Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHOD FOR CREATING RINK ICE AND UTILIZING
HIGH-TEMPERATURE HEAT GENERATED WHEN CREATING RINK ICE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a system and method for
creating skating rink ice and utilizing high-temperature heat
when creating rink ice, more specifically for creating skating
rink ice and maintaining the ice in a proper condition and for
producing hot water required for ancillary facilities of the
skating rink by utilizing high temperature heat generated when
creating rink ice.
Description of the Related Art
In an ice-skating rink, it is required to create rink ice
and maintain the ice created in a proper condition. Proper
temperature of the ice to maintain it in a proper condition
is different depending on intended use such as for competitive
sport such as ice hockey and figure skating, for leisure sport,
etc., usually the temperature of the ice must be maintained
at a range of -1--5 C. Generally, to maintain the temperature
of ice layer at a range of -1--5 C, brine of temperature of
-8--12 C is flown in cooling tubes laid under the ice layer.
(In the present invention, "brine" includes fluid cooling
agent such as ethylene glycol solution, propylene glycol
solution and the like.)
Such an art is disclosed for example in Japanese Laid-Open
Patent Application No.07-241363(Patent literature 1).
On the other hand, in a skating rink facility are needed
in addition to refrigerating equipment for creating ice and
maintaining the ice created in a proper condition, equipment
for producing hot water to perform resurfacing of the ice,
melting the ice scraped for the resurfacing, and heating of
the rink floor. Further, there are ancillary facilities in the
skating rink facility which require space heating or supply
of hot water, such as spectors' stands, shower room, etc.
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Furthermore, many of skating rink facilities have accompanying
facilities such as a heated swimming pool, library, public hall,
etc. These accompanying facilities may also require space
heating and supply of hot water.
Cooling and heating equipment used generally at the present
day in an ice-skating rink will be explained with reference
to FIGS.4-6.
FIG.4 is a schematic representation of an ice-skating rink
facility commonly used.
A skating rink facility 1 has an accompanying facility 12
which may include a library, for example.
An ice layer 2 on the skating rink is created by spraying
water on a concrete layer 3 and freezing the water by flowing
cold brine in ice creation cooling tubes 4 laid in the concrete
layer 3.
In a concrete layer 5 underneath the concrete layer 3 are
laid heating tubes 6 in order to prevent freezing of moisture
contained in the soil underneath the concrete layer 5 by flowing
warm brine in the heating tubes.
As ruts are formed on the surface of the rink ice by skates,
the rink ice is resurfaced by an ice resurfacing vehicle 8.
The ice resurfacing vehicle 8 scraps a thin layer of ice and
sprays water over the ice to allow fresh thin ice layer to be
formed. As water for spraying is used hot water of about 70 C
in order to smooth the roughened surface of the rink ice by
melting the surface layer thereof. The shavings scraped by the
resurfacing vehicle 8 is transported to an ice shavings melting
pot 9 to be melted there by warm water of 40-50 C.
Further, a space heating unit 10 with which warm air is
obtained by allowing air to exchange heat with the warm water
of 40-50 C to be used for the heating of the skating rink space,
and an underfloor heating system 14 consisting of heating tubes
laid underneath spectors' stands 11 to perform underfloor
heating by flowing the warm water, are provided.
A shower bath 13 and a rest room 15 are provided in the
accompanying facility 12, where hot water is supplied.
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Heating and cooling equipment as shown in FIG.4 is necessary
to be provided in a common skating rink facility.
In FIG. 5 are shown places or devices where high temperature
water, medium temperature water, and cold brine are used in
the common skating rink facility as shown in FIG.4.High
temperature water of 70-80 C is used for the resurfacing
vehicle 8, shower bath 13, and rest room 15. Medium temperature
water of 40-50 C is used for the under rink heating tubes 6 in
the concrete layer 5, ice shavings melting pit 9, space heating
unit 10, and underfloor heating system 14. Cold brine is used
for ice creation cooling tube 4 for creating rink ice.
