CA1292873C - Air conditioning system - Google Patents
Air conditioning systemInfo
- Publication number
- CA1292873C CA1292873C CA000550958A CA550958A CA1292873C CA 1292873 C CA1292873 C CA 1292873C CA 000550958 A CA000550958 A CA 000550958A CA 550958 A CA550958 A CA 550958A CA 1292873 C CA1292873 C CA 1292873C
- Authority
- CA
- Canada
- Prior art keywords
- thermal
- piping
- thermal source
- storage tank
- heat
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000004378 air conditioning Methods 0.000 title claims abstract description 34
- 230000005484 gravity Effects 0.000 claims abstract description 14
- 239000007788 liquid Substances 0.000 claims description 25
- 238000001816 cooling Methods 0.000 claims description 13
- 239000006200 vaporizer Substances 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 28
- 238000010792 warming Methods 0.000 description 11
- 239000002002 slurry Substances 0.000 description 9
- 239000000126 substance Substances 0.000 description 6
- 239000003921 oil Substances 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 239000012808 vapor phase Substances 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000008016 vaporization Effects 0.000 description 3
- 230000005494 condensation Effects 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 239000010721 machine oil Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000003595 mist Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Classifications
-
- Y02B30/125—
Landscapes
- Other Air-Conditioning Systems (AREA)
Abstract
Abstract:
An air conditioning system for a building has a first thermal storage tank as a cold thermal source which is installed at a high place in the building, and a second thermal storage tank as a hot thermal source which is installed at a low place in the building. Air conditioners are installed at various heights between the first and second tanks, and a heat pipe system of the gravity type connects the air conditioners to the first and second tanks. This system dispenses with passages for water as the thermal medium at the places where the air conditioners are installed. The system makes it possible to lower the capacities of the air conditioning equipment, especially the capacity of the refrigerator included in the cold thermal source equipment.
An air conditioning system for a building has a first thermal storage tank as a cold thermal source which is installed at a high place in the building, and a second thermal storage tank as a hot thermal source which is installed at a low place in the building. Air conditioners are installed at various heights between the first and second tanks, and a heat pipe system of the gravity type connects the air conditioners to the first and second tanks. This system dispenses with passages for water as the thermal medium at the places where the air conditioners are installed. The system makes it possible to lower the capacities of the air conditioning equipment, especially the capacity of the refrigerator included in the cold thermal source equipment.
Description
1~3Z~3~73 Air conditioning system The present invention relates generally to an air conditioning system for buildings and, more particularly, to an air conditioning system that dispenses with passages for water as a thermal medium at the locations where air conditioners are installed, and which, moreover, permits the air conditionlng equipment, especially the refrigerator, to be relatively small in capacity.
Generally, in air conditioning systems for buildings, water has been used as the medium for thermal conveyance between the thermal source equipment and the individual air conditioners. Such use of water, however, has involved problems with leakage. Recently, therefore, in air conditioning systems for buildings, there has been introduced a volatile substance, such as freon, as the thermal medium flowing between the thermal source equipment and the heat exchangers of the respective air conditioners to reduce leakage troubles by virtue of the volatility of the substance.
Such a system using a volatile thermal medium comprises, for both cooling and warming, an outdoor unit which may be placed on the roof of a building, and a plurality of indoor units at the locations to be air-conditioned, the outdoor unit being an assembly of thermal source equipment including, for example, a refrigerator that also functions as a heat pump, and each of said indoor units being an air conditioner . ~
. .. ^, 1'~9Z~7~
and a thermal medium conduit interconnecting the outdoor unit and the indoor unit.
Such an air conditioning system is based on a direct expansion method, according to which the thermal medium, 5 liquefied by a condenser in the outdoor unit, is supplied through a conduit directly to a vapori~er in each indoor unit.
In this system the ice machine oil used in the compressor in the outdoor unit partly mixes in the form of a mist into the thermal medium and circulates through the conduit. It is 10 necessary for this oil, carried to the indoor unit by the flow of the thermal medium, to be recovered and returned to the compressor in the outdoor unit. This necessity imposes various restrictions on the operation of the system.
For example, whereas it is desirable that the variation 15 of the air conditioning load at the air-conditioned location should be met by adjustment of the flow rate of the thermal medium supplied to the indoor unit, the conveyance of the oil for recovery requires the flow rate of the vapor in the thermal medium conduit to be maintained at approximately 6 m/sec. or 20 more. There is thus a limit to throttling, because of the need to maintain an adequate vapor flow. Normal throttling thus being unacceptable for `the adjustment of the flow rate of the thermal medium, the only alternative means for controlling the output that is available to indoor operators, 25 if variation of the load necessitates it, is to repeatedly open and close the throttle for short intervals, more or less simultaneously with turning on and off of the fans in the individual air conditioners. This method of control is not advisable.
The need to recover the oil also sets a strict limit on the number of indoor units that can be connected to one out-door unit. In fact, the number of indoor units is normally limited to two or three for one outdoor unit.
The thermal source equipment, which is in fact a refrigerator, is required to have a relatively large capacity, because of the need to cope with peaks in the load. Another .';~! ~ `
'~._ '' 129Z8~3 factor that requires the capacity to be large is the fact that the thermal medium is circulated under the pressure applied by the compressor in the refrigerator.
With these problems in mind, the present invention has been developed to provide an advantageous means to solve them.
