JPS5952736B2 - heat storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar heat storage device used in a greenhouse.

Traditionally, greenhouses have been heated using steam, hot air steam, and electric heat, but these methods all use electricity or fuel such as oil, so they are energy-saving. From this point of view, it is desired to save the fuel.

In order to meet the above requirements, underground heat storage type greenhouses have recently been proposed, but since these all use a 1T system for storing and dissipating heat throughout the day, they are easily affected by the weather, and the amount of solar radiation in the winter. The disadvantage is that it is impossible to store enough heat during periods when there is little.

The present invention was made in order to eliminate the above-mentioned drawbacks, and it stores solar heat collected by a solar heat collector in the underground part of the greenhouse.
In a greenhouse that is heated by this accumulated heat, underground radiators are buried in the shallow and deep parts of the basement of the greenhouse, and these underground radiators are connected to the solar collector, receiver tank, and pump or compressor. This feature is characterized in that the fluid is connected to both underground radiators, and the fluid is circulated through both the underground radiators individually, in parallel, or in series.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is a greenhouse, and 2 and 3 are underground 1.
They are a deep underground radiator and a shallow underground radiator (hereinafter referred to as deep radiators and shallow radiators) buried in a deep part of around 5 m and a shallow part of around 0.5 m underground, respectively.

4 is a solar heat collector (hereinafter referred to as a heat collector), 5 is a pump (
or compressor), 6 is a receiving tank.

One side of the two heat radiators 2 and 3 and the suction side of the pump 5 are communicated with a receiving tank 6, and both sides of the shallow radiator 3 and the other side of the deep radiator 2 are connected to a heat collector 4 and a pump 5. are connected to the discharge side of each.

7.8 is an on-off valve provided between the shallow radiator 3 and the receiving tank 6 and between the multiple heaters 2 and 3, respectively; 9 and 10 are the discharge sides of the pump 9 and the shallow radiator 3; This is a switching valve installed in each.

By appropriately operating these valves 7 to 10,
It is possible to circulate the fluid through both heaters 2, 3 individually, in series or in parallel.

Further, the heat transfer area of the shallow heat radiator 3 to the soil is half the heat transfer area of the deep heat radiator 2.

Next, the operation of this embodiment configured as described above will be explained.

First, when the solar radiation reaches an appropriate intensity, a temperature difference occurs between the inlet and the outlet of the solar heat collector 4, so the pump 5 is activated by detecting the temperature difference.

Next, for long-term heat storage in the deep radiator 2, operation is performed so that the fluid temperature at the inlet of the deep radiator 2 is around 50°C using a circulation system of the heat collector 4 → the deep radiator 2 → the receiving tank 6 → the pump 5. Take control.

In this way, the operation is continued from around October to early January and February to store heat for a long period of time, and the heat is obtained by the heat collector 4.

Operation will be stopped when the water temperature falls below 50°C.

On the other hand, since the temperature level of the shallow radiator 3 should be 40 to 30°C judging from the underground temperature distribution, the heat storage system is integrated when the heat storage in the deep radiator 2 is stopped as described above. The system is switched to the heater 4 → shallow radiator 3 → receiving tank 6 → pump 5, and operation control is performed under the condition that the fluid temperature at the inlet of the shallow radiator 3 is around 40° C. to start short-term heat storage.

If for some reason the ground temperature level around 0.5m underground drops to 30℃ or less and short-term heat collection becomes impossible, fluid will be added to the system in which both heaters 2 and 3 are connected in series. By circulating the heat and urgently transporting heat from the deep radiator 2 to the shallow radiator 3, it is possible to maintain the soil temperature necessary for plant growth without any hindrance.

In addition, during the long-term heat storage period by the deep radiator 2, if the water temperature level from the heat collector 4 is high around 50 degrees Celsius, it is transferred to the deep radiator 2, when the water temperature level is low around 40 to 30 degrees Celsius. If the system is switched and operated so that heat is stored in each of the shallow heat radiators 3, the period required for long-term heat storage can be shortened, and the required area of the heat collector can be reduced.

After one month or more has passed since the start of heat storage, the input to the deep radiator 2 becomes constant, and the underground temperature distribution becomes like the curve 11 shown in FIG. 2.

A depth of 30 cm corresponding to the area directly below the extension area of this curve 11
At this location, the temperature is maintained at 25-30°C even in winter.

When short-term heat storage in the shallow radiator 2 is further superimposed on this, the temperature distribution at this time becomes like the refraction line 12.

To find the amount of heat stored only by long-term heat storage, the specific heat of the soil is set to 2.
．． If I'L is 52 KJ/kg°C, the density is 1500 kg/m·, and the temperature difference between the deep part and the surface is 30 degrees, the amount of heat storage per unit area is 23 kWh/m'.

On the other hand, the amount of heat used (heat radiation amount) in a greenhouse is actually measured to be 0.21 kwh/m·d, so if heat radiation is continued at this rate, heating for three months or more is possible with the above heat storage amount.

Further, to calculate the increase in heat storage amount due to short-term heat storage, if the winter heat collection time is 2 hours per day, it will be 5.9 kWh/m2 per unit area for three months in winter.

This is equivalent to the amount of heat used (heat released) in a greenhouse for one month, so in areas where low temperatures persist until late in spring, the heating effect will be significant when the short-term heat storage method is used in combination.

As explained above, according to the present invention, crops can be grown using solar heat not only in regions that require heating until mid-March, but also in cold regions that require heating until mid-April. .

Further, by providing a shallow underground radiator, emergency heating can be performed effectively and the required area of the heat collector can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the heat storage device of the present invention, and FIG. 2 is a temperature distribution diagram of the same embodiment. 2...Deep underground radiator, 3...Shallow underground radiator, 4...Solar heat collector, 5...
...Pump, 6...Receive tank.

Claims (1)

[Claims] 1. In a greenhouse that accumulates solar heat collected by a solar heat collector in the basement of the greenhouse and is heated by this accumulated heat,
Underground radiators are buried in the shallow and deep parts of the basement of the greenhouse, and both of these radiators are connected to the solar collector, the receiving tank, and the pump or compressor, and fluid is supplied to both of the radiators. A heat storage device characterized by circulating heat independently, in parallel, or in series. 2. The heat storage device according to claim 1, wherein the operating conditions of the shallow underground radiator are set in the range of 25 to 40'C.