U.S. patent application number 10/159654 was filed with the patent office on 2003-12-04 for recoverable ground source heat pump.
Invention is credited to Xu, Yunsheng.
Application Number | 20030221436 10/159654 |
Document ID | / |
Family ID | 32070549 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221436 |
Kind Code |
A1 |
Xu, Yunsheng |
December 4, 2003 |
Recoverable ground source heat pump
Abstract
Recoverable Ground Source Heat Pump system with energy storage
function which uses and stores off-peak-hours electricity to
maintain the ground medium temperature to ensure the efficient
operation of the system during on-peak electricity hours. The
release and receiving of energy is accomplished through the ground
heat exchanger by flowing the fluid through different routings of
the circulation loop using reversing vales. Space heating and
cooling is assured while the underground medium temperature is
recovered. The heat pump system of the invention has less initial
investment compared to conventional ground source heat pump and ice
energy storage cooling systems; requires less ground space; provide
operating energy cost savings; assures performance of operation;
and avoids using antifreeze solution in the ground circulation
fluid that may cause environmental, safety and erosion
problems.
Inventors: |
Xu, Yunsheng; (Beijing,
CN) |
Correspondence
Address: |
Yunsheng Xu
4514 E. Bridgewood Dr.
Columbia
MO
65203
US
|
Family ID: |
32070549 |
Appl. No.: |
10/159654 |
Filed: |
May 31, 2002 |
Current U.S.
Class: |
62/260 ;
62/324.1 |
Current CPC
Class: |
F25B 40/04 20130101;
F25B 30/06 20130101; F25B 2313/002 20130101; F25B 2313/004
20130101; F25B 13/00 20130101; F25B 2400/24 20130101; F25B
2313/02541 20130101; F25B 2313/02543 20130101; F25B 2313/008
20130101; F25B 25/005 20130101 |
Class at
Publication: |
62/260 ;
62/324.1 |
International
Class: |
F25D 023/12; F25B
013/00 |
Claims
1. An apparatus for heating and cooling, comprising: (a)
refrigeration device with at least two heat exchangers conducting
energy transfer with in-door medium and out-door environment,
respectively. (b) ground heat exchanger in connection with or
buried within underground medium, pavement or surface water body,
and/or earth-side heat exchanger connecting the said ground heat
exchanger and the refrigeration device, and (c) flow routing
devices conducting flow loop to different direction(s), which is
connected with the said ground heat exchanger or the said
earth-side heat exchanger, whereby the said ground heat exchanger
can be routed to the same side of either the in-door heat exchanger
or the out-side heat exchanger,
2. Apparatus of claim 1 wherein said refrigeration device is
mechanical heat pump compromising compressor and expansion
device,
3. Apparatus of claim 1 wherein said flow routing device one
multi-way valve manually or automatically operated,
4. Apparatus of claim 1 wherein said ground heat exchanger is
closed pipe loops connected with or buried within ground medium
selected from group including sand, soil, rock, payment, and
water,
5. Apparatus of claim 1 wherein supplementary heat source is
connected on the loop for additional heating.
6. Apparatus of claim 1 and 2 wherein extra heat exchanger is
connected in the refrigeration loop next to compressor for hot
water heating.
7. Apparatus of claim 1 and 5 wherein the supplementary heater can
be connected either the refrigeration loop, or the in-door water
circulation loop.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This invention uses the transmission of my pending
application in foreign country (China), application number:
01118555.4 filed Jun. 1, 2001.
BACKGROUND--FIELD OF INVENTION
[0002] This invention relates to heat pump for heating and cooling,
specifically to such heat pump with ground source.
BACKGROUND--DESCRIPTION OF PRIOR ART
[0003] Ground Source Heat Pump System
[0004] Ground source heat pump uses ground soil, sand, rock, and/or
water as a medium to provide energy for heating in winter. A minor
energy input can produce 3-5 times as much heating energy in the
winter through subtracting thermal energy from the ground. In the
summer, the ground medium is used as a "heat sink" to receive the
heat dissipation from the refrigeration device. Due to its great
savings in operational costs in comparison with conventional
heating and cooling devices, ground source heat pump has been used
more and more for heating and cooling, but nevertheless all the
closed loop heat pump system using ground medium (soil, sand and/or
rock) heretofore have a number of critical disadvantages:
[0005] (1) The underground heat exchange system requires extensive
drilling and/or trenching plus a significant amount of pipe loop
material. This results in a higher initial cost. The loop system
must be large enough to provide sufficient heat transfer efficiency
and energy storage capacity to ensure an acceptable temperature
elevation of the ground medium during the entire summer season
(cooling) and winter season (heating). This limits greatly the
overall cost effectiveness of ground source heat pumps.
