JPH07104041B2 - Heat pipe type water heater with high temperature heat storage - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot water supply device for providing hot water by supplying heat of a heat storage body to water via a heat pipe, and particularly to a heat pipe type heat storage body using a heat storage body having a high heat storage temperature. The present invention relates to a hot water supply device.

2. Description of the Related Art A water heater used in a small-scale facility such as a general household is required to be small in size and to have a low running cost in addition to quickly obtaining hot water of a necessary and sufficient temperature. Be done. Therefore, in the hot water supply device of the type that heats water with an electric heater or gas burner, there is a problem that the time required for hot water supply such as opening the faucet cock until the actual hot water supply is long, resulting in lack of quickness of hot water supply. In addition, there is also a disadvantage that inexpensive late-night power cannot be used when an electric heater is used as a heat source. On the other hand, in a device equipped with a hot water storage tank, hot water can be obtained at the same time when the faucet cock is opened in order to constantly store hot water of a predetermined temperature, and inexpensive midnight power can also be used. On the other hand, since a hot water storage tank with a large capacity is required, there is a problem that the device becomes large. Therefore, the present applicants connect the heat storage body and the heat exchanger with a heat pipe, and convey the heat stored in the heat storage body to the heat exchanger through the heat pipe according to the request for hot water supply, and heat the water here. We have already proposed a device configured to obtain hot water.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, as a heat pipe for carrying the heat of the heat storage body to the heat exchanger in the device according to the above-mentioned applicant's proposal, the temperature of the hot water to be obtained is at most about 80 ° C. Alternatively, a condensable fluid similar to this is used as the working fluid. Further, as the heat storage body, in order to miniaturize the device, it is desirable that the heat storage amount per unit volume is as large as possible, and accordingly the heat storage temperature becomes high.
Therefore, in the heat receiving part of the heat pipe, that is, in the part that contacts the heat storage body so that heat can be transferred, heat is applied from the outside to the working fluid at a temperature considerably higher than the boiling point of the working fluid, but the droplets of the working fluid come into contact with it. When the inner surface temperature of the heat pipe to be heated is such a high temperature, the Leidenfrost phenomenon may occur and the evaporation of the working fluid may become slow.
That is, the internal temperature of the heat pipe is lower than the temperature of the working fluid.
When the temperature rises by about 300 ° C, the first working fluid droplets that come into contact with the inner surface of the heat pipe instantaneously evaporate, and the vapor separates the droplets from the inner surface of the heat pipe to transfer heat to the droplets. It will be hindered and as a result it will take a considerable amount of time for all the droplets to completely vaporize. This is a phenomenon called the Leidenfrost phenomenon, and when such a phenomenon occurs, there is a disadvantage that the heat transport capacity of the heat pipe is reduced and hot water cannot be obtained at a necessary and sufficient speed.

In order to eliminate such inconvenience, it is conceivable to use a heat pipe that uses a high boiling point mercury or potassium as a working fluid, but such a heat pipe is expensive and requires considerable handling. It is not suitable for water heaters used in small-scale facilities such as general households because it requires water.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hot water supply apparatus that can quickly supply hot water even if the heat storage temperature is increased and that is small and inexpensive.

Means for Solving the Problems The present invention, in order to achieve the above object, an evaporation part of a heat pipe in which a condensable fluid is sealed as a working fluid in a hermetically sealed container in which a non-condensable gas is degassed, In a heat pipe type hot water supply device, which is in contact with a high-temperature heat storage body so that heat can be transferred, and the condensing part of the heat pipe is a heat exchange part for performing heat exchange with water, in the high-temperature heat storage part of the heat pipe. It is characterized in that a protrusion extending inwardly in a needle shape is provided on the inner surface of the evaporating portion which is in contact with and capable of exchanging heat.

Action In the device of the present invention, the heat of vaporization of the heat pipe comes into contact with the heat storage body whose temperature is considerably higher than the temperature of the working fluid, and the condensing part of the heat pipe serves as a heat exchanging part for exchanging heat with water. Therefore, the working fluid evaporates at the end on the heat storage body side, the steam flows to the heat exchange section side, and then radiates heat and condenses. That is, the heat of the heat storage body is carried to the heat exchange section via the heat pipe, and the water is heated to become hot water. In that case, the temperature of the heat storage body is higher than the temperature of the working fluid, so that the temperature of the inner surface of the heat pipe becomes higher than the temperature of the working fluid, so that the droplets of the working fluid contacting the inner surface of the heat pipe immediately evaporate. Instead, it is ejected from the inner surface of the heat pipe in a droplet state, but the working fluid in a droplet state is formed on the inner surface side of the heat pipe because a protrusion extending inward like a needle is arranged. Contacts the needle-shaped protrusions, takes heat from the needle-shaped protrusions, and at the same time is divided by the protrusions, so that evaporation is accelerated. In particular, since the protrusion has a small heat capacity, it does not always reach a temperature as high as that of the inner surface of the heat pipe, and therefore, the Leidenfrost phenomenon does not easily occur here, so that evaporation of the working fluid in a droplet state is promoted also in this respect.

