Canadian Patents Database / Patent 2662986 Summary

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(12) Patent: (11) CA 2662986
(54) English Title: CO2 REFRIGERATION UNIT
(54) French Title: UNITE DE REFRIGERATION AU DIOXYDE DE CARBONE
(51) International Patent Classification (IPC):
  • F25B 1/00 (2006.01)
(72) Inventors :
  • DUBE, SERGE (Canada)
(73) Owners :
  • DUBE, SERGE (Canada)
(71) Applicants :
  • DUBE, SERGE (Canada)
(74) Agent: NORTON ROSE FULBRIGHT CANADA LLP/S.E.N.C.R.L., S.R.L.
(74) Associate agent:
(45) Issued: 2012-02-07
(22) Filed Date: 2009-04-17
(41) Open to Public Inspection: 2009-10-18
Examination requested: 2011-02-25
(30) Availability of licence: N/A
(30) Language of filing: English

(30) Application Priority Data:
Application No. Country/Territory Date
61/046,004 United States of America 2008-04-18

English Abstract

A refrigeration unit comprises a CO2 refrigeration circuit having a CO2 compression stage in which CO2 refrigerant is compressed, a CO2 condensation stage having a tank in which CO2 refrigerant is accumulated in a liquid state, at least one of pressuring means and an expansion stage to direct the CO2 refrigerant from the CO2 condensation stage to a CO2 evaporation stage in which CO2 refrigerant absorbs energy to refrigerate. A condensation circuit has a second refrigerant being circulated between a second compression stage, a second condensation stage, a second expansion stage and a second evaporation stage. A heat-exchanger unit by which the CO2 refrigerant from the CO2 refrigeration circuit is in heat exchange with the second refrigerant in the second evaporation stage such that the second refrigerant absorbs heat from the CO2 refrigerant to at least partially liquefy the CO2 refrigerant for the CO2 condensation stage. A defrost circuit directing defrost CO2 refrigerant from the CO2 compression stage to the CO2 evaporation stage to defrost at least one evaporator of the CO2 evaporation stage, the defrost CO2 refrigerant being subsequently returned to the CO2 refrigeration circuit.


French Abstract

Une unité de réfrigération compte un circuit de réfrigération au CO2 comportant une étape de compression, à laquelle le réfrigérant au CO2 est compressé, une étape de condensation, à laquelle le réfrigérant au CO2 est accumulé à l'état liquide dans un réservoir, au moins un moyen de pressurisation ainsi qu'une étape d'expansion, à laquelle le réfrigérant au CO2 est acheminé de l'étape de condensation à l'étape d'évaporation, à laquelle le réfrigérant au CO2 absorbe l'énergie afin d'assurer la réfrigération. Un circuit de condensation comporte un réfrigérant secondaire qui circule entre une seconde étape de compression, une seconde étape de condensation, une seconde étape d'expansion et une seconde étape d'évaporation. Il y a une unité d'échange de la chaleur dans laquelle le réfrigérant au CO2 du circuit de réfrigération au CO2 échange la chaleur avec le second réfrigérant à la seconde étape d'évaporation de telle sorte que le second réfrigérant absorbe la chaleur du réfrigérant au CO2 afin de liquéfier au moins en partie le réfrigérant au CO2 pour l'étape de condensation du CO2. Il y a un circuit de dégivrage acheminant le réfrigérant au CO2 de dégivrage issu de l'étape de compression du CO2 de manière à dégivrer au moins au moins un évaporateur de l'étape d'évaporation du CO2, le réfrigérant au CO2 de dégivrage étant ensuite retourné dans le circuit de réfrigération au CO2.


Note: Claims are shown in the official language in which they were submitted.



CLAIMS:

1. A refrigeration unit comprising:
a CO2 refrigeration circuit having a CO2
compression stage in which CO2 refrigerant is compressed, a
CO2 condensation stage having a tank in which CO2
refrigerant is accumulated in a liquid state, at least one
of pressuring means and an expansion stage to direct the CO2
refrigerant from the CO2 condensation stage to a CO2
evaporation stage in which CO2 refrigerant absorbs energy to
refrigerate;
a condensation circuit having a second refrigerant
being circulated between a second compression stage, a
second condensation stage, a second expansion stage and a
second evaporation stage;
a heat-exchanger unit by which the CO2 refrigerant
from the CO2 refrigeration circuit is in heat exchange with
the second refrigerant in the second evaporation stage such
that the second refrigerant absorbs heat from the CO2
refrigerant to at least partially liquefy the CO2
refrigerant for the CO2 condensation stage; and
a defrost circuit directing defrost CO2
refrigerant from the CO2 compression stage to the CO2
evaporation stage to defrost at least one evaporator of the
CO2 evaporation stage, the defrost CO2 refrigerant being
subsequently returned to the CO2 refrigeration circuit.


2. The refrigeration unit according to claim 1,
wherein a discharge of the CO2 compression stage is fed to
the heat-exchanger unit for releasing heat to then reach the
tank of the CO2 condensation stage.


3. The refrigeration unit according to claim 1,
wherein the CO2 evaporation stage has at least medium-
temperature evaporators and low-temperature evaporators,
with a line directing CO2 refrigerant exiting the low-
temperature evaporators to the CO2 compression stage, and

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with the pressuring means upstream of the medium-temperature
evaporators to feed CO2 refrigerant to the medium-
temperature evaporators, with another line directing CO2
refrigerant exiting the medium-temperature evaporators to
the CO2 condensation stage.

4. The refrigeration unit according to claim 1,
wherein the CO2 evaporation stage has at least medium-
temperature evaporators and low-temperature evaporators,
with a line directing CO2 refrigerant exiting the low-
temperature evaporators to the CO2 compression stage, and
with the expansion stage upstream of the medium-temperature
evaporators to feed CO2 refrigerant to the medium-
temperature evaporators, with another line directing CO2
refrigerant exiting the medium-temperature evaporators to
the CO2 compression stage.


5. The refrigeration unit according to claim 1,
further comprising a defrost reservoir between the CO2
evaporation stage and the CO2 compression stage to collect
the defrost CO2 refrigerant exiting the defrost circuit, a
suction of the CO2 compression stage connected to the
defrost reservoir to collect CO2 refrigerant in a gas state
for the CO2 refrigeration circuit.


6. The refrigeration unit according to claim 5,
wherein a discharge line extends from the CO2 compression
stage to the defrost reservoir to selectively flush CO2
refrigerant from the defrost reservoir through another line
extending from the defrost reservoir to the tank in the CO2
condensation stage.