[0006] (2) For the same reason, in order to keep the temperature
change of the ground medium to a moderate level after a season's
heat injection or heat abstraction, there must be sufficient ground
space to build a large heat exchange system. This greatly restricts
the application of ground source heat pumps for buildings without a
large open space, especially for multi-story and high-rise
buildings.
[0007] (3) Because of the need to limit initial cost and to apply
the system to buildings with small open space, there is a greater
risk that the system will under perform. This poor performance
could manifest as higher energy consumption and/or insufficient
heating/cooling output due to the temperature being too high in the
cooling fluid out of the ground heat exchange system in the cooling
mode, or too low in the heating fluid in the heating mode. This
risk is significantly increased when there is insufficient site
information, poor understanding of local geological conditions, or
little design experience. To retroactively correct such a poor
performing system requires significant additional cost.
[0008] (4) The worst situations of poor design includes freezing of
the circulation fluid, which can be caused by continuous heat
extraction from the ground. In order to minimize this risk,
antifreeze solution is generally used in most pipe loops in
northern locations where the system operates primarily in the
heating domain. Use of antifreeze solution causes one or more of
the following problems: (a) environmental pollution, (b) increased
health and safety risk, (c) corrosion of equipment, and (d)
increase the initial cost.
[0009] Energy Storage System
[0010] Most energy storage system materials have moderate melting
temperatures so that the great amount of latent heat during the
phase change can be used. The most popular storage medium is water.
Cooling of water to make ice in the off-peak hours and using ice to
cool building space is the most common energy storage system. It
can significantly reduce the operational cost by using cheaper
electricity in the off-peak hours, but the disadvantages are
obvious:
[0011] (1) Similar to the ground source heat pump, the ice storage
system is also always associated with a larger additional cost.
There has been much effort to develop a cheaper storage medium and
a cheaper mechanical system. However, the additional cost is still
significant.
[0012] (2) The storage medium must be cooled to a temperature below
its freezing point in order to use the latent heat capacity of the
medium released and absorbed during phase change. Cooling the
storage medium to an unnecessarily low level is not efficient from
the energy saving point of view.
[0013] (3) Low temperature of the storage medium (for instance,
0.degree. C. for water) will release low temperature cold air to
the building in the day time. The low temperature air supply may
cause water to condense on the surface of duct work and terminal
units (diffusers, fan/coil units). Special effort must be made to
prevent damage from the moisture and condensation to the building
wall and ceiling.
[0014] (4) Most energy storage systems are designed only for space
cooling but not for heating. For example, the ice-ball storage
system may be able to extract sufficient energy from water-to-ice
phase change to store "cold", but the heat storage in the same
volume of water is far less from the energy needed for heating of
the building space.
SUMMARY
[0015] In accordance with the present invention, a ground source
heat pump system with recovery and storage functions that uses
electricity in off-peak hours to storage energy to, or abstract
energy from the ground medium to service in on-peak hours.
OBJECTIVES AND ADVANTAGES
[0016] In addition to the objectives and advantages of the
conventional closed loop heat pump using ground medium (soil, sand,
and/or rock), the objectives and advantages of the present
invention are:
[0017] (1) To provide a ground source heat pump with significantly
reduced initial cost due to the dramatic reduction in the size of
the underground heat exchanger. For conventional ground source heat
pump, there is a minimal requirement for underground loop size to
assure that the medium can cumulatively receive or release enough
energy to last the entire season. Using the present invention, the
minimal requirement for underground loop size is to ensure that the
medium can cumulatively receive or release enough energy to last
only one or a few days. This gives the designer much more
flexibility in sizing the underground heat exchanger, and increases
the design safety factor, thus reducing risk and liability.
[0018] (2) To provide a ground source heat pump system which
requires much less ground space for the same reason as explained in
the above paragraph, and can be used for buildings without large
ground space, especially for large multi-story and high rise
buildings
[0019] (3) To provide a ground source heat pump system with much
better reliability through the control of ground medium
temperature. The ground circulation fluid temperature can be
controlled and maintained at a moderate level through the recovery
function of the system during off-peak-hours. Extremely high
circulation fluid temperature in the summer and low temperature in
the winter can be avoided. The risk of the circulation fluid
freezing will be eliminated.