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of the present invention, which is an example in which a loop type heat pipe 1 is used. That is, the evaporation unit 2 is formed in a grid shape as a whole by disposing a plurality of pipes 5 in parallel with each other between the upper header pipe 3 and the lower header pipe 4, and the condensing unit 6 is also similarly formed in the upper header pipe. A plurality of pipes 9 are arranged in parallel with each other between the lower header pipe 8 and the lower header pipe 8 and are formed in a lattice shape as a whole. The evaporating part 2 is arranged at a position lower than the condensing part 6, and the upper header pipes 3, 7 are connected to each other by the steam pipe 1.
Further, the lower header pipes 4 and 8 are communicated with each other by the liquid return pipe 11, and a liquid reservoir 12 is provided in the middle of the liquid return pipe 11 and a flow rate adjusting valve 13 is provided below the liquid reservoir 12. Has been done. In this way, in the inside of the pipe line formed in a loop shape as a whole, a condensable fluid having a boiling point of about 100 ° C. such as water is vacuum-degassed from a non-condensable gas such as air. It is enclosed as.

The entire evaporation unit 2 described above is embedded in a high-temperature heat storage body 16 covered with a heat insulating material 15 so that the high-temperature heat storage body 16 is covered.
To be able to transfer heat. Where high temperature heat storage
Reference numeral 16 is for storing heat at a temperature higher than the boiling point of the working fluid 14, and is specifically cast iron, steel, ceramics, rock, etc., and stores heat at a temperature of about 300 to 500 ° C.

Further, inside the pipe 5 in the above-mentioned evaporation unit 2, as shown in FIGS. 2 and 3, needle-like protrusions are directed inward.
17 are provided. As a specific means for providing the needle-like protrusions 17 as described above, for example, a wire mesh 18 acting as a wick is arranged along the inner surface of the pipe 5, and the wires forming the wire mesh 18 are partially formed. Cut into
Bending the cut part of the wire inward to make it protrude,
Alternatively, it is possible to apply means such as cutting the wire mesh 18 over a certain area and bending the cut-out portion inward. As such a wire net 18, a wire having a diameter of 1 mm and a mesh of about 10 mesh can be used.

On the other hand, the condensing part 6 is surrounded in a watertight state by a jacket 21 having a water supply port 19 and a tap hole 20, and a heat exchange part for exchanging heat with water is formed here.

In the hot water supply device having the above-mentioned configuration, the heat storage body 16 is, for example, 50
When the temperature is raised to about 0 ° C. to store heat, and when the inside of the jacket 21 is supplied with water, the flow rate adjusting valve 13 is opened and the working fluid 14 in the liquid phase is supplied to the evaporator 2. The working fluid 14 is fed into the header tubes 3 and 4 and the pipe 5 by the head pressure and the capillary pressure of the wire mesh 18. The working fluid 14 has the evaporator 2 heated by the heat storage body 16, so that the heat storage body 1 is passed through the header walls 3 and 4 of the heat pipe 1 and the pipe wall of the pipe 5.
Heated by 6. In that case, since the temperature of the heat storage body 16 is significantly higher than the boiling point of the working fluid 14, the working fluid 14 in the liquid phase contacting with the inner wall surface of the heat pipe 1 does not immediately evaporate but is liquid by the Leidenfrost phenomenon. A situation occurs in which the droplets are splashed inward from the inner wall surface of the heat pipe 1. As shown in FIG. 4, the ejected liquid droplets penetrate the needle-like projections 17 and are stuck in the needle-like projections 17. The needle-like projections 17 are also formed in the heat pipe 1.
Since it is heated by the heat transfer from the inner wall surface of the liquid droplet, the liquid droplet stuck in this is heated from the inside thereof, and as a result, the evaporation of the liquid droplet of the working fluid 14 is promoted. The heat of the needle-shaped protrusions 17 is removed by contacting the needle-shaped protrusions 17 and evaporating the droplets of the working fluid 14, but the needle-shaped protrusions 17 have a small volume and a small heat capacity. The temperature of the needle-like protrusions 17 is maintained at a lower temperature than other parts such as the inner wall surface of the heat pipe 1 due to continuous contact of the droplets and evaporation thereof, so that the Leidenfrost phenomenon occurs in the needle-like protrusions 17. This is prevented, and the evaporation of the working fluid 14 on the needle-shaped protrusions 17 becomes active.
Further, since the droplets of the working fluid 14 that have crossed the needle-like protrusions 17 are divided by the needle-like protrusions 17 into small droplets, evaporation of the working fluid 14 is promoted also in this respect.