Accordingly, an essential object of the invention is to provide an air conditioning system for buildings which, for both cooling and warming, dispenses with passages for water as a thermal medium at a location where an air conditioner is installed, permits the air conditioning equipment, especially the refrigerator, to be relatively small in capacity, permits the output to be controlled at each of the indoor units with ease, and permits one outdoor unit to be connected with a larger number of indoor units than in an air conditioning system of the direct expansion type.
To this end, the present invention comprises an air conditioning system for a building, said system comprising:
a cold thermal source at which a relatively low temperature is developed, said cold thermal source comprising a first thermal storage tank disposed at a relatively high location on the building; a hot thermal source at which a relatively high temperature is developed as compared to the temperature developed at said cold thermal source, said hot thermal source comprising a second thermal storage tank disposed at a relatively low location on the building as compared to the location at which said first thermal storage tank is disposed; a plurality of air conditioners for air conditioning respective areas in the building, each of said air conditioners disposed at a respective location between said first and said second thermal tanks;
and gravity type heat piping extending between and operatively connecting said plurality of air conditioners with said cold and said hot thermal sources for allowing 1~928~73 :*
thermal medium to circulate between said cold thermal source and said plurality of air conditioners and between said hot thermal source and said plurality of air conditioners.
It is preferable for the first tank to comprise an ice thermal storage tank.
The heat piping of the gravity type is essentially designed to allow a thermal medium to circulate therethrough under natural pressure, for a circulation generated by a phase change in the thermal medium. The circulation according to the present invention, however, is not restricted to natural circulation alone, but can be partly forced by means such as a pump to supplement the natural circulating force, or to adjust the circulating flow of the thermal medium.
An air conditioning system according to the preferred orm of the present invention is operated as follows.
A thermal medium, such as freon*, is circulated through heat pipes of the gravity type, with the motive force for the circulation being provided by a phase change and gravity, so as to transfer heat by natural circulation between the air conditioner at the air-conditioned location and each of the thermal reservoirs. For cooling, the thermal medium absorbs a thermal load at the air-conditioned location, through the heat exchanger in the air conditioner, changes from li~uid phase to vapor phase as it absorbs the heat, and rises through a heat pipe to the irst thermal stora9e tank. The thermal medium in the vapor phase is then condensed by cooling in the first tank, descends through a heat pipe by gravity, and returns to the air conditioner. For warming, the thermal medium absorbs a thermal load at the air-conditioned location, through the heat exchanger in the air conditioner, changes from vapor phase to liquid phase, and descends through a heat pipe by gravity to the second thermal storage tank. The thermal * Trade Mark ~'~
lZ9Z8~73 - 4a -medium in the liquid phase is then vaporized by heating in the second tank, and rises through a heat pipe to the air conditioner.
In an air conditioning system in a building according to the present invention, there is no occurrence of ice machine oil being carried to an indoor unit, nor is there any need to recover it, for heat exchange takes place between the system of the thermal medium, which is forced to circulate in a thermal reservoir, and that of the thermal medium which performs a natural circulation through heat pipes of the gravity type. The heat pipes constitute a circulatory system of the thermal medium, and so does the thermal reservoir, each system being different from and independent of the other. Accordingly, there is no - s -restriction with respect to the flow rate of the thermal medium which circulates naturally through the heat pipes, while the flow rate of the thermal medium at each indoor unit can be so controlled as to correspond to an amount of heat exchange proportional to the load at the respective unit.
There is no particular limit to the number of indoor units for one outdoor unit where the conduit resistance of the heat pipes is small enough to allow the thermal medium to circulate naturally with ease. Since there is no need to recover oil, the flow rate of the thermal medium in the vapor phase has no minimum limit. An ice thermal storage tank used for the first thermal storage tank has a large thermal storage capacity for its weight, as compared with a water-based tank, so that an ice thermal storage tank can be rendered light in weight, which minimizes the problems involved in installing a thermal storage tank at a high location, such as the roof of a building, where the permitted weight is limited.
As is clear from the foregoing description, the advantages of an air conditioning system according to the present invention can be reduced to the following points.
Since the system requires no passages for water as the thermal medium where an air conditioner is installed, such as in an air-conditioned room, there is no problem of water leakage at the location of installation. Since the thermal medium used in the heat pipes is a volatile substance such as freon, there is little likelihood of liquid leakage causing troubles, the substance vaporizing quickly if leakage should occur. Since a thermal reservoir is used for the cold thermal source, the system can cope satisfactorily with peaks of the air conditioning load, even if the capacity of the refrigerator which cools the thermal reservoir is small. The system makes it possible to adjust the flow rate of the thermal rate within a wide range at each indoor unit, and accordingly control of the air conditioning capacity can be achieved with ease. The system permits the indoor units, which can be connected to one outdoor unit, to be increased to a larger -` lZ~?Z873 number than in an air conditioning system of the direct expansion type.
These and other features of embodiments the present invention will become apparent from the following description with reference to the accompanying drawings, in which:
Fig. 1 is a schematic flowchart of an air conditioning system for buildings according to a first embodiment of the present invention; and Fig. 2 is a schematic flowchart of an air conditioning system for buildings according to a second embodiment of the present invention.
