JPH0680381B2 - Defrosting method with electric field - Google Patents
Defrosting method with electric fieldInfo
- Publication number
- JPH0680381B2 JPH0680381B2 JP2140227A JP14022790A JPH0680381B2 JP H0680381 B2 JPH0680381 B2 JP H0680381B2 JP 2140227 A JP2140227 A JP 2140227A JP 14022790 A JP14022790 A JP 14022790A JP H0680381 B2 JPH0680381 B2 JP H0680381B2
- Authority
- JP
- Japan
- Prior art keywords
- heat transfer
- electric field
- frost
- crystals
- needle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Defrosting Systems (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、寒冷地におけるヒートポンプ室外機等の熱交
換器、あるいはその他の伝熱面の表面に霜が付着するの
を抑制するための電場により除霜方法に関するものであ
る。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electric field for suppressing the adhesion of frost to the surface of a heat exchanger such as a heat pump outdoor unit in a cold region, or other heat transfer surfaces. Is related to the defrosting method.
［従来の技術］ 伝熱面の表面温度をある程度以下にすると、伝熱面には
霜が生成、成長してくる。このような着霜現象は、空気
を熱源とするヒートポンプなどの熱交換器においてしば
しば観察される現象であるが、着霜が発生すると熱や空
気流動の抵抗が増大し、熱伝達の抵抗となるため、シス
テムの効率が著しく低下する。[Prior Art] When the surface temperature of the heat transfer surface is lowered to a certain level or less, frost is generated and grows on the heat transfer surface. Such a frosting phenomenon is a phenomenon often observed in heat exchangers such as heat pumps that use air as a heat source, but when frosting occurs, the resistance of heat and air flow increases and becomes a resistance of heat transfer. Therefore, the efficiency of the system is significantly reduced.
したがって、この着霜現象を能動的に制御することがで
きれば、システムの高効率化を達成することが可能にな
るが、霜の生成・成長に対する制御は、従来から一般的
に行われておらず、通常は、着霜が発生し、ある程度経
過して着霜量が増大すると、装置を止めて除霜運転に移
るという方法を用いているに過ぎない。しかしながら、
このような除霜運転をを行うことは、装置の効率的な稼
働を阻害することになる。Therefore, if this frost formation phenomenon can be actively controlled, it is possible to achieve high efficiency of the system, but control for the generation and growth of frost has not been generally performed conventionally. Normally, only a method is used in which, when frost occurs and the amount of frost increases after a certain amount of time, the device is stopped and the defrosting operation is started. However,
Performing such defrosting operation impedes efficient operation of the apparatus.
［発明が解決しようとする課題］ 誘電性物質に電場を付与することにより、物質内に電磁
力が加わり、伝熱性能が大きく変化することはよく知ら
れた現象であり、特に最近では沸騰、凝縮における伝熱
促進との関連で注目されている。これは、誘電性物質内
では電流が流れないため、与えるエネルギーが少なくて
大きな伝熱促進効果が期待できるからである。[Problems to be Solved by the Invention] It is a well-known phenomenon that when an electric field is applied to a dielectric substance, electromagnetic force is applied to the substance and the heat transfer performance is greatly changed. It has attracted attention in connection with the promotion of heat transfer in condensation. This is because a current does not flow in the dielectric substance, so that a small amount of energy is applied and a large heat transfer promotion effect can be expected.
一方、着霜現象で重要となる水分子が誘電性物質である
ことを考えると、着霜現象に対しても電場は何らかの影
響を与えるものと考えられる。本発明者は、このような
観点から、着霜伝熱面付近に電場を作り、電場が着霜現
象にどのような影響を与えるかを実験的に調べた結果、
高電圧の印加により霜が伝熱面から取り去られることを
見いだした。On the other hand, considering that water molecules, which are important in the frost formation phenomenon, are dielectric substances, the electric field is considered to have some influence on the frost formation phenomenon. From such a viewpoint, the present inventor creates an electric field near the frost heat transfer surface, and experimentally examines how the electric field affects the frost formation phenomenon.
It has been found that the application of high voltage removes frost from the heat transfer surface.
本発明は、このような知見に基づくものであり、したが
って、その技術的課題は電場を利用して伝熱面の除霜を
容易に実施可能にすることにある。The present invention is based on such knowledge, and therefore, a technical problem thereof is to enable defrosting of a heat transfer surface easily by utilizing an electric field.
