JP2007255803A - Waste heat storing and utilizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a temperature of a part buried in the ground is locally increased or decreased in an indoor heating/cooling system using an underground heat exchanger, by storing waste heat. <P>SOLUTION: The waste hot air or waste cold air is allowed to pass through the heat exchanger of a double tube structure buried in the ground, so that the waste heat of the hot air or cold air diffuses into and penetrates the ground kept into contact with the heat exchanger and is stored, the air flows in the heat exchanger to give and receive the heat between the air and the stored ground heat, and the stored heat is transmitted to the air to be carried out and utilized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for storing and using waste heat, and more specifically, waste heat that can be used for air conditioning of buildings such as detached houses, apartment houses, hotels, hospitals, schools, gymnasiums, and other general buildings. This relates to the heat storage and utilization method.

Since geothermal heat is relatively cool in summer and relatively warm in winter, in order to recover this heat, a heat exchange pipe with a double-pipe structure has been buried underground, Geothermal heat recovery is performed through outside air through the exchange pipe (Patent Document 1). In Japan, for example, in an area with an average temperature of 15 ° C, the geothermal heat averages 15 ° C even when the temperature is 32 ° C in summer and minus 0.5 ° C in winter. This difference in temperature between the outside air and geothermal heat is used for air conditioning. In the conventional method, the underground temperature in the area where the double-pipe heat exchanger is buried in summer or winter is the heat of the earth. Due to the slow diffusion rate, it is locally higher in summer than in other places (average temperature in the ground) or locally lower in winter. Thermal diffusion proceeds slowly by leaving it at night, and in the early morning it approaches the original average temperature in the ground, but if a hot or cold day continues for a long time, the temperature in the ground where the heat exchanger is buried There are many cases where the average temperature does not recover.

In order to remedy this problem, the inventors of the present invention densely embedded materials, minerals, metal masses, and grains having good heat conductivity in the ground where the underground heat exchanger is embedded and in the surrounding area. However, this method has a drawback in that it takes time for construction and increases construction costs, in order to promote thermal diffusion and level the temperature (Japanese Patent Application No. 2004-214184).

On the other hand, Patent Document 1 discloses that waste heat is stored in the ground, but the equipment is complicated and the economic effect is doubtful.
JP-A-2005-337645

The present invention has been made in view of such problems, and the purpose thereof is extremely low in construction cost, and in the underground in which a heat exchange pipe is embedded by utilizing cold energy or thermal energy storage that has been discarded conventionally. It is to provide a new waste heat storage and utilization method that can prevent the local rise or fall of temperature.

As a result of diligent research on the above problems, the present inventors can solve the above problems by storing waste heat and cold waste heat through a double-tube heat exchanger in the ground. The present invention has the following configuration.
1. Waste warm air or waste cold air is passed through a heat exchanger with a double pipe structure embedded in the ground, and the waste heat of the warm air or cold air is diffused and penetrated into the ground in contact with the heat exchanger to store heat. In addition, air is passed through the heat exchanger, heat is transferred between the air and the stored geothermal heat, and the stored heat is transferred to the air and carried out for use. How to store and use waste heat.
2. Waste warm air or waste cold air is passed through a pile layer of guristone, and the waste heat of the hot air or cold air is diffused and permeated into the pile layer of guristone to store heat. Heat storage and utilization of waste heat, characterized by flowing air, transferring heat between the air and the heat storage of the grits, transferring the heat storage to the air and carrying it out Method.
3. Waste warm air or waste cold air is passed through a heat exchanger having a double-pipe structure embedded in the pile layer and the underground layer of guristone. It diffuses and penetrates into the ground in contact with the heat exchanger to store heat, and air is passed through the pile layer and the heat exchanger between the air and the stored hot stone and geothermal heat. A method for storing and using waste heat, wherein the heat transfer is performed in step (b), and the stored heat is transferred to the air and carried outside.
4). 4. The discarded cold air is cold air discharged on the refrigerant evaporation side of a heat pump type water heater used in a nighttime midnight power time zone. How to store and use waste heat.
5). The heat pump water heater comprises a condenser, a compressor, an evaporator, an expansion valve, and a water tank. The condenser is immersed in the water tank, and the refrigerant compressed and heated by the compressor is passed through the condenser. The heat storage and utilization method of waste heat according to the above 4, which is a structure for heating water in a water tank.
6). The heat exchanger having the double tube structure is a double tube having a structure in which an inner tube having both ends opened is loosely fitted to an outer tube having a sealed end and the other end opened. An exchanger with a structure where the tip is buried underground and heat is exchanged with geothermal heat by flowing air through the gap between the inner and outer tubes, and the outer tube is buried to a depth of 5 m underground. The heat storage and utilization method of waste heat according to any one of the above 1 to 5, characterized in that:

It is possible to prevent a local temperature increase and a temperature decrease at the site where the heat exchanger is embedded.
Since the waste heat that was originally discarded can be stored, it is extremely energy-saving.
There is almost no equipment cost.

