JPH0133746B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in water return operation in a solar heat storage tank.

Thermal storage water tanks that use solar heat are usually constructed so that return water from the heat collector or return water from loads such as refrigerators or hot water supply equipment flows in, and the same amount of water flows out. However, it is inevitable that the temperature levels of the return water flowing into the heat storage water tank not only differ from each other but also fluctuate over time. Ideally, even if there are such fluctuations in return water temperature, temperature stratification is always formed without water of different temperature levels mixing with each other. In the conventional method, which only connects the two sides with piping, it is not possible to maintain a state where temperature stratification is formed.

The present invention was made for the purpose of improving the heat storage characteristics of a solar heat storage water tank in which two or more systems of return water with different temperature levels flow in and the temperature of each return water changes over time. A primary circulating water circuit system in which hot and cold water circulates between the heat collector and the heat storage water tank; a secondary circulating water circuit system in which hot and cold water circulates between the heat storage water tank and the load; In a solar system, the inside of the heat storage water tank is divided into a small tank and a main tank by a nearly vertical partition plate with communicating holes arranged vertically and reaching from the bottom of the tank to the top of the liquid level, The water going to the solar heat collector is taken from the bottom of the main tank, and the water going to the load is taken from the top of the main tank, and the return water from the solar heat collector and/or the load is taken in as described above. It is characterized by being introduced into a small tank.

To explain the present invention in detail with reference to the drawings, Fig. 1 is a system diagram showing an example of a solar system according to the present invention, in which 1 is a solar heat collector, 2 is a heat storage water tank, and 3 is a refrigerator and a hot water heater. This is the load on equipment, etc. A primary circulating water circuit system is formed between the solar heat collector 1 and the heat storage water tank by a return water pipe 4 and an outgoing water pipe 5, and a return water pipe 6 and a water return pipe are formed between the heat storage water tank 2 and the load. The outgoing water pipe 7 forms a secondary circulating water circuit system. The heat storage water tank 2 is divided into a small tank 9 and a main tank 10 by an almost vertical partition plate 8.
The main tank 10 is in communication with the main tank 10 through a communication hole 11 provided in the partition plate 8. A large number of communication holes 11 are formed in a row from the bottom of a vertical partition plate 8 having a height from the bottom of the tank to the top of the liquid level to near the liquid level. The shape and number of the communication holes 11 may be such that the layers of cold water and hot water based on the temperature difference formed in the small tank 9 can be directly moved in parallel to the main tank 10 side. A small tank 9 formed by the partition plate 8 having such a communication hole 11 is used as a return water tank. Therefore, from now on, this small tank may be referred to as a return water tank.

Return water from the solar heat collector 1 and/or the load 3 is introduced into the substantially center of the return water tank 9. Also, the water going to the solar collector is taken from the bottom of the main tank, and the water going to the load is taken from the top of the main tank.
This creates a highly desirable temperature stratification within the main tank 10. The conditions under which this temperature stratification is formed will be specifically explained below using examples shown in FIGS. 3 to 16.

Figures 3 and 4 show the configuration of the heat storage tank that was implemented.
It is divided into return water tank 9 (width = 170mm) and main tank 10. At approximately the center of the partition plate 8, nine circular communication holes 11 each having a diameter of 25 mm are provided at a pitch of 50 mm in the height direction from the bottom of the tank. The water return pipe 6 is immersed in approximately the center of the water return tank 9, and is a horizontal discharge pipe 12 having a large number of openings.
is connected to the end of this water return pipe 6. This discharge pipe 12 is located approximately at the center in the height direction of the liquid in the water return tank 9, and has many upward openings. Further, a buffer plate 13 is attached to the upper part of this opening. On the other hand, in the main tank 10, a box-shaped opening 14 is attached to the wall surface corresponding to the partition plate 8 so that the liquid in the upper part of the tank can be taken out, and this is connected to the outflow pipe 7. Note that the x mark in the figure indicates the temperature measurement position by the thermocouple.

Figures 5 to 7 show two layers formed in the tank configured in this way: a high temperature layer ( _TH layer) with a temperature of 35℃ and a low temperature layer (T _M layer) with a temperature of 17℃. Figure 5 shows the inside of the tank when a return water flow (T _L layer) at a temperature of 4°C is introduced from the return pipe 6 at a return rate of G = 4.6/min, U = 0.415 m/S. Figure 6 shows the flow state immediately before water return, and Figure 7 shows the flow state 15 minutes after water return. Also, Figure 8 shows the 3rd
Figure 4 shows the change in water temperature over time at the temperature measurement positions shown in Figure 4.