THE FIRST EMBODIMENT
Referring now to the drawings, there is shown in Fig. 1 an air conditioning system for a building. The installations in this system are positioned with respect to height. As the first thermal storage tank an ice type thermal reservoir 1 is used and is installed at a high place, such as the roof, whereas the second thermal storage tank is a hot water type thermal reservoir 2 installed at a low place, such as the basement of the building. The reservoir 1 is designed to store both sensible heat and latent heat, which is approximately 80 times as large in terms of thermal energy than the sensible heat, and has a larger thermal storage capacity than a cold water type of thermal reservoir which only stores sensible heat. An ice type thermal reservoir is much smaller in dimensions than a cold water type thermal reservoir and can have as large a thermal storage capacity as the cold water type of reservoir. Therefore it is convenient for an ice type of thermal reservoir to be installed on a -oof. The air conditioners 3, each as an indoor unit, are arranged at various heights and installed at air-conditioned locations on each floor, between the reservoirs 1 and 2.
Heat pipes of the gravity type 4, 5 connect the air conditioner 3 at each air-conditioned location with each of lZ9~8~3 the tanks 1, 2. The thermal medium, such as freon, (the solid arrow denotes liquid flow and the broken arrow vàpor flow) in the heat pipes 4, 5 undergoes a phase change by heat exchange in the air conditioners 3 and either of the thermal storage tanks 1 or 2, and circulates in the heat pipes 4, 5 in the manner of a back and forth flow therebetween. In the heat pipe 4 after the reservoir 1 there is a liquid receptacle 6 in the section passing thermal medium in the liquid phase, at a position before the liquid branchés to different air conditioners 3. There is also a flow adjusting valve 7 in each of the downstream pipes leading to the respective air conditioners 3. This arrangement enables an air conditioner to be provided with thermal medium from the liquid receptacle 6 in an amount proportional to the cooling load at the air-conditioned location. In the heat pipe 5 before the reservoir2 there is a liquid receptacle 8 in the section passing liquid thermal medium, at a position following the point where the liquid thermal medium discharged from each air conditioner 3 meets in the flow towards the reservoir 2. In an upstream location passing liquid thermal medium in the heat pipes 5, there is a flow adjusting valve 9 in each of the pipes from the respective air conditioners 3. A flow adjusting valve 10 controls the total flow of the liquid thermal medium at a downstream location. It is not water, but a volatile substance, such as freon, that is passed as the thermal medium to the air-conditioned room. There is little likelihood that this thermal medium will damage the area where the air conditioner is installed. Even if a leak occurs, the substance will vaporize quickly.
The thermal source device to provide the thermal storage tank 1 with cold energy or hot energy is a heat pump chiller 11, with an ice-making machine 12. A slurry pump 13 is provided between the ice type thermal reservoir 1 and the machine 12, so that ice made by the machine 12 is forced into the reservoir 1 by the slurry pump 13. A hot water heat - ~Z~2Eil~;3 recovery pipe 15 is provided between a heat exchanger 14 that is incorporated into the condensation device in the heat pump chiller 11, and the reservoir 2. ~ pump 16 in the pipe 15 forces hot water into the reservoir 2.
It is preferable to operate the heat pump chiller 11 at night, when electric power is available at a reduced rate, so as to store the thermal energy obtained in the thermal storage tank 1 or 2. The thermal energy stored in the thermal storage tank 1 or 2 is, in principle, used to meet the air-conditioning load during the day. In a different method, wherein additional thermal source equipment is connected directly to each air conditioning device 3 (not shown in drawings), the load on the additional thermal source equipment can be reduced by combining the output of the thermal source equipment with the thermal energy obtainable from the thermal storage tank 1 or 2. When this additional thermal source is used as the main thermal source and the energy from the thermal storage tank is used as supplementary energy, the capacity of the additional thermal source equipment to meet the peak load can be reduced. The same effect can be achieved without using supplementary thermal sources: the vaporizer (the vaporizer contained in the ice-making machine 12) of the heat pump chiller 11 is divided into two alternative systems, the vaporizer in one system being led to the machine 12 in a manner similar to the above example and the vaporizer in the other system being led directly to the heat pipe 4, apart from the ice type thermal reservoir 1, to directly condense the thermal medium in the heat pipe 4.
The above description has dealt with a refrigeration circuit. Also for warming, the condenser in the heat pump chiller 11 can be divided into two alternative systems, one system being led to the reservoir 2 and the other system being led directly to the heat pipe 4, so as to form a hot thermal source to directly vaporize the thermal medium in the heat pipe 4, apart from the reservoir 2, and the same effect as above can be obtained. The performance coefficient of the 12~2873 thermal storage operation for cooling is approximately 2.5, but the performance coefficient when the heat pipe 4 is directly cooled is expected to be approximately 4.5.
In the drawings 17 denotes an accumulator, 18 an expansion valve, 19 an air-heat exchanger, 20 a compressor, and 21 a fan.
THE SECOND EMBODIMENT
Fig. 2 is an air conditioning system for a building as a second embodiment of the present invention. In Fig. 1, the heat pipes 4 are installed separately from the heat pipes 5, the former for cooling and -the latter for warming. In the second embodiment, the same single heat pipes of the gravity type 31 are used for both cooling and warming, by switching.