[0020] (4) To provide a ground source heat pump using
off-peak-hours electricity to reduce operational cost that is
equivalent to the reduction in operational cost of a phase-change
energy storage system, but with a lower initial cost than a
phase-change energy storage system.
[0021] (5) To provide a ground source heat pump using
off-peak-hours electricity to reduce operational cost that is
equivalent to the reduction in operational cost of a phase-change
energy storage system, but results in more efficient performance
than a phase-change energy storage system because the medium does
not have to be cooled to an unnecessarily low temperature.
[0022] (6) To provide a ground source heat pump using
off-peak-hours electricity to provide cooled air at a moderate
temperature and thus eliminate the problem of water condensation in
ductwork and/or terminal units (diffusers or fan-coil units).
Potential damage to ceiling and wall due to water and moisture can
be avoided.
[0023] (7) To provide a ground source heat pump which can use
off-peak-hours electricity in a manner similar to a phase change
storage system but which can serve both heating and cooling in
comparison with the phase change storage system which can only
serve for cooling.
[0024] Further objectives and advantages of my invention will
become apparent from a consideration of the drawings and ensuing
descriptions.
DRAWING FIGURES
[0025] In the drawings, closely related figures have the same
number but different alphabetic suffixes.
[0026] FIG. 1. Shows a heat pump system with recovery and energy
storage functions where two air force heat exchangers serve as
out-door and in-door heat transfer equipment, respectively.
[0027] FIG. 1A. Shows the operation of the system of FIG. 1 in
cooling mode during service period in on-peak hours (summer).
[0028] FIG. 1B. Shows the operation of the system of FIG. 1 in
recovery period with off-peak electricity after cooling service in
on-peak hours (summer).
[0029] FIG. 1C. Shows the operation of the system of FIG. 1 in
heating mode during service period in on-peak hours (winter).
[0030] FIG. 1D. Shows the operation of the system of FIG. 1 in
recovery period with off-peak electricity after heating service in
on-peak hours (winter).
[0031] FIG. 2. Shows an alternative embodiment where the out-door
heat exchanger in FIG. 1 is replaced with a fluid-to-fluid heat
exchanger.
[0032] FIG. 3. Shows an alternative embodiment where the in-door
heat exchanger in FIG. 1 is replaced with a fluid-to-fluid heat
exchanger. Terminal units are fan-coil units instead of
diffusers.
[0033] FIG. 4. Shows an alternative embodiment where the out-door
heat exchanger in FIG. 1 is replaced with a fluid-to-fluid heat
exchanger, and furthermore, in-door heat exchanger in FIG. 1 is
substituted with a fluid-to-fluid heat exchanger. Terminal units
are fan-coil units instead of diffusers.
[0034] FIG. 5. Shows an additional embodiment of FIG. 1, where heat
exchangers are routed in different way.
[0035] FIG. 5A. Shows the operation of the system of FIG. 5 in
cooling mode during service period in on-peak hours (summer).
[0036] FIG. 5B. Shows the operation of the system of FIG. 5 in
recovery period with off-peak electricity after cooling service in
on-peak hours (summer).
[0037] FIG. 5C. Shows the operation of the system of FIG. 5 in
heating mode during service period in on-peak hours (winter).
[0038] FIG. 5D. Shows the operation of the system of FIG. 5 in
recovery period with off-peak electricity after heating service in
on-peak hours (winter).
[0039] FIG. 5E. Shows the direct use of ground loop water for
heating and cooling of the building space, with system
configuration as described in FIG. 5.
[0040] FIG. 6. Shows an alternative looping of heat pump system
with two forced air-to-fluid heat exchangers as in-door and
out-door heat transfer equipment.
REFERENCE NUMERALS IN DRAWINGS
[0041] The two typical heat exchangers used in heat pump systems
are condenser and evaporator. They are referred in this application
as out-door heat exchanger and in-door exchanger, respectively,
since the system in my invention is designed to perform reverse
operation for different modes (heating and cooling) and different
periods of time (service and recovery). This means that the
out-door and in-door heat exchangers will function as both
condenser and evaporator depending upon the direction of fluid
flow. Heat pump loop excluding evaporator and condenser is
compacted as a unit set 1.