FIG.6 is a schematic representation of an example of
conventional system for producing high temperature water,
medium temperature water, and cold brine. In FIG.6, a brine
chiller 120 for producing cold brine for creating rink ice and
maintaining the ice in a proper condition comprises a
compressor 121, an electric motor 122 for driving the
compressor, an evaporation type condenser 123, a liquid
receiver 124, an expansion valve 125, and an evaporator 126,
and a refrigerating cycle is performed by circulating a primary
refrigerant. A secondary refrigerant (brine) supplied from a
brine tank 128 to the evaporator 126 by means of a primary brine
pump 127 is cooled in the evaporator 126 and returned to the
brine tank 128. The cold brine in the brine tank 128 is sent
to the ice creation cooling tubes 4 by means of a secondary
brine pump 129, freezes the water sprayed over the concrete
layer 3 passing through the cooling tubes and serves also to
maintain the ice in a proper condition.
Heat transferred to the brine in the cooling tubes from water
on the surface of the ice or the ice created is transferred
to the primary refrigerant such as ammonia in the evaporator
126 to evaporate the primary refrigerant and received in the
course of the circulation by a coolant supplied to the condenser
123 to be finally released to the atmosphere.
A system for producing hot water to be supplied to the
ancillary facilities of the skating rink facility is comprised
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of a hot-water boiler 150, a first hot-water pump 151, a heat
exchanger 155 for medium temperature water, a heat exchanger
156 for high temperature water, and a second hot-water pump
154. High temperature water of 90 C or higher produced in the
hot-water boiler 150 is introduced to both the heat exchanger
155 for medium temperature water and heat exchanger 156 for
high temperature water.
In the heat exchanger 155 for medium temperature water, water
is heated to medium temperature of 40-50 C by heat exchange with
the high temperature water of 90 C or higher produced by the
hot-water boiler 150, and the medium temperature water is
supplied to the under-rink-floor heating tubes 6, ice shavings
melting pit 9, space heating unit 10 etc., where medium
temperature water is required by means of the second hot-water
pump 154. Water decreased in temperature in these devices is
returned to the heat exchanger 155 f or medium temperature water
to be again heated therein and again supplied those devices.
In the heat exchanger 156 for high temperature water, service
water supplied to the heat exchanger 156 is heated to high
temperature water by heat exchange with the high temperature
water of about 70-80 C produced by the hot-water boiler 150
to be supplied to the shower bath 13, rest room 15, and ice
resurfacing vehicle 8, etc., where high temperature water is
required.
However, in the prior art like this, the refrigerating
apparatus 120for producing cold brine and the hot-water boiler
150 for producing hot water are provided independently.
Therefore, electric power is consumed by the electric motor
122 to drive the compressor 121, and heat the secondary
refrigerant(brine) received from water on the surface of the
ice or the ice created is not recovered, since the heat is
received by the primary refrigerant in the evaporator 126 and
released in the atmosphere. On the other hand, in the hot-water
boiler 150 is produced hot water by using fossil fuel.
As mentioned above, waste heat generated in the cooling
system is not recovered and hot water is produced using fossil
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fuel in the prior art, so energy efficiency is not high.
Measures against ozone layer destruction and global warming
is strongly required at the present day, and development of
systems not using alternative refrigerant HFC as refrigerant
and improved in energy efficiency is urgently demanded in
skating rink facilities, not only getting away from using HCFC,
HFC.
As measures for preventing ozone layer destruction and
global warming, adoption of heat pump using a natural
refrigerant such as ammonia, hydrocarbon, air, C02r etc. and
utilization of heat generated in the refrigerating system is
conceivable.
However, ammonia is used as a refrigerant in many of
refrigerating systems in skating rinks, and ammonia is
increased more in temperature when compressed as compared with
fluorocarbon group refrigerant because of its higher adiabatic
index, so carbonization of lube oil used in the compressor tends
to occur, occurrence of malfunction of the compressor due to
the carbonization of the lube oil is feared. Further, from view
point of heat utilization, the temperature of the hot water
depends on the condensation temperature in the condenser, so
almost all of the temperature of heat utilization is limited
when using ammonia as the refrigerant. Because of these reasons,
to use a refrigerating system using ammonia as a heat pump is
not prevailed.
