2 is different from the coiled corrugated pipe of the first embodiment in that other reference factors are the straight pipe and the first embodiment is a coil having a bending radius Rcoil of 60 mm. Although the same, in contrast, the heat transfer performance of Example 1 is higher than that of Reference 2, and by having the bent portion, the refrigerant flowing through the pipe collides with the protrusion 3 and is transferred. Improved thermal performance has been obtained. However, the pressure loss of Example 1 is higher than that of Reference 2 due to the bent portion. However, the difference between the heat transfer performance is small from the comparison between Standard 2 and Comparative Examples 1 to 7, and Comparative Examples 1 to 7 have the same heat transfer performance as that of the straight corrugated pipe, and the improvement of the heat transfer performance is obtained. You can see that it is not.

本発明は、低レイノルズ数の流体が流れる用途の伝熱管として、この低レイノルズ数の範囲で、圧力損失の増大を抑制しつつ、伝熱性能を著しく高めることができるため、極めて有益である。   INDUSTRIAL APPLICABILITY The present invention is extremely useful as a heat transfer tube for applications in which a fluid with a low Reynolds number flows, because heat transfer performance can be remarkably enhanced while suppressing an increase in pressure loss in the range of the low Reynolds number.

1:伝熱管、2:コルゲート溝、3:突起、4:凹部、15:伝熱管 1: Heat transfer tube, 2: Corrugated groove, 3: Protrusion, 4: Recess, 15: Heat transfer tube

Claims (3)

管外面に溝が螺旋状に形成され、前記溝に対応して管内面に突起が形成され、前記管内面の前記突起間に前記突起先端よりもDcだけ深い凹部が形成されたコルゲート管を半径Rcoilで円形コイル状に曲げ加工されたものからなり、
管内に単相流流体をレイノズル数3000以下で流し、この単相流流体と、管外の流体、物質又は輻射熱との間で、熱交換を行う管内単相流用伝熱管において、
管外径ODが6乃至20mm、管内径IDが5乃至19mmであり、
前記溝の管軸方向におけるピッチPcが、15乃至25mmであり、
前記曲げの半径Rcoilが48乃至82mmであることを特徴とする管内単相流用伝熱管。
Grooves are formed spirally outside the tube surface, the projections on the inner surface corresponding to the groove is formed, the corrugated tube Dc only deeper recess than the projecting tip is formed between the projections of the inner surface radius It is made of Rcoil bent into a circular coil shape ,
In a heat transfer tube for a single-phase flow in a pipe that flows a single-phase flow fluid in a pipe with a lay nozzle number of 3000 or less and performs heat exchange between the single-phase flow fluid and a fluid, substance, or radiant heat outside the pipe.
The tube outer diameter OD is 6 to 20 mm, the tube inner diameter ID is 5 to 19 mm,
The pitch Pc in the tube axis direction of the groove is 15 to 25 mm,
A heat transfer tube for single-phase flow in a tube, wherein the bending radius Rcoil is 48 to 82 mm.
前記コルゲート管の材質が、銅又は銅合金からなることを特徴とする請求項1に記載の管内単相流用伝熱管。 The in-tube single-phase flow heat transfer tube according to claim 1, wherein the corrugated tube is made of copper or a copper alloy. 前記管内面の前記凹部の深さDcは、Dc/IDが、0.051乃至0.097を満たすものであることを特徴とする請求項1又は2に記載の管内単相流用伝熱管。 The in-tube single-phase flow heat transfer tube according to claim 1 or 2, wherein the depth Dc of the recess on the inner surface of the tube satisfies Dc / ID of 0.051 to 0.097.
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