The working fluid 14 vaporized as described above flows through the steam pipe 10 to the condensing unit 7, where heat is deprived of the water in the jacket 21 and condensed, and at the same time, the water is heated to become hot water. Then, the liquefied working fluid 14 passes through the liquid return pipe 11 and the liquid reservoir
Return to 12.

Here, a test example and a comparative example performed by the present inventors to confirm the effect will be shown.

<< Test example >> Inside the part that becomes the evaporation part of the sealed pipe that constitutes the heat pipe, a wire mesh of 10 mesh with a wire diameter of about 1 mm is arranged along the inner surface, and the wire is at multiple locations. Then, it was cut with and protruded inward to form needle-like protrusions. Water was enclosed as a working fluid to form a heat pipe. When the other end of the heat pipe, which is the condensation part, is cooled with water,
Heated to 500 ° C. When the transition of the temperature of the working fluid vapor in the heat pipe immediately after the start of heating was examined, it took about 10 seconds.
It became 120 ℃ at 100 ℃ for about 15 seconds and became stable thereafter.

<< Comparative Example >> Performing the same operation as the above-mentioned test using a wire mesh and a general heat pipe without needle-shaped projections in the above-mentioned test example, and examining the transition of the temperature of the working fluid vapor in the heat pipe, 50 ℃ in about 10 seconds, 55 ℃ in about 15 seconds, 1 in about 300 seconds
It reached 00 ℃.

From these test examples and comparative examples, it was confirmed that the so-called rising of the heat transport start of the heat pipe can be improved by providing the needle-shaped protrusions or similar protrusions inside the evaporation portion of the heat pipe.

Therefore, in the hot water supply device having the above-described configuration, heat is rapidly and largely transferred from the evaporator 2 in contact with the heat storage body 16 to the condenser 6 in contact with the heat exchanger, so that hot water of a necessary and sufficient temperature can be supplied to the hot water supply. Can be supplied promptly.

In addition, in the above-mentioned embodiment, an example using a loop type heat pipe has been described, but the heat pipe in the present invention is not limited to the loop type.

EFFECTS OF THE INVENTION As is clear from the above description, in the hot water supply device of the present invention, the working fluid can be quickly evaporated even if the temperature of the heat storage body is higher than the temperature of the working fluid, so that the responsiveness is good. A water heater can be obtained. In other words, since the heat storage temperature can be increased without impairing the responsiveness, the heat storage body can be downsized, and thus the entire device can be downsized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment of the present invention,
FIG. 2 is a partial sectional view of the evaporation portion, and FIG. 3 is II of FIG.
FIG. 4 is a cross-sectional view taken along the line I-III, and FIG. 4 is a schematic diagram for explaining a state in which a droplet of a working fluid is in contact with a needle-shaped protrusion. 1 ... Heat pipe, 2 ... Evaporator, 6 ... Condenser, 10
…… Steam pipe, 11 …… Liquid return pipe, 14 …… Working fluid, 16 ……
High-temperature heat storage body, 17 ... Needle-like projections, 21 ... Jacket.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Muneo Okada 1-3-3 Uchisaiwaicho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Inc. (72) Kiyoki Ishiya 8-7 Iwazono-cho, Ashiya-shi, Hyogo ( 72) Inventor Ryuichi Okiayu 1-5-1, Kiba, Koto-ku, Tokyo Within Fujikura Electric Line Co., Ltd. (72) Inventor Masataka Mochizuki 1-5-1, Kiba, Koto-ku, Tokyo Within Fujikura Electric Line Co., Ltd. (56) References JP-A-60-174452 (JP, A) Actual development 61-161555 (JP, U) JP-B 50-7290 (JP, B1) JP-56-50306 (JP, Y2)

Claims (1)

[Claims] 1. An evaporation part of a heat pipe in which a condensable fluid is sealed as a working fluid in a hermetically sealed container from which non-condensable gas has been deaerated, is brought into contact with a high-temperature heat storage body in a heat transferable manner, and the heat pipe. In the heat pipe type hot water supply device which is a heat exchange part for exchanging heat between the condensing part and water, in the inner surface of the evaporating part of the heat pipe, which is in contact with the high temperature heat storage body in a heat transferable manner, A heat pipe type hot water supply device having a high temperature heat storage body, characterized in that a protrusion extending in a needle shape is provided.