When considering using of a refrigerating system as a heat
pump, it is conceivable to use alternate refrigerant HFC such
as HFC404A. However, global warming potential of HFC is high
although it does not destruct ozone. Therefore, to use such
refrigerants is retrogression against prevention of global
warming policy.
Further, when using natural refrigerants other than ammonia,
hydrocarbon is high in flammability and there is a fear of
explosion, and using of air deteriorates thermal efficiency,
so to use these as refrigerant for heat pump system is not
prevailed.
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SUMMARY OF THE INVENTION
Therefore, the present invention aims in light of the
problems mentioned above to provide a refrigerating and hot
water producing system using a natural refrigerant for
ice-skating rink facility which works to create ice rink and
maintaining the ice created in a proper condition and at the
same time is possible to produce hot water of temperature of
70 C or higher required for ancillary facilities of the skating
rink by utilizing high-temperature heat generated when
creating rink ice.
To attain the object mentioned above, the invention proposes
a system for creating rink ice and utilizing high-temperature
heat generated when creating rink ice, the rink ice being
created by spraying water over a base material layer and flowing
cold brine through cooling tubes embedded in the base material
layer including: a heat pump performing a refrigerating cycle
using C02 as a refrigerant for producing cold brine and hot
water, and a means for introducing the brine which has worked
to freeze the water sprayed over the base material layer and
received heat from the water sprayed over the base material
layer and the ice created to the heat pump, by which the hot
water is produced by the heat pump by using heat contained in
the brine introduced to the heat pump as a heat source and the
brine deprived of the heat in the heat pump is returned to the
cooling tubes to be used as the cold brine, thus the cold brine
for creating the rink ice and cooling the ice layer created
and the hot water to be used in ancillary facilities of the
ice-skating rink facility are produced.
The word "brine" in the explanation includes fluid cooling
agent such as ethylene glycol solution, propylene glycol
solution and the like.
C02 reaches its supercritical point at a moderate
temperature of 31.3 C and pressure of 7.3 MPa. Therefore, by
using C02 as a refrigerant, the refrigerant can be easily
brought to a supercritical state of high-temperature and
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high-pressure.
In the supercritical zone, C02 can not be discriminated
between liquid phase and vapor phase and does not condense,
so the temperature of the C02 in a supercritical state decreases
continuously when cooled by the heat medium without condensing
at a constant temperature. Therefore, temperature difference
is maintained large during it is cooled and transfer of heat
from the C02 in a supercritical state to the heat medium is
performed effectively. Therefore, by adopting the heat pump
using C02 as a refrigerant and compressing C02 to a
supercritical state, hot water of high temperature higher than
70 C that has not been attained by conventional heat pumps can
be obtained. Thus, high temperature hot water higher than 70 C
demanded in the ice-skating rink for use for its ancillary
facilities can be obtained by using heat released from C02 in
the heat exchanger.
In this way, heat that the brine received when freezing water
can be utilized to produce hot water without releasing to the
atmosphere, and it is not needed to use fossil fuel to produce
high temperature hot water higher than 70 C by a hot-water
boiler, so energy efficiency is increased and equipment cost
is saved with the need of the hot-water boiler eliminated.
Further, as C02 is low in viscosity, heat transfer
performance is increased resulting in decreased loss in heat
exchange, thermal efficiency of the system can be increased
by producing hot water by utilizing heat released from the C02.
On the other hand, as high-pressure high temperature C02 of
supercritical state is used, equipment cost is increased to
deal with the high-pressure high temperature C02r however, this
is compensated for by the reduction of running cost and said
reduction in equipment cost, and total cost of the system
including running cost does not increase much.
Further, ozone destruction potential of C02 is zero, and
global warming potential of C02 is as small as 1/1500-1/1700
of that of alternative refrigerant such as HFC, and moreover
C02 is atoxic, nonflammable, and safe heat transfer medium,
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the system of the invention can comply with the demand against
ozone destruction and global warming.
The heat pump includes a plurality of heat exchangers for
heating water utilizing C02 compressed by a compressor to a
supercritical state, the heat exchangers are arranged in
series in a discharge side of the compressor, and hot water
of different temperature ranges can be obtained separately
from each of the heat exchangers.
As mentioned previously, high temperature water of 70-80 C
and medium temperature water of 40-50 C are demanded generally
in the ancillary facilities of the ice-skating rink. By
arranging a plurality of heat exchangers in series, plural
kinds of hot water different in temperature range can be
obtained. Thus, hot water of different temperature ranges can
be supplied from the plurality of heat exchangers.
The nearer the heat exchanger to the discharge side of the
compressor, the larger the heat carried by the compressed C02r
so the higher the temperature of hot water produced. It is
preferable to provide a control valve to each of the heat
exchangers to control the flow rate of water to be heated so
that the hot water at the exit thereof from each of the heat
exchangers is maintained at a constant temperature.
The invention is characterized in that a conduit is provided
to introduce water heated in one of the heat exchangers to the
other heat exchanger or exchangers provided nearer the
compressor discharge side.
With this construction, hot water obtained one of the heat
exchangers is further heated in the other heat exchanger or
exchangers and hot water of higher temperature is obtained,
so thermal efficiency is further increased.
The invention proposes a method of creating rink ice and
producing hot water used in an ice-skating rink facility, the
rink ice being created by spraying water over a base material
layer and flowing cold brine through cooling tubes embedded
in the base material layer, in which said cold brine is produced
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by a heat pump performing a refrigerating cycle using CO2 as
a refrigerant, and said brine which has worked to freeze the
water sprayed over the base material layer and received heat
from the water sprayed on the base material layer and the ice
created to the heat pump is introduced to the heat pump, thereby
the hot water is produced by the heat pump by introducing the
brine containing heat received from the water sprayed over the
base material layer and the ice created to the heat pump and
utilizing the heat of the brine as a heat source, and the brine
deprived of the heat in the heat pump is returned to the cooling
tubes to be used as the cold brine, thus the cold brine for
creating the rink ice and cooling the ice layer created and
the hot water which is to be used in ancillary facilities of
the ice-skating rink facility are produced.
In the heat pump, the COZ refrigerant is evaporated by the
heat of the brine received heat from the water sprayed on the
base material layer and the ice created, the evaporated COZ
is compressed to a supercritical state, and the compressed CO2
is introduced to a plurality of heat exchangers arranged in
the discharge side of the compressor to heat water.
The method of the invention is characterized in that a part
of water heated in one of the heat exchangers is introduced
to the other heat exchanger or exchangers provided nearer the
compressor discharge side so that the water is further heated.
As has been described in the foregoing, according to the
invention, a system and method for creating rink ice and
producing hot water used in an ice-skating rink can be provided
in which CO2 is used as a refrigerant of a heat pump which
performs a refrigerating cycle.
The system of the invention can be installed subsidiarily
to a chiller or a boiler used in an existing ice rink.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG.1 is a schematic representation of system configuration
of the first embodiment for producing high temperature water,
medium temperature water and cold brine.
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FIG.2 is a schematic representation of system configuration
of the second embodiment for producing high temperature water,
medium temperature water and cold brine.
FIG.3 is a mollier diagram to explain working of
refrigeration and heat pump cycle.
FIG.4 is a schematic representation of an ice-skating rink
facility commonly used.
FIG.5 is a diagram showing places or devices where high
temperature water, medium temperature water, and cold brine
are used in the common skating rink facility of FIG.4.
FIG. 6 is a schematic representation of system configuration
in the conventional skating rink facility of FIG.4 for
producing high temperature water, medium temperature water and
cold brine.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will now be
detailed with reference to the accompanying drawings. It is
intended, however, that unless particularly specified,
dimensions, materials, relative positions and so forth of the
constituent parts in the embodiments shall be interpreted as
illustrative only not as limitative of the scope of the present
invention.
[The first embodiment]
A first embodiment of the system for creating ice rink and
producing hot water used in an ice-skating rink will be
explained with reference to FIG.1 and FIGS.3-5. Over all
construction of the skating rink and places or devices where
high temperature water, medium temperature water, and cold
brine of the embodiment are similar to those of the conventional
ice-skating rink shown in FIG.4 and FIG.5, and explanation of
the overall construction is omitted.
FIG.1 shows a system flowchart of the first embodiment for
producing high temperature water, medium temperature water and
cold brine.
Referring to FIG.1, a brine chiller 20 for producing cold
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brine for creating rink ice and maintaining the ice in a proper
condition and producing hot water comprises a compressor 21,
an electric motor 22 for driving the compressor, a heat
exchanger 23, an expansion valve 25, and an evaporator 26, and
a refrigerating cycle is performed by circulating C02r which
is a natural refrigerant, as a refrigerant. A secondary
refrigerant(brine) supplied from a brine tank 28 to the
evaporator 26 by means of a primary brine pump 27 is cooled
in the evaporator 26 and returned to the brine tank 28. The
cold brine in the brine tank 28 is sent to ice creation cooling
tubes 4 by means of a secondary brine pump 29, freezes the water
sprayed over the concrete layer 3 passing through the cooling
tubes 4 and serves also to maintain the ice in a proper
condition.
Heat transferred to the brine in the cooling tubes 4 from
water on the surface of the ice or the ice created is transferred
to the primary refrigerant (C02) in the evaporator 26. The
refrigerant C02 evaporates in the evaporator 26 by receiving
heat from the brine which received heat from the water on the
rink ice and rink ice created. This is shown by a line D-A
in FIG.3.
The compressor 21 is driven by the electric motor 22 and
compresses C02 evaporated in the evaporator 26 to a pressure
above critical pressure. The amount of discharge from the
compressor can be varied by controlling the rotation speed of
the motor 22. The compressed C02 reaches a temperature of about
90 C in the supercritical zone at its discharge side. This is
shown by a line A-B in FIG.3. C02 reaches its supercritical
point at a moderate temperature of 31.3 C and pressure of 7.3
MPa. Therefore, by using C02 as a refrigerant, the refrigerant
can be easily brought to a supercritical state of
high-temperature and high-pressure.
In the heat exchanger 23, the C02 of supercritical state
exchanges heat with a heat transfer medium such as low
temperature water and raises the temperature of the heat
transfer medium to about 80-90 C. In the supercritical zone,
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C02 can not be discriminated between liquid phase and vapor
phase does not condense, and the temperature of the C02 in a
supercritical state decreases continuously when cooled by the
heat medium without condensing at a constant temperature.
Therefore, temperature difference is maintained large during
it is cooled and transfer of heat from the C02 in a supercritical
state to the heat medium is performed effectively. Accordingly,
by using C02 in a supercritical state, the heat medium can be
raised to high temperature of 80-90 C easily. Thus, high
temperature water of 70-80 C required for the ancillary
facilities in the ice-skating rink can be produced.
The C02 which has given its heat to the heat transfer medium
is decreased in temperature as shown by a line B-C in FIG.3.
The C02 decreased in temperature in the heat exchanger 23
is expanded and reduced in pressure through the expansion valve
25 located between the heat exchanger 23 and the evaporator
26 to be reduced to wet vapor in a state of 2-phase, i. e. mixture
of liquid and vapor and received in the evaporator 26. This
is shown by a line C--->D in FIG.3.
The heat transfer medium heated to temperature of 80-90 C
in the heat exchanger 23 is introduced to the high temperature
heat exchanger 36, where heat exchange is performed between
the heat transfer medium of temperature of 80-90 C and service
water supplied to the heat exchanger 36 to produce high
temperature water of 70-80 C, which is supplied to the shower
bath 13, rest room 15, ice resurfacing vehicle 8, etc., where
high temperature water is required. Control of the temperature
of high temperature water is performed by providing a
temperature indicating and adjusting devices (TIC) at the exit
of the service water from the high temperature heat exchanger
36 and providing a control valve at the inlet of the service
water to the heat exchanger 36 or at the inlet of the heat medium
to the heat exchanger 36 and controlling the flow rate of the
service water or the heat medium to the heat exchanger 36.
Further, the heat transfer medium heated to temperature of
80-90 C is introduced also to the medium temperature heat
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exchanger 35. In the medium temperature heat exchanger 35 is
performed heat exchange between the heat transfer medium
raised in temperature to 80-90 C and water after utilized for
the under-rink-floor heating tubes 6, ice shavings melting pit
9, space heating unit 10, etc., which is decreased in
temperature to lower than 40 C, the water is raised in
temperature to about40-50 C to obtain medium temperature water,
and the medium temperature water is supplied by means of a
medium temperature water pump 39 to the under-rink-floor
heating tubes 6, ice shavings melting pit 9, space heating unit
10, etc., where medium temperature water required. The medium
temperature water decreased in temperature in places or
devices is returned to the medium temperature heat exchanger
35, thus the medium temperature water is again utilized by
circulating it. Control of the temperature of medium
temperature water is performed by providing a temperature
indicating and adjusting devices (TIC) at the exit of the water
from the medium temperature heat exchanger 35 and providing
a control valve at the inlet of the water to the water heat
exchanger 35 or at the inlet of the heat transfer medium to
the heat exchanger 35 and controlling the flow rate of the water
or the heat transfer medium to the heat exchanger 35. The heat
transfer medium decreased in temperature by heat exchange in
the high temperature heat exchanger 36 and medium temperature
heat exchanger 35 is returned to a liquid tank 32 to be stored
there, and introduced by means of a pump 31 to the heat exchanger
23 to be heated again.
It is possible to provide a hot-water boiler 50 as is in
the prior art. In this case, when using water as the heat
transfer medium heated in the heat exchanger 23, piping for
the water can be used in common with water piping of the boiler
50, hot water produced by the hot-water boiler 50 can be used
as complementary heat source by providing a first hot-water
pump 51.
When a large amount of hot water supply is demanded, it is
possible to heat service water directly by the heat exchanger
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23 to 80-90 C for hot water supplying without using the high
temperature heat exchanger 36.
[The second embodiment]
A second embodiment of the system for creating ice rink and
producing hot water used in an ice-skating rink will be
explained with reference to FIGS.2-5. Over all construction
of the skating rink and places or devices where high temperature
water, medium temperature water, and cold water of the
embodiment are similar to those of the conventional
ice-skating rink shown in FIG.4 and FIG.5, and explanation of
the over all construction is omitted.
FIG.2 shows a system flowchart of the second embodiment for
producing high temperature water, medium temperature water and
cold brine.
Referring to FIG.2, a brine chiller 20a for producing cold
brine for creating rink ice and maintaining the ice in a proper
condition and producing hot water comprises a compressor 21,
an electric motor 22 for driving the compressor, two heat
exchangers 23 and 24 arranged parallel to each other, an
expansion valve 25, and an evaporator 26, and a refrigerating
cycle is performed by circulating CO2, which is a natural
refrigerant, as a refrigerant.
A secondary refrigerant (brine) supplied from a brine tank
28 to the evaporator 26 by means of a primary brine pump 27
is cooled in the evaporator 26 and returned to the brine tank
28. The cold brine in the brine tank 28 is sent to ice creation
cooling tubes 4 by means of a secondary brine pump 29, freezes
the water sprayed over the concrete layer 3 passing through
the cooling tubes 4 and serves also to maintain the ice in a
proper condition.
Heat transferred to the brine in the cooling tubes 4 from
water on the surface of the ice or the ice created is transferred
to the primary refrigerant (CO2) in the evaporator 26. The
refrigerant C02 evaporates in the evaporator 26 by receiving
heat from the brine which received heat from the water on the
rink ice and rink ice created. This is shown by a line D-A
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in FIG.3.
The compressor 21 is driven by the electric motor 22 and
compresses C02 evaporated in the evaporator 26 to a pressure
above critical pressure. The amount of discharge from the
compressor can be varied by controlling the rotation speed of
the motor 22. The compressed C02 reaches a temperature of about
90 C in the supercritical zone at its discharge side. This is
shown by a line A-B in FIG.3. C02 reaches its supercritical
point at a moderate temperature of 31.3 C and pressure of 7.3
MPa. Therefore, by using CO2 as a refrigerant, the refrigerant
can be easily brought to a supercritical state of
high-temperature and high-pressure.