As seen in FIGS. 5 to 8, according to the method of the present invention, when low-temperature water flows in, high-temperature water in the tank can be effectively taken out. That is, in the main tank 10, the hot water layer is successively pushed up by the cold water layer without being disturbed, and the hot water effectively flows out into the outgoing water pipe in the form of a rigid piston flow.

To explain this aspect in more detail, the inflow water collides with the buffer plate provided at the upper part of the water return pipe outlet, and then flows to the left and right, and descends along the tank wall surface and partition plate in the buffer tank. The inflow water descending inside the buffer tank becomes a mixed flow while involving the _TM water layer in the initial water tank, and is slightly heated up and discharged into the heat collecting tank through the communication hole of the partition plate in the low temperature layer region. Inside the heat collection tank, the flow flows downward due to the density difference.
As time passes, a low-temperature layer of reflux water gradually forms from the bottom of the tank. Near the discharge outlet of the water return pipe, the high-temperature layer and the low-temperature layer are mixed by the inflowing water, and a portion of the mixture flows into the high-temperature layer of the heat collection tank through the communication holes in the partition plate near this point, but there is a difference in density within the tank. This causes a downward flow that sinks below the high-temperature layer, and eventually becomes a horizontal flow in the low-temperature layer where the density difference disappears. Therefore, the flow inside the tank is slightly disturbed near the return pipe outlet and the boundary between the hot water layer, but overall the warm water layer is not disturbed and is gradually pushed up by the cold water layer and flows out from the water outlet at the top of the tank. The high temperature water in the tank can be effectively taken out as a rigid piston flow.

Figures 9 to 11 show the warm water layer ( _TM layer) at a temperature of 27℃.
and a cold water layer (T _L layer) with a temperature of 6°C, and high temperature water (T _H layer) with a temperature of 40°C.
from return water pipe 6, return water amount G = 4.6/min, U =
It shows the situation when introduced at 0.416m/S,
Figure 9 shows the state immediately before water return, Figure 10 shows the flow state at the initial stage of water return, and Figure 11 shows the state 15 minutes after water return. Moreover, FIG. 12 shows the change in water temperature over time at the temperature measurement positions shown in FIGS. 3 and 4.

As seen in Figures 9 to 12, when high temperature water returns, it can be taken out as is without mixing with low temperature water in the tank.

To explain this situation in more detail, after the inflow water discharged from the return pipe collides with the buffer plate,
It separates to the left and right and rises along the inner wall of the buffer tank and the partition plate, enveloping the _TM hot water layer inside the tank.
Therefore, at the beginning of discharge, the flow within the buffer tank becomes a mixed flow, and as this mixed flow rises within the buffer tank, it flows out into the heat collection tank from the partition plate communication hole in the vicinity. The flow from the communication hole is initially discharged in a horizontal direction, but due to the decrease in jet energy and density difference, it slowly flows toward the top of the tank, and the hot water layer inside the tank is slightly disturbed by this flow. As time passes, the area above the water return pipe outlet in the buffer tank is replaced with high-temperature return water flow, and the return water flow flows horizontally into the tank through the communication hole at the top of the partition plate and reaches the water inlet.
Finally, the inside of the tank is composed of three temperature layers as shown in FIG. That is, the flow in the tank due to the return water flow is slightly turbulent at the beginning of the return water flow, but as time passes, the return water flow bypasses the inside of the tank and flows. Therefore, for example, when high-temperature water collected by a solar collector is returned, it can be supplied to the load side at high temperature without mixing with the low-temperature water in the tank. Able to drive extremely effectively.

Figures 13 to 15 show the high temperature layer (T _H
The reflux water flow ₍ T _M
layer) is from the return pipe 6, the return water amount is 4.6/min, U=
It shows the situation when introduced at 0.416m/S,
Figure 13 shows the state immediately before water return, Figure 14 shows the flow state at the initial stage of water return, and Figure 15 shows the state 15 minutes after water return. Moreover, FIG. 16 shows the change in water temperature over time at the temperature measurement positions shown in FIGS. 3 and 4.

As seen in Figures 13 to 16, the low-temperature water at the bottom of the tank becomes a dead zone, and without mixing, the high-temperature water in the tank is successively pushed up by the hot water, forming a rigid piston flow, which is effective. It can be taken out.