1 1 Refrigeration unit 1a refrigerant compressor 1b four-way
reversing valve 1c expansion device 1d hot water unit 1e
supplementary electric heater 2 Out-door heat exchanger 2a forced
air-to-fluid heat exchanger 2b fluid-to-fluid heat exchanger 3, 6,
9 Circulation water pumps 4 Cooling tower 5 In-door heat exchanger
5a forced air-to-fluid heat exchanger 5b fluid-to-fluid heat
exchanger 7 In-door terminal units 6a air diffusers 6b fan-coil
units 8 Earth-side heat exchanger 10 Ground heat exchanger 11, 12
Reversing valves 13 Reversing air valve
DESCRIPTION--FIGS. 1, 1A, 1B, 1C AND 1D--PREFERRED EMBODIMENT
[0042] A preferred embodiment of the ground source heat pump system
with recovery and energy storage functions is illustrated in FIG.
1. The refrigeration loop is shown as, but not limited to, a
mechanical compression cycle. Refrigeration loop consists of the
compressor 1a, reversing valve 1b, expansion device 1c, optional
hot water unit 1d and optional supplementary electrical heating
units 1e. The refrigeration loop is closed with two heat
exchangers: out-door heat exchanger 2 and in-door heat exchanger 5.
In-door heat exchanger 5 is attached with terminal units 7.
[0043] Out-door heat exchanger 2 conducts heat transfer between
refrigerant and out-door air, and the in-door heat exchanger 5
conducts heat transfer between refrigerant and in-door space. The
earth-side heat exchanger 8 conducts heat transfer between the
refrigerant and the ground loop fluid. Ground loop fluid is driven
by water pump 9 to circulate through earth-side heat exchanger and
underground medium (soil, rock, and/or sand). The ground loops 10
can be buried horizontally or vertically in the ground at a variety
of depths.
[0044] Two reversing valves, 11 and 12, connect with the inlet and
outlet pipes of the heat exchangers 2a, 5a, 8, and expansion device
1c. More specifically in this embodiment, valve 11 connects with
one end of the out-door heat exchanger 2a, one end of the expansion
device 1c, and one end of the earth-side heat exchanger 8, while
the other reversing valve 12 connects with the other end of the
earth-side heat exchanger 8, in-door heat exchanger 5a, expansion
devices 1c and the supplementary heating device 1e, if it is
available.
[0045] FIGS. 1A, 1B, 1C, and 1D show different operational modes of
the heat pump system described in FIG. 1. Detailed explanations are
given as follows.
[0046] Operation FIG. 1A
[0047] FIG. 1A shows the operation of the heat pump system
described in FIG. 1 in cooling mode during service period in
on-peak hours (summer).
[0048] In cooling mode, the compressed hot refrigerant first passes
through heat exchanger 1d and release thermal energy to the water,
if the unit has a hot water option. In this situation, the domestic
hot water is free of cost since it is heated with "waste" thermal
energy, which is dissipated to the environment in the summer.
Refrigerant, with a certain temperature drop after releasing
thermal energy to tap water, then goes to out-door heat exchanger
2a and has further energy transfer. Heat is moved from heat
exchanger 2a by forced air convection.
[0049] The reversing valve 11 is in the status shown in FIG. 1A so
that the refrigerant out of the out-door heat exchanger 2a flows to
the earth-side heat exchanger 8 for further cooling. Fluid, driven
by pump 9, circulates within the closed loops 10 and transfers heat
from earth-side heat exchanger 8 to the ground medium (soil, rock
and/or sand). The heat exchanger loops 10 can be horizontally or
vertically buried underground, or can be any other kind of heat
exchanger buried in ground. The underground medium with a moderate
year-round temperature works as a "heat sink" and can absorb a
certain amount of heat from the refrigerant. After giving thermal
energy to the atmosphere in out-door heat exchanger 2a and ejecting
heat to underground medium through earth-side heat exchanger 8, the
refrigerant, with a significant temperature drop but still warm and
with high pressure, flows through reversing valves 12 and is then
routed to expansion device 1c. Warm refrigerant with high pressure
passing through the expansion device 1c reduces its pressure and
causes a corresponding reduction in temperature. The
low-temperature, low-pressure refrigerant then flows to in-door
heat exchanger 5a. Warm air from internal space and/or fresh air
from external space is forced to flow across the heat exchanger 5a
and then to flow to the internal building space through duct work
attached to the heat exchanger. Cold air is distributed through the
in-door terminal units, that functions as diffusers 7a in this
application.
[0050] Refrigerant, with temperature recovered after receiving
energy from the in-door space through in-door heat exchanger 5a,
then returns to the compressor 1a for another cycle. It passes
through the optional supplementary electric heater 1e, but in this
cooling mode, the heater is off, and there is no heat exchange
between refrigerant and the environment.
[0051] Operation FIG. 1B
[0052] FIG. 1B shows the operation of the above heat pump system
during the recovery period using off-peak-hour electricity
providing cooling service during on-peak hours (summer).