Accordingly, each air conditioner 3 has only one heat exchanger 32. The thermal medium conduits formed of the heat pipes 31 have an upright main conduit 35 for liquid, and an upright main conduit 38 for vapor, which are passed between the heat exchanger at the cold thermal source (the heat exchanger for condensing thermal medium in the heat pipe 32 is hereinafter abbreviated as condenser) 33, 33' located at a high place in the building and the heat exchanger at the hot thermal source (the heat exchanger to vaporize the thermal medium in the heat pipes 31 is hereinafter abbreviated as vaporizer) 34 located at a low place in the building. Further-more, at each floor a horizontal main pipe 36 for liquid branches out from an upright main pipe 35 for liquid, and a horizontal main pipe 39 for vapor branches out from an upright main pipe 38 for vapor. From the horizontal main pipes 36 for liquid and from the horizontal main pipes 39 for vapor, branch pipes 37 for liquid and branch pipes 40 for vapor are extended to the respective air conditioners to form thermal medium circuits. In the drawing, the solid arrows denote pipes for liquids and the direction in which the liquid flows and broken arrows denote pipes for vapor and the direction in which the vapor flows, all in the cooling operation. The arrows in parentheses denote the flows of thermal medium in warming operation. Switching between cooling and warming is ~ ~ .
~.Z92~73 done by the valves 41, 42, 42', 43, and 44 provided in the upright main pipe 35 for liquid and the upright main pipe 38 for vapor. Reference numeral 50 denotes a thermal medium flow adjusting valve for the warming operation. The switching valve 41 is provided in the horizontal main pipe 36 for liquid at a position higher than the highest branching point, the switching valves 42 and 42' are provided in the horizontal main pipe 39 for vapor at positions higher than the highest branching points, the switching valve 43 is provided in the horizontal main pipe 36 for liquid at a position lower than the lowest branching point, and the switching valve 44 is provided in the horizontal main pipe 39 for vapor at a position lower than the lowest branching point. For the cooling operation, the switching valves 41, 42, 42' are opened, whereas the switching valves 43, 44 are closed. For the warming operation, the switching valves 43, 44 are opened, whereas the switching valves 41, 42, 42'are closed. The same heat pipes 31 are used for both the cooling and the warming operation by switching the respective thermal medium circuit, so that only one heat exchanger 32 serves the purpose in each air conditioner 3, and for adjusting the supply of cold thermal medium to the heat exchanger 32 this system needs only one flow rate adjusting valve 49 to serve only one heat exchanger 32.
To cool the thermal medium in the heat pipe 31 there are condensers 33 and 33' placed in parallel~ One condenser 33 is supplied with chilled water through a chilled water pipe system 46, with a pump 45 in a reciprocal circulation between the reservoir 1 and the condenser, and cools the condensation section of the heat pipe 31 at the top end. The ice type thermal reservoir 1 is selectively connected to an ice slurry pipe system (a slurry pump 13 is provided) which extends from the ice-making machine 12 in a heat pump chiller 11 and branches out to be connected with said ice type thermal reservoir. The other end of the ice slurry pipe system is connected directly with the condenser 33'. The .~
,.
1~9Z~73 chilled water pump 45 is structurally the same as the slurry pump, being capable of pumping ice slurry besides cold water.
The ice-making machine 12 can be used as a water chiller by raising the vaporizing point. Then the reservoir 1 is used as a chilled water type thermal reservoir, the ice slurry pipe system as a chilled water pipe system, and the slurry pump 13 as a chilled water pump.
With condensers 33, 33' installed in parallel the system enables the storage of thermal energy in the ice type thermal reservoir by utilizing electric power at a reduced rate at night. When the load is low, the operation utilizes only the condenser 33, and, when high, both condensers 33, 33' can be used.
The vaporizer 34 for the heat pipe 31 is supplied with hot water from a hot water pipe system 48 which, having a hot water pump 47, reciprocally circulates hot water between a hot water type thermal reservoir and the vaporizer 34. The vaporizer heats the vaporizing section of the heat pipe 31 at the lower end.
Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art.
Therefor, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as included therein.
..... .~
Generally, in air conditioning systems for buildings, water has been used as the medium for thermal conveyance between the thermal source equipment and the individual air conditioners. Such use of water, however, has involved problems with leakage. Recently, therefore, in air conditioning systems for buildings, there has been introduced a volatile substance, such as freon, as the thermal medium flowing between the thermal source equipment and the heat exchangers of the respective air conditioners to reduce leakage troubles by virtue of the volatility of the substance.
Such a system using a volatile thermal medium comprises, for both cooling and warming, an outdoor unit which may be placed on the roof of a building, and a plurality of indoor units at the locations to be air-conditioned, the outdoor unit being an assembly of thermal source equipment including, for example, a refrigerator that also functions as a heat pump, and each of said indoor units being an air conditioner . ~
. .. ^, 1'~9Z~7~
and a thermal medium conduit interconnecting the outdoor unit and the indoor unit.
Such an air conditioning system is based on a direct expansion method, according to which the thermal medium, 5 liquefied by a condenser in the outdoor unit, is supplied through a conduit directly to a vapori~er in each indoor unit.
In this system the ice machine oil used in the compressor in the outdoor unit partly mixes in the form of a mist into the thermal medium and circulates through the conduit. It is 10 necessary for this oil, carried to the indoor unit by the flow of the thermal medium, to be recovered and returned to the compressor in the outdoor unit. This necessity imposes various restrictions on the operation of the system.
