JPH0461195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pump that heats and simultaneously pumps a liquid by simply heating the liquid without using any external mechanical drive.

(Prior art) Heat-driven pumps have been known as pumps that do not require external power such as motors or compressors, and can generate pumping action simply by heating the liquid (Magazine Soda and Chlorine 1983, No. 2, p. 64) P77
(See "About heat-driven pumps").

That is, as shown in FIG. 15, this heat-driven pump consists of a heating section consisting of a suction pipe 1, a discharge pipe 2, and two heating pipes 3 and 4 provided between these pipes. The suction pipe 1 and the discharge pipe 2 are each equipped with check valves 5 and 6 for flowing liquid in one direction.

The inside of each tube 1, 2, 3, 4 is filled with liquid, and when the heating section is heated from the outside, the liquid inside boils and bubbles are generated and grow inside the tube. As a result, liquid corresponding to the volume of the bubbles passes through the check valve 5 and is discharged from the discharge pipe 2. Thereafter, the grown bubbles eventually cool down and begin to contract, which lowers the pressure inside the heating tube, and the cooled liquid that has passed through the check valve 6 from the suction tube 1 flows into the tube. By repeating this process, it works as a pump.

However, this heat-driven pump has the following problems because the heating section is a pipe and is not thermally isolated from the suction pipe 1 and the discharge pipe 2. In other words, there is a loss of energy input into the pump, resulting in poor efficiency. In addition, it is structurally complicated as it requires two heating tubes, one above and the other. Furthermore, if the amount of heating is small, it will not work efficiently.

(Object of the Invention) The present invention solves the drawbacks of the conventional heat-driven pump.The purpose of the present invention is to generate and grow bubbles reliably with a small amount of heating, and to ensure the pump action. To provide a thermally driven pump.

(Structure of the Invention) According to the present invention, a heat-driven pump includes a heating section made of a material with high thermal conductivity and having a recess inside, in a single tube made of a material with low thermal conductivity. A flapper type check valve is provided at each end of the pipe, and a suction part is disposed in the pipe adjacent to the heating part.

The inside of the tube is filled with liquid, and when the heating part is heated from the outside, a bubble is generated from the tip of the internal recess, and the inside of the heating part and the liquid discharge side are made of materials with low thermal conductivity. It grows inside the tube. The liquid displaced thereby passes through the discharge side check valve and is discharged to the outside of the pump. On the other hand, the air bubbles that have grown inside the pipe cool and contract, and when the inside of the pump becomes negative pressure relative to the outside, the suction side check valve opens, and cold liquid flows in from the outside and fills the inside of the pump again. Repeat.

(Example) Examples of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, the heat-driven pump recess is connected between a pipe G ₁ and a pipe G ₂ made of a material with low thermal conductivity, and has a conical recess P inside.
have. The heating part is made of a material with high thermal conductivity, such as copper, for example. The solid angle of the recess P is smaller than the wetting angle between the liquid used and the material of the recess P. On the other hand, check valves are installed at both ends of pipes G ₁ and G ₂ .
CV ₁ and CV ₂ are installed. The check valves CV ₁ and CV ₂ each consist of a flapper F made of a rubber sheet or metal foil inside, a diagonal valve seat surface T that receives it, and an O-ring S for sealing provided on this valve seat surface. It's summery. The flapper F is pressed against the O-ring S with a weak force by an integral leaf spring F' at its base. Also, between the pipe _G1 and the heating part B, a suction part I made of a material with low thermal conductivity and well wetted with the liquid to be used is installed in the pipe _G1.In this example, the suction part is Consists of tapered holes.

As a modification, the heating section B may have a conical cavity R at the apex of the conical recess P, as shown in FIG. The check valves CV ₁ and CV ₂ also have a flapper F in the form of a disc and are placed in the retainer D at right angles to the flow, as shown in Figures 4 and 5, and are left free with respect to the valve seat. It may be a solid piece, or it may be one that is pressed against the valve seat with a weak spring. The suction portion I may also have a dividing hole made of a cross-shaped piece, as shown in FIGS. 6 and 7. Usable liquids include water and various refrigerants (R-11,
R-12, ammonia, etc.) liquid metals, low melting metals, etc.
Anything that evaporates and leaves no solids behind is fine.

Next, FIGS. 8 to 13, and 16 to 1
The operation of the pump of this embodiment will be explained with reference to the operation explanatory diagram of FIG.

First, fill the pump with the liquid to be pumped. At this time, since the solid angle of the recess P is smaller than the contact angle between the material of the recess and the liquid, the liquid cannot completely wet the recess P, and air bubbles N remain at the tip of the recess P of the heating section B ( Figure 8). Next, when heating B is heated, the liquid covering the bubble N is heated, and when the pressure inside the bubble exceeds the saturation temperature, evaporation occurs from the liquid side to the bubble side from the interface between the bubble and the liquid, and the bubble N starts to grow ( Figure 9).

As a result, the pressure inside the pump rises slightly from the outside of the check valve CV ₂ , and the check valve CV ₂ opens. Check valve CV ₁ is closed. As the bubbles grow, the volume of liquid is pumped to the outside through the check valve CV ₂ . As the bubbles grow toward the pipe _G2 side, their surface area increases, and when the amount of evaporation from the surrounding liquid to the heating section B and the amount of vapor reduction on the surface are balanced, the bubbles stop growing. Growth stops (Figure 10).

This state is unstable and eventually the amount of condensation exceeds the amount and the bubbles begin to contract. Then check valve CV ₂ closes and the check valve
CV ₁ opens. At this time, suction part I has a hole whose inner diameter decreases toward the heating part, so a pump action works to suck the interface between the bubbles and liquid into the heating part by capillary force, and the interface closes. When the bubbles reach the entrance of the heating section, the area around them is cooled and the bubbles begin to contract further (Figure 11). Eventually, a strong negative pressure is generated due to the drop in bubble temperature, and cold liquid flows into the pump from the outside through the check valve CV ₁ (Fig. 12).

This process involves the contraction of a bubble, the inflow of cold liquid, the lowering of the temperature of the bubble, the generation of negative pressure, and the inflow of cold liquid.The bubble collapses in an instant, and an amount of liquid corresponding to its volume is replenished from the outside. Ru. At this time, like the first time, the liquid cannot wet the tip of the recess, leaving a nucleus for the next bubble growth. Further, heating of the liquid is performed at the gas-liquid interface during the bubble growth process.

The above explanation applies to combinations where the contact angle between the recess material and the liquid is relatively large. For example, when the recess is made of copper and the liquid is R-11, the contact angle is
The angle is around 30°.

Next, a case will be described in which a combination of a liquid and a material for the heating part is such that the liquid well wets the recessed part of the heating part, such as a case where the heating part is made of copper and the liquid is water. In this case, the contact angle between the two is almost zero. Therefore, the recesses are filled with liquid and no air bubbles can exist as described above.

However, due to another effect of the recesses, bubbles can be generated more quickly than in the conventional method. That is, FIG. 16 is a cross-sectional view showing a state in which the recess P is filled with liquid, and the heating part is at a temperature T _S sufficiently higher than the saturation temperature of the liquid,
This is the state when cold liquid is introduced from the outside and the recess P is completely filled with liquid, and a short time has passed. At this time, heat is transmitted from the recess wall surface R to the liquid by conduction in the perpendicular direction, so the isotherms T ₁ , T ₂ ,
T ₃ and T ₄ can be assumed. Therefore, the temperature increases toward the tip of the recess P. In other words, the liquid in the recess, which is uniformly heated from the surroundings, rises in temperature faster at the tip of the recess where the distance between the peripheries is shorter than the liquid at the inlet.

Therefore, if the isotherm T ₄ is equal to the saturation temperature of the liquid, the liquid at the tip becomes supersaturated and bubbles can be generated at any time. Note that T ₀ is the temperature of the cold liquid introduced from the outside.

Furthermore, since the time from when the recesses are filled with liquid to when bubbles are generated is relatively short, the influence of convection is considered to be negligible.

FIG. 17 shows the tip wall surface R of the recess in such a state.
A certain point becomes a nucleus of steam generation, and very small bubbles N are generated. This shows a state in which bubbles N grow due to evaporation _ST from the surrounding supersaturated liquid to the generated bubbles. Figure 18 shows the state in which the bubble N has grown further. In this figure, B _SL indicates the gas-liquid interface, through which evaporation from the liquid to the bubble N occurs.
_ST is performed.

(Effects of the invention) Since it operates through the process described above, it has the following advantages compared to the conventional system.

In conventional pumps, the heating section is simply constructed of metal pipes, so heat leaks through the pipes, and a considerable amount of heat is required to produce sufficient pumping action. The present invention is insulated with a pipe with low thermal conductivity, and has a conical concave portion inside, so bubble nuclei are always present or bubbles are generated very quickly, so it takes time for bubble generation and growth. Since it is short and does not transfer excess heat to the liquid, it is possible to generate one bubble with a smaller heating amount and heating degree.

To explain in more detail, the energy required to discharge the same volume of liquid will be compared between the conventional tubular heating section and the recessed section of the present invention. The energy expended simply to generate the same volume of bubbles is the same in both cases. However, the temperature of the liquid discharged thereby differs significantly between the two. In other words, in the case of the present invention, since there is a concave part in the heating part, either bubbles exist at the tip, or the temperature of the liquid at the tip rises significantly faster than the liquid in other places, causing bubbles to form and grow. go. Thus,
The time it takes for bubbles to grow becomes shorter, and the liquid in other areas is discharged without heating up much.

On the other hand, in the conventional tubular heating section, bubbles are generated from the wall surface of the tube. Therefore, in order to raise the temperature of all the liquid near the inner circumference of the tube to above the saturation temperature, the temperature must also be raised to near the saturation temperature in the center. It takes a longer time to generate bubbles, and the temperature of the discharged liquid is much higher than in the case of the present invention.

This takes a longer time than when the amount of heating is small, and the temperature of the discharged liquid also rises, making it difficult to shrink the bubbles, which will be described later. Even in a conventional tubular heating section, it is possible to quickly raise the temperature and lower the temperature of the discharged liquid by constricting a part of the tube to the inner diameter of the tip of the recess of the present invention. This is not preferable since it causes significant flow resistance when flowing.

As described above, the conventional pump requires extra energy to raise the temperature of the discharged liquid, and is less efficient as a pump than the pump of the present invention.

Furthermore, when the same energy is input into the heating part, the heating part is thermally insulated as in the present invention, and the conventional one which does not consider insulation at all. Heat escapes into the pipes connected to the pipes, raising the temperature of the liquid inside. On the other hand, in the case of the present invention, since the heating parts are connected by a heat insulating tube, less heat escapes and the temperature is higher, so that more active bubble generation is possible.

Furthermore, there is no need to increase the temperature of the liquid in the pipe connected to the heating section. This is very important in order to reliably deflate the grown bubbles and maintain stable pump operation. In other words, in the case of the present invention, the discharge side pipe connected to the heating section is kept at a low temperature, so the air bubbles that have entered the pipe are cooled down and begin to contract, which creates a negative pressure inside the pump and causes the pump to undergo the contraction process. Create a trigger that leads to On the other hand, in conventional pumps, the heat from the heating section is transmitted to the piping, raising the temperature of the piping, making it difficult for the grown bubbles to contract, and stable pump operation cannot be expected.

The check valve of the present invention is a flapper type and has high pressure sensitivity, so the valve opens at a lower degree of superheat, and can be pulled into the contraction process by sensing the slight pressure at which bubble growth stops and contraction begins.

This pump works as a pump by introducing liquid from the outside by condensing the liquid and extruded bubbles through evaporation by heating the heated vapor bubbles, but when the external load becomes large (for example, due to a water level difference), it is insufficient for bubble growth. A certain degree of superheating is required, and the bubbles grow tightly inside the tube _G2 , heating the tube _G2 and making it difficult to enter the contraction process. In order to improve this, as shown in Fig. 14, a heat exchanger EX made of a material with high thermal conductivity is installed between the pipe G ₂ and the liquid introduction pipe G ₀ connected to the check valve CV ₁ . Good to include. In this configuration, the bubbles that have grown inside the tube _G2 are transferred to the liquid introduction tube.
Touching a sufficiently cold heat exchanger EX with external liquid in G ₀ carries away heat, where air bubbles can be forced into the contraction process, thus increasing the working range and stability of the pump. I can do it.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the heat-driven pump according to the present invention, FIG. 2 is a front view showing the flapper of the check valve, FIG. 3 is a cross-sectional view showing a modified example of the heating section, and FIG.
The figure is a cross-sectional view showing a modified example of the check valve, FIG. 5 is a cross-sectional view thereof, FIG. Figures 8 to 13 are explanatory diagrams of the operation of the pump of the present invention;
The figure is a sectional view showing a modified example of the pump of the present invention.
FIG. 5 is a schematic diagram of a conventional heat-driven pump, and FIGS. 16 to 18 are explanatory diagrams of the generation of bubbles in the heating section. C...Condensing pipe, D...Holding pipe, F, F'...Flapper type, _G1 , _G2 ...Pipe, _CV1 , _CV2 ...Check valve, B...Heating part, P...Conical recess, I ...Suction part, EX...Heat exchanger, N...Bubble, R...Wall surface, S...O ring, S _T
...Steam, T ₀ - T ₅ ... Concavity isotherm, a... Distance, G ₀ ...
Liquid introduction tube.

Claims (1)

[Claims] 1. A single tube made of a material with low thermal conductivity,
A heating section made of a material with high thermal conductivity and having an internal recess is connected, a flapper type check valve is provided at each end of the tube, and a suction section is provided in the tube adjacent to the heating section. A heat-driven pump characterized by comprising: 2 In a single tube made of a material with low thermal conductivity,
A heating section made of a material with high thermal conductivity and having an internal recess is connected, a flapper type check valve is provided at each end of the tube, and a check valve of the flapper type is provided in the upstream tube adjacent to the heating section. 1. A heat-driven pump characterized in that a suction section is provided, and the introduction pipe connected to the check valve on the upstream side and the pipe on the downstream side are connected by a heat exchanger.