The structure of the present invention and its function will be described with reference to the drawings.
FIG. 1 is a general explanatory diagram when the hot and cold exhaust heat of the present invention is stored and used for air conditioning.
The underground heat exchanger according to the present invention has a structure in which an inner pipe having both ends opened is loosely fitted in a metal pipe having good heat conduction, and the tip of the outer pipe is sealed and the other end is sealed. Is open and this sealed tip is buried vertically in the ground.
Exhaust warm air and exhaust cool air flow through the gap between the inner and outer tubes to exchange heat with geothermal heat, that is, waste warm air, waste heat from the cold, absorbs and stores heat, waste heat air that has been heat exchanged, Waste cold air is raised through the inner pipe and discharged outside.
The temperature of the waste warm air must be at least higher than the temperature of the ground where the underground heat exchanger is embedded, while the temperature of the waste cold air is at least the ground where the underground heat exchanger is embedded. It needs to be lower than the medium temperature.
The temperature near the ground where the underground heat exchanger is buried is locally higher than the average underground temperature in the summer and locally lower in the winter. By passing waste warm air that is at least above the ground temperature in the winter and waste cold air that is below the ground temperature in the summer, heat exchange takes place and local temperature peaks in the ground are eliminated and leveled. Come. Or, conversely, a reverse peak higher than the average temperature in the ground in the winter or a reverse peak lower than the average temperature in the ground in the summer is formed.
The waste warm air and waste cold air that have risen up the inner pipe may be diverted directly to indoor air conditioning as needed, or may be discharged outside.

  The present invention is most suitable when waste warm air and waste cold air are obtained intermittently or intermittently. In other words, if the waste warm air and waste cool air can be obtained for 24 hours, the waste warm air and waste cool air can be used directly for indoor air conditioning, but the waste warm air and waste cold air are intermittent or limited. If only time is available, it will be difficult to use as a heating / cooling heat source. In such a case, if the waste warm air of the present invention, the warm heat of the waste cold wind, and the cold heat are temporarily stored in the ground, the heat is exchanged with the air, and then taken out and used as a small amount for 24 hours. Air conditioning is possible.

  In the present invention, the waste heat and waste heat may not necessarily be warm air or cold air. That is, even waste heat possessed by a liquid or solid may be used by exchanging it into hot air or cold air.

FIG. 2 is an explanatory diagram when the waste cold air discharged from the heat pump type water heater is stored and used for cooling.
The example of FIG. 2 is composed of a combination of a heat pump type water heater and a heat exchanger having a double pipe structure embedded in the ground.
The heat pump water heater (right side in Fig. 2) consists of a condenser, a compressor, an evaporator, an expansion valve, and a water tank. The refrigerant is immersed in the water tank and compressed and heated by the compressor (CO ₂ ) Is passed through a condenser to heat the water in the aquarium.
In the present invention, the condenser refers to a heat exchanger on the condensing side in FIG. In the figure, an evaporator refers to a heat exchanger on the evaporation side.
In the condenser, the gaseous refrigerant pressurized and heated by the compressor is cooled with water in the water tank and liquefied. On the other hand, the temperature of water rises with the heat of condensation released by the gaseous refrigerant. The water in the aquarium can be heated up to boiling depending on the purpose, but is kept at an economical temperature of about 70-80 ° C.
The liquid refrigerant that has passed through the condenser is jetted from the expansion valve, expands in volume and decreases in temperature, and further passes through the evaporator and is heated by the outside air to be vaporized. At this time, in order to remove the evaporation heat from the outside air and vaporize it, the outside air is cooled and discharged outside.
This is why the cold air is always discharged from the evaporator of the heat pump water heater.
In summer, the temperature of cold air is 15.5-18 ° C. On the other hand, the underground temperature of the portion in contact with the underground heat exchanger is 20 to 25 ° C., and the underground temperature of the portion in contact with the heat exchanger is lowered by flowing cold air through the underground heat exchanger. That is, the cold air of cold wind is stored in the ground.