For example, whereas it is desirable that the variation 15 of the air conditioning load at the air-conditioned location should be met by adjustment of the flow rate of the thermal medium supplied to the indoor unit, the conveyance of the oil for recovery requires the flow rate of the vapor in the thermal medium conduit to be maintained at approximately 6 m/sec. or 20 more. There is thus a limit to throttling, because of the need to maintain an adequate vapor flow. Normal throttling thus being unacceptable for `the adjustment of the flow rate of the thermal medium, the only alternative means for controlling the output that is available to indoor operators, 25 if variation of the load necessitates it, is to repeatedly open and close the throttle for short intervals, more or less simultaneously with turning on and off of the fans in the individual air conditioners. This method of control is not advisable.
The need to recover the oil also sets a strict limit on the number of indoor units that can be connected to one out-door unit. In fact, the number of indoor units is normally limited to two or three for one outdoor unit.
The thermal source equipment, which is in fact a refrigerator, is required to have a relatively large capacity, because of the need to cope with peaks in the load. Another .';~! ~ `
'~._ '' 129Z8~3 factor that requires the capacity to be large is the fact that the thermal medium is circulated under the pressure applied by the compressor in the refrigerator.
With these problems in mind, the present invention has been developed to provide an advantageous means to solve them.
Accordingly, an essential object of the invention is to provide an air conditioning system for buildings which, for both cooling and warming, dispenses with passages for water as a thermal medium at a location where an air conditioner is installed, permits the air conditioning equipment, especially the refrigerator, to be relatively small in capacity, permits the output to be controlled at each of the indoor units with ease, and permits one outdoor unit to be connected with a larger number of indoor units than in an air conditioning system of the direct expansion type.
To this end, the present invention comprises an air conditioning system for a building, said system comprising:
a cold thermal source at which a relatively low temperature is developed, said cold thermal source comprising a first thermal storage tank disposed at a relatively high location on the building; a hot thermal source at which a relatively high temperature is developed as compared to the temperature developed at said cold thermal source, said hot thermal source comprising a second thermal storage tank disposed at a relatively low location on the building as compared to the location at which said first thermal storage tank is disposed; a plurality of air conditioners for air conditioning respective areas in the building, each of said air conditioners disposed at a respective location between said first and said second thermal tanks;
and gravity type heat piping extending between and operatively connecting said plurality of air conditioners with said cold and said hot thermal sources for allowing 1~928~73 :*
thermal medium to circulate between said cold thermal source and said plurality of air conditioners and between said hot thermal source and said plurality of air conditioners.
It is preferable for the first tank to comprise an ice thermal storage tank.
The heat piping of the gravity type is essentially designed to allow a thermal medium to circulate therethrough under natural pressure, for a circulation generated by a phase change in the thermal medium. The circulation according to the present invention, however, is not restricted to natural circulation alone, but can be partly forced by means such as a pump to supplement the natural circulating force, or to adjust the circulating flow of the thermal medium.
An air conditioning system according to the preferred orm of the present invention is operated as follows.
A thermal medium, such as freon*, is circulated through heat pipes of the gravity type, with the motive force for the circulation being provided by a phase change and gravity, so as to transfer heat by natural circulation between the air conditioner at the air-conditioned location and each of the thermal reservoirs. For cooling, the thermal medium absorbs a thermal load at the air-conditioned location, through the heat exchanger in the air conditioner, changes from li~uid phase to vapor phase as it absorbs the heat, and rises through a heat pipe to the irst thermal stora9e tank. The thermal medium in the vapor phase is then condensed by cooling in the first tank, descends through a heat pipe by gravity, and returns to the air conditioner. For warming, the thermal medium absorbs a thermal load at the air-conditioned location, through the heat exchanger in the air conditioner, changes from vapor phase to liquid phase, and descends through a heat pipe by gravity to the second thermal storage tank. The thermal * Trade Mark ~'~
lZ9Z8~73 - 4a -medium in the liquid phase is then vaporized by heating in the second tank, and rises through a heat pipe to the air conditioner.
In an air conditioning system in a building according to the present invention, there is no occurrence of ice machine oil being carried to an indoor unit, nor is there any need to recover it, for heat exchange takes place between the system of the thermal medium, which is forced to circulate in a thermal reservoir, and that of the thermal medium which performs a natural circulation through heat pipes of the gravity type. The heat pipes constitute a circulatory system of the thermal medium, and so does the thermal reservoir, each system being different from and independent of the other. Accordingly, there is no - s -restriction with respect to the flow rate of the thermal medium which circulates naturally through the heat pipes, while the flow rate of the thermal medium at each indoor unit can be so controlled as to correspond to an amount of heat exchange proportional to the load at the respective unit.
There is no particular limit to the number of indoor units for one outdoor unit where the conduit resistance of the heat pipes is small enough to allow the thermal medium to circulate naturally with ease. Since there is no need to recover oil, the flow rate of the thermal medium in the vapor phase has no minimum limit. An ice thermal storage tank used for the first thermal storage tank has a large thermal storage capacity for its weight, as compared with a water-based tank, so that an ice thermal storage tank can be rendered light in weight, which minimizes the problems involved in installing a thermal storage tank at a high location, such as the roof of a building, where the permitted weight is limited.
As is clear from the foregoing description, the advantages of an air conditioning system according to the present invention can be reduced to the following points.