[0053] During cooling operation, the underground medium keeps
receiving energy from the refrigerant and its temperature may
significantly increase depending on the cooling load of the
building and also on the ground loop size. The ground loop does not
necessarily to be sized to receive heat from or provide heat to the
heat pump without substantial temperature increase of the
underground medium after the operation of an entire season. The
recovery model shown in FIG. 1B is used for the cases where the
loop is not as large as required in conventional ground source heat
pump design for a season's operation for different reasons
including (a) saving initial cost; (b) limitation of the ground
space for loop installation; (c) using off-peak hour electricity to
save operational cost.
[0054] While the temperature of the returning fluid from the ground
loops 10 substantially increases after a period of operation, the
system will manually or automatically shift to the recovery cycle
in the off-peak hours as shown in FIG. 1B. In the recovery mode,
the reversing valve 1b in the refrigeration side remains in the
same position as in the cooling mode show in FIG. 1A, but both
reversing valves 11 and 12 are in opposite positions. Refrigerant
out of the out-door heat exchanger 2a is routed to the expansion
device 1c through reversing valve 11. As described in FIG. 1A, the
refrigerant passing through the expansion device will cause a
temperature reduction and a corresponding pressure drop. The
low-temperature, low pressure refrigerant then passes through the
in-door heat exchanger 5a first, and provides cold air to the
building space through duct work and diffusers 7a. This ensures
that even in the recovery cycle in the off-peak hours, the cooling
of the building space is still the priority and remains secure.
Refrigerant at this point still has a moderately low temperature.
It then secondly goes to the earth-side heat exchanger 8 via valves
12. The cold refrigerant will receive energy from circulation fluid
in the earth-side heat exchanger 8. The energy is withdrawn from
the underground medium through ground loops 10, and then the ground
medium is cooled and "recovers" from heat accumulation. Refrigerant
out of the earth-side heat exchanger 8 then returns to the
compressor for another cycle.
[0055] During the operation, the temperature of the fluid which is
circulating between the earth-side heat exchanger and the ground
loop needs to be monitored in order to optimize the operational
strategies, including when to start the recovery cycle and when to
stop the recovery cycle. The system operational strategies mainly
depend on the water temperature of the ground loop, electricity
price structure as a function of time, heat pump operational
performance, the underground materials, and weather conditions.
[0056] Operation FIG. 1C
[0057] FIG. 1C shows the operation of the system of FIG. 1 in
heating mode during service period in on-peak hours (winter).
[0058] In the winter, the heat pump system is shifted to heating
mode shown in FIG. 1C. In heating mode, the reversing valve 1b is
in an opposite position to the cooling mode shown in FIG. 1A. The
compressed refrigerant passes through the hot water exchanger 1d
first, if it is available. It must be noted that at this time, hot
water will use extra electricity and will not be free of cost.
[0059] A supplementary electric heater 1e is shown as an option.
Compressed high temperature refrigerant receives further energy
from the electric heater, if it is installed. Valves 11 and 12 are
in the same position as in the cooling mode. Valve 12 routes the
refrigerant coming out of the electric heater 1e directly to the
in-door heat exchanger 5a. After giving heat to the in-door space,
the refrigerant is led to the expansion device 1e by valve 11. The
expanded low-temperature and low-pressure refrigerant passes
through the earth-side heat exchanger 4. Ground loops 10 abstract
energy from the underground medium and warm up the refrigerant
before it goes back to compressor for another cycle. Out-door heat
exchanger 2a will be manually or automatically turned off or
bypassed if the temperature of refrigerant out of the earth-side
heat exchanger 4 is higher then the ambient temperature. An
additional reversing valve can be used to shift the out-door heat
exchanger 2a prior to the earth-side heat exchanger if the ambient
temperature is higher then both the ice point and the temperature
of refrigerant coming out of the expansion devices.
[0060] Operation FIG. 1D
[0061] FIG. 1D shows the operation of the system of FIG. 1 in
recovery period using off-peak electricity after heating service in
on-peak hours (winter).
[0062] The temperature of the underground medium material decreases
as the system extracts energy from it. The lower the ground
temperature, the lower the system heating efficiency. When the
fluid temperature is approaching the freezing point, the system is
close to its operational limit and will not function properly. An
appropriate threshold for the fluid temperature can be defined
based on the electricity price and system performance. When the
temperature of the ground circulation fluid reaches the threshold,
the system will return to recovery cycle during the next off-peak
hours. The supplementary electric heater 1e is needed if the
ambient temperature during the off-peak hours (usually in the
winter night) is near the ice point, and the out-door air cannot
provide sufficient energy to recover underground heat losses. The
refrigerant re-heated by supplementary electric heater 1e then
flows to the in-door heat exchanger 5a via reversing valve 12.