The pipe from which the cold air is discharged is connected to the outside air intake of the underground heat exchanger.
During the summer, night, and late-night power hours (23:00 to 4am the next morning), the switching valve is opened and cold air flows through the underground heat exchanger.
In FIG. 2, the cold air is passed through the underground pipe through the underground stone layer, but the unnecessary stone layer is not always necessary. You may remove as needed. In FIG. 2, the breeze and the wind that has passed through the underground pipe are discharged below the first floor of the house (not shown).
It is not necessarily limited to this, the reverse flow, that is, cold wind first enters the underground pipe,
Then, it may be released to the outside air through the guristone layer. In short, any structure may be used as long as at least cold air passes through the underground pipe and the cold air of the cold air can be stored in the ground.

FIG. 3 is an explanatory diagram in the case of summer daytime.
In this case, since the heat pump type water heater is at rest, the changeover valve is switched, and the outside heat is taken into the underground heat exchanger. Although FIG. 3 has illustrated the case without grit stone, it is needless to say that the present invention is not limited to this. Take in the outside air with or without cobblestone. This is the traditional use of underground heat exchangers.

Fig. 4 shows the structure of Fig. 3. The heat pump water heater is operated during nighttime and late-night power hours (22:00 to 4:00 the next morning), the switching valve is switched to shut off the outside air, and the cold air is exchanged with the ground heat. It is the figure which showed the temperature condition of the discharge | emission side when flowing in a container and storing cold heat in the ground, taking in outside air in the daytime, passing the underground heat exchanger, and discharging it under the floor. This is the case without the calcite layer.
Specification of underground heat exchanger Outer pipe: Outer diameter 250mm, Length: 5,000mm
Outer tube material: Aluminum pipe with a thickness of 3.2mm Inside: Outer diameter φ150mm, Length: 5,500mm
Inner tube material: Polyethylene pipe with a thickness of 3.8mm Specifications of heat pump water heater Rated power: 6KW
Tank capacity: 460 liters Hot water temperature: 65-95 ° C
Rated COP: 4.51
Cold air temperature: 15.5-18 ℃

In FIG. 4, eco exhaust is the exhaust temperature of cold air. The GEO pipe shows the temperature change of a normal underground heat exchanger when no cold air flows at night. Eco + GEO pipe is a change in temperature when cold air is passed through the GEO pipe at night. In addition, the temperature of the underground vicinity which contacts the underground heat exchanger before flowing eco exhaust is 20-25 degreeC.
By using a GEO pipe (Ground Heat Exchanger), the outside air temperature drops by about 7.5 ° C, and by using Eco + GEO Pipe, that is, by letting the cool air of night eco exhaust flow through the GEO Pipe (Ground Heat Exchanger) In the daytime, it can be seen that the temperature of the air coming out of the GEO pipe (ground heat exchanger) is further lowered by 1.4 to 3.4 ° C. than the case of the GEO pipe alone. The temperature will drop by nearly 10 ° C from the outside temperature.
The area of the difference between the eco + GEO pipe curve and the eco exhaust curve from 10 o'clock at night to 6 o'clock the next morning (the area of the shaded area) is a measure of the amount of cold stored in the ground.
The area of the difference between the curve of the GEO pipe from 6 am to 10 pm and the curve of the eco + GEO pipe (area of the shaded area) is the cooling effect brought about by the cold stored in the ground is there.
Since the cold energy of the heat pump water heater is energy that was originally released to the outside air and was discarded, the cooling effect caused by the above-described cold energy stored in the ground is exactly the energy of the discarded energy. It is an effect born from the utilization, and it can be seen that the present invention is an extremely excellent energy-saving invention.

The waste heat of the present invention is not limited only to the above-mentioned cold heat, but also warm waste heat, for example, warm air discharged from a large-scale cooking place, warm drainage of a bathhouse, and warm drainage of a household bath are also used as a waste heat source. It can be used effectively.

The underground heat exchanger of the present invention has a structure in which an inner pipe having both ends opened is loosely fitted in a metal pipe having good heat conduction.
The tip of the outer tube is sealed, the other end is opened, and this sealed tip is buried vertically in the ground.
Outside air flows through the gap between the inner tube and the outer tube to exchange heat with geothermal heat, and ascends through the inner tube.
In the summer, when the outside air temperature is 32 ° C., the temperature of the air that is heat-exchanged and rises up the inner pipe is lowered to 26 ° C. In winter, even when the outside temperature is 0 ° C., the heat-exchanged air rises to about 10 ° C.
The outer pipe is made of a metal pipe (for example, made of aluminum) having good heat conduction, and the inner pipe is made of a pipe having a poor heat conduction, for example, resin (eg, polyethylene).
The underground temperature is almost constant (average temperature) at a depth of 6 m or more, but the depth portion of 2 to 5 m is lower in summer and higher in winter.
Therefore, the depth of the outer pipe is most preferably 5 m from the viewpoint of thermal efficiency and excavation cost.