Since the system requires no passages for water as the thermal medium where an air conditioner is installed, such as in an air-conditioned room, there is no problem of water leakage at the location of installation. Since the thermal medium used in the heat pipes is a volatile substance such as freon, there is little likelihood of liquid leakage causing troubles, the substance vaporizing quickly if leakage should occur. Since a thermal reservoir is used for the cold thermal source, the system can cope satisfactorily with peaks of the air conditioning load, even if the capacity of the refrigerator which cools the thermal reservoir is small. The system makes it possible to adjust the flow rate of the thermal rate within a wide range at each indoor unit, and accordingly control of the air conditioning capacity can be achieved with ease. The system permits the indoor units, which can be connected to one outdoor unit, to be increased to a larger -` lZ~?Z873 number than in an air conditioning system of the direct expansion type.
These and other features of embodiments the present invention will become apparent from the following description with reference to the accompanying drawings, in which:
Fig. 1 is a schematic flowchart of an air conditioning system for buildings according to a first embodiment of the present invention; and Fig. 2 is a schematic flowchart of an air conditioning system for buildings according to a second embodiment of the present invention.
THE FIRST EMBODIMENT
Referring now to the drawings, there is shown in Fig. 1 an air conditioning system for a building. The installations in this system are positioned with respect to height. As the first thermal storage tank an ice type thermal reservoir 1 is used and is installed at a high place, such as the roof, whereas the second thermal storage tank is a hot water type thermal reservoir 2 installed at a low place, such as the basement of the building. The reservoir 1 is designed to store both sensible heat and latent heat, which is approximately 80 times as large in terms of thermal energy than the sensible heat, and has a larger thermal storage capacity than a cold water type of thermal reservoir which only stores sensible heat. An ice type thermal reservoir is much smaller in dimensions than a cold water type thermal reservoir and can have as large a thermal storage capacity as the cold water type of reservoir. Therefore it is convenient for an ice type of thermal reservoir to be installed on a -oof. The air conditioners 3, each as an indoor unit, are arranged at various heights and installed at air-conditioned locations on each floor, between the reservoirs 1 and 2.
Heat pipes of the gravity type 4, 5 connect the air conditioner 3 at each air-conditioned location with each of lZ9~8~3 the tanks 1, 2. The thermal medium, such as freon, (the solid arrow denotes liquid flow and the broken arrow vàpor flow) in the heat pipes 4, 5 undergoes a phase change by heat exchange in the air conditioners 3 and either of the thermal storage tanks 1 or 2, and circulates in the heat pipes 4, 5 in the manner of a back and forth flow therebetween. In the heat pipe 4 after the reservoir 1 there is a liquid receptacle 6 in the section passing thermal medium in the liquid phase, at a position before the liquid branchés to different air conditioners 3. There is also a flow adjusting valve 7 in each of the downstream pipes leading to the respective air conditioners 3. This arrangement enables an air conditioner to be provided with thermal medium from the liquid receptacle 6 in an amount proportional to the cooling load at the air-conditioned location. In the heat pipe 5 before the reservoir2 there is a liquid receptacle 8 in the section passing liquid thermal medium, at a position following the point where the liquid thermal medium discharged from each air conditioner 3 meets in the flow towards the reservoir 2. In an upstream location passing liquid thermal medium in the heat pipes 5, there is a flow adjusting valve 9 in each of the pipes from the respective air conditioners 3. A flow adjusting valve 10 controls the total flow of the liquid thermal medium at a downstream location. It is not water, but a volatile substance, such as freon, that is passed as the thermal medium to the air-conditioned room. There is little likelihood that this thermal medium will damage the area where the air conditioner is installed. Even if a leak occurs, the substance will vaporize quickly.
The thermal source device to provide the thermal storage tank 1 with cold energy or hot energy is a heat pump chiller 11, with an ice-making machine 12. A slurry pump 13 is provided between the ice type thermal reservoir 1 and the machine 12, so that ice made by the machine 12 is forced into the reservoir 1 by the slurry pump 13. A hot water heat - ~Z~2Eil~;3 recovery pipe 15 is provided between a heat exchanger 14 that is incorporated into the condensation device in the heat pump chiller 11, and the reservoir 2. ~ pump 16 in the pipe 15 forces hot water into the reservoir 2.
It is preferable to operate the heat pump chiller 11 at night, when electric power is available at a reduced rate, so as to store the thermal energy obtained in the thermal storage tank 1 or 2. The thermal energy stored in the thermal storage tank 1 or 2 is, in principle, used to meet the air-conditioning load during the day. In a different method, wherein additional thermal source equipment is connected directly to each air conditioning device 3 (not shown in drawings), the load on the additional thermal source equipment can be reduced by combining the output of the thermal source equipment with the thermal energy obtainable from the thermal storage tank 1 or 2. When this additional thermal source is used as the main thermal source and the energy from the thermal storage tank is used as supplementary energy, the capacity of the additional thermal source equipment to meet the peak load can be reduced. The same effect can be achieved without using supplementary thermal sources: the vaporizer (the vaporizer contained in the ice-making machine 12) of the heat pump chiller 11 is divided into two alternative systems, the vaporizer in one system being led to the machine 12 in a manner similar to the above example and the vaporizer in the other system being led directly to the heat pipe 4, apart from the ice type thermal reservoir 1, to directly condense the thermal medium in the heat pipe 4.