Thermal energy is transferred to the building spaces through duct
work and diffusers. This assures the space heating while the system
is trying to warm up the underground medium. The refrigerant, after
leaving the in-door heat exchanger 5a, is still at a moderate
temperature, and flows to the earth-side heat exchanger 8 and
transfers the remainder of the energy to the circulating fluid
which moves the heat to ground. The underground medium is then
warmed up with the lower cost electricity during off-peak hours.
After flowing through the heat exchange in the earth-side heat
exchanger 8, refrigerant is routed to expansion devices 1c. The
expanded low-temperature and low-pressure refrigerant then returns
to the compressor through the out-door heat exchanger 2a. A high
ambient temperature will be helpful for the low-temperature (mostly
below the ice point) refrigerant to gain energy from the
atmosphere. Generally speaking, the more significant difference
between the electricity rates in off-peak and on-peak hours, the
more complete recovery is suggested until the ground circulating
fluid heated to a higher level. The elevation of the underground
medium temperature means storage of energy given by off-peak-hours
electricity. Higher underground temperature will more energy
storage will greatly improve the heating efficiency.
DESCRIPTION--FIG. 2--PREFERRED EMBODIMENT
[0063] FIG. 2. shows an alternative embodiment where the out-door
heat exchanger in FIG. 1 is replaced with a fluid-to-fluid heat
exchanger. Circulation fluid (water) is driven by pump 3 to flow
through fluid-to-fluid out-door heat exchanger 2 and a cooling
tower 4. The cooling tower 4 is used to dissipate heat to the
atmosphere. The cooling tower can be air-cooled or water-cooled.
Configuration of the remaining parts is the same as the system in
FIG. 1.
DESCRIPTION--FIG. 3--PREFERRED EMBODIMENT
[0064] FIG. 3. shows an alternative embodiment where forced
air-to-fluid in-door heat exchanger 2a in FIG. 1 is replaced with a
fluid-to-fluid heat exchanger 2b. Heat transfer between refrigerant
and the in-door space is conducted by fluid circulating through
in-door heat exchange 5b and the terminal units 7b. Here the
terminal units are fan-coil units 7b instead of diffusers 7a as
shown in FIG. 1.
DESCRIPTION--FIG. 4--PREFERRED EMBODIMENT
[0065] FIG. 4. shows an alternative embodiment where the forced
air-to-air out-door heat exchanger 2a in FIG. 1 is replaced with a
fluid-to-fluid heat exchanger 2b, and furthermore, forced
air-to-fluid in-door heat exchanger 5a in FIG. 1 is substituted
with a fluid-to-fluid heat exchanger 5b. Again, fan-coil units 7b,
instead of diffusers 7a, are used to dispute cold or warm air to
the building space.
DESCRIPTION--FIGS. 5, 5A, 5B, 5C, 5D, AND 5E--ALTERNATIVE
EMBODIMENT
[0066] FIG. 5. show an alternative embodiment of FIG. 4, where heat
exchangers are routed in different way.
[0067] In this application, two reversing valves 11, and 12, are
not installed in refrigerant loop, but in the water circulation
loops. Four ends of the valve 11 are connected with cooling tower
4, out-door heat exchanger 2b, ground loops 10, and another
reversing valve 12, respectively. Another reversing valve 12 is
connected with in-door terminal units 7b, in-door heat exchanger
5b, ground loops 10, and the other reversing valve 11. The ground
loop is directly connected to the two reversing valves, and the
earth-side heat exchanger 8 in FIG. 4 is omitted. Three water pumps
3, 6, and 9 are used to circulate fluid (water) to pass through the
out-door loop, in-door loop, and ground loop, respectively.
[0068] Operation--FIGS. 5A, 5B, 5C, 5D, AND 5E
[0069] FIGS. 5A, 5B, 5C, 5D, and 5E show a different operation
model of the heat pump system described in FIG. 5. The operation is
very similar to the operation described in FIGS. 1A, 1B, 1C and 1D.
Here only the flow routings are listed for different cycles.
[0070] FIG. 5A, Cooling in summer, during on-peak-hour service:
[0071] Refrigeration loop: Compressor 1a->hot water heat
exchanger 1d->out-door heat exchanger 2b->expansion devices
1c->in-door heat exchanger 5b->supplementary electric heater
1e->compressor 1a
[0072] Out-door heat exchange loop (circulated by pump 3 and 9):
Out-door heat exchanger 2b->cooling tower 4->ground loops
10->out-door heat exchanger 2b
[0073] In-door heat exchange loop (circulated by pump 6): In-door
heat exchanger 5b->terminal units (fan-coils) 7b->In-door
heat exchanger 5b
[0074] FIG. 5B, Recovery of underground temperature--off-peak hours
(electricity, after a period of cooling operation in on-peak hours
in summer):
[0075] Refrigeration loop (same as the cooling loop in FIG. 5A):
Compressor 1a->hot water heat exchanger 1d->out-door heat
exchanger 2b->expansion devices 1c->in-door heat exchanger
5b->supplementary electric heater 1e->compressor 1a
[0076] Out-door heat exchange loop (circulated by pump 3): Out-door
heat exchanger 2b->cooling tower 4->out-door heat exchanger
2b. (It must be noted that the ground loops 10 are not connected to
out-door circulation loop here. The cooling tower 4 is the only
heat exchanger to remove thermal energy from refrigerant)
[0077] In-door heat exchange loop (circulated by pump 3 and 6):
In-door heat exchanger 5b->terminal units (fan-coils)
7b->ground loops 10 ->In-door heat exchanger 5b (Here the
ground loops 10 are connected to the in-door loop through the
reversing of valve 11 and 12. In the loop circulation, fluid
(water) first receives energy from indoor hot air, and then receive
heat from underground medium through the closed loops 10 until the
heat accumulation during the cooling cycle is fully released, or
recovered).
[0078] FIG. 5C, Heating in winter, during the service period of
on-peak hours:
[0079] Refrigeration loop: Compressor 1a->hot water heat
exchanger 1d->supplementary electric heater 1e->in-door heat
exchanger 5b->expansion devices 1c->out-door heat exchanger
2b->compressor 1a
[0080] Out-door heat exchange loop (circulated by pump 3 and 9):
Out-door heat exchanger 2b->cooling tower 4->ground loops
10->out-door heat exchanger 2b (It must be noted that the
cooling tower is the place where refrigerant abstracts heat from
the atmosphere, before it goes to the ground loops 10 to extract
energy from the underground medium. The refrigerant has to pass
through the cooling tower first to receive energy in a low
temperature level while it is just comes out the expansion device,
and with temperature of itself below the ice point.)
[0081] In-door heat exchange loop (circulated by pump 6): In-door
heat exchanger 5b->terminal units (fan-coils) 7b->In-door
heat exchanger 5b
[0082] FIG. 5D, Recovery of the underground temperature--off-peak
hours (after a period of heating operation in on-peak hours in
winter):
[0083] Refrigeration loop (same as the heating loop in FIG. 5C):
Compressor 1a->hot water heat exchanger 1d->supplementary
electric heater 1e->in-door heat exchanger 5b->expansion
devices 1c->out-door heat exchanger 2b->compressor 1a
[0084] Out-door heat exchange loop (circulated by pump 3): Out-door
heat exchanger 2b->cooling tower 4->out-door heat exchanger
2b. (It must be noted that the ground loops 10 are not connected to
out-door circulation loop. The cooling tower 4 is the only heat
exchanger to gain energy from the environment for the
refrigerant)
[0085] In-door heat exchange loop (circulated by pump 3 and 6):
In-door heat exchanger 5b->terminal units (fan-coils)
7b->ground loops 10->In-door heat exchanger 5b (Here the
ground loops 10 are connected to the in-door loop through the
reversing of valves 11 and 12. In the loop circulation, fluid
(water) first receives energy from in-door heat exchanger 2b. The
energy is basically generated by supplementary electric heater 1e,
and partially subtracted from atmosphere through cooling tower 4.
After dissipating energy to the building space through in-door heat
exchanger 5b, the fluid goes to fan-coil units 7b, and the fluid is
still in a relatively high temperature. Part of remaining energy
then dissipates to the underground medium through loops 10. The
underground medium keeps receiving energy from circulation fluid
until the energy subtraction during the building heating period in
on-peak hours is fully recharged, or recovered. In this model, the
energy is generated mainly by off-peak-hour electricity and stored
within the underground medium, and released during the on-peak
hours.