7. The refrigeration unit according to claim 1,
further comprising at least one dedicated compressor in the
CO2 compression stage to collect at least part of the
defrost CO2 refrigerant exiting the defrost circuit, to

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compress and discharge the defrost CO2 refrigerant to the
CO2 refrigeration circuit.


8. The refrigeration unit according to claim 1,
further comprising a pressure-reducing valve on a discharge
line of the CO2 compression stage, downstream of a defrost
line feeding defrost CO2 refrigerant to the defrost circuit,
to maintain a pressure of the CO2 refrigerant in the CO2
refrigeration circuit downstream of the pressure-reducing
valve lower than the pressure of the defrost CO2
refrigerant.


9. The refrigeration unit according to claim 1,
wherein the defrost CO2 refrigerant is circulated in the CO2
evaporation stage of the defrost circuit at a pressure below
700 Psi.


10. The refrigeration unit according to claim 9,
wherein the defrost CO2 refrigerant is circulated in the CO2
evaporation stage of the defrost circuit at a pressure
between 300 and 425 Psi.


11. The refrigeration unit according to claim 1,
further comprising a heat reclaim stage in a discharge line
of the CO2 compression stage to reclaim heat from the CO2
refrigerant.


12. The refrigeration unit according to claim 11,
wherein the heat reclaim stage comprises a coil in a
ventilation duct to heat ventilation air.


13. The refrigeration unit according to claim 1,
wherein the condensation circuit has a pressure-maintaining
line extending from a discharge of the second compression
stage to a suction of the second compression stage, the
pressure-maintaining line being selectively opened to

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maintain a minimum operating pressure at a suction of the
second compression stage.


14. The refrigeration unit according to claim 1,
wherein the condensation circuit has a second heat-
exchanger by which the second refrigerant exiting the second
compression stage selectively heats the second refrigerant
exiting the second condensation stage to subsequently feed
the second refrigerant exiting the second condensation stage
directly to the second compression stage.


15. The refrigeration unit according to claim 1,
further comprising a line extending from the CO2 evaporation
stage to the CO2 condensation stage to direct defrost CO2
refrigerant from the defrost circuit to the refrigeration
circuit.


16. A refrigeration unit comprising:
a casing;
a CO2 refrigeration circuit having a CO2
compression stage in which CO2 refrigerant is compressed, a
CO2 condensation stage having a tank in which CO2
refrigerant is accumulated in a liquid state, at least one
of pressuring means and an expansion stage to direct the CO2
refrigerant from the CO2 condensation stage to a CO2
evaporation stage in which CO2 refrigerant absorbs energy to
refrigerate, with at least the CO2 compression stage, and
the CO2 condensation stage being in the casing;
a condensation circuit having a second refrigerant
being circulated between a second compression stage, a
second condensation stage, a second expansion stage and a
second evaporation stage, at least the second compression
stage, the second expansion stage and the second evaporation
stage being in the casing; and
a heat-exchanger unit in the casing by which the
CO2 refrigerant from the C02 refrigeration circuit is in
heat exchange with the second refrigerant in the second

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evaporation stage such that the second refrigerant absorbs
heat from the CO2 refrigerant to at least partially liquefy
the CO2 refrigerant for the CO2 condensation stage.


17. The refrigeration unit according to claim 16,
further comprising a defrost circuit directing defrost CO2
refrigerant from the CO2 compression stage to the CO2
evaporation stage to defrost at least one evaporator, the
defrost CO2 refrigerant being subsequently returned to the
CO2 refrigeration circuit.


18. The refrigeration unit according to claim 16,
wherein the at least one of pressuring means and expansion
stage are in the casing.


19. The refrigeration unit according to claim 16,
further comprising a ventilation circuit in which circulates
a third refrigerant between a third compression stage, a
third condensation/gas cooling stage, a third expansion
stage and a third evaporation stage, at least the third
compression stage, the third condensation/gas cooling stage,
and the third expansion stage being in the casing, with the
third evaporation stage adapted to be in a ventilation duct
to absorb heat from ventilation air.


20. The refrigeration unit according to claim 19,
further comprising a heat reclaim stage in a discharge line
of the CO2 compression stage to reclaim heat from the CO2
refrigerant, the heat reclaim stage comprising a coil
adapted to be in said ventilation duct to heat ventilation
air.


21. The refrigeration unit according to claim 16,
further comprising at least an other one of the
refrigeration unit in another one of the casing, the other
one of the refrigeration unit being without one of the
condensation circuit, and being in heat-exchange relation

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with the heat-exchange unit of the first one of the
refrigeration unit.


22. A refrigeration unit of the type having a CO2
refrigeration circuit with a CO2 compression stage in which
CO2 refrigerant is compressed, a CO2 condensation stage
having a tank in which CO2 refrigerant is accumulated in a
liquid state, an expansion stage to direct the CO2
refrigerant from the CO2 condensation stage to a CO2
evaporation stage in which CO2 refrigerant absorbs energy to
refrigerate, the CO2 evaporation stage having at least two
evaporators, the refrigeration unit comprising at least one
line connected from the CO2 condensation stage to one
expansion valve of the expansion stage, the line diverging
into at least two lines each connected to a balancing valve
and an own one of the evaporators, such that CO2 refrigerant
expanded by the one expansion valve is directed to the at
least two evaporators through the balancing valves.


23. The refrigeration unit according to claim 22,
wherein the expansion stage is in a casing with the CO2
compression stage and the CO2 condensation stage at a distal
location from the CO2 evaporation stage.


24. The refrigeration unit according to claim 23,
wherein the refrigeration unit is retrofitted to existing
evaporators.


25. The refrigeration unit according to claim 22,
further comprising a defrost circuit directing defrost CO2
refrigerant from the CO2 compression stage to the CO2
evaporation stage to defrost the evaporators, the defrost
CO2 refrigerant being subsequently returned to the CO2
refrigeration circuit.


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Note: Descriptions are shown in the official language in which they were submitted.


CA 02662986 2011-08-16

CO2 REFRIGERATION UNIT
FIELD OF THE APPLICATION

The present application relates to CO2
refrigeration systems, for instance used in commercial
applications such as supermarkets, industrial storage and
the like.

BACKGROUND OF THE ART

With the growing concern for global warming, the
use of chlorofluorocarbons (CFCs) and hydrochlorofluoro-
carbons (HCFCs) as refrigerant has been identified as having
a negative impact on the environment. These chemicals have
non-negligible ozone-depletion potential and/or global-
warming potential.
As alternatives to CFCs and HCFCs, ammonia, hydro-
carbons, and CO2 are used as refrigerants. Although ammonia
and hydrocarbons have negligible ozone-depletion potential
and global-warming potential as does C02, these refrigerants
are highly flammable and therefore represent a risk to local
safety. On the other hand, CO2 is environmentally benign
and locally safe.