［課題を解決するための手段］ 上記課題を解決するための本発明の除霜方法は、除霜す
べき伝熱面とそれに対向して配置した電極との間に高電
圧を印加し、電場を形成することを特徴とするものであ
る。[Means for Solving the Problems] A defrosting method of the present invention for solving the above problems applies a high voltage between a heat transfer surface to be defrosted and an electrode arranged so as to face the electric field. Is formed.
さらに具体的に説明すると、本発明の除霜方法は、熱交
換器あるいはその他の各種伝熱面であって、表面に霜が
付着するのを抑制する必要がある面を対象とし、その除
霜伝熱面には、望ましくはそれと平行に電極を設置し
て、伝熱面と電極間に高電圧を印加し、電場を形成させ
る。上記高電圧は、一般的には、10〜20kV/cm程度が適
しているが、条件によってはこの範囲を逸脱してもよ
い。More specifically, the defrosting method of the present invention is directed to a heat exchanger or other various heat transfer surfaces, which is required to suppress adhesion of frost to the surface. An electrode is installed on the heat transfer surface, preferably parallel to the heat transfer surface, and a high voltage is applied between the heat transfer surface and the electrode to form an electric field. Generally, the high voltage is preferably about 10 to 20 kV / cm, but may deviate from this range depending on the conditions.
［作用］ 電極との間に高電圧を印加した伝熱面に着霜が発生する
と、電極間で霜が誘電分極を引き起こす。この作用によ
り、霜層表面に初期に発生する針状晶の成長がますます
促進されるが、最終的には、その針状晶が電極に引かれ
て、伝熱面から離脱する。[Operation] When frost forms on the heat transfer surface to which a high voltage is applied between the electrodes, the frost causes dielectric polarization between the electrodes. This action further promotes the growth of needle-like crystals that are initially generated on the surface of the frost layer, but eventually the needle-like crystals are attracted to the electrode and detach from the heat transfer surface.
したがって、結果的に、完全に除霜することはできない
が、上記高電圧の印加がすぐれた除霜効果を示し、除霜
運転に入る時間すなわち装置の稼働時間を伸ばすことが
可能となる。Therefore, as a result, it is not possible to completely defrost, but the application of the high voltage exhibits an excellent defrosting effect, and it is possible to extend the time to enter the defrosting operation, that is, the operating time of the device.
［実施例］ 以下に本発明の基礎となった実験例について詳述する。[Examples] Hereinafter, experimental examples which are the basis of the present invention will be described in detail.
第１図は、除霜実験に用いた装置の概要を示すもので、
厚さ20mmのアクリル樹脂により内部の着霜現象を可視化
した実験容器１内に、先端面を伝熱面３とする直径20mm
のステンレス鋼製円柱状の伝熱ブロック２を配置し、そ
の背面に冷媒供給装置４から約−40℃に冷却されたブラ
インを流して冷却した。伝熱面温度および熱流束は伝熱
ブロック中心軸上に３本の銅・コンスタンタン熱電対５
を埋め込み測定した。側面を断熱するため、伝熱ブロッ
ク２は直径100mmのアクリル製断熱筒６内に取付け、伝
熱面３が水平上向き面となるように実験容器１内に設置
した。高電圧発生装置８に接続した電極７としては、第
２図に示すような線径0.5mm、ピッチ2mmのメッシュ電極
を用い、それを伝熱面３から10mm離して設置し、均一電
場となるようにした。また、容器内部の圧力を測定する
ための圧力計11、および容器内の湿度を測定するための
鏡面冷却式露点計12を、それぞれ容器上部に設置した。Figure 1 shows the outline of the equipment used for the defrosting experiment.
20mm diameter with the end surface as the heat transfer surface 3 in the experimental container 1 in which the internal frost phenomenon was visualized by the acrylic resin with the thickness of 20mm
The cylindrical heat transfer block 2 made of stainless steel was placed, and brine cooled to about -40 ° C. was flowed from the refrigerant supply device 4 to the back surface of the heat transfer block 2 for cooling. The heat transfer surface temperature and heat flux are 3 copper-constantan thermocouples 5 on the center axis of the heat transfer block.