[0086] Operation--FIG. 5E
[0087] Using us off-peak electricity to heat the underground
medium, it is sometimes even an economic strategy to heat the
underground medium to a sufficient high level so that the heating
in on-peak hours can directly come from the ground circulating
fluid. In this embodiment show in 6E, the refrigerant loop is not
necessarily operated, while the fluid is circulated by pump 6 and 9
between the in-door heat exchange 5b and the ground loops 10. The
operation cost will be based up on, again, the electricity price
structure in operation time sections.
[0088] While using off-peak electricity to cool down the
underground medium, it is also possible to cool the medium into a
sufficient lower level so that it can be directly used during the
on-peak cooling service hours. The refrigeration system can be shut
down, and only the circulation pumps 6 and 9 move the fluid from
ground loops 10 to indoor heat exchanger 5b, as shown in FIG.
5E.
DESCRIPTION--FIG. 6--ALTERNATIVE EMBODIMENT
[0089] FIG. 6. shows an alternative looping of the heat pump system
with two forced air-to-fluid heat exchangers used as in-door and
out-door heat transfer equipment.
[0090] In this application, the system is simplified to use only
two heat exchangers, out-door heat exchanger 2b and in-door heat
exchanger 5a. Heat exchanger 2b has to be fluid-to-fluid type and
connected to ground loops 10. The in-door heat transfer equipment
7a must be an air-to-fluid heat exchanger. The duct work attached
to the heat exchanger 7a is divided into to directions. A reversing
valve 13 is installed to change the direction of the forced air to
in-door or out door space.
OPERATION DESCRIPTION AND BENIFTS
[0091] A specific operation strategy needs define two important
operation parameters, including how frequently the recovery cycle
needs to work, and what a temperature level it has to be recovered
up to. All this operation optimization needs to be done based on
the electricity prices, initial cost for underground loops, actual
pipe size and heat transfer capacity, and the heat pump equipment
performance characteristics.
[0092] Apparently, with the recovery and energy storage function,
the yearly seasonal heat accumulation in the year around will not
be problem. A much small size of ground heat exchanger can perform
as well as a large size conventional system. The operation cost,
since more using of off-peak electricity may be less then the
conventional ground source heat pump systems. For most conventional
ground source heat pump, antifreeze solution is needed to avoid the
freezing of circulation fluid in the winter, especially when
operating in the North regions. Antifreeze solution, and the
resultant environmental, safety and erosion problems, are
eliminated in this invention.
CONCLUSION, RAMIFICATIONS, AND SCOPE
[0093] Thus the reader can see that this invention provides a
recoverable ground source heat pump system with energy storage
function, which can reduce the initial cost of the underground
loop, require less underground space, minimize the operational cost
through using off-peak hours electricity, assure the performance of
operational, and avoid using of antifreeze solution in to ground
circulation fluid, which may cause environmental, safety and
erosion problems.
[0094] While my above description contains many specificities,
these should not be constructed as limitation on the scope of the
invention, but rather as an exemplification of one preferred
embodiment thereof. Many other variations are possible. For
example,
[0095] 1. The refrigeration unit can be a mechanical compressing
system as shown in the sample embodiments. It can also be any of
other refrigeration apparatus including absorption refrigeration,
electric-magnetic refrigeration, thermal-electric refrigeration, et
al.
[0096] 2. The ground heat exchanger can be any type of heat
exchanger which is buried in the ground medium (sand, soil, and/or
rock) or laid under the asphalt or concrete pavement. The heat
exchanger can be closed pipe loop(s) buried underground vertically
or horizontally. The ground heat exchanger can also be heat
transfer equipment or loop laid on the bottom of surface
waters.
[0097] 3. The reversing valves can be four-way as show in the
sample embodiment, or two-way, or simple one way valves but
mechanically combined to reach the same open/close function. The
valve can be manually operated, or automatically operated with
control units. The control units can be programmable so that the
system operation can be timely optimized based on all, or part of
the information including electricity price, heat pump performance,
ground heat transfer capacity, and the sensed temperature of the
ground circulation fluid.
[0098] 4. The routing of the system in recovery model after heating
or cooling service shown in the embodiments are just some examples.
Many other loops can be routed.
[0099] 5. Heat exchangers can be any type to contact heat transfer
between liquid and air. The terminal units can be duct work and
diffuser, or fan-coil units or any other air distribution and heat
transfer units.
[0100] 6. Supplementary heating is mainly provided by electricity,
but it can also be other energy sources including solar, oil, coal,
gas, and propane, which would be used in on-peak hours.
[0101] The scope of the invention should be determined by the
appended claims and their legal equivalents, rather than by the
examples given.
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