SUMMARY OF THE APPLICATION

It is therefore an aim of the present application
to provide a novel CO2 refrigeration systems.
Therefore, in accordance with a first embodiment
of the present application, there is provided a
refrigeration unit comprising: a CO2 refrigeration circuit
having a CO2 compression stage in which CO2 refrigerant is

- 1 -

10.0 WOO
CA 02662986 2009-04-17

compressed, a CO2 condensation stage having a tank in which
C02 refrigerant is accumulated in a liquid state, at least
one of pressuring means and an expansion stage to direct the
002 refrigerant from the C02 condensation stage to a CO2
evaporation stage in which C02 refrigerant absorbs energy to
refrigerate; a condensation circuit having a second
refrigerant being circulated between a second compression
stage, a second condensation stage, a second expansion stage
and a second evaporation stage; a heat-exchanger unit by
which the CO2 refrigerant from the CO2 refrigeration circuit
is in heat exchange with the second refrigerant in the
second evaporation stage such that the second refrigerant
absorbs heat from the CO2 refrigerant to at least partially
liquefy the CO2 refrigerant for the C02 condensation stage;
i5 and a defrost circuit directing defrost C02 refrigerant from
the CO2 compression stage to the CO2 evaporation stage to
defrost at least one evaporator of the C02 evaporation
stage, the defrost C02 refrigerant being subsequently
returned to the C02 refrigeration circuit.
Further in accordance with the first embodiment, a
discharge of the C02 compression stage is fed to the heat-
exchanger unit for releasing heat to then reach the tank of
the CO2 condensation stage.
Still further in accordance with the first
embodiment, the CO2 evaporation stage has at least medium-
temperature evaporators and low-temperature evaporators,
with a line directing CO2 refrigerant exiting the low-
temperature evaporators to the CO2 compression stage, and
with the pressuring means upstream of the medium-temperature
evaporators to feed CO2 refrigerant to the medium-
temperature evaporators, with another line directing CO2
refrigerant exiting the medium-temperature evaporators to
the CO2 condensation stage.
Still further in accordance with the first
embodiment, the CO2 evaporation stage has at least medium-
temperature evaporators and low-temperature evaporators,
with a line directing C02 refrigerant exiting the low-
- 2 -


CA 02662986 2009-04-17

temperature evaporators to the C02 compression stage, and
with the expansion stage upstream of the medium-temperature
evaporators to feed C02 refrigerant to the medium-
temperature evaporators, with another line directing CO2
refrigerant exiting the medium-temperature evaporators to
the CO2 compression stage.
Still further in accordance with the first
embodiment, a defrost reservoir between the CO2 evaporation
stage and the CO2 compression stage collects the defrost C02
refrigerant exiting the defrost circuit, a suction of the
CO2 compression stage connected to the defrost reservoir to
collect C02 refrigerant in a gas state for the C02
refrigeration circuit.
Still further in accordance with the first
embodiment, a discharge line extends from the C02
compression stage to the defrost reservoir to selectively
flush CO2 refrigerant from the defrost reservoir through
another line extending from the defrost reservoir to the
tank in the C02 condensation stage.
Still further in accordance with the first
embodiment, at least one dedicated compressor is provided in
the C02 compression stage to collect at least part of the
defrost C02 refrigerant exiting the defrost circuit, to
compress and discharge the defrost C02 refrigerant to the
C02 refrigeration circuit.
Still further in accordance with the first
embodiment, a pressure-reducing valve on a discharge line of
the CO2 compression stage, downstream of a defrost line
feeding defrost CO2 refrigerant to the defrost circuit,
maintains a pressure of the C02 refrigerant in the C02
refrigeration circuit downstream of the pressure-reducing
valve lower than the pressure of the defrost CO2
refrigerant.
Still further in accordance with the first
embodiment, the defrost C02 refrigerant is circulated in the
C02 evaporation stage of the defrost circuit at a pressure
below 700 Psi.

3 -


CA 02662986 2009-04-17

Still further in accordance with the first
embodiment, the defrost CO2 refrigerant is circulated in the
002 evaporation stage of the defrost circuit at a pressure
between 300 and 425 Psi.
Still further in accordance with the first
embodiment to claim 1, a heat reclaim stage in a discharge
line of the CO2 compression stage reclaims heat from the 002
refrigerant.
Still further in accordance with the first
embodiment, the heat reclaim stage comprises a coil in a
ventilation duct to heat ventilation air.
Still further in accordance with the first
embodiment, the condensation circuit has a pressure-
maintaining line extending from a discharge of the second
compression stage to a suction of the second compression
stage, the pressure-maintaining line being selectively
opened to maintain a minimum operating pressure at a suction
of the second compression stage.
Still further in accordance with the first
embodiment, the condensation circuit has a second heat-
exchanger by which the second refrigerant exiting the second
compression stage selectively heats the second refrigerant
exiting the second condensation stage to subsequently feed
the second refrigerant exiting the second condensation stage
directly to the second compression stage.
Still further in accordance with the first
embodiment, a line extends from the CO2 evaporation stage to
the CO2 condensation stage to direct defrost 002 refrigerant
from the defrost circuit to the refrigeration circuit.
In accordance with a second embodiment of the
present application, there is provided a refrigeration unit
comprising: a casing; a CO2 refrigeration circuit having a
002 compression stage in which 002 refrigerant is
compressed, a CO2 condensation stage having a tank in which
CO2 refrigerant is accumulated in a liquid state, at least
one of pressuring means and an expansion stage to direct the
CO2 refrigerant from the CO2 condensation stage to a CO2
- 4 -

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CA 02662986 2009-04-17

evaporation stage in which CO2 refrigerant absorbs energy to
refrigerate, with at least the CO2 compression stage, and
the CO2 condensation stage being in the casing; a
condensation circuit having a second refrigerant being
circulated between a second compression stage, a second
condensation stage, a second expansion stage and a second
evaporation stage, at least the second compression stage,
the second expansion stage and the second evaporation stage
being in the casing; and a heat-exchanger unit in the casing
by which the CO2 refrigerant from the CO2 refrigeration
circuit is in heat exchange with the second refrigerant in
the second evaporation stage such that the second
refrigerant absorbs heat from the CO2 refrigerant to at
least partially liquefy the CO2 refrigerant for the CO2
i5 condensation stage.
Further in accordance with the second embodiment,
a defrost circuit directs defrost CO2 refrigerant from the
CO2 compression stage to the CO2 evaporation stage to
defrost at least one evaporator, the defrost CO2 refrigerant
being subsequently returned to the CO2 refrigeration
circuit.
Still further in accordance with the second
embodiment, the at least one of pressuring means and
expansion stage are in the casing.
Still further in accordance with the second
embodiment, a ventilation circuit is provided in which
circulates a third refrigerant between a third compression
stage, a third condensation/gas cooling stage, a third
expansion stage and a third evaporation stage, at least the
third compression stage, the third condensation/gas cooling
stage, and the third expansion stage being in the casing,
with the third evaporation stage adapted to be in a
ventilation duct to absorb heat from ventilation air.
Still further in accordance with the second
embodiment, a heat reclaim stage is provided in a discharge
line of the CO2 compression stage to reclaim heat from the
CO2 refrigerant, the heat reclaim stage comprising a coil
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CA 02662986 2009-04-17

adapted to be in said ventilation duct to heat ventilation
air.
Still further in accordance with the second
embodiment, at least an other one of the refrigeration unit
in another one of the casing, the other one of the
refrigeration unit being without one of the condensation
circuit, and being in heat-exchange relation with the heat-
exchange unit of the first one of the refrigeration unit.
In accordance with a third embodiment of the
present application, there is provided a refrigeration unit
of the type having a CO2 refrigeration circuit with a CO2
compression stage in which CO2 refrigerant is compressed, a
CO2 condensation stage having a tank in which CO2
refrigerant is accumulated in a liquid state, an expansion
stage to direct the CO2 refrigerant from the CO2
condensation stage to a CO2 evaporation stage in which CO2
refrigerant absorbs energy to refrigerate, the CO2
evaporation stage having at least two evaporators, the
refrigeration unit comprising at least one line connected
from the CO2 condensation stage to one expansion valve of
the expansion stage, the line diverging into at least two
lines each connected to a balancing valve and an own one of
the evaporators, such that CO2 refrigerant expanded by the
one expansion valve is directed to the at least two
evaporators through the balancing valves.
Further in accordance with the third embodiment,
the expansion stage is in a casing with the CO2 compression
stage and the CO2 condensation stage at a distal location
from the CO2 evaporation stage.
Still further in accordance with the third
embodiment, the refrigeration unit is retrofitted to
existing evaporators.
Still further in accordance with the third
embodiment, a defrost circuit directs defrost CO2
refrigerant from the CO2 compression stage to the CO2
evaporation stage to defrost the evaporators, the defrost
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CA 02662986 2009-04-17

CO2 refrigerant being subsequently returned to the CO2
refrigeration circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram of a CO2 refrigeration
unit in accordance with a first embodiment of the present
application;
Fig. 2 is a block diagram of a CO2 refrigeration
unit in accordance with a second embodiment of the present
application, featuring refrigerant defrost;
Fig. 3 is a block diagram of CO2 refrigeration
units sharing a high-pressure condensing circuit, in
accordance with a third embodiment of the present
application;
Fig. 4 is a schematic view of a CO2 condensation
tank, as used in the CO2 refrigeration units of Figs. 1-3;
Fig. 5 is a schematic plan of the CO2 refrigera-
tion unit of Figs. 1 and 2;
Fig. 6 is a block diagram of the high-pressure
condensing circuit of the CO2 refrigeration unit of Fig. 1,
in accordance with another embodiment of the present
application;
Fig. 7 is a block diagram of the CO2 refrigeration
unit of Fig. 1, with high-temperature evaporation;
Fig. 8 is a block diagram of a CO2 refrigeration
unit in accordance with a fourth embodiment of the present
application, featuring medium-temperature compression;
Fig. 9 is a block diagram of a CO2 refrigeration
unit in accordance with a fifth embodiment of the present
application, featuring a defrost-reservoir;
Fig. 10 is a block diagram of the high-pressure
condensing circuit of Fig. 6, with a pressure-maintaining
line; and
Fig. 11 is a block diagram of an expansion
arrangement of a CO2 refrigeration unit.

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CA 02662986 2009-04-17
DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and more
particularly to Fig. 1, a CO2 refrigeration unit in
accordance with a first embodiment of the present
application is generally at 10. The CO2 refrigeration unit
of Fig. 1 is defined by a casing that encloses parts of a
CO2 refrigeration circuit 12, a high-pressure condensing
circuit 13 cascaded with the CO2 refrigeration circuit 12,
and a ventilation circuit 14. The CO2 refrigeration unit 10
10 is primarily used as a rooftop unit providing refrigeration
for the needs of a building, but may also be used within a
building, for instance in a mechanical room. The CO2
refrigeration unit described hereinafter are well suited for
being retro-fitted to existing installations, using the
existing evaporators and/or condensers on site. Some of the
embodiments described hereinafter pertain to a casing
enclosing most components, which casing is readily installed
as a whole with all components ready for operation.
The CO2 refrigeration unit 10 provides cooling
energy for medium-temperature and low-temperature refri-
gerated cabinets and enclosures in the form of liquid or
gaseous CO2 as fed by the CO2 refrigeration circuit 12.
Moreover, the CO2 refrigeration unit 10 provides air-
conditioning and heating energy for a ventilation system, as
fed by the ventilation circuit 14.
The CO2 refrigeration circuit 12 is a closed
circuit in which liquid/gaseous CO2 circulates. The CO2
refrigeration circuit 12 has a compression stage, in which
gaseous CO2 is compressed by one or more compressors. The
compressed CO2 then reaches a condensation stage 21, in
which the compressed CO2 releases energy. The condensation
stage 21 features a condensation tank in heat exchange with
the high-pressure condensing circuit 13, as will be
described hereinafter. The cascaded relation with the high-
pressure condensing circuit 13 is due to the limitations in
ambient temperature condensation for the CO2. The high-
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-aw-CA 02662986 2009-04-17

pressure condensing circuit 13 provides refrigerant at a
temperature allowing condensation of the C02-
Liquid CO2 then exits the condensation stage 21
and the CO2 refrigeration circuit 12 to reach the refri-
gerated units (e.g., refrigerated cabinets or enclosures)
within the building.
In the embodiment of Fig. 1, the liquid CO2 is
directed either to medium-temperature refrigerated units
(e.g., for non-frozen goods, such as produce, meats, dairy)
or low-temperature refrigerated units (e.g., for frozen
goods).
In the medium-temperature branch, liquid CO2 is
fed to the evaporation stage 23 by pressuring means 22 (in
or out of the casing of the refrigeration unit 10) The
pressuring means 22 are a pump or like mechanical device
suitable to direct the flow of liquid CO2 to the evaporation
stage 23. The evaporation stage 23 comprises one or more
evaporators located in refrigerated enclosures or cabinets.
The evaporators are in a heat-exchange relation with a
fluid, such as air, blown thereon. The evaporators absorb
heat from the air, to provide the refrigerated units with
cold energy. The liquid CO2 exiting the medium-temperature
evaporation stage 23 is then directed to the condensation
stage 21.
In the low-temperature branch, liquid CO2 is fed
to the expansion stage 24. The expansion stage 24 features
expansion valves to vaporize the liquid C02, so as to
subsequently feed gaseous CO2 to the low-temperature
evaporation stage 25. The evaporation stage 25 comprises
one or more evaporators located in refrigerated enclosures
or cabinets, typically enclosing frozen goods. The
evaporators are in a heat-exchange relation with a fluid,
such as air, blown thereon. The evaporators absorb heat
from the air, to provide the refrigerated units with cold
energy. The gaseous CO2 exiting the low-temperature
evaporation stage 25 is then directed to the compression
stage 20.

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CA 02662986 2009-04-17

It is pointed out that the higher volumetric
capacity/high working pressures of CO2 enable the use of
small-dimension lines toward the evaporation stages 23 and
25, and back to the compression stage 20.
It is commonly known to reclaim heat from
refrigerant downstream of the compression stage 20, as the
heat is otherwise lost in the condensation stage. In the
embodiment of Fig. 1, the CO2 refrigeration circuit 12 has a
heat reclaim coil 26, in heat exchange relation with the
ventilation circuit 14. The heat reclaim stage 26 is a
dehumidifier coil that is for instance positioned in a
ventilation duct to dehumidify air-conditioning air. The
dehumidifier coil may alternatively or concurrently be a
heating coil in a ventilation duct to heat the ventilation
air. It is pointed out that the CO2 directed to the heat
reclaim stage 26 is in a transcritical state. The heat
reclaim 26 can be used for other purposes, for instance to
heat water. It is considered to interrelate all heat
reclaim coils 26 (e.g., for various units 10, 10' or the
like) with one circuit in which another refrigerant
circulates, to accumulate heat from the heat reclaim
coils 26.
Still referring to Fig. 1, a valve is provided on
the line connecting the heat reclaim stage 26 to the
condensation stage 21. The valve is a modulating or
floating valve, or any other suitable type of valve, that
controls the condensation pressure in the heat reclaim stage
26. The condensation pressure is increased or lowered as a
function of the exterior/interior temperature, as an
example. Other configurations are considered to control the
pressure in the heat reclaim stage 26.
In Fig. 7, a CO2 refrigeration unit similar to the
CO2 refrigeration unit 10 of Fig. 1 is illustrated with
high-temperature evaporation, for instance for refrigerated
cabinets for fruits and vegetables. The circuit features an
expansion stage 28 and the evaporators 29, and a dedicated
compressor at the suction of the evaporators 29. An inlet
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CA 02662986 2009-04-17

regulating valve 20B' is optionally provided in the
discharge line of the dedicated compressor 20B to maintain
suitable operating pressures for the dedicated compressor
20B. Alternative features and configurations (e.g.,
defrost) are available for the CO2 refrigeration unit for
Fig. 7, but are not illustrated for simplicity purposes.
Still referring to Fig. 1, the high-pressure condensing
circuit 13 is a closed circuit cascaded with the CO2
refrigeration circuit 12. A chemical refrigerant (i.e.,
io synthetic refrigerant, glycol or the like) circulates in the
high-pressure condensing circuit 13. In the embodiment of
Fig. 1, the high-pressure condensing circuit 13 is at least
partially enclosed in the casing of the CO2 refrigeration
unit 10.
The condensing circuit 13 has a compression stage
30, in which at least one compressor produces high-pressure
gas refrigerant. The compressors of the compression stage
30 are conventional compressors, variable-speed ammonia
compressors or oil-free magnetic-bearing compressors, such
as Danfoss-Turbocor compressors. The gas refrigerant is
directed from the compression stage 30 to the condensation
stage 31, in which the refrigerant releases heat. It is
contemplated to provide the condensation stage 31 with a
condenser coil and fans that will expel heat to the
environment. The condenser coil and fans may be existing
units from a retrofitted system.
The refrigerant is then directed to an expansion
stage 32, wherein the refrigerant is vaporized to
subsequently reach the heat-exchange evaporation stage 33.
In the heat-exchange evaporation stage 33, the refrigerant
absorbs heat from the gaseous CO2 in the condensation stage
21 of the CO2 refrigeration circuit 12. The refrigerant is
then directed to the compression stage 30 to complete the
refrigeration cycle.
In the embodiment of Fig. 1, the high-pressure
condensing circuit 13 is fully enclosed in the casing of the
CO2 refrigeration unit 10. Accordingly, the volume of
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CA 02662986 2009-04-17

refrigerant required to operate the condensing circuit 13 is
reduced when compared to a similar rooftop refrigeration
unit having lines extending to the refrigerated cabinets and
enclosures within a building. Instead, CO2 is used as high-
volume refrigerant, and CO2 is considered less harmful to
the environment.
Referring to Fig. 1, the ventilation circuit 14 is
a closed circuit in which circulates a chemical refrigerant.
In the embodiment of Fig. 1, the ventilation circuit 14 is
fully enclosed in the casing of the CO2 refrigeration unit
10, with a ventilation duct circulating air in the CO2
refrigeration unit 10. Alternatively, some parts of the
ventilation circuit 14 may extend into the building, such as
evaporation coils, the compression stage 40 and the
condensation stage 41.
The ventilation circuit 14 has a compression stage
40, in which at least one compressor compresses the
refrigerant to a gas state. The gas refrigerant is directed
from the compression stage 40 to the condensation stage 41,
in which the refrigerant releases heat. It is contemplated
to provide the condensation stage 41 with a condenser coil
and fans that will expel heat to the environment. It is
pointed out that the condensation stage 41 may simply be a
gas-cooling stage as the refrigerant does not necessarily
change phase, for instance if CO2 refrigerant is used. To
simplify the illustrations, stage 41 is referred to as
condensation stage.
The refrigerant is then directed to an expansion
stage 42, wherein the refrigerant is vaporized to
subsequently reach the evaporation stage 43. In the
evaporation stage 43, the refrigerant absorbs heat
ventilation air, so as to produce air-conditioned air. The
refrigerant is then directed to the compression stage 40 to
complete the refrigeration cycle.
The ventilation circuit 14 is optional in the CO2
refrigeration unit 10, as some buildings may not need air-
conditioning, or might already have independent air-
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CA 02662986 2009-04-17

conditioning units. The ventilation circuit 14 may be in
its own casing, and shared amongst a plurality of
ventilation ducts.
Referring to Fig. 2, a CO2 refrigeration unit is
illustrated at 10'. The CO2 refrigeration unit 10' is
similar to the CO2 refrigeration unit 10 of Fig. 1, but
features refrigerant defrost by way of a defrost circuit.
Accordingly, like elements between the CO2 refrigeration
units 10 and 10' will bear like reference numerals.
io The defrost circuit of the CO2 refrigeration unit
10' has refrigerant lines A extending from the compression
stage 20 to the evaporation stages 23 and 25, to feed hot
gaseous CO2 refrigerant to the evaporation stages 23 and/or
25. Although not illustrated, suitable valves, pressure
i5 controls and/or regulators are provided in the lines A and
in the evaporation stages 23 and 25 to temporarily stop the
flow of cooling refrigerant to the evaporators, so as to
proceed with the defrost of evaporators from the stages 23
and 25. For instance, the defrost refrigerant may be fed to
20 the low-temperature evaporation stage 25 upstream of the
expansion stage 24, so as not to have a defrost line
extending from the compression stage 20 to the refrigerated
cabinet. Suitable valves are thus required to feed defrost
refrigerant to the low-temperature evaporation stage 25,
25 including for instance a by-pass solenoid valve and line to
by-pass the expansion stage 24. It is preferred that any
CO2 refrigerant in a liquid state from the refrigeration
circuit be flushed out of the evaporators 23 and/or 25 prior
to a defrost cycle. This is performed by exposing the
30 evaporators 23 and/or 25 (where applicable) to the suction
of the compression stage 20 while cutting the feed of CO2
refrigerant from the condensation stage 21. The flush
allows the defrosting of the evaporators 23 and/or 25 more
efficiently, and in less time.
35 At the outlet of a defrost evaporator from the
stages 23 and 25, the defrost CO2 is directed to any other
stage of the CO2 refrigeration circuit 12 that can receive
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CA 02662986 2009-04-17

the CO2 in the state it is in. In the embodiment of Fig. 2,
the defrost CO2 is directed to the compression stage 20. It
is considered to provide a dedicated compressor 20B that
will be dedicated to receiving defrost C02, and feeding
defrost CO2 to the defrost circuit, as illustrated by line
A. Line B is provided at the evaporation stages 23 and 25
to direct defrost CO2 to the dedicated compressor 20B, or to
mix with condensed CO2 in the tank 50 of the condensation
stage 20, or downstream of the condensation stage 20, with a
valve B' facilitating this latter option. The other
compressors 20A receive the CO2 circulating in the
refrigeration cycle, from the low-temperature evaporation
stage 25. Other configurations are also considered.
An inlet regulating valve 20A' is optionally
provided in the discharge of the compressors 20A so as to
ensure that the pressure in the discharge line is suitable
for the compressors 20A. The valve 20A' may also be used to
direct some refrigerant of the compressors 20A to the
defrost line A, as illustrated in Fig. 2.
It is also observed that the pressuring means 22
are within the casing of the CO2 refrigeration unit 10', and
are therefore part of the roof-top unit. However, the
pressuring means 22 may also be positioned adjacent to the
medium-temperature evaporators 23 within the building, as is
illustrated in Fig. 1.
Referring to Fig. 3, a plurality of CO2
refrigeration units are illustrated at 10". The CO2
refrigeration units 10" are similar to the CO2 refrigeration
unit 10 of Fig. 1, but without the high-pressure condensing
circuit 13 within the casing of the refrigeration unit.
Accordingly, like elements between the CO2 refrigeration
units 10 and 10" will bear like reference numerals.
In the embodiment of Fig. 3, the CO2 refrigeration
units 10" share the high-pressure condensing circuit 13. As
in some instances the condensing load of the CO2 refrigerant
is relatively low, it is considered to share amongst at
least two refrigeration units a high-pressure condensing
- 14 -


CA 02662986 2009-04-17

circuit 13. Accordingly, by sharing the high-pressure
condensing circuit 13, the C02 refrigeration units 10"
represent a cost-efficient solution. All refrigeration
units 10" are in a heat-exchange relation with the heat-
exchange evaporation stage 33 of the high-pressure
condensing circuit 13. Although three C02 refrigeration
units 10" are illustrated in the embodiment of Fig. 3, a
high-pressure condensing circuit 13 can be shared by two or
more of the C02 refrigeration units 10". Moreover, the
high-pressure condensing circuit 13 may be in its own
rooftop casing, or may be in one of the C02 refrigeration
units 10" that are part of the network of C02 refrigeration
units 10" sharing the high-pressure condensing circuit 13.
Referring to Fig. 4, a C02 condensation tank is
shown at 50. The tank 50 is a pressure vessel receiving
gaseous C02 from the compression stage 20 and possibly from
the heat reclaim stage 26. The gaseous C02 is then directed
to the heat-exchange evaporation stage 33 of the circuit 13,
in which heat from the gaseous C02 is absorbed by the
refrigerant circulating in the circuit 13. By the heat
exchange, the gaseous C02 is at least partially liquefied
and returns to the tank 50 through line D. Accordingly,
liquid C02 51 accumulates in the tank 50, and by gravity
accumulates in the bottom of the tank 50, as is illustrated
in Fig. 4. Liquid C02 51 supplied from the bottom of the
tank 51 is then directed to the evaporation stages 23 and
25. Gaseous C02 from the tank 50 may also be directed to a
suction of a C02 dedicated compressor, by having a pressure-
reduction valve 52 or like means between the tank 50 and the
dedicated compressor.
In Fig. 4, a schematic view of the tank 50 is
provided. Although not shown, it is however pointed out
that all suitable valves, pressure controls and/or
regulators are provided in order to ensure the heat exchange
between the gaseous C02 and the refrigerant from the high-
pressure refrigeration circuit 13 in the heat-exchange
evaporation stage 33.

15 -


CA 02662986 2009-04-17

In order to reduce material costs, it is
considered to have the condensation stages 31 and 41 share
condenser components in the casing of the refrigeration unit
10, as is illustrated in Fig. 5. For instance, fans, water
cooling systems and the like are preferably shared by the
coils of the condensation stages 31 and 41.
Referring to Fig. 8, there is illustrated another
embodiment of a CO2 refrigeration unit at 80 similar to the
CO2 refrigeration units 10, 10' and 10". Accordingly, like
elements will bear like reference numerals. The CO2
refrigeration unit 80 has a medium-temperature compression
stage 81, the suction of which collects refrigerant from the
medium-temperature evaporation stage 23. The CO2
refrigerant is in a suitable gas/liquid state, having been
expanded via an expansion stage 82 prior to reaching the
medium-temperature evaporation stage 23, with suitable means
(e.g., accumulators, heat exchangers) that may prevent
liquid refrigerant from reaching the compression stage 81,
and that lower the pressure of refrigerant fed to the
compression stage 20/81.
The discharge of the low-temperature compression
stage 20 and of the medium-temperature compression stage 81
is then directed to the condensation stage 21, optionally
via the heat reclaim stage 26, as described above for the
C02 refrigeration units 10, 10' and 10". Alternatively, the
discharge of the compression stages 20 and/or 81 may be fed
directly to the heat-exchange evaporation stage 33 via line
83 prior to reaching the condensation reservoir 21 in a
liquid state. This configuration may also be used for the
CO2 refrigeration units 10, 10' and 10". Although not
shown, the CO2 refrigeration unit 80 may be equipped with a
defrost circuit, as set for above for the CO2 refrigeration
units 10, 10' and 10".
Referring to Fig. 9, there is illustrated another
embodiment of a CO2 refrigeration unit at 90 similar to the
CO2 refrigeration units 10, 10', 10" and 80. Accordingly,
like elements will bear like reference numerals. The CO2
- 16 -


CA 02662986 2009-04-17

refrigeration unit 90 has a defrost reservoir 91, positioned
between the suction of the dedicated compression stage 20B
and the low-temperature evaporation stage 25. The suction
of the dedicated compression stage 20B is typically on top
of the defrost reservoir 91, such that CO2 refrigerant in a
gas state is collected thereby.
In order to periodically flush the liquid contents
of the defrost reservoir 91, a line 92 extends from the
discharge of the compression stages 20A and 20B, with
appropriate valves (not shown). The line 92 is selectively
opened to direct the discharge into the defrost reservoir
91, and flush the liquid CO2 refrigerant into the
condensation reservoir 21 via line 93 (also provided with
appropriate valves).
It is observed that pressure-reducing valve 94 may
be connected to a discharge line of the compression stages
20A and/or 20B, so as to ensure that the defrost refrigerant
is fed to the evaporators of the evaporation stages 23/25 at
a higher pressure than in the condensation reservoir 21.
This is to ensure a flow of defrost refrigerant back into
the refrigeration circuit after defrost.
In Fig. 9, both the pressuring means 22 and the
expansion stage 24 are in the casing of the CO2
refrigeration unit 90. This configuration is therefore well
suited for retro-fitting existing evaporators to the
refrigeration unit 90, as lines are drawn from the casing to
the evaporators. The various configurations of the CO2
refrigeration unit 90 may be used for the CO2 refrigeration
units 10, 10', 10" and/or 80.
The CO2 refrigeration units 10, 10', 10", 80 and
90 are equipped with a processing unit that ensures the
proper operation of the refrigeration cycles.
According to one embodiment, the processing unit
controls the operation of the electrically powered
components of the refrigeration units 10, 10' , 10", 80 and
90. The processing unit will be programmed with procedures
to operate the CO2 refrigeration units 10, 10', 10", 80 and
- 17 -


CA 02662986 2009-04-17

90 in a cost-effective fashion, while optimizing energy
consumption.
In an embodiment, all fans of the evaporators of
the evaporation stages 23 and 25 are controlled by the
processor unit of the CO2 refrigeration units 10, 10', 10",
80 and 90. According to this feature, fans are
automatically turned off when an evaporator of the stages 23
and/or 25 goes into a defrost cycle, as commanded by the
processor unit which also controls the operation of defrost
cycles. Accordingly, all defrost commands are centralized
through the processor unit.
The processor unit is also programmed to restart
the components of the CO2 refrigeration units 10, 10' and
10" in case of a power outage. According to one sequence of
command, the fans of the evaporator stages 23 and 25 in a
refrigeration cycle are turned on gradually to avoid a high
load on the CO2 refrigeration circuit 12, so as to maintain
the pressure of CO2 below the relief threshold. Moreover,
the pressure of CO2 is monitored throughout the
refrigeration circuit 12 to avoid having the CO2 pressure go
above the relief threshold. In an example, if the CO2
pressure in the tank 50 is too high, the processing unit may
stop some of the fans in the evaporation stages 23 and 25 to
reduce the load, and avoid the relief of CO2. The operator
of the system is warned by an alarm of the high pressure.
In case of an extended power outage, the processor unit of
the CO2 refrigeration units 10" of Fig. 3 may be operated in
a preservation mode from the limited power supply of a power
generator. In such a case, it is considered to operate the
refrigeration units 10" one after the other, each for a
given amount of time, so as to optimize the use of the
limited power supply of the power generator. In these
cases, it is considered to operate the oil-free magnetic-
bearing compressors of the compression stages 20 and 30, and
potentially of the compression stage 40, and to operate the
compressors at the minimum.

- 18 -


CA 02662986 2009-04-17

In order to minimize energy consumption, it is
considered to have variable compressors of the CO2
refrigeration units 10, 10', 10", 80 and 90 for some or all
compression stages, namely stages 20, 30 and 40. Also, the
CO2 refrigeration circuit 12 is typically provided with
pressure relief valves to exhaust CO2 above a given pressure
threshold. In the event of a power outage, the restart of
the compression stage 20 may cause the CO2 pressure to be
above the relief threshold, whereby it is preferred to use
variable compressors in the compression stage 20 to
gradually build the pressure in the circuit 12 so as to
avoid the relief of CO2. The temperature of the CO2 is
controlled by the variation of the speed of the compressors
from the compression stage 20. Moreover, the compressors of
the stages 20, 30 and/or 40 preferably operate in floating
control so as to produce a floating head pressure, and
minimize energy consumption.
Although the CO2 refrigeration units of Figs. 1 to
3 show at least two of the CO2 refrigeration circuit 12, the
high-pressure condensing circuit 13 cascaded with the CO2
refrigeration circuit 12, and the ventilation circuit 14 in
the same roof-top casing, it is considered to have the three
circuits 12, 13 and 14 each in its own casing.
The CO2 refrigeration units 10, 10', 10", 80 and
90 described previously are used in different climates, but
are particularly well suited for warmer climates, in that
the CO2 defrost circuit can be operated at relatively low
pressures. More specifically, the pressure of the CO2
defrost refrigerant is typically below 700 Psi, but
preferably ranges between 300 and 425 Psi. These low
pressures result from the low pressures in the refrigeration
circuit, and more particularly in the condensation stage 21.
The CO2 refrigerant is kept at a low pressure by the heat-
exchange relation with the secondary refrigerant in the
high-pressure condensing circuit 13.
Referring to Fig. 6, an alternative embodiment of
the high-pressure condensing circuit is illustrated at 13'.
- 19 -


CA 02662986 2009-04-17

The primary function of the high-pressure condensing circuit
13' is to cool the CO2 refrigerant of the CO2 refrigeration
circuit 12.
In one embodiment, the compressors of the
compression stage 30 are oil-free magnetic-bearing
compressors, which operate under specific conditions. In
such a case, it is required to maintain the pressure of the
refrigerant above given thresholds. Accordingly, an
optional loop featuring a heat exchanger 60 is provided in
the circuit 13' to increase the pressure at the compression
stage 30. The loop has a valve 61 that directs hot
refrigerant from the discharge of the compression stage 30
to the heat exchanger 60 via lines 62. In the heat
exchanger 60, the hot refrigerant is in heat-exchange with
cold refrigerant exiting the condensation stage 31. The
cold refrigerant exiting the condensation stage 31 is
directed to the heat exchanger 60 via line 63 to absorb heat
from the hot refrigerant, and then reaches the suction line
of the compression stage 30, thereby mixing with refrigerant
exiting from the evaporation stage 33, to increase the
pressure in the suction line. As illustrated in Fig. 6, by
way of example, a valve 63' such as an expansion valve is
provided to adjust the pressure prior to the heat exchanger
60. The valve 631 represents one of numerous other
possibilities for controlling the pressure in the heat
exchanger 60. The hot refrigerant exiting the heat
exchanger 60 is then returned upstream of the condensation
stage 31, via line 62.
It is also considered to provide heat reclaim 64.
In an example, heat reclaim 64 is a heat exchanger by which
a refrigerant such as glycol absorbs heat from the
refrigerant of the condensing circuit 13'. A glycol circuit
may then circulate hot glycol through the facilities, for
instance for an auxiliary heating system.
Referring to Fig. 10, there is provided an
additional pressure-maintaining line 100 extending from the
discharge of the compression stage 30 to the suction of the
- 20 -


CA 02662986 2009-04-17

compression stage 30. A control valve 101 is provided in
the line 100 for appropriate control of the flow of
refrigerant. The pressure-maintaining line 100 ensures that
a suitable pressure is maintained at the suction of the
compression stage 30. As some types of compressors (e.g.,
oil-free magnetic compressors) stop operating below a given
pressure, the pressure-maintaining line 100 keeps the
compression stage 30 in operation.
Referring to Fig. 11, an expansion arrangement is
generally shown 110, and is particularly well suited for any
of the CO2 refrigeration units 10, 10', 10", 80 and 90, with
suitable modifications. As illustrated in the CO2
refrigeration unit 90 of Fig. 9, the expansion stage 24 is
in the casing of the units 10, 10' , 10", 80 or 90. In the
expansion arrangement 110, at least one of the expansion
valves 24 is shared by different evaporators 25. More
specifically, a line 111 extends from the expansion valve 24
to a plurality of the evaporators 25, with a balancing valve
112 being provided upstream of each evaporator 25, to ensure
that the evaporators 25 are fed with CO2 refrigerant at
similar conditions. In the event that defrost refrigerant
is subsequently fed to any one of the evaporators 25, a
bypass line with, for instance, a check valve 113 is
provided upstream of the evaporators 25. It is pointed out
that the expansion valve 24 may be out of the casing, and in
proximity to the evaporators 25.

- 21 -

A single figure which represents the drawing illustrating the invention.

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Admin Status

Title Date
Forecasted Issue Date 2012-02-07
(22) Filed 2009-04-17
(41) Open to Public Inspection 2009-10-18
Examination Requested 2011-02-25
(45) Issued 2012-02-07

Abandonment History

There is no abandonment history.

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Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $400.00 2009-04-17
Advance an application for a patent out of its routine order $500.00 2011-02-25
Request for Examination $800.00 2011-02-25
Maintenance Fee - Application - New Act 2 2011-04-18 $100.00 2011-04-15
Final Fee $300.00 2011-11-17
Maintenance Fee - Patent - New Act 3 2012-04-17 $100.00 2012-01-25
Maintenance Fee - Patent - New Act 4 2013-04-17 $100.00 2013-04-17
Maintenance Fee - Patent - New Act 5 2014-04-17 $200.00 2014-01-27
Maintenance Fee - Patent - New Act 6 2015-04-17 $200.00 2015-04-17
Maintenance Fee - Patent - New Act 7 2016-04-18 $200.00 2016-03-31
Maintenance Fee - Patent - New Act 8 2017-04-18 $200.00 2017-04-03
Maintenance Fee - Patent - New Act 9 2018-04-17 $200.00 2018-02-08
Maintenance Fee - Patent - New Act 10 2019-04-17 $250.00 2019-04-16
Maintenance Fee - Patent - New Act 11 2020-04-17 $250.00 2020-01-24
Maintenance Fee - Patent - New Act 12 2021-04-19 $255.00 2021-03-04
Current owners on record shown in alphabetical order.
Current Owners on Record
DUBE, SERGE
Past owners on record shown in alphabetical order.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.

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Description
Date
(yyyy-mm-dd)
Number of pages Size of Image (KB)
Representative Drawing 2009-09-23 1 12
Abstract 2009-04-17 1 35
Description 2009-04-17 21 1,054
Claims 2009-04-17 6 266
Drawings 2009-04-17 11 269
Cover Page 2009-10-15 2 53
Description 2011-08-16 21 1,047
Cover Page 2012-01-17 2 53
Prosecution-Amendment 2011-03-11 1 11
Correspondence 2009-06-01 3 95
Assignment 2009-04-17 6 191
Correspondence 2010-09-02 1 13
Prosecution-Amendment 2011-08-16 4 165
Prosecution-Amendment 2011-02-25 4 145
Prosecution-Amendment 2011-05-16 2 61
Correspondence 2011-11-17 2 66