The above description has dealt with a refrigeration circuit. Also for warming, the condenser in the heat pump chiller 11 can be divided into two alternative systems, one system being led to the reservoir 2 and the other system being led directly to the heat pipe 4, so as to form a hot thermal source to directly vaporize the thermal medium in the heat pipe 4, apart from the reservoir 2, and the same effect as above can be obtained. The performance coefficient of the 12~2873 thermal storage operation for cooling is approximately 2.5, but the performance coefficient when the heat pipe 4 is directly cooled is expected to be approximately 4.5.
In the drawings 17 denotes an accumulator, 18 an expansion valve, 19 an air-heat exchanger, 20 a compressor, and 21 a fan.
THE SECOND EMBODIMENT
Fig. 2 is an air conditioning system for a building as a second embodiment of the present invention. In Fig. 1, the heat pipes 4 are installed separately from the heat pipes 5, the former for cooling and -the latter for warming. In the second embodiment, the same single heat pipes of the gravity type 31 are used for both cooling and warming, by switching.
Accordingly, each air conditioner 3 has only one heat exchanger 32. The thermal medium conduits formed of the heat pipes 31 have an upright main conduit 35 for liquid, and an upright main conduit 38 for vapor, which are passed between the heat exchanger at the cold thermal source (the heat exchanger for condensing thermal medium in the heat pipe 32 is hereinafter abbreviated as condenser) 33, 33' located at a high place in the building and the heat exchanger at the hot thermal source (the heat exchanger to vaporize the thermal medium in the heat pipes 31 is hereinafter abbreviated as vaporizer) 34 located at a low place in the building. Further-more, at each floor a horizontal main pipe 36 for liquid branches out from an upright main pipe 35 for liquid, and a horizontal main pipe 39 for vapor branches out from an upright main pipe 38 for vapor. From the horizontal main pipes 36 for liquid and from the horizontal main pipes 39 for vapor, branch pipes 37 for liquid and branch pipes 40 for vapor are extended to the respective air conditioners to form thermal medium circuits. In the drawing, the solid arrows denote pipes for liquids and the direction in which the liquid flows and broken arrows denote pipes for vapor and the direction in which the vapor flows, all in the cooling operation. The arrows in parentheses denote the flows of thermal medium in warming operation. Switching between cooling and warming is ~ ~ .
~.Z92~73 done by the valves 41, 42, 42', 43, and 44 provided in the upright main pipe 35 for liquid and the upright main pipe 38 for vapor. Reference numeral 50 denotes a thermal medium flow adjusting valve for the warming operation. The switching valve 41 is provided in the horizontal main pipe 36 for liquid at a position higher than the highest branching point, the switching valves 42 and 42' are provided in the horizontal main pipe 39 for vapor at positions higher than the highest branching points, the switching valve 43 is provided in the horizontal main pipe 36 for liquid at a position lower than the lowest branching point, and the switching valve 44 is provided in the horizontal main pipe 39 for vapor at a position lower than the lowest branching point. For the cooling operation, the switching valves 41, 42, 42' are opened, whereas the switching valves 43, 44 are closed. For the warming operation, the switching valves 43, 44 are opened, whereas the switching valves 41, 42, 42'are closed. The same heat pipes 31 are used for both the cooling and the warming operation by switching the respective thermal medium circuit, so that only one heat exchanger 32 serves the purpose in each air conditioner 3, and for adjusting the supply of cold thermal medium to the heat exchanger 32 this system needs only one flow rate adjusting valve 49 to serve only one heat exchanger 32.
To cool the thermal medium in the heat pipe 31 there are condensers 33 and 33' placed in parallel~ One condenser 33 is supplied with chilled water through a chilled water pipe system 46, with a pump 45 in a reciprocal circulation between the reservoir 1 and the condenser, and cools the condensation section of the heat pipe 31 at the top end. The ice type thermal reservoir 1 is selectively connected to an ice slurry pipe system (a slurry pump 13 is provided) which extends from the ice-making machine 12 in a heat pump chiller 11 and branches out to be connected with said ice type thermal reservoir. The other end of the ice slurry pipe system is connected directly with the condenser 33'. The .~
,.
1~9Z~73 chilled water pump 45 is structurally the same as the slurry pump, being capable of pumping ice slurry besides cold water.
The ice-making machine 12 can be used as a water chiller by raising the vaporizing point. Then the reservoir 1 is used as a chilled water type thermal reservoir, the ice slurry pipe system as a chilled water pipe system, and the slurry pump 13 as a chilled water pump.
With condensers 33, 33' installed in parallel the system enables the storage of thermal energy in the ice type thermal reservoir by utilizing electric power at a reduced rate at night. When the load is low, the operation utilizes only the condenser 33, and, when high, both condensers 33, 33' can be used.
The vaporizer 34 for the heat pipe 31 is supplied with hot water from a hot water pipe system 48 which, having a hot water pump 47, reciprocally circulates hot water between a hot water type thermal reservoir and the vaporizer 34. The vaporizer heats the vaporizing section of the heat pipe 31 at the lower end.
Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art.
Therefor, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as included therein.