On the other hand, since the summer temperature is high at the depth of 500 to 1000 mm from the ground surface and the winter temperature is low, the depth of 500 to 1000 mm from the ground surface of the heat exchange pipe embedded in the ground is affected by this heat. Usually, aluminum alloy with excellent thermal conductivity is used for the pipe material, so this thermal effect propagates to the deeper part of the pipe, generating a part that is higher than the ground that the pipe contacts. . Naturally, the heat exchange efficiency of the pipe will be lowered.

In the underground heat exchanger used in the present invention, it is preferable that the opening is formed of a heat insulating material as an embedded portion having a depth of 500 to 1000 mm from the ground surface to block the heat influence from the ground surface.
As the heat insulating material, ceramics and resins are preferable. Resins are particularly preferable.

By separating the opening, the body, and the tip so that they can be attached and detached as appropriate, a sharp increase in transportation costs can be prevented.
When transporting long objects, the transportation cost increases sharply at a length of 4m, but the body and tip are made of aluminum or aluminum alloy with good thermal conductivity, and the body and tip are combined. By setting the length of the body portion to 4 m or less by setting the tip portion to about 4 to 4.5 m and the tip portion to about 0.5 m, it is possible to prevent a sharp increase in transportation cost.

The body part, the tip part, and the opening part may be joined by attaching a flange or the like to the end face of each pipe, and the adjacent pipes may be joined by sandwiching an O-ring between the flanges and fastening the flange with a bolt. .

It can be used for cooling buildings in general.
It can be used for temperature control in animal breeding and plant cultivation green houses.
It can be used for cooling and temperature raising of industrially generated gases and liquids such as cooling of water and other fluids and temperature rising.

FIG. 1 is a general explanatory diagram when the heat and cooling waste heat of the present invention is stored and used for air conditioning. FIG. 2 is a functional explanatory diagram of a cooling system that uses the cold energy of the heat pump water heater. FIG. 3 is an explanatory diagram for the summer daytime of FIG. FIG. 4 is a diagram showing a temperature change of the underground heat exchanger when the cold energy of the heat pump type water heater shown in FIG. 2 is stored.

Claims (6)

Waste warm air or waste cold air is passed through a heat exchanger with a double pipe structure embedded in the ground, and the waste heat of the warm air or cold air is diffused and penetrated into the ground in contact with the heat exchanger to store heat. In addition, air is passed through the heat exchanger, heat is transferred between the air and the stored geothermal heat, and the stored heat is transferred to the air and carried out for use. How to store and use waste heat. Waste warm air or waste cold air is passed through a pile layer of guristone, and the waste heat of the hot air or cold air is diffused and permeated into the pile layer of guristone to store heat. Heat storage and utilization of waste heat, characterized by flowing air, transferring heat between the air and the heat storage of the grits, transferring the heat storage to the air and carrying it out Method. Waste warm air or waste cold air is passed through a heat exchanger having a double-pipe structure embedded in the pile layer and the underground layer of guristone. It diffuses and penetrates into the ground in contact with the heat exchanger to store heat, and air is passed through the pile layer and the heat exchanger between the air and the stored hot stone and geothermal heat. A method for storing and using waste heat, wherein the heat transfer is performed in step (b), and the stored heat is transferred to the air and carried outside. The said abandoned cool air is a cool air discharged | emitted by the evaporating side of the refrigerant | coolant of the heat pump type water heater used in the time zone of the night midnight electric power, The any one of Claims 1-3 characterized by the above-mentioned. Storage and use of waste heat. The heat pump water heater comprises a condenser, a compressor, an evaporator, an expansion valve, and a water tank. The condenser is immersed in the water tank, and the refrigerant compressed and heated by the compressor is passed through the condenser. The heat storage and utilization method of waste heat according to claim 4, which has a structure for heating water in a water tank. The heat exchanger having the double tube structure is a double tube having a structure in which an inner tube having both ends opened is loosely fitted to an outer tube having a sealed end and the other end opened. An exchanger with a structure where the tip is buried underground and heat is exchanged with geothermal heat by flowing air through the gap between the inner and outer tubes, and the outer tube is buried to a depth of 5 m underground. The heat storage and utilization method of waste heat according to any one of claims 1 to 5, wherein:

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