JPS6359057B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of constructing a solar pond.

A solar pond is a pond that has the ability to absorb and store solar energy in the form of heat on a large scale without the use of mechanical devices.

Solar ponds are characterized by the ability to utilize all solar radiation, including direct and scattered solar radiation, and to be able to collect and store heat at the same time.The temperature of the heat storage part, which has a maximum temperature of over 90°C, is largely affected by solar radiation depending on the weather and time of day. Solar ponds are currently being used domestically and internationally for agricultural heating, drying, and building heating and cooling, which require a constant supply of large amounts of heat, as well as for low-temperature heating and cooling of buildings. Development is progressing for uses such as power generation and desalination in latitudinal regions, and snow melting in snowy regions.

Conventionally, in order to maintain a high solar heat collection temperature, a method was adopted to reduce heat radiation, for example by using the concentration (density) of a salt solution, and Figure 1 shows a solar pond constructed using this method. be.

To explain a solar pond based on this, a solar pond generally consists of an upper non-convective layer 1 and a lower convective layer 2, and sunlight passes through the upper non-convective layer and is stored in the lower convective layer 2, resulting in a low temperature. Water 5 is heat-stored in this convection layer 2, becomes high-temperature water 6, and exits, and is supplied to a utilization system 4 via a heat exchanger 3.

In the non-convection layer 1, a concentrated salt solution 7 flows in from the lower part, that is, slightly above the convection layer 2, and fresh water 8 flows in from the upper part, and these are mixed to form a solution with a reduced concentration (dilute solution). 9 is discharged from approximately the middle of the non-convection layer 1.

Due to this forced circulation, the concentration, density, and temperature are all constant in the convective layer 2, as shown in the relationship between concentration, density, temperature, and depth in Figure 2.
In the non-convection layer 1, a gentle gradient line is formed.

Therefore, by appropriately selecting the type of salt in the non-convection layer 1 and the concentration of the concentrated salt solution 7 to be supplied, a density gradient can be formed in accordance with the concentration gradient.
This eliminates the density difference due to temperature difference, which in turn prevents the occurrence of convection due to buoyancy, and forms a non-convection layer 1. In this non-convection layer 1, even if the temperature at the bottom of the tank increases, the density Since convection due to the gradient is prevented, heat radiation is suppressed and long-term heat storage becomes possible.

However, in this method of constructing a solar pond, in order to forcibly form a concentration gradient, it is necessary to flow a large amount of concentrated salt solution 7 and fresh water 8, which requires considerable cost and requires a lot of maintenance and management. Yes. In addition, with this method, it takes several months to form a saltwater gradient and start storing heat, and there is a risk of salt damage due to water leakage, which can be fatal during fish hatching, aquaculture, and farming. Furthermore, if the depth of the pond is shallow, the salt water concentration gradient will be insufficient, making it difficult to suppress convection.

In view of the above circumstances, the present invention proposes an effective and economical solar pond construction method that compensates for the drawbacks of conventional solar pond construction. A solar pond is constructed by putting multiple bodies into it.

That is, when a water inclusion body sealed with a gelling agent sheet is put into an aquarium as in the present invention, the sheet formed by the gelling agent becomes viscous with water inside and outside, and the inclusion bodies adhere to each other. convection no longer occurs,
As time passes, the outer sheet dissolves or breaks, and the aqueous phase becomes a uniform gel due to the gelling agent.
Similarly, convection is suppressed and heat radiation is suppressed.

If a plastic bag or the like is used instead of the gelling agent for the outer sheet, convection will occur and a large amount of heat will escape from the pound.

In addition, if you add the gelling agent directly to water, the gelling agent will form a lump and will not dissolve and disperse easily. It requires a lot of energy and time,
The construction of a solar pond would cost a huge amount of money. Moreover, as the size of the solar pond increases, the number increases geometrically.

However, according to the method of the present invention, it is only necessary to pour water into a gelling agent bag, close the bag, and throw it into a pond, which is very simple. If the pound is large, a long and narrow bag may be used, and the larger the pound, the more powerful the present invention is, and it is also optimal as a method for constructing a large-scale solar pound.

The gelling agent used in the present invention increases the viscosity of water by adding it to water, making it difficult to cause convection and suppressing heat radiation from the solar pond. For example, polyacrylic acid and its salts, polyacrylamide, polyvinyl alcohol, polyethylene glycol, cellulose water-soluble resins such as hydroxypropyl cellulose, hydroxyethyl cellulose, and methyl cellulose, polysaccharide derivatives such as amylose, polyhydroxyethyl methacrylate, polyvinylpyrrolidone, etc. can be mentioned.

The sheet 10 made of the gelling agent as described above is
For example, it is made into a bag shape and water 11 is sealed inside to form a water-filled body 12 (FIG. 3). In addition, sheet 10
In addition to being shaped like a bag, it can be shaped like a tube or have other shapes in which water is sealed within a range that does not impair the intended effects of the present invention.

The water inclusion body 12 formed as described above has the fourth
As shown in the figure, a plurality of solar ponds are placed in a water tank to form a solar pond. In this embodiment, the heat collecting section 13 is constructed by providing a member coated with black paint or a black sheet that easily absorbs sunlight on the bottom of the aquarium, and a heat exchanger such as a heat exchanger or heat pipe installed above it. A container 14 is provided to extract the stored heat to the outside.

In the water-enclosed bodies 12 introduced in the manner described above, the gelling agent sheets 10 on the surface become viscous and adhere to each other due to the water inside and outside (FIG. 4).

In such a state, the water phase above the heat collecting part 13 does not cause convection, and heat radiation is suppressed. Then, as time passes, the gelling agent constituting the sheet 10 dissolves into the aqueous phase, forming a uniform aqueous phase, but since the gelling agent is included in this,
It becomes a uniform gel, which also suppresses convection and heat radiation.

As described above, according to the solar pond of the present invention, all that is required is to seal water in a bag made of a gelling agent and place it in a pond, so that gelation can be achieved as easily as when adding a gelling agent directly to water. There is no need to stir the agent to prevent it from clumping or dissolve it in hot water, which shortens the construction period for solar ponds.

In addition, unlike conventional solar ponds, it is no longer necessary to provide a device for feeding concentrated salt solution and fresh water and discharging diluted solution to forcibly create a concentration gradient and form a non-convection layer, thus reducing the maintenance required. In addition to cost savings, there is no need to worry about salt damage, so it can be used for a wide range of purposes, including fish hatching, aquaculture, and cultivation.

In addition, according to the present invention, a solar pond can be constructed even when the water tank is shallow, and this practical effect is extremely large.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view showing the structure of a conventional solar pond using salt, Figure 2 is a diagram showing the relationship between concentration, density, temperature, and depth in the solar pond of Figure 1. Figure 3 is a diagram showing the relationship between concentration, density, temperature, and depth in the solar pond of Figure 1. FIG. 4 is a cross-sectional view showing an example of the water enclosing body used. FIG. 4 is a longitudinal sectional view showing an example of the solar pond constructed according to the present invention, in which the water enclosing bodies are bonded to each other.

Claims (1)

[Claims] 1. A method for constructing a solar pond, which is characterized in that a plurality of water inclusions sealed with a gelling agent sheet are placed in a water tank.