Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02672747 2009-07-20
1
FORCED-AIR CROSS-DEFROST TYPE AIR-CONDITIONING SYSTEM
2
Field of the Invention
4
The present invention relates to a forced-air cross-defrost type air-
conditioning system, more
6 particularly to a forced-air cross-defrost type air-conditioning system
capable of frost-prevention
and air-ventilation in the cold region.
8
The present invention can be applied on residential, greenhouse, and
commercial air-conditioning
purposes.
CA 02672747 2009-07-20
2
BACKGROUND OF THE INVENTION
2
The present invention is a divisional application of the patent application of
application number
4 2,530,567, entitled "Multi-range cross defrosting heat pump system and
humidity control system."
6 The objective of the present invention is to provide an efficient control
methods for cross defrosting
air-conditioning under different temperature and humidity conditions.
8
Current ventilation and humidity control systems can not fully utilize the
heat energy of the indoor
air exhaust, therefore it is another objective to provide a ventilation and
humidity control system to
combine with the multi-range cross defrosting heat pump systems of the present
invention. The
12 ventilation and humidity control system recycles the heat energy from the
indoor exhaust and
adjusts the ventilation rate according to the humidity percentage. For the
human comfort in most
14 indoor space, the ventilation rate required is directly proportional to the
humidity percentage, the
ventilation and humidity control system of the present invention raises the
ventilation rate by
16 automatically adjusting the defrosting duration, since the multi-range
cross defrosting heat pump
system of the present invention requires more defrosting time when the
humidity percentage of the
18 working environment is high.
CA 02672747 2009-07-20
3
SUMMARY OF THE INVENTION
2
1. It is the primary objective of the present invention to provide a forced-
air cross-defrost type air-
4 conditioning system capable of cross-defrosting with the heat energy
absorbed from the
environment and the heat energy of the indoor air.
6
2. It is the secondary objective of the present invention to provide a
ventilation and humidity control
8 method for the forced-air cross-defrost type air-conditioning system.
3. It is the third objective of the present invention to provide a forced-air
cross-defrost type air-
conditioning system capable of frost-prevention over an outdoor temperature
range 20 degree
12 Celsius to negative 40 degree Celsius.
CA 02672747 2009-07-20
4
BREIF DESCRIPTION-OF THE DRAWINGS
2
FIG.5A to FIG.5E are illustrative diagrams of the forced-air cross-defrost
type air-conditioning
4 system of the present invention.
6 FIG.5F is an illustrative diagrams of the forced-air cross-defrost type air
conditioning system with
four sets of evaporators.
CA 02672747 2009-07-20
DESCRIPTION OF TIDE PREFERRED EMBODIMENTS
2
FIG.5A shows the forced-air cross-defrost type air-conditioning system. The
system comprising:
4 main compressor 501, main condenser 502, expansion valve 503, first
evaporator 511, second
evaporator 512, first control valve 521, second control valve 522, first
venting fan 541, second
6 venting fan 542, first temperature sensor 531, second temperature sensor
532, outdoor temperature
sensor 599, outdoor-air-intake duct 590, cold-air-exit duct 592, first outdoor-
air-intake valve 571,
8 second outdoor-air-intake valve 572, first indoor-air-intake valve 561,
second indoor-air-intake
valve 562, first indoor-air-intake fan 551, second indoor-air-intake fan 552,
separate heat insulation
means for each evaporator.
12 First evaporator 511 and second evaporator 512 can be disposed in indoor
space with separate heat
insulation means. This system is capable of two defrosting methods; the first
defrosting method can
14 be used in the outdoor temperature range of 20 degree Celsius to 5 degree
Celsius, the second
defrosting method can be used in the outdoor temperature range of 20 degree
Celsius to negative 40
16 degree Celsius. A combination of the two defrosting methods is preferred
for raising the system
efficiency; an exemplary control logics can be arranged as follows, the first
defrosting method is
18 used from the outdoor temperature of 20 degree to 12 degree Celsius, while
the second defrosting
method is used for the outdoor temperature of lower than 12 degree to negative
40 degree Celsius.
The purpose of the two defrosting methods is to prevent the malfunctioning of
the evaporators due
to the accumulated frost on the evaporator coils.
22
The following Table.5a will be used as a reference to the first defrosting
method, Table.5b will be
24 used as a reference to the second defrosting method, Table.5c will be used
as a reference to the full
capacity heating operation and the forced ventilation mode.
26
CA 02672747 2009-07-20
6
Table.5a
Cross-outdoor-flow Cross-outdoor-flow
Label Component Name defrosting process of defrosting process of
First evaporator Second evaporator
502 Main condenser Condensation Process Condensation Process
512 First evaporator Defrosting with Evaporation Process
Outdoor-air-flow
511 Second evaporator Evaporation Process Defrosting with
Outdoor-air-flow
521 First control valve Closed Open
522 Second control valve Open Closed
561 First indoor-air-intake valve Closed Closed
562 Second indoor-air-intake Closed Closed
valve
571 First outdoor-air-intake Open Open
valve
572 Second outdoor-air-intake Open Open
valve
551 First indoor-air-intake fan Disabled Disabled
552 Second indoor-air-intake fan Disabled Disabled
541 First venting fan Operating at Operating at
full speed full speed
542 Second venting fan Operating at Operating at
full speed full speed
CA 02672747 2009-07-20
7
Table.5b
Cross-indoor-flow Cross-indoor-flow
Label Component Name defrosting process of defrosting process of
First evaporator Second evaporator
502 Main condenser Condensation Process Condensation Process
512 First evaporator Defrosting with Operating
Indoor-air-flow
511 Second evaporator Operating Defrosting with
Indoor-air-flow
521 First control valve Closed Open
522 Second control valve Open Closed
561 First indoor-air-intake valve Open Closed
562 Second indoor-air-intake Closed Open
valve
571 First outdoor-air-intake Closed Open
valve
572 Second outdoor-air-intake Open Closed
valve
551 First indoor-air-intake fan Operating to provide Disabled
Indoor-air-flow
552 Second indoor-air-intake fan Disabled Operating to provide
Indoor-air-flow
541 First venting fan Decreasing speed or Operating at
Stop full speed
542 Second venting fan Operating at Decreasing speed or
full speed Stop
2
CA 02672747 2009-07-20
8
Table.5c
Label Component Name Full capacity heating Forced-ventilation
502 Main condenser Condensation Process Condensation Process
512 First evaporator Evaporation Process Evaporation Process
with mixed air flow
511 Second evaporator Evaporation Process Evaporation Process
with mixed air flow
521 First control valve Open Open
522 Second control valve Open Open
561 First indoor-air-intake valve Closed Open
562 Second indoor-air-intake Closed Open
valve
571 First outdoor-air-intake Open Open
valve
572 Second outdoor-air-intake Open Open
valve
551 First indoor-air-intake fan Disabled Operating to provide
Indoor-air-flow
552 Second indoor-air-intake fan Disabled Operating to provide
Indoor-air-flow
541 First venting fan Operating at Operating at
full speed controlled speed
542 Second venting fan Operating at Operating at
full speed controlled speed
2
Now referring to each drawing to elaborate the system conditions during the
first defrosting method
4 and the second defrosting method; the first defrosting method can be also
called as the cross-
outdoor-flow defrosting process, the second defrosting method can be also
called as the cross-
6 indoor-flow defrosting process.
8 Before the defrosting process is required, the forced-air cross-defrost type
air-conditioning system
will operate as shown in FIG.5A; the first evaporator 511 and the second
evaporator 512 will receive
a flow of evaporated refrigerant from the expansion valve 503, and the first
evaporator and the
second evaporator will absorb the heat from the outdoor air provided through
the first outdoor-air-
12 intake valve 571 and the second out-door-air-intake valve 572 respectively;
the first indoor-air-
intake valve 561 and the second indoor-air-intake valve 562 are shut to
conserve the indoor
CA 02672747 2009-07-20
9
temperature; the first venting fan 541 and the second venting fan 542 are
venting the cold air to open
2 air through cold-air-exit duct 592.
4 Now referring to FIG.5B and FIG.5C for the operation of the first defrosting
method, which is also
called as the cross-outdoor-flow defrosting process; the first evaporator 511
and the second
6 evaporator 512 will alternately stop the refrigerant-flow and defrost with
the first defrosting method
as shown in FIG.5B and FIG.5C. An exemplary defrost-cycle can be arranged as
follows, the first
8 evaporator 511 will defrost with the outdoor-air-flow as shown in FIG.5B for
5 minutes, and next
the second evaporator 512 will defrost with the outdoor-air-flow as shown in
FIG.5C for 5 minutes,
and next the control system repeats the defrost-cycle until further change in
the outdoor temperature
is detected.
12
As shown in FIG.5B the first evaporator is defrosting with the cross-outdoor-
flow defrosting process;
14 the first control valve 521 is shut to stop the refrigerant-flow of the
first evaporator 511, the outdoor
air is forced into the heat insulated space of the first evaporator 511 with
the first venting fan 541,
16 and the frost on the first evaporator 511 will melt with the heat energy of
the outdoor-air-flow; at the
same time, the second control valve 522 is open, the second evaporator 512
will continue the
18 evaporation process to provide a flow of evaporated refrigerant to the main
compressor 501.
As shown in FIG.5C, the second evaporator is defrosting with the cross-outdoor-
flow defrosting
process; the second control valve 522 is shut to stop the refrigerant-flow of
the second evaporator
22 512, the outdoor air is forced into the heat insulated space of the second
evaporator 512 with the
second venting fan 542, and the frost on the second evaporator 512 will melt
with the heat energy of
24 the outdoor-air-flow; at the same time, the first control valve 521 is
open, the first evaporator 511
will continue the evaporation process to provide a flow of evaporated
refrigerant to the main
26 compressor 501.
28 Now referring to FIG.5D and FIG.5E for the operation of the second
defrosting method, which is
also called as the cross-indoor-flow defrosting process; the first evaporator
511 and the second
evaporator 512 will alternately stop the refrigerant-flow with each associated
control valve, and the
first evaporator 511 and the second evaporator 512 will take turns to stop the
outdoor-air-flow and
32 feed in the indoor-air-flow for providing the heat energy; an exemplary
defrost-cycle is shown as
follows, the first evaporator 511 defrosts with the csecond defrosting method
as shown in FIG.5D
CA 02672747 2009-07-20
for 5 minute, and next.the second evaporator 512 defrosts with the second
defrosting method as
2 shown in FIG.5E for 5 minute, and next the control system repeats the cycle
until further change in
the outdoor temperature is detected.
4
As shown in FIG.5D, the first evaporator 511 is defrosting with the cross-
indoor-flow defrosting
6 process; the first control valve 521 is shut to stop the refrigerant-flow of
the first evaporator 511, the
second control valve 522 is open to continue the refrigerant-flow of the
second evaporator 512; the
8 first outdoor-air-intake valve 571 is shut and the first indoor-air-intake
valve 561 is open, and the
first venting fan 541 will spin slowly to inhale the indoor air into the heat
insulated space of the first
10 evaporator 511 until the temperature of the heat insulated space of the
first evaporator 511 is close to
the indoor temperature, thus the frost on the first evaporator 511 will absorb
the heat energy of the
12 indoor-air-flow and melt; at the same time, the second evaporator 512 will
continue the evaporation
process to provide a flow of evaporated refrigerant to the main compressor
501, the second outdoor-
14 air-intake valve 572 is open and the second indoor-air-intake valve 562 is
shut, and the second
venting fan 542 will be operating at full speed to provide a sufficient
outdoor-air-flow through the
16 second evaporator 512.
18 As shown in FIG.5E, the second evaporator 512 is defrosting with the cross-
indoor-flow defrosting
process; the second control valve 522 is shut to stop the refrigerant-flow of
the second evaporator
512, the first control valve 521 is open to continue the refrigerant-flow of
the first evaporator 511;
the second outdoor-air-intake valve 572 is shut and the second indoor-air-
intake valve 562 is open,
22 and the second venting fan 542 will spin slowly to inhale the indoor air
into the heat insulated space
of the second evaporator 512 until the temperature of the heat insulated space
of the second
24 evaporator 512 is close to the indoor temperature, thus the frost on the
second evaporator 512 will
absorb the heat energy of the indoor-air-flow and melt; at the same time, the
first evaporator 511
26 will continue the evaporation process to provide a flow of evaporated
refrigerant-flow to the main
compressor 501, the first outdoor-air-intake valve 571 is open and the first
indoor-air-intake valve
28 561 is shut, and the first venting fan 541 will be operating at full speed
to provide a sufficient
outdoor-air-flow through the first evaporator 512.
When the system is defrosting the second defrosting method, either one of the
first evaporator 511
32 and the second evaporator 512 will be continuing the evaporation process,
therefore the main
compressor 501 and the main condenser 502 can continue the air-conditioning
operation.
CA 02672747 2009-07-20
11
2 Additional control logic can be applied to the speed of the first indoor-air-
intake fan 551 and the
second indoor-air-intake fan 552 for higher defrosting efficiency, while the
basic concept is to fully
4 utilize the heat energy of the indoor-air-flow during each defrosting
process; for instance, when the
first evaporator 511 is defrosting with the second defrost method, the speed
of the first-indoor-air-
6 intake fan 551 will adjust according to the temperature difference of the
indoor air and the heat
insulated space of the first evaporator 511, so that when the heat insulated
space of the first
8 evaporator is much colder than the indoor temperature, the first-indoor-air-
intake fan 551 will raise
its speed to shorten the required time for the defrosting process.
When the system is defrosting with the second defrosting method, each indoor-
air-intake fan is
12 drawing the indoor air into its associated evaporator, and the outdoor air
is drawing into the indoor
space through other ventilation duct for ventilation purpose, or an indoor
ventilation fan can co-
14 work with this system and draws outdoor air into the indoor space.
16 The forced-air cross-defrost type air-conditioning system can operate with
the following three basic
operation mode.
18
First operation mode is the scheduled defrosting mode, where each evaporator
takes turn to defrost
on a fixed time schedule. This operation mode can further employ a defrosting
process sensor means
to detect if the evaporator has melted all the ice on the evaporator, if no
further defrosting is required,
22 the control logic reset it to the next step of the working schedule. The
defrosting process sensor
means can be a pressure or temperature sensor on the defrosting evaporator.
24
Second operation mode is the automatic defrost mode, where the evaporators are
running under an
26 environment condition that will take a very long time before the defrosting
process is needed. A
defrosting process sensor is used to determine when the system requires
defrosting. If the system
28 requires defrosting, the system will change into the schedule defrosting
mode until no further
defrosting is required.
Third operation mode is the forced-ventilation mode, where each indoor-air-
intake valve is open and
32 its associated indoor-air-intake fan is running to draw in the indoor air
for ventilation purpose during
the operation of its associated evaporator.
CA 02672747 2009-07-20
12
2 Under third operation mode, the outdoor air flow is mixed with the indoor
air flow through each
indoor-air-intake control valve. By controlling the temperature of this mixed
air flow, the time
4 required for each defrosting process can be greatly reduced, or under some
conditions, the system
can continue to operate without defrosting. In the case when the outdoor
temperature is between 5 to
6 12 degree Celsius, the temperature of the mixed air flow can be raised to 12
degree so that the
system can greatly increase the operation time of both first evaporator 511
and second evaporator
8 512 before any defrosting process is required.
The control system will need to adjust the frequency of the defrost-cycle so
that all evaporators will
not be completely frosted at the same time; at least one of the first
evaporator and the second
12 evaporator must be able to absorb the heat energy from the outdoor air flow
during the defrost-cycle.
14 It should be noted that the control logic of the venting fans is different
when the system is operating
under the forced-ventilation mode, where each venting fan is not operating at
the speed based on the
16 temperature difference between the outdoor temperature and the temperature
within the heat
insulated space associated with each evaporator. The venting fans are
operating at the speed based
18 on the ventilation rate required or the temperature of the mixed air flow
required.
The forced-air cross-defrost type air-conditioning system can operate with
more than two sets of the
evaporator as shown in FIG.5F; the system operate in the similar manner for
more than 2 sets of
22 evaporators, for example, when the second evapotor 512 is defrosting with
second defrost method,
the first evaporator 511 and the third evaporator 513 and the fourth
evaporator 514 will continue the
24 refrigerant-flow and the evaporation process, while the second evapotor 512
will receive the indoor-
air-flow through the second indoor-air-intake control valve 562, thus three of
the evaporators will be
26 generating the heat energy for air-conditioning when one of the evaporators
utilizes part of said heat
energy to defrost in the form of the indoor-air-flow.
28