..... .~
Claims (6)
1. An air conditioning system for a building, said system comprising:
a cold thermal source at which a relatively low temperature is developed, said cold thermal source comprising a first thermal storage tank disposed at a relatively high location on the building;
a hot thermal source at which a relatively high temperature is developed as compared to the temperature developed at said cold thermal source, said hot thermal source comprising a second thermal storage tank disposed at a relatively low location on the building as compared to the location at which said first thermal storage tank is disposed;
a plurality of air conditioners for air conditioning respective areas in the building, each of said air conditioners disposed at a respective location between said first and said second thermal tanks; and gravity type heat piping extending between and operatively connecting said plurality of air conditioners with said cold and said hot thermal sources for allowing thermal medium to circulate between said cold thermal source and said plurality of air conditioners and between said hot thermal source and said plurality of air conditioners.
a cold thermal source at which a relatively low temperature is developed, said cold thermal source comprising a first thermal storage tank disposed at a relatively high location on the building;
a hot thermal source at which a relatively high temperature is developed as compared to the temperature developed at said cold thermal source, said hot thermal source comprising a second thermal storage tank disposed at a relatively low location on the building as compared to the location at which said first thermal storage tank is disposed;
a plurality of air conditioners for air conditioning respective areas in the building, each of said air conditioners disposed at a respective location between said first and said second thermal tanks; and gravity type heat piping extending between and operatively connecting said plurality of air conditioners with said cold and said hot thermal sources for allowing thermal medium to circulate between said cold thermal source and said plurality of air conditioners and between said hot thermal source and said plurality of air conditioners.
2. An air conditioning system for a building as claimed in claim 1, wherein said first thermal storage tank is an ice type thermal reservoir.
3. An air conditioning system for a building as claimed in claim 1, and further comprising a heat pump chiller operatively connected to said hot and said cold thermal sources for cooling said first thermal storage tank and for heating said second thermal storage tank.
4. An air conditioning system for a building as claimed in claim 3, wherein said cold thermal source further comprises a heat exchanger operatively connected in parallel to said first thermal storage tank, said heat pump chiller comprises a vaporizer, said heat exchanger is operatively connected to said vaporizer, and said gravity type heat piping is operatively connected to said cold thermal source at said heat exchanger thereof.
5. An air conditioning system for a building as claimed in claim 1, wherein said gravity type heat piping comprise first heat piping and second heat piping, said first heat piping connecting said air conditioners with said first thermal storage tank and said second heat piping connecting said air conditioners with said second thermal storage tank.
6. An air conditioning system as claimed in claim 1, wherein said gravity type heat piping comprises upright main liquid piping having an upper end connected to said cold thermal source and a lower end connected to said hot thermal source, upright main vapor piping having an upper end connected to said cold thermal source and a lower end connected to said hot thermal source, horizontal main liquid piping extending between and operatively connecting said plurality of air conditioners and said upright main liquid piping, horizontal main vapor piping extending between and operatively connecting said plurality of air conditioners and said upright main vapor piping, and further comprising a respective valve disposed at each of said upper and said lower ends of said main upright liquid piping and of said main upright vapor piping for selectively opening and closing said main upright liquid piping and said main upright vapor piping to said cold and said hot thermal sources.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000550958A CA1292873C (en) | 1987-11-03 | 1987-11-03 | Air conditioning system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000550958A CA1292873C (en) | 1987-11-03 | 1987-11-03 | Air conditioning system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1292873C true CA1292873C (en) | 1991-12-10 |
Family
ID=4136781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000550958A Expired - Lifetime CA1292873C (en) | 1987-11-03 | 1987-11-03 | Air conditioning system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1292873C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114562676A (en) * | 2022-04-27 | 2022-05-31 | 浙江浙能航天氢能技术有限公司 | Heat energy collecting and utilizing system of hydrogenation station |
-
1987
- 1987-11-03 CA CA000550958A patent/CA1292873C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114562676A (en) * | 2022-04-27 | 2022-05-31 | 浙江浙能航天氢能技术有限公司 | Heat energy collecting and utilizing system of hydrogenation station |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4796439A (en) | Air conditioning system | |
| US4608836A (en) | Multi-mode off-peak storage heat pump | |
| KR0153546B1 (en) | Regenerative air conditioning system and defrosting method | |
| AU598982B2 (en) | Three function heat pump system | |
| CN203203305U (en) | Air conditioner device | |
| CA2485757C (en) | Thermo-siphon chiller refrigerator for use in cold district | |
| US4569207A (en) | Heat pump heating and cooling system | |
| CN100587348C (en) | Heat storage air conditioner | |
| EP0134015B1 (en) | Space cooling and heating and hot water supplying apparatus | |
| KR19990067577A (en) | Heat energy storage air conditioner | |
| KR20120042922A (en) | Air conditioning/hotwater supply system and heat pump unit | |
| US20140338389A1 (en) | Vapor compression system with thermal energy storage | |
| JP2004003801A (en) | Refrigeration system using carbon dioxide as refrigerant | |
| JP2006313034A (en) | Geothermal equipment | |
| WO2021231619A1 (en) | Switching flow water source heater/chiller | |
| CN116706320A (en) | All-in-one energy storage temperature control system | |
| CN102947653A (en) | Refrigerating air-conditioning device | |
| CN102753915B (en) | Air conditioner | |
| JPS6155018B2 (en) | ||
| JP2006292313A (en) | Geothermal unit | |
| JP2004156806A (en) | Heating and cooling system | |
| CA1292873C (en) | Air conditioning system | |
| JPH01174834A (en) | Air conditioning system for building | |
| JPS6367633B2 (en) | ||
| JPH01107031A (en) | Air conditioning system for building |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |