JPH0225692A - Heat accumulating type heat transfer tube - Google Patents

Abstract

PURPOSE:To improve the utilizing rate of heat accumulating material during the operation of a heat exchanger and permit the distribution of voids, generated in accordance with the change of the phase of the heat accumulating material, into respective parts of a vessel by constituting an area, in which a heat transfer tube makes contact with the heat accumulat ing material in the vessel, is constituted so as to be spiral. CONSTITUTION:Heat accumulating material 12 is sealed into a vessel 11 while a first spiral heat transfer tube 13a, penetrating the vessel 11 lengthwisely, and a second spiral heat transfer tube 13b, pairing with the first spiral heat transfer tube 13a, are provided in the vessel 11 respectively. In this case, the first and second spiral heat transfer tubes 13a, 13b are formed so that a distance between the first and second spiral heat transfer tubes 13a, 13b and another distance L between the heat transfer tubes and the internal surface of the vessel 11 become given values. In above-described constitution, medium to be heated flows through the spiral heat transfer tubes 13a, 13b from the side of sunshine to the side of shade and the heat accumulating material at the side of shade is heated by the medium to be heated, whose temperature is increased, and, therefore, the utilizing rate of the heat accumulating material 12 may be increased. On the other hand, the distance L is kept in the vessel 11 and, therefore, initial solidified parts A appear between the spiral heat transfer tubes 13a, 13b and the like whereby voids are distributed in respective parts of the vessel 11.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a regenerative heat exchanger, and more specifically to a heat exchanger used in a zero gravity and vacuum environment such as outer space. The present invention relates to a heat storage heat exchanger tube equipped with a spiral heat exchanger tube applied to.

(Prior art) The heat storage heat exchanger tube applied to a typical heat storage type heat exchanger is the 6th heat transfer tube.
As shown in the figure, a container 1 in which a heat storage material 2 is sealed
A heat exchanger tube 3 is provided so as to penetrate in the longitudinal direction.
Here, the fluid to be heated is guided into the heat exchanger tube 3 from one opening a of the heat exchanger tube 3, flows inside toward the other end, and during this period receives and absorbs the heat released from the heat storage material 2, and It is designed to be collected once it is opened.

By the way, the reason why a regenerative heat exchanger is used in a space environment (in orbit around the earth) is because of the following problems. In other words, at a space base in a so-called low orbit, where the orbit is close to the Earth, there are two periods: the time when the sun is directly exposed to sunlight (solar radiation time), and the time when it is in the shadow of the earth and is not directly exposed to sunlight (solar eclipse time).
There is no extreme difference between the two. For example, if the orbital period is 90 minutes, the solar radiation time is 60 minutes and the solar eclipse time is 30 minutes, so the heat supply will be cut off for a long time, and the function of the heat exchanger will be affected. It stops.

For this reason, it is essential to use a heat exchanger with a heat storage function so that the heat exchanger can work continuously even when the heat supply is cut off.

On the other hand, in the space environment, heat-generating songs are established based on unique mechanisms, and appropriate consideration is required.

For example, the heat received or taken from the outside is dominated by radiation from sunlight, and at this time, there is no fluid around the heat exchanger tube, so no heat transfer occurs by convection, so the heat exchanger tube Therefore, in Fig. 6, sunlight incident from the direction of arrow is transmitted, heat is transferred from the container 1 to the heat storage material 2 sealed inside by conduction.As a result, the temperature of the heat storage material 2 rises, and a part of the heat flows inside the heat transfer tube 3. It is transmitted to the heated body, and all the surplus is stored there,
It is designed to be ready for solar eclipses. As a heat storage method,
Normally, latent heat storage using heat of fusion is used, but in zero gravity, convection does not occur even within the molten liquid phase.
Heat transfer within the container 1 is limited to conduction only.

(Problem to be solved by the invention) Considering that the solar radiation time in low orbit is limited to 60 minutes as mentioned above, in the heat transfer mode described below, the shaded side There is a possibility that the solar eclipse state will occur before the heat storage material 2 has sufficiently melted, and the latent heat will not be effectively utilized.

On the other hand, if the capacity is determined so that all of the heat storage material 2 melts, the temperature of the metal surface that constitutes the container 1 on the side receiving solar radiation will become too high, and the structure will not be viable or the temperature will be too large. This will result in restrictions.

Next, consider the following issues that must be taken into consideration: ``Structure associated with phase change of heat storage material 2.'' In other words, in the case of latent heat storage, the latent heat of fusion that exists between the same phase and the liquid phase is used, but when changing from the solid phase to the liquid phase, there is generally a change in volume, and its size is may reach up to 30%. In the heat storage heat transfer tube, if all of the heat storage material 2 that fills the container 1 in a solid state changes to a liquid phase, it is difficult to absorb the volumetric expansion by elastic deformation of the container 1. It is. Therefore, the capacity of container 1 is determined by including the liquid phase, and in the solid phase, the capacity of container 1 is determined.
However, in this case, it is necessary to keep the position and size distribution of the voids generated within the container 1 within an appropriate range, and in the unlikely event that control fails, , due to the difference in heat transfer between the void part and the solid phase part, a localized overheated part will occur during the next heating, and the container 1 will not be adversely affected. In this way, in the case of latent heat storage, the large change in specific volume between the solid phase and the liquid phase tends to cause structural problems, and in particular, the distribution between the same phase and the liquid phase tends to be biased. This is difficult to deal with in the case of heat storage and heat exchanger tubes.

The present invention was developed with the aim of solving these problems, and it improves the utilization rate of the heat storage material during heat exchanger operation, and also improves the structural issues caused by the volume change accompanying the phase change of the heat storage material. The present invention aims to provide a heat storage and heat exchanger tube suitable for avoiding problems.

[Structure of the Invention] (Means for Solving the Problems) The heat storage and heat transfer tube according to the present invention includes a heat storage material sealed in a cylindrical container, and a heat transfer tube that extends through the container in the longitudinal direction. In a heat storage heat exchanger tube that transfers heat from the outside through a heat storage material (2) to the heated fluid flowing inside the heat transfer tube and stores excess heat in the heat storage material, the heat transfer tube is placed inside the container. It is characterized in that the region in contact with the heat storage material is configured in a spiral shape.

(Function) The heat received on the solar radiation side surface of the container containing the heat storage material is transferred by conduction to the inside of the heat storage material and further to the heated fluid flowing inside the heat transfer tube. Here, since the heat transfer tube has a spiral configuration, the heated fluid whose temperature has increased is guided to the negative side of the container. Since the heat storage material still remains at a low temperature on the shaded side, the heated fluid inside the heat transfer tube acts as a heating source 12 on the heat storage material at the portion T.

In other words, in this case, the fluid to be heated functions as a heat transport medium in the container (1). Since the material is used effectively, its utilization rate can be improved, and the secondary effect of reducing the required amount of heat storage material can also be obtained.

On the other hand, the reason why the present invention is effective against various structural problems associated with phase changes of heat storage materials is as follows. That is, FIG. 2 shows the initial state of solidification in the structure of the present invention, where the shaded area indicates the initial solidification part A of the heat storage material 12. In the helical heat exchanger tube 13, a narrow space exists between the heat exchanger tubes and between the heat exchanger tube and the container 11, and the starting point of solidification can be defined here. As shown in the figure, as a result of the initial solidification part A appearing at a fixed position, the voids that occur thereafter are
1, and the locally overheated parts are transferred to the container 1.
1 will not occur. Note that the configuration using such a spiral heat exchanger tube 13 can be said to be an excellent and advantageous method in that it can absorb the difference in thermal expansion between the container 11 and the heat exchanger tube.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figure, reference numeral 11 is a cylindrical container, and a heat storage material 12 is sealed inside the container 11. Furthermore, a first helical heat exchanger tube 13a that penetrates the container 11 in the longitudinal direction and a second helical heat exchanger tube 13b that is paired with the first helical heat exchanger tube 13a are provided, respectively. Here, the first and second spiral heat exchanger tubes 13a, 13
b are formed so that the distances between them and between them and the inner surface of the container 11 are constant values.

In addition, as shown in the figure, spiral heat exchanger tubes 13a, 13b
The area in contact with the heat storage material 12 inside the container 11 is configured in a spiral shape, and the other area is configured in a straight line.

In the above configuration, the heated medium flows through the spiral heat transfer tubes 13.a, 13b from the sunlight side to the shaded side, and the heat storage material on the shaded side is heated by the heated medium whose temperature has increased. This increases the rate at which the heat storage material 12 on the shaded side is used, and on the other hand, since the distance is maintained within the container 11, the initial solidification part A (see FIG. 2) , 13b, etc., and voids appear between containers 11 and 13b.
distributed to various parts.

Next, another embodiment of the present invention will be described with reference to FIG. Although the above embodiment can be said to be very useful for effectively utilizing the heat storage material 12 especially on the shade side, there is some heat storage material 12 that remains unused near the inlet of the fluid to be heated. Therefore,
As shown in FIG. 3, the forward path and the return path are configured to be formed by first spiral heat exchanger tubes 14a and second spiral heat exchanger tubes 14b, respectively.

The medium to be heated is first introduced into the first spiral heat exchanger tube 1 through the opening a.
Guided by 4a, it flows inside toward the 0-shaped end and reverses,
Next, it is guided to the second spiral heat exchanger tube 14b, flows inside toward the other end, and is recovered at the opening. That is, near the inlet of the heated fluid, the temperature of the fluid is low and does not have enough heat to melt the heat storage material 12 on the shade side, but in this embodiment, the heated medium that has become high temperature through the outward path passes through the return path. When it is returned, the heat storage material 12 on the shade side is heated,
A transition to a liquid phase is attempted. The arrangement of such outward and return routes is determined by the operating temperature conditions, the type of heat storage material 12, the operating method, etc.
Arrangement (c) is possible. That is, the arrangement in (a) is one in which the first spiral heat exchanger tubes 14a (outward path) and the second spiral heat exchanger tubes 14b (inward path) are arranged alternately, and the arrangement in (b) is in which the first spiral heat exchanger tubes 14a (outward path) and the second spiral heat exchanger tubes 14b (inward path) are arranged alternately. In the concentric arrangement with the heat exchanger tubes 14b inside, the second spiral heat exchanger tube 14b is constructed of a single tube and is placed at the axis of the container 11. As described above, according to this embodiment, the utilization rate of the heat storage material 12 is further improved, and the bias in the distribution of voids is small, as in the above embodiment.

Further, FIG. 5 shows a special configuration of a spiral heat exchanger tube that enhances the effects of the present invention. Here, the spiral heat exchanger tube 15 is provided with fin-like protrusions 16 on its outer surface.

In this embodiment, not only is it intended to further improve the heat transfer performance by increasing the surface area of the heat transfer tube by using the fin-like protrusions 16, but also the purpose is to specify the starting point of solidification by applying this means. It is possible to bring it to the ideal state.

[Effects of the Invention] As is clear from the above description, in the present invention, the region where the heat transfer tube contacts the heat storage material in the container is configured in a spiral shape, so that the heated fluid inside the heat transfer tube is directed to the shaded side. Acting as a heating source for a certain heat storage material and effectively utilizing the heat storage material on both the solar radiation side and the shaded side is an ability that greatly contributes to improving the utilization rate of the heat storage material. On the other hand, by dispersing voids over a wide range of structural problems caused by volume changes associated with phase changes in the heat storage material, the safety of the container is ensured, which is highly effective in increasing the reliability of the regenerative heat exchanger. , excellent and useful.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the heat storage heat exchanger tube according to the present invention, Fig. 2 is an explanatory diagram showing the effect of the solidified portion generated around the heat exchanger tube, and Figs. 3 to 5 are from different books. FIG. 6 is a block diagram showing another embodiment of the invention. FIG. 6 is a block diagram showing an example of a conventional heat storage heat transfer tube. 11... Container 12... Heat storage material 13a, 14a... First spiral heat exchanger tube 13b, 14
b...Second helical heat exchanger tube 15......Spiral heat exchanger tube 16...Fin-like protrusion

Claims (1)

[Claims] A heat storage material is sealed in a cylindrical container, and a heat transfer tube is provided so as to penetrate the container in the longitudinal direction, whereby heat given from the outside of the container is passed through the heat storage material and flows into the heat transfer tube. A heat storage heat transfer tube configured to transfer heat to a fluid and store surplus heat in the heat storage material, wherein a region of the heat transfer tube in contact with the heat storage material within the container is configured in a spiral shape. heat tube.