In the heat exchanger 23, the C02 of supercritical state
exchanges heat with a heat transfer medium heated in the heat
exchanger 24 as mentioned later to about 40-50 C to raise the
temperature of the heat transfer medium to about 80-90 C. In
the supercritical zone, C02 can not be discriminated between
liquid phase and vapor phase and does not condense, and the
temperature of the C02 in a supercritical state decreases
continuously when cooled by the heat medium without condensing
at a constant temperature. Therefore, temperature difference
maintained large during it is cooled and transfer of heat from
the C02 in a supercritical state to the heat medium is performed
effectively. Accordingly, by using C02in a supercritical state,
the heat medium can be raised high temperature of 80-90 C easily.
Thus, high temperature water of 70-80 C required for the
ancillary facilities in the ice-skating rink can be produced.
The C02 refrigerant brought to a supercritical state by the
compressor 21 and decreased in temperature in the heat
exchanger 23 by heat exchange with the heat transfer medium
is introduced to the heat exchanger 24 where the heat transfer
medium is heated to about 40-50 C by heat exchange with the C02
refrigerant decreased in temperature introduced from the heat
exchanger 23. Thus, by arranging two heat exchangers 23 and
24 in series, hot water of two temperature ranges required for
the ancillary facilities can be obtained.
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In order to control the temperature of the heat transfer
medium exiting the heat exchanger 24 to 40-50 C, there are
provided a temperature indicating and adjusting device(TIC)
at the exit of the heat transfer medium from the heat exchanger
24 and a control valve at the inlet of the heat transfer medium
to the heat exchanger 24, thereby the flow rate of the heat
transfer medium introduced to the heat exchanger is controlled.
The C02 which has given its heat to the heat transfer medium
in the heat exchanger 23 and 24 is decreased in temperature
as shown by a line B-C in FIG.3.
The C02 decreased in temperature in the heat exchanger 23
is expanded and reduced in pressure through the expansion valve
25 located between the heat exchanger 23 and the evaporator
2 6 to be reduced to wet vapor in a state of 2-phase, i. e. mixture
of liquid and vapor and received in the evaporator 26. This
is shown by a line C-D in FIG.3.
The heat transfer medium heated to temperature of 80-90 C
in the heat exchanger 23 is introduced to the high temperature
heat exchanger 36, where heat exchange is performed between
the heat transfer medium of temperature of 80-90 C and service
water supplied to the heat exchanger 36 to produce high
temperature water of 70-80 C, which is supplied to the shower
bath 13, rest room 15, ice resurfacing vehicle 8, etc., where
high temperature water is required. Control of the temperature
of high temperature water is performed by providing a
temperature indicating and adjusting devices (TIC) at the exit
of the service water from the high temperature heat exchanger
36 and providing a control valve at the inlet of the service
water to the heat exchanger 36 or at the inlet of the heat medium
to the heat exchanger 36 and controlling the flow rate of the
service water or the heat medium to the heat exchanger 36.
A part of the heat transfer medium heated to 40-50 C in the
heat exchanger 24 is introduced to the heat exchanger 23, where
it is heated to about 80-90 C. The rest of the heat transfer
medium is sent to a medium temperature heat medium storage
section 32a of a liquid tank 32 which is partitioned with
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partition wall 32c into two sections of 32a and 32b to be stored
therein. The medium temperature heat transfer medium is
supplied by means of a secondary pump 34 from the section 32a
of the liquid tank 32 to the under-rink-floor heating tubes
6, ice shavings melting pit 9, space heating unit 10, etc.,
where medium temperature water is required.
The heat transfer medium decreased in temperature in the
high temperature heat exchanger 3 6 and the heat transfer medium
after used in the under-rink-floor heating tubes 6, ice
shavings melting pit 9, space heating unit 10, etc., which is
decreased in temperature, are recovered to the section 32b of
the liquid tank 32 to be stored therein, then sent to the heat
exchanger 24 by means of a pump 31 to be again heated.
It is possible to provide a hot-water boiler 50 as is in
the prior art. In this case, when using water as the heat
transfer medium heated in the heat exchanger 23, piping for
the water can be used in common with water piping of the boiler
50, hot water produced by the hot-water boiler 50 can be used
as complementary heat source by providing a first hot-water
pump 51.
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