Was embedded and measured. In order to insulate the side surface, the heat transfer block 2 was mounted in an acrylic heat insulating cylinder 6 having a diameter of 100 mm, and was installed in the experimental container 1 so that the heat transfer surface 3 was a horizontal upward surface. As the electrode 7 connected to the high voltage generator 8, a mesh electrode having a wire diameter of 0.5 mm and a pitch of 2 mm as shown in FIG. 2 is used, which is placed 10 mm away from the heat transfer surface 3 to form a uniform electric field. I did it. Further, a pressure gauge 11 for measuring the pressure inside the container and a mirror-cooled dew point meter 12 for measuring the humidity inside the container were installed on the upper part of the container.
容器１内の湿度の制御は、まず最初に容器全体を真空ポ
ンプ15により10-2Torr程度まで真空に引き、次に水蒸気
発生装置16より水蒸気を容器内に導いて所定の圧力と
し、最後に空気ボンベ17より空気を導入し、標準大気圧
101.3kPaとすることにより行った。To control the humidity in the container 1, first, the entire container is evacuated to a vacuum of about 10 -2 Torr by the vacuum pump 15, and then steam is guided from the steam generator 16 into the container to a predetermined pressure. Air is introduced from the air cylinder 17 and the standard atmospheric pressure
It was carried out by setting the pressure to 101.3 kPa.
霜層性状の変化は、容器１の側方に配置したハロゲンラ
ンプ18およびスリット19により、容器側面からスリット
光を照射して観察した。The change in the frost layer property was observed by irradiating slit light from the side surface of the container with the halogen lamp 18 and the slit 19 arranged on the side of the container 1.
なお、図中、20はデータレコーダ、21はパーソナルコン
ピュータを示している。実験は、湿度および電場の強さ
を変化させ、霜層性状の変化を測定した。なお、着霜現
象では霜層の発生過程が重要となるため、実験開始後１
時間を観察・測定の対象とした。In the figure, 20 is a data recorder and 21 is a personal computer. In the experiment, changes in humidity and electric field strength were measured, and changes in frost layer properties were measured. In addition, since the frost layer generation process is important in the frost formation phenomenon, 1
The time was observed and measured.
次に、実験の結果について説明する。Next, the results of the experiment will be described.
まず、霜層性状は、電場を印加することにより大きく変
化した。初期湿度約8.5×10-3kg/kgの場合について、電
場を印加しなかった場合と印加した場合（印加電圧10kV
/cm）を比較すると、前者の場合には、最初に針状晶が
発生し、その後、針状晶の間を埋めるように結晶が成長
し、最終的には霜層表面が平坦化してくる。これに対
し、後者の場合には、霜層表面に初期に発生する針状晶
は、電圧印加しない場合と比較して径が小さく、その高
さがより高くまで成長する。また、電圧を印加しないと
針状晶は一本の結晶となってくるが、電圧を印加すると
針状晶の先端が枝別れし、樹枝状晶のようになる。しか
し、30分ほど経過すると、そのような樹枝状晶や針状晶
は現れず、ほぼ着霜面は平面となって成長する。First, the properties of the frost layer changed significantly when an electric field was applied. For an initial humidity of approximately 8.5 × 10 -3 kg / kg, with and without application of an electric field (applied voltage 10 kV
/ cm), in the former case, needle-like crystals are first generated, then the crystals grow to fill the spaces between the needle-like crystals, and finally the surface of the frost layer becomes flat. . On the other hand, in the latter case, the acicular crystals initially generated on the surface of the frost layer have a smaller diameter and grow to a higher height as compared with the case where no voltage is applied. Further, when no voltage is applied, the needle-like crystals become a single crystal, but when a voltage is applied, the tips of the needle-like crystals branch off and become like dendrites. However, after about 30 minutes, such dendrites and acicular crystals did not appear, and the frosted surface grew almost flat.
電場を印加した効果が顕著に現れる実験開始後10分10秒
から５秒間隔で写真撮影して観察した結果、５秒の間に
霜層表面の針状晶が大きく変化することがわかった。ま
た、目視観察を行うとあたかも一瞬のうちに針状晶が消
えるように見えたため、200コマ／秒の高速度ビデオに
よる観察を行ったところ、1/200秒の間に針状晶が電場
の効果により取り去られていることがわかった。As a result of observing the photographs taken at intervals of 5 minutes to 10 minutes and 10 seconds after the start of the experiment, the effect of applying the electric field becomes remarkable, and it was found that the needle-like crystals on the surface of the frost layer significantly changed within 5 seconds. In addition, the visual observation revealed that the needle-shaped crystals disappeared in an instant, so when the high-speed video at 200 frames / second was observed, the needle-shaped crystals appeared in the electric field within 1/200 seconds. It turned out that it was removed by the effect.
一方、湿度が低くなると、このような現象は印加電圧を
15kV/cm程度まで高めても現われず、霜層性状は、針状
晶の発生・成長・消滅をある一定期間（最終的に伝熱面
と周囲との水蒸気濃度勾配がある程度小さくなり、熱的
過冷がなくなるまで、すなわち針状晶を発生させる駆動
力がなくなるまで）繰り返す。On the other hand, when the humidity is low, such a phenomenon can reduce the applied voltage.
It does not appear even if it is increased to about 15 kV / cm, and the frost layer property is the occurrence, growth, and disappearance of needle-shaped crystals for a certain period of time (finally, the water vapor concentration gradient between the heat transfer surface and the surrounding becomes small to some extent Repeat until supercooling is eliminated, that is, until the driving force for generating needle-like crystals is eliminated.
これらの観察結果から、電場は霜の鉛直方向の成長に対
して大きな効果を持ち、すなわち、電極との間に高電圧
を印加した伝熱面に着霜が発生すると、霜が誘電分極を
引き起こし、この作用により針状晶はますますその成長
が促進されるが、最終的には、その針状晶が電極に引か
れて、伝熱面から離脱する。From these observations, the electric field has a large effect on the vertical growth of frost, that is, when frost forms on the heat transfer surface to which a high voltage is applied between the frost and the electrode, the frost causes dielectric polarization. This action further promotes the growth of needle-like crystals, but eventually the needle-like crystals are pulled by the electrode and detach from the heat transfer surface.
したがって、結果的に、完全に除霜することはできない
が、上記高電圧の印加がすぐれた除霜効果を示し、除霜
運転に入る時間すなわち装置の稼働時間を伸ばすことが
可能となる。Therefore, as a result, it is not possible to completely defrost, but the application of the high voltage exhibits an excellent defrosting effect, and it is possible to extend the time to enter the defrosting operation, that is, the operating time of the device.
［発明の効果］ 以上に詳述したように、本発明の除霜方法によれば、電
場の形成により霜層発生期における針状晶が発生・成長
・消滅を繰り返すため、その利用により伝熱面の除霜を
簡易に実現することができる。[Effects of the Invention] As described in detail above, according to the defrosting method of the present invention, needle crystals are repeatedly generated, grown, and disappeared in the frost layer generation period due to the formation of an electric field, and therefore, heat transfer by the use thereof. Defrosting of the surface can be easily realized.
第１図は本発明の除霜方法の実験に用いた装置の構成
図、第２図はその装置において用いた電極の平面図であ
る。 ３……伝熱面、７……電極。FIG. 1 is a configuration diagram of an apparatus used for an experiment of the defrosting method of the present invention, and FIG. 2 is a plan view of electrodes used in the apparatus. 3 ... Heat transfer surface, 7 ... Electrode.
Claims (1)
た電極との間に高電圧を印加し、電場を形成することを
特徴とする電場による除霜方法。1. A defrosting method using an electric field, which comprises applying a high voltage between a heat transfer surface to be defrosted and an electrode arranged opposite thereto to form an electric field.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2140227A JPH0680381B2 (en) | 1990-05-30 | 1990-05-30 | Defrosting method with electric field |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2140227A JPH0680381B2 (en) | 1990-05-30 | 1990-05-30 | Defrosting method with electric field |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0432672A JPH0432672A (en) | 1992-02-04 |
| JPH0680381B2 true JPH0680381B2 (en) | 1994-10-12 |
Family
ID=15263866
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2140227A Expired - Lifetime JPH0680381B2 (en) | 1990-05-30 | 1990-05-30 | Defrosting method with electric field |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0680381B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024021904A1 (en) * | 2022-07-29 | 2024-02-01 | 广东美的制冷设备有限公司 | Heat exchanger assembly, air conditioner outdoor unit, air conditioner indoor unit, air conditioner and antifrost control method |
-
1990
- 1990-05-30 JP JP2140227A patent/JPH0680381B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0432672A (en) | 1992-02-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |