Title:
Air conditioning system, interior heat exchanger coil unit and method for conditioning ambient air
Kind Code:
A1


Abstract:
An air conditioning system for conditioning ambient air of an environment, an interior heat exchanger coil used in such air conditioning system, and a method for conditioning ambient air of the environment. The air conditioning system has first and second reverse cycle refrigeration apparatuses each including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil, and an exterior portion located outside of the environment. The heat exchanger coil of the second reverse cycle refrigeration apparatus is distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus and extends substantially along at least a portion of a given path along which the latter extends. The system also has a group of fins extending between both heat exchanger coils along the portion of the given path for allowing a heat exchange between both heat exchanger coils.



Inventors:
Alexandre, Alex (Beauport, CA)
Application Number:
10/339360
Publication Date:
07/15/2004
Filing Date:
01/09/2003
Assignee:
ALEXANDRE ALEX
Primary Class:
Other Classes:
62/278
International Classes:
F25B13/00; F25B47/02; (IPC1-7): F25B47/00; F25B13/00
View Patent Images:



Primary Examiner:
ZEC, FILIP
Attorney, Agent or Firm:
Fogg and Associates, LLC (P.O. Box 581339, Minneapolis, MN, 55458-1339, US)
Claims:
1. An interior heat exchanger coil unit comprising: a first heat exchanger coil extending along a given path; a second heat exchanger coil distinct from the first heat exchanger coil and extending substantially along at least a portion of said given path; and a group of fins extending between both heat exchanger coils along said at least a portion of said given path for allowing a heat exchange between the heat exchanger coils.

2. An air conditioning system for conditioning ambient air of an environment, the air conditioning system comprising: a first reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil extending along a given path, and an exterior portion located outside of the environment; a second reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus and extending substantially along at least a portion of said given path, and an exterior portion located outside of the environment; and a group of fins extending between both heat exchanger coils along said at least a portion of said given path for allowing a heat exchange between both heat exchanger coils.

3. An air conditioning system according to claim 2, wherein each of the reverse cycle refrigeration apparatuses comprises: a compressor for compressing and driving a fluid through its circuit, and a controllable valve operatively connected to said compressor for controlling flow direction of the fluid through a part of its circuit, said part including the interior portion and a section of the exterior portion of its circuit.

4. An air conditioning system according to claim 3, wherein each of the reverse cycle refrigeration apparatuses comprise: a condenser integrated to said section of the exterior portion of its circuit, and first and second expansion valves respectively integrated to the interior portion and to said section of the exterior portion of its circuit.

5. An air conditioning system according to claim 4, wherein each of the reverse cycle refrigeration apparatuses comprise a drier integrated to said section of the exterior portion of its circuit.

6. An air conditioning system according to claim 2, wherein each of the heat exchanger coils comprises several coil sections mounted in parallel to one another.

7. An air conditioning system according to claim 3, wherein each of the heat exchanger coils comprises several coil sections mounted in parallel to one another.

8. An air conditioning system according to claim 4, wherein each of the heat exchanger coils comprises several coil sections mounted in parallel to one another.

9. An air conditioning system according to claim 5, wherein each of the heat exchanger coils comprises several coil sections mounted in parallel to one another.

10. A method for conditioning ambient air of an environment, the method comprising the steps of: a) conditioning the ambient air of the environment with a first reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil extending along a given path, and an exterior portion located outside of the environment; b) conditioning the ambient air of the environment with a second reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus and extending substantially along at least a portion of said given path, and an exterior portion located outside of the environment; and c) exchanging heat between both heat exchanger coils via a group of fins extending between both heat exchanger coils along said at least a portion of said given path.

11. A method according to claim 10, wherein step a) comprises the step of operating the first reverse cycle refrigeration apparatus in a heating mode; step b) comprises the step of operating the second reverse cycle refrigeration apparatus in a cooling mode; and in step c), the heat exchanger coil of the second reverse cycle refrigeration apparatus is heated by the heat exchanger coil of the first reverse cycle refrigeration apparatus via the group of fins.

12. A method according to claim 10, wherein step a) comprises the step of operating the first reverse cycle refrigeration apparatus in a cooling mode; step b) comprises the step of operating the second reverse cycle refrigeration apparatus in a heating mode; and in step c), the heat exchanger coil of the first reverse cycle refrigeration apparatus is heated by the heat exchanger coil of the second reverse cycle refrigeration apparatus via the group of fins.

13. A method according to claim 10, wherein step a) comprises the step of operating the first reverse cycle refrigeration apparatus in a heating mode.

14. A method according to claim 13, wherein step b) comprises the step of operating the second reverse cycle refrigeration apparatus in a heating mode.

15. A method according to claim 10, wherein step a) comprises the step of operating the first reverse cycle refrigeration apparatus in a cooling mode.

16. A method according to claim 15, wherein step b) comprises the step of operating the second reverse cycle refrigeration apparatus in a cooling mode.

17. A method according to claim 10, comprising the steps of: operating the first reverse cycle refrigeration apparatus in a heating mode in step a), and the second reverse cycle refrigeration apparatus in a cooling mode in step b) during a few minutes; and then operating the first reverse cycle refrigeration apparatus in a cooling mode in step a), and the second reverse cycle refrigeration apparatus in a heating mode in step b) during a few minutes.

Description:

FIELD OF THE INVENTION

[0001] The present invention is concerned with an air conditioning system for conditioning ambient air of an environment, an interior heat exchanger coil unit used in such air conditioning system, and a method for conditioning ambient air of the environment. More specifically, the invention relates to air conditioning systems which utilize reverse cycle refrigeration apparatuses to either heat or cool air inside a building. More specifically, the present invention is efficient for heat pumps.

BACKGROUND OF THE INVENTION

[0002] Air conditioning systems found in most public and residential buildings operate according to certain thermodynamic principles using the property of certain gases. These air conditioning systems are generally composed of a compressor, a heat exchanger having a heat exchanger coil located inside a building, and a heat exchanger located outside the building.

[0003] An air conditioning system comprises a closed circuit in which a refrigeration fluid flows. This fluid is converted from a gaseous state to a liquid state under the effect of pressures and temperatures present in the system, and vice versa. Under the effects of the pressures inside the system, the refrigeration fluid is pushed towards an evaporator. The evaporator, whose heat exchanger coil is generally found inside of the building for cooling, enables the refrigeration fluid to absorb ambient heat. This exchange is carried out by passing hot air from the room to be cooled on the heat exchanger coil of the evaporator. At this moment, the refrigeration fluid which is in a liquid state heats up under the effect of heat present in the ambient air and passes then from a liquid state to a gaseous state.

[0004] This passage from liquid state to gaseous state requires a significant amount of heat. This amount of heat is provided by the ambient air which is intended to be cooled. By heating the refrigeration fluid, the ambient air which passes on the heat exchanger coil of the evaporator thus cools itself and returns to the room after having been cooled in order to improve the comfort of the occupants.

[0005] The passage to a gaseous state enables the compressor to pump the fluid in order to push it towards the exchanger of a condenser which is generally located outside the building. The gas thus driven towards the exchanger of the condenser is cooled under the effect of the exterior temperature and returns to its liquid state in order to complete a refrigeration cycle.

[0006] Over the years, with increasing development of technology, certain companies have developed more sophisticated machines enabling to circulate the refrigeration fluid along two directions. The refrigeration fluid is either sent towards the exchanger of the evaporator if one wishes to cool, or towards the condenser if one wishes to heat. Hence, the flow direction of the refrigeration fluid is determined by the environment requirement. Devices known as heat pumps or “thermo pumps” operate according to this principle.

[0007] The working principle of thermo pumps enables to reduce considerably the cost of energy required for the heating, more particularly in the fall and spring seasons, as well as during certain days of the winter when the temperature is not excessively low.

[0008] Known in the art, there is the U.S. Pat. No. 4,565,070 of Glendon A. RAYMOND, granted on Jan. 21, 1986, in which there are described apparatus and method for providing a refrigeration circuit and for effecting defrost. Multiple outdoor heat exchangers are utilized to effect defrost of one of the outdoor heat exchanger while the other serves as an evaporator. In the refrigeration circuit, the indoor heat exchanger is not utilized during defrost and the outdoor heat exchangers are separated such that one is defrosted while the other serves as an evaporator. The circuit may then be reversed such that the non-defrosted outdoor heat exchanger is then defrosted while the other heat exchanger serves as an evaporator. This refrigeration circuit allows for effective defrost of the outdoor heat exchangers without necessitating electric resistance heat or the transfer of heat energy from the indoor air to the outdoor heat exchangers.

[0009] Also known in the art, there is the U.S. Pat. No. 5,709,100 of Daniel B. BAER et al., granted on Jan. 20, 1998, in which there is described a redundant, dual circuit air conditioning apparatus for communications enclosures which is wall mounted thereon. Internested evaporator coils of two discrete refrigeration circuits share common fin connections for efficiency and each includes a dual line input performing in conjunction with an expansion valve and a simple Y distribution fitting coupled to those lines which achieves requisite pressure drops a low cost. Compressor and condenser components are located within a condenser system housing in mutual isolation and perform in conjunction with discrete separate power inputs and controls such that servicing may take place safely.

[0010] Also known in the art, there is the U.S. Pat. No. 5,228,504 of Mario MANTEGAZZA et al. granted on Jul. 20, 1993, in which there is described a tube and fin heat exchanger having two adjacent fluid circuits through which compressed air and a refrigeration fluid flow so as to be in heat exchange relationship with respect to one another. In one embodiment, the areas between the tubes and fins of the heat exchanger are filled with a mass of moist material which ices and operates to accumulate energy to thereby transfer the energy when the refrigerant fluid is not circulated.

[0011] Also known in the art, there are the following U.S. patent which describe several air conditioning apparatuses and methods: U.S. Pat. Nos. 5,771,699; Re. 29,966; 4,914,926; 6,050,101; 6,109,339; 6,276,158 B1; 5,105,629; 3,815,672; 5,715,889; 5,649,428; 5,291,738; 4,128,410; and 5,964,284.

[0012] A drawback with all of the systems and methods described above is that neither means nor steps are described for easily and economically defrosting a heat exchanger coil while providing a machine or method that can be very efficient for heating or cooling an environment.

[0013] An object of the present invention is to overcome the above-mentioned drawbacks.

SUMMARY OF THE INVENTION

[0014] According to the present invention, there is provided an interior heat exchanger coil unit comprising a first heat exchanger coil extending along a given path; a second heat exchanger coil distinct from the first heat exchanger coil and extending substantially along at least a portion of said given path; and a group of fins extending between both heat exchanger coils along said at least a portion of said given path for allowing a heat exchange between the heat exchanger coils.

[0015] According to the present invention, there is also provided an air conditioning system for conditioning ambient air of an environment, the air conditioning system comprising a first reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil extending along a given path, and an exterior portion located outside of the environment; a second reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus and extending substantially along at least a portion of said given path, and an exterior portion located outside of the environment; and a group of fins extending between both heat exchanger coils along said at least a portion of said given path for allowing a heat exchange between both heat exchanger coils.

[0016] According to the present invention, there is also provided a method for conditioning ambient air of an environment, the method comprising the steps of: a) conditioning the ambient air of the environment with a first reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil extending along a given path, and an exterior portion located outside of the environment; b) conditioning the ambient air of the environment with a second reverse cycle refrigeration apparatus including a circuit having an interior portion located inside of the environment and being provided with a heat exchanger coil distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus and extending substantially along at least a portion of said given path, and an exterior portion located outside of the environment; and c) exchanging heat between both heat exchanger coils via a group of fins extending between both heat exchanger coils along said at least a portion of said given path.

[0017] Objects, advantages and other features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof given for the purpose of exemplification only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is schematic perspective view of two distinct heat exchanger coils shown as being separated from each other to better show each coil;

[0019] FIG. 2 is a schematic perspective view of the heat exchanger coils of FIG. 1 in operating position with a group of common fins;

[0020] FIG. 3 is a schematic front view of what is shown in FIG. 2;

[0021] FIG. 4 is a schematic perspective view showing an air conditioning system according to the present invention within its environment, with a heat furnace;

[0022] FIG. 5 is a circuit diagram of an air conditioning system according to the present invention, in a first operating position;

[0023] FIG. 6 is a circuit diagram of an air conditioning system according to the present invention, in a second operating position;

[0024] FIG. 7 is a circuit diagram of an air conditioning system according to the present invention, in a third operating position; and

[0025] FIG. 8 is a circuit diagram of an air condition system according to the present invention, in a fourth operating position.

DETAILED DESCRIPTION OF THE DRAWINGS

[0026] In the following description, the same numerical references refer to similar elements. The embodiments shown in the figures are preferred.

[0027] Moreover, although the present invention is particularly efficient with heat pumps, also commonly known as “thermo pumps”, it may be used with other Heating, Ventilating and Air Conditioning (HVAC) devices and in other fields, as apparent to a person skilled in the art. For this reason, expressions such as “heat”, “thermo”, “pump”, etc. used herein should not be taken as to limit the scope of the present invention and includes all other kinds of air conditioning devices or methods with which the present invention could be used and may be useful.

[0028] Moreover, in the context of the present invention, the expressions “system”, “device”, “unit”, and any other equivalent expression known in the art will be used interchangeably. Furthermore, the same applies for any other mutually equivalent expressions, such as “environment” and “air”, as well as “heat” and “energy” for example, as also apparent to a person skilled in the art.

[0029] Indeed, in the context of the present description, the expression “heat” is not to be taken in its commonly known sense, but rather refers to “any form of energy associated with the motion of atoms or molecules and capable of being transmitted through solid and fluid media by conduction, through fluid media by convection, and through empty space by radiation”, as is known by a person skilled in the art.

[0030] In addition, although the preferred embodiment of the present invention as illustrated in the accompanying drawings comprises various components and although the preferred embodiment of the present air conditioning system and corresponding coils as shown consists of certain geometrical configurations as explained and illustrated herein, not all of these components and geometries are essential to the invention and thus should not be taken in their restrictive sense, i.e. should not be taken as to limit the scope of the present invention. It is to be understood, as also apparent to a person skilled in the art, that other suitable components and cooperations thereinbetween, as well as other suitable geometrical configurations may be used for present air conditioning system and corresponding parts according to the present invention, as can be easily understood, without departing from the scope of the invention.

[0031] Referring now to FIGS. 1, 2 and 3, there is shown an interior heat exchanger coil unit which comprises heat exchanger coil 2 extending along a given path and heat exchanger coil 4 distinct from the first heat exchanger coil 2. Exchanger coil 4 extends substantially along at least a portion of the given path. In FIG. 1, the coils are shown as being separated to each other to better show each coil but, in operating position, the coils are positioned as shown in FIGS. 2 and 3. The interior heat exchanger coil unit also comprises a group of fins 6 extending between both heat exchanger coils 2 and 4 along the path portion for increasing heat exchange between the coils 2 and 4. Such configuration of the heat exchanger coils 2 and 4 with the fins 6 allows different operating modes which will be described in reference to FIGS. 5 to 8.

[0032] Each exchanger coil 2 or 4 is independent from the other in that the fluid circulating through one of the coil does not circulate in the other. However, both coils 2 and 4 are welded together by means of a series of parallel and spaced apart fins 6. The fins 6 and the proximity of the coils 2 and 4 allow heat conduction between them. Ambient air is driven between the fins 6 to contact the coils 2 and 4 which are symmetrically arranged in such a way that ambient air contacts equal portions of both coils 2 and 4. An advantage of using such coils 2 and 4 is that it substantially increases the efficiency of heating or cooling with only a small amount of supplemental energy. Another advantage of such coils 2 and 4 is that a defrosting operation of the coils is more efficient and more economical than the prior art.

[0033] For example, in a defrosting operation, the fluid circulation through the coil 2 is reversed while the other 4 keeps providing cooling of the ambient air. Both coils are defrosted but the defrosting may not be uniform along the entire length of the coils. Indeed, fluid circulating though the heating coil 2 losses its capacity to heat along the way. Therefore, fluid circulation of both coils is then reversed to defrost from the other end portions of the coils that might still be frosted.

[0034] When both coils 2 and 4 are defrosted, they can now be operated in a cooling mode. As it can be appreciated, a defrosting operation can be performed even if the system partially operates in a cooling mode. In conventional thermal pump using a single coil, the defrost mode is energy consuming and expensive.

[0035] Another advantage of using the configuration shown in FIGS. 1 to 3 is that such interior heat exchanger coil unit does not take much more room than a single coil used in conventional apparatuses. Another advantage of the interior heat exchanger coil unit shown in FIGS. 1 to 3 is that it provides a greater heating or cooling capacity than conventional systems because, for the same amount of air circulating through the fins 6, it can provide greater heating or cooling capacity, when compared with conventional systems.

[0036] Referring now to FIGS. 4 to 8, there is shown an air conditioning system for conditioning ambient air in an environment 8. The air conditioning system comprises a first reverse cycle refrigeration apparatus 14 including a circuit having an interior portion 18 located inside the environment 8 and provided with a heat exchanger coil extending along a given path, and an exterior portion 20 located outside of wall 10. The heat exchanger coil described above is shown with more details as part of the heat exchanger coil unit 5 shown in FIGS. 2 and 3.

[0037] The air conditioning system also comprises a second reverse cycle refrigeration apparatus 16 including a circuit having an interior portion 22 located inside the environment 8 and provided with a heat exchanger coil distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus 14 and extending substantially along at least a portion of said given path, and an interior portion 24 located outside of wall 10. The heat exchanger coil of the second reverse cycle refrigeration apparatus 16 is shown with more details as part of the heat exchanger coil unit 5 shown in FIGS. 2 and 3.

[0038] The air conditioning system also comprises a group of fins extending between both each exchanger coil along said at least portion of the given path for increasing a heat exchange between both heat exchanger coils. This group of fins 6 is shown more specifically in FIG. 2.

[0039] Preferably, each of the reverse cycle refrigeration apparatuses 14 and 16 comprise a compressor 30 for compressing and driving fluid through its circuit, and a controllable valve 32 operatively connected to the compressor 30 for controlling flow direction of the fluid through a part of its circuit. The part in question includes the interior portion 18 or 22, located inside the environment, and a section of the exterior portion, located outside the environment. A heat exchanger 34 is integrated to said section of the exterior portion. First and second expansion valves 35 and 36 are integrated to the interior portion and to said section of the exterior portion. A dryer 38 is preferably integrated to said section of the exterior portion. Each of the heat exchanger coils comprises several coil sections mounted in parallel to one another and integrated into several coils units 5, as it can be seen in the right portion of FIGS. 5 to 8.

[0040] Referring now to FIGS. 5 to 8, there are described different methods for conditioning ambient air of an environment. Generally, the method comprises the following steps: a) conditioning the ambient air of the environment 8 with the first reverse cycle refrigeration apparatus 14 including a circuit having an interior portion located inside the environment 8 and being provided with a heat exchanger coil extending along a given path, and an exterior portion located outside the environment 8; b) conditioning the ambient air of the environment with the second reverse cycle refrigeration apparatus 16 including a circuit having an interior portion located inside of the environment 8 and being provided with a heat exchanger coil distinct from the heat exchanger coil of the first reverse cycle refrigeration apparatus 14 and extending substantially along at least a portion of the given path and an exterior portion located outside of the environment 8; and c) exchanging heat between both each exchanger coil via a group of fins extending between along said at least a portion of said given path.

[0041] The inventor noticed that ambient air which is blown in a single coil such as with standard air conditioning units or thermo pumps, does not reach a sufficiently high temperature and, as a result, the air conserves additional capacity of exchange. Thus, the idea has originated in adding a second coil in order to recuperate the energy still present in the air. After having worked with two coils, the inventor had the idea to integrate two separate coils into a single unit with common fins. The inventor had also the idea to extend the second coil substantially along at least a portion of the path of the first coil.

[0042] The combination of two heat exchanger coils as shown in FIGS. 1 to 3 increases substantially the cooling or the heating, with only a small incremental amount of energy supplied to the system.

[0043] Furthermore, as conventional air conditioning machines require to be defrosted, a defrosting operation is generally carried out by means of electrical heating coils that are operated during periods going up to thirty minutes for conventional units. All of this energy that has to be supplied for defrosting can be very expensive because electricity rates usually penalize any excessive power demand. For conventional thermo pumps, the defrosting is carried out either by electrical coils or by inverting the gases within the thermo pump in order to make them produce heat in the coil until the frost disappears. It is easy to understand that the latter way of defrosting prevents the user from its normal operation mode during the defrosting operation.

[0044] In contrast, the coil unit as shown in FIGS. 1 to 3 enables to defrost the refrigeration circuits by inverting fluid flow in one coil while the other still operates in its cooling mode. This defrosting operation does not prevent the system to operate in a cooling mode, it simply reduces its cooling capacity slightly. This contributes equally to assure a greater comfort because the defrosting time is reduced to a few minutes. All of this defrosting process is carried out without additional electricity for electric heating elements. Once the defrosting by means of one of the apparatuses reaches a certain level, fluid direction in both coils are reversed to complete the defrosting operation. Another advantage of the present system is that the coil unit as shown in FIGS. 1 to 3 does not take that much more space than a single coil unit used in conventional machines. The coil unit according to the present invention offers the advantage of providing a cooling or heating capacity which is much more than conventional system especially in the heating mode, which is particularly useful during winter season.

[0045] Referring now to FIG. 5, there is shown a first example of the method according to the present invention. According to this example of the method, step a) comprises step of operating the first reverse cycle refrigeration apparatus 14 in a cooling mode. Step b) of the method comprises step of operating the second reverse cycle refrigeration apparatus 16 in a heating mode. In step c), the heat exchanger coil of the first reverse cycle refrigeration apparatus 14 is heated by the heat exchanger coil of the second reverse cycle refrigeration apparatus via the group of fins. Preferably, a defrosting operation can comprise the steps of operating the first reverse cycle refrigeration apparatus in a heating mode in step a), and the second reverse cycle refrigeration apparatus in a cooling mode in step b) during a few minutes; and then operating the first reverse cycle refrigeration apparatus in a cooling mode in step a), and the second reverse cycle refrigeration apparatus in a heating mode in step b) during a few minutes.

[0046] Referring now to FIG. 6, there is shown another example of the method according to the present invention. In this example, step a) comprises the step of operating the first reverse cycle refrigeration apparatus 14 in a heating mode. Step b) of the method comprises the step of operating the second reverse cycle refrigeration apparatus 16 in a cooling mode. In step c), the heat exchanger coil of the second reverse cycle refrigeration apparatus 16 is heated by the heat exchanger coil of the first reverse cycle refrigeration apparatus via the group of fins.

[0047] By still referring to FIG. 6, we will now describe with more details the defrosting of apparatus 16 by means of apparatus 14. The following description can be also applied to the defrosting of the apparatus 14 by reversing the operation mode of both apparatuses 14 and 16. The defrosting cycle is performed in a very economically manner because it does not require the use of electrical coils. During the cooling mode, the heat exchanger coils contain vapours which absorb heat of the ambient air. As there is water vapour in ambient air, frost may appear on the coils. The effect of having frost on the coils is that it reduces heat exchange between coils and ambient air. If there is too much frost, the heat exchange between coils and ambient air can be reduced to nil. Usually, safety means are provided for detecting when the air conditioning system has too much frost accumulated on the coils and needs to be defrosted.

[0048] When apparatus 16 has to be defrosted, apparatus 14 is set to operate into a heating mode to defrost the coils of the apparatus 16. Then, for a short period of time, apparatus 14 operates in heating mode while apparatus 16 continues to operate in cooling mode to continue its air conditioning of the ambient air. The unit shown in FIGS. 1 to 3 facilitates heat exchange between the heat exchanger coils of apparatuses 14 and 16. Enough heat exchange is provided from one coil to the other for the defrosting which is performed during a period of time that is much shorter than conventional systems. When the coil of apparatus 16 is substantially defrosted, the operation modes of both apparatuses 14 and 16 may be reversed to ensure complete defrosting of both coils so that they may subsequently be set to resume their proper operation. As can be appreciated, within minutes, both each exchanger coils are defrosted without substantially disturbing the cooling operation of the whole system. Such defrosting operation prevents high temperature changes in the ambient air, which is not the case with conventional systems. Furthermore, for a given flow of air through the fins, the heating or the cooling capacity can be substantially increased. The present invention can be applied to roof top unit, chiller and most of the existing refrigeration systems.

[0049] As the apparatuses 14 and 16 are independent, step a) of the method can comprise step of operating the first reverse cycle refrigeration apparatus in a heating mode, while the second apparatus can be operated in any mode. In a similar manner, step a) can comprise the step of operating the first reverse cycle refrigeration apparatus 14 in a cooling mode, while the second apparatus 16 can be operated in any mode.

[0050] Referring now to FIG. 7, there is shown an example of the method according to the present invention where in step a) comprises the step of operating the first reverse cycle refrigeration apparatus 14 in a cooling mode, and step b) comprises the step of operating the second reverse cycle refrigeration apparatus 16 also in a cooling mode. The refrigeration fluid which is in a liquid state exits from the exchanger 34 which operates as a condenser, towards the expansion valves 35 to be transformed into vapour under the effect of the valves. The vapour is sent under the effect of the pressure towards the expansion valves 36 to be distributed in the heat exchanger coil units 5. Within each unit 5, both each exchanger coils share the same fins and are heated by the same flow of ambient air. Liquid vapour is gradually transformed into hot gas directed towards the inversion valve 32 which will determine where the hot gas is sent, according to the setting of a thermostat. This inversion valve 32 is used as a circulation controller which decides of the fluid flow according to the thermostat setting. As the system operates in a cooling mode, the refrigeration fluid which is in a gaseous state will be sent towards the compressor 30. The compressor can only compress a fluid in a gaseous state. Any liquid supply to its input will probably damage it. The hot gas is compressed by the compressor 30 so that it can be treated by the exchanger 34. Under the effect of the exchanger 34, the fluid in a hot gaseous state becomes liquid by rejecting a major portion of its heat into the atmosphere. The liquid by-passes the expansion valve 35 and is sent to expansion valve 36.

[0051] Each of the expansion valves 35 and 36 is provided with a by-passing circuit with a directional valve to prevent fluid circulation in a wrong direction through the corresponding valve. The apparatuses 14 and 16 operate in a cooling operation mode during several cycles until the cooling needs are satisfied.

[0052] Referring now to FIG. 8, there is shown another example of the method according to the present invention, wherein step a) comprises the step of operating the first reverse cycle refrigeration apparatus 14 in a heating mode, and step b) comprises the step of operating the second reverse cycle refrigeration apparatus 16 also in its heating operation mode. The heat exchangers 34 operate now as evaporators. Thus, the heat exchangers 34 which are outside operate as evaporators, and the heat exchanger coils which are inside operate as condensers. Liquid passes through the expansion valve 35 and becomes vapour under the effect of the valve. This vapour is sent to the exchanger 34 to be transformed into hot gas. As the fluid is in hot gas state, it is sent towards the compressor 30 via the inversion valve 32 to be pressurized. The pressurized hot gas is sent, via inversion valve 32, towards the heat exchanger coils which now operate as condensers. Within the heat exchanger coils, the fluid in a hot gaseous state heats ambient air. The fins of the coil units 5 improve heat exchange with ambient air. The heat that is transferred to ambient air has the effect of cooling the fluid which turns gradually into liquid at the end of the heat exchanger coils. As the fluid is now in a liquid state, it does not go through the expansion valve 36 but it is rather by-passed by the derivation circuit of the valve. The fluid in a liquid state goes back to the heat exchanger 34, then goes through the expansion valve 35 where it is transformed into vapour. As it goes through the exchanger 34, the vapour becomes a hot gas which is ready to begin a new heating cycle as described above. It can be seen that the heat production costs are very low in that it is sufficient to circulate a liquid/gas fluid through the system and to operate external ventilators of heat exchanger 34 to produce heat.

[0053] Of course, numerous modifications could be made to the above-described embodiments without departing from the scope of the invention as defined in the appended claims.