To explain this aspect in more detail, after the inflow water discharged from the return pipe into the buffer tank collides with the buffer plate, it is divided to the left and right, and along the buffer tank wall and partition plate, the hot water and cold water layers are drawn up and down. The flow is divided into the flow toward the water return pipe and the flow discharged from the partition plate communication hole near the water return pipe position to the heat collection tank. The vertical flow inside the bath tank is
It progresses up and down forming a mixed layer with a warm water layer on the top and a cold water layer on the bottom. This mixed laminar flow does not advance much toward the low-temperature water layer due to the position of the inlet, but increases in layer thickness toward the high-temperature layer. As the layer thickness increases, the return water flows out into the heat collection tank from the partition plate communication holes in that region, and flows in the heat collection tank between the high temperature water layer and the low temperature water layer, that is, toward the vicinity of the boundary layer. Therefore, the return water flowing out to the high temperature water layer side in the heat collection tank flows downward, and the return water flowing out to the low temperature water layer side flows upward, and when the temperature difference becomes small, it becomes a horizontal flow toward the opposite wall surface. On the other hand, the return water flow that flowed into the heat collection tank from the partition plate communication hole near the return pipe outlet was directed toward the almost horizontally opposing wall surface because the return water outlet was located near the boundary between the high-temperature water layer and the low-temperature water layer. It flows and eventually collides with the wall and flips upside down. In this way, the flow in the water tank increases the return water flow layer by combining the flow from the communication hole as the mixed water layer in the buffer tank advances and the flow from the communication hole near the return water outlet, and the high temperature in the upper part of the flow increases. This creates a rigid piston flow that gradually pushes up the water layer and flows out from the inlet. In this case, the low-temperature water layer will be responsible for the dead zone. Therefore, even in this case, the high-temperature water in the tank can be effectively taken out without mixing with the low-temperature water.

As explained above, according to the present invention, natural temperature stratification is formed in the heat storage water tank due to the density difference, and even when low temperature water, high temperature water, or medium temperature water is returned to the tank, high temperature water is effectively It can be taken out. Therefore, even if the temperature of the return water from the solar collector and/or the load side fluctuates, only high-temperature water can be selectively supplied to the load, which solves the problem of conventional heat supply fluctuations in solar systems. According to the invention, this problem can be effectively solved with a simple configuration.

[Brief explanation of drawings]

Figure 1 is a system diagram of the solar system of the present invention.
Fig. 2 is a plan view of the heat storage water tank shown in Fig. 1, Fig. 3 is a sectional view of the heat storage water tank according to the embodiment of the present invention, Fig. 4 is a view taken along the - line in Fig. 3, and Figs. 5 to 7 are cold water Figure 5 shows the state immediately before water return, Figure 6 shows the initial flow of water return, and Figure 7 shows the state 15 minutes after return water. Figure 8 shows the fifth to
Figure 7 is a diagram of the temperature of the water in the tank over time in the example shown, and Figures 9 to 11 are diagrams showing the state of the tank when high-temperature water is returned, and Figure 9 shows the state immediately before the return of water. ,
Figure 10 is the initial flow of water return, Figure 11 is water return 15
Fig. 12 is a diagram of the temperature change over time of the tank water in the examples shown in Figs. 9 to 11, and Fig. 13 to 1
Figure 5 is a diagram showing the state inside the tank when return water is returned at medium temperature, and Figure 13 is a diagram showing the state immediately before return water, and
FIG. 4 shows the flow at the initial stage of water return, FIG. 15 shows the situation 15 minutes after water return, and FIG. 16 is a diagram of the temperature change over time in the tank in the example of FIGS. 13 to 15. 1...Solar heat collector, 2...Thermal storage water tank, 3...Load,
4, 6...Return water pipe line, 8...Partition plate, 9...Small tank (return water tank), 10...Main tank, 11...Communication hole.

Claims (1)

[Claims] 1. A primary circulating water circuit system in which hot and cold water circulates between the solar heat collector and the heat storage water tank, and a secondary circulating water circuit system in which hot and cold water circulates between the heat storage water tank and the load. In a solar system consisting of, the inside of the heat storage water tank is divided into a small tank and a main tank by a nearly vertical partition plate with communicating holes arranged vertically and reaching from the bottom of the tank to the top of the liquid level. death,
The water going to the solar heat collector is taken from the bottom of the main tank, and the water going to the load is taken from the top of the main tank, and the return water from the solar heat collector and/or the load is taken in as described above. A solar system water return method characterized by introducing water into a small tank.