Refrigerating apparatus

TECHNICAL FIELD

0001The present invention relates to a refrigeration apparatus in which a refrigeration cycle is performed.

BACKGROUND ART

0002Conventionally, a refrigeration apparatus in which a refrigeration cycle is performed has been broadly used for a cooler such as a refrigerator and a freezer for storing food etc., an air conditioner for cooling/heating a room, etc. The refrigeration apparatus of this type is disclosed in, e.g., Patent Document 1.

0003A refrigeration apparatus of Patent Document 1 is an air conditioner including an outdoor unit and two indoor units. In the air conditioner, the two indoor units are connected to the outdoor unit through a fluid-side communication pipe and a gas-side communication pipe. The two indoor units are connected together in parallel.

0004In addition, Patent Document 2 discloses refrigerant represented by Molecular Formula 1: C₃H_mF_n (note that "m" and "n" are integers equal to or greater than 1 and equal to or less than 5, and a relationship represented by an expression m + n = 6 is satisfied) and having a single double bond in a molecular structure (hereinafter referred to as "C₃H_mF_n refrigerant") as refrigerant for a refrigeration apparatus.

0005Further, Non-Patent Document 1 describes HFO-1234yf (2, 3, 3, 3-tetrafluoro-1-propene) which is one of the C₃H_mF_n refrigerants, as refrigerant having low global warming potential (GWP).

CITATION LIST

PATENT DOCUMENT

0006<ul id="ul0001" list-style="none" compact="compact"><li>PATENT DOCUMENT 1: Japanese Patent Publication No. <patcit id="pcit0001" dnum="JP2002147878A"><text>2002-147878</text></patcit></li><li>PATENT DOCUMENT 2: Japanese Patent Publication No. <patcit id="pcit0002" dnum="JP4110388A"><text>04-110388</text></patcit></li><li>NON-PATENT DOCUMENT 1: "DuPont and Honeywell present update at VDA Alternative Refrigerant Winter Meeting in Saalfelden, Austria," DuPont [online], [searched on March 4, 2008], Internet <URL:http://refrigerants.dupont.com/Suva/en_US/pdf/registered_pdf/MAC_VDA08_HFO_1234yf.p df></li></ul>

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

0007When using single component refrigerant of the C₃H_mF_n refrigerant for the refrigeration apparatus, various problems arise. For example, the C₃H_mF_n refrigerant is so-called "low-pressure refrigerant." Thus, when using the single component refrigerant of the C₃H_mF_n refrigerant, a theoretical operational efficiency (coefficient of performance) increases. However, in reality, an influence of a pressure loss of the refrigerant is relatively large, and an actual operational efficiency may be extremely degraded due to the pressure loss.

0008The present invention has been made in view of foregoing, and it is an object of the present invention to, in a refrigeration apparatus using refrigerant containing the C₃H_mF_n refrigerant, solve the problems arisen when using the single component refrigerant of the C₃H_mF_n refrigerant by using an appropriate composition ratio of refrigerant mixture to which HFC refrigerant is added, or by using refrigerant mixed with particular refrigerant other than the HFC refrigerant.

SOLUTION TO THE PROBLEM

0009A first aspect of the invention is intended for a refrigeration apparatus including a refrigerant circuit (10) in which a refrigeration cycle is performed by circulating refrigerant. The refrigerant circuit (10) of the refrigeration apparatus is filled with refrigerant mixture in which the proportion of C₃H_mF_n refrigerant is equal to or greater than 70% by mass and equal to or less than 94% by mass, and the proportion of HFC refrigerant is equal to or greater than 6% by mass and equal to or less than 30% by mass.

0010In the first aspect of the invention, the refrigerant mixture containing the C₃H_mF_n refrigerant and the HFC refrigerant is used. In the refrigerant mixture, the proportion of the C₃H_mF_n refrigerant is equal to or greater than 70% by mass and equal to or less than 94% by mass, and the proportion of the HFC refrigerant is equal to or greater than 6% by mass and equal to or less than 30% by mass.

0011A second aspect of the invention is intended for the refrigeration apparatus of the first aspect of the invention, in which HFC-32 (difluoromethane) is used as the HFC refrigerant in the refrigerant mixture.

0012In the second aspect of the invention, the HFC refrigerant used for the refrigerant mixture is the HFC-32.

0013A third aspect of the invention is intended for the refrigeration apparatus of the second aspect of the invention, in which only the HFC-32 is used as the HFC refrigerant in the refrigerant mixture, the proportion of the C₃H_mF_n refrigerant is equal to or greater than 77% by mass and equal to or less than 87% by mass, and the proportion of the HFC-32 is equal to or greater than 13% by mass and equal to or less than 23% by mass.

0014In the third aspect of the invention, the refrigerant mixture is used, in which the proportion of the C₃H_mF_n refrigerant is equal to or greater than 77% by mass and equal to or less than 87% by mass, and the proportion of the HFC-32 is equal to or greater than 13% by mass and equal to or less than 23% by mass.

0015A fourth aspect of the invention is intended for the refrigeration apparatus of the third aspect of the invention, in which, in the refrigerant mixture, the proportion of the C₃H_mF_n refrigerant is equal to or greater than 77% by mass and equal to or less than 79% by mass, and the proportion of the HFC-32 is equal to or greater than 21 % by mass and equal to or less than 23% by mass.

0016In the fourth aspect of the invention, the refrigerant mixture is used, in which the proportion of the C₃H_mF_n refrigerant is equal to or greater than 77% by mass and equal to or less than 79% by mass, and the proportion of the HFC-32 is equal to or greater than 21 % by mass and equal to or less than 23% by mass.

0017A fifth aspect of the invention is intended for the refrigeration apparatus of the first aspect of the invention, in which HFC-125 (pentafluoroethane) is used as the HFC refrigerant in the refrigerant mixture.

0018In the fifth aspect of the invention, the HFC refrigerant used for the refrigerant mixture is the HFC-125. The C₃H_mF_n refrigerant is low flammable refrigerant. Thus, in the fifth aspect of the invention, the HFC-125 which is non-flammable refrigerant is added to the C₃H_mF_n refrigerant.

0019A sixth aspect of the invention is intended for the refrigeration apparatus of the fifth aspect of the invention, in which, in the refrigerant mixture, the proportion of the HFC-125 is equal to or greater than 10% by mass and equal to or less than 30% by mass.

0020In the sixth aspect of the invention, the refrigerant mixture is used, in which the proportion of the HFC-125 is equal to or greater than 10% by mass. In the sixth aspect of the invention, the HFC-125 of equal to or greater than 10% by mass is added in order to reduce flammability of the refrigerant mixture.

0021A seventh aspect of the invention is intended for the refrigeration apparatus of the sixth aspect of the invention, in which, in the refrigerant mixture, the proportion of the HFC-125 is equal to or greater than 10% by mass and equal to or less than 20% by mass.

0022In the seventh aspect of the invention, the refrigerant mixture is used, in which the proportion of the HFC-125 is equal to or greater than 10% by mass and equal to or less than 20% by mass.

0023A eighth aspect of the invention is intended for a refrigeration apparatus including a refrigerant circuit (10) in which a refrigeration cycle is performed by circulating refrigerant. The refrigerant circuit (10) of the refrigeration apparatus is filled with refrigerant mixture containing C₃H_mF_n refrigerant and hydrocarbons.

0024In the eighth aspect of the invention, as the refrigerant of the refrigerant circuit (10), the refrigerant mixture made by adding hydrocarbons to the C₃H_mF_n refrigerant is used.

0025A ninth aspect of the invention is intended for a refrigeration apparatus including a refrigerant circuit (10) in which a refrigeration cycle is performed by circulating refrigerant. The refrigerant circuit (10) of the refrigeration apparatus is filled with refrigerant mixture containing C₃H_mF_n refrigerant and dimethyl ether.

0026In the ninth aspect of the invention, as the refrigerant of the refrigerant circuit (10), the refrigerant mixture made by adding dimethyl ether which is so-called "high-pressure refrigerant," to the C₃H_mF_n refrigerant is used.

0027A tenth aspect of the invention is intended for a refrigeration apparatus including a refrigerant circuit (10) in which a refrigeration cycle is performed by circulating refrigerant. The refrigerant circuit (10) of the refrigeration apparatus is filled with refrigerant mixture containing C₃H_mF_n refrigerant and bis-trifluoromethyl-sulfide.

0028In the tenth aspect of the invention, as the refrigerant of the refrigerant circuit (10), the refrigerant mixture made by adding bis-trifluoromethyl-sulfide which is so-called "high-pressure refrigerant," to the C₃H_mF_n refrigerant is used.

0029An eleventh aspect of the invention is intended for a refrigeration apparatus including a refrigerant circuit (10) in which a refrigeration cycle is performed by circulating refrigerant. The refrigerant circuit (10) of the refrigeration apparatus is filled with refrigerant mixture containing C₃H_mF_n refrigerant and helium.

0030In the eleventh aspect of the invention, as the refrigerant of the refrigerant circuit (10), the refrigerant mixture made by adding helium which is so-called "high-pressure refrigerant," to the C₃H_mF_n refrigerant is used.

0031A twelfth aspect of the invention is intended for the refrigeration apparatus of any one of the first to eleventh aspects of the invention, in which, in the refrigerant mixture, HFO-1234yf (2, 3, 3, 3-tetrafluoro-1-propene) is used as the C₃H_mF_n refrigerant.

0032In the twelfth aspect of the invention, the C₃H_mF_n refrigerant used for the refrigerant mixture is the HFO-1234yf.

0033A thirteenth aspect of the invention is intended for a refrigeration apparatus including a refrigerant circuit (10) in which a refrigeration cycle is performed by circulating refrigerant. The refrigerant circuit (10) of the refrigeration apparatus is filled with refrigerant mixture containing HFO-1234yf and carbon dioxide.

0034In the thirteenth aspect of the invention, as the refrigerant of the refrigerant circuit (10), the refrigerant mixture made by mixing carbon dioxide which is so-called "high-pressure refrigerant," to the HFO-1234yf is used.

0035A fourteenth aspect of the invention is intended for the refrigeration apparatus of any one of the first to thirteenth aspects of the invention, in which a heat exchanger (11, 15) for exchanging heat between air and refrigerant is connected to the refrigerant circuit (10), and the air exchanging heat with the refrigerant in the heat exchanger (11, 15) is supplied to a room.

0036In the fourteenth aspect of the invention, a refrigeration apparatus (20) supplies air exchanging heat with refrigerant in the heat exchanger (11, 15) connected to the refrigerant circuit (10), to the room. That is, the refrigeration apparatus (20) serves as an air conditioning system for adjusting a room temperature.

0037A fifteenth aspect of the invention is intended for the refrigeration apparatus of the fourteenth aspect of the invention, in which only a heating operation is performed, in which air heated by refrigerant in the heat exchanger (11, 15) is supplied to a room.

0038In the fifteenth aspect of the invention, the refrigeration apparatus (20) performs only the heating operation in which air heated in the heat exchanger (11, 15) is supplied to the room. That is, the refrigeration apparatus (20) serves as an air conditioning system only for heating.

0039A sixteenth aspect of the invention is intended for the refrigeration apparatus of the fourteenth or fifteenth aspect of the invention, in which, in the refrigerant circuit (10), an outdoor unit (22) provided outside a room is connected to indoor units (51) provided inside the room, through communication pipes (18, 19).

0040In the sixteenth aspect of the invention, the indoor units (51) are connected to the outdoor unit (22) through the communication pipes (18, 19). In the refrigeration apparatus (20), if the indoor units (51) are installed apart from the outdoor unit (22), the length of the communication pipes (18, 19) increases, resulting in an increase in a pressure loss of refrigerant during an operation.

0041A seventeenth aspect of the invention is intended for the refrigeration apparatus of any one of the first to thirteenth aspects of the invention, in which a heat exchanger (43) for exchanging heat between water and refrigerant is connected to the refrigerant circuit (10), and the water is heated by the refrigerant in the heat exchanger (43) to boil the water.

0042In the seventeenth aspect of the invention, the refrigeration apparatus (20) heats water by refrigerant in the heat exchanger (43). The refrigeration apparatus (20) supplies the water heated in the heat exchanger (43) (i.e., hot water) to a heat exchanger for air conditioning, a bathtub of a bath, etc.

ADVANTAGES OF THE INVENTION

0043In each of the first to seventh aspects of the invention, the refrigerant mixture in which the C₃H_mF_n refrigerant and the HFC refrigerant are mixed at a predetermined ratio is used. An influence of a pressure loss of refrigerant on an operation of the refrigeration apparatus (20) will be described below. For example, if the inlet pressure of the heat exchanger is 2000 kPa, and the pressure loss of refrigerant caused in the entire heat exchanger is 100 kPa, the outlet pressure is 1900 kPa, resulting in the ratio of the pressure loss to the inlet pressure is 5% (100/2000 = 0.05). If the inlet pressure of the heat exchanger is 1000 kPa, and the pressure loss of refrigerant caused in the entire heat exchanger is 100 kPa, the outlet pressure is 900 kPa, resulting in the ratio of the pressure loss to the inlet pressure is 10% (100/1000 = 0.10). if the inlet pressure of the heat exchanger is 500 kPa, and the pressure loss of refrigerant caused in the entire heat exchanger is 100 kPa, the outlet pressure is 400 kPa, resulting in the ratio of the pressure loss to the inlet pressure is 20% (100/500 = 0.20). As described above, the higher operating pressure of refrigerant results in the smaller influence of the pressure loss of refrigerant on the operation of the refrigeration apparatus (20). In the present invention, the C₃H_mF_n refrigerant and the HFC refrigerant are mixed at the predetermined ratio, thereby increasing, e.g., the operating pressure of refrigerant, and reducing the influence of the pressure loss of refrigerant on the operation of the refrigeration apparatus (20). Thus, e.g., an actual operational efficiency of the refrigeration apparatus (20) can be improved, thereby solving problems arisen when the single component refrigerant of the C₃H_mF_n refrigerant is used.

0044When using the HFC-32 as the HFC refrigerant as in the second aspect of the invention, the refrigerant mixture is preferably used, in which the proportion of the C₃H_mF_n refrigerant is equal to or greater than 77% by mass and equal to or less than 87% by mass, and the proportion of the HFC-32 is equal to or greater than 13% by mass and equal to or less than 23% by mass as in the third aspect of the invention. More preferably, the refrigerant mixture is used, in which the proportion of the C₃H_mF_n refrigerant is equal to or greater than 77% by mass and equal to or less than 79% by mass, and the proportion of the HFC-32 is equal to or greater than 21% by mass and equal to or less than 23% by mass as in the fourth aspect of the invention.

0045In the fifth aspect of the invention, the HFC-125 which is non-flammable refrigerant is added to the C₃H_mF_n refrigerant. Thus, the refrigerant of the refrigerant circuit (10) becomes flame-resistant, thereby improving reliability of the refrigeration apparatus (20).

0046In the eighth aspect of the invention, the refrigerant mixture made by adding hydrocarbons to the C₃H_mF_n refrigerant is used. Thus, if hydrocarbons are so-called "high-pressure refrigerant," the operating pressure of refrigerant can be higher than that when using the single component refrigerant of the C₃H_mF_n refrigerant. Consequently, while reducing the influence of the pressure loss of refrigerant on the operation of the refrigeration apparatus (20), the actual operational efficiency of the refrigeration apparatus (20) can be improved.

0047In each of the ninth to eleventh aspects of the invention, the refrigerant mixture made by adding particular refrigerant which is so-called "high-pressure refrigerant" (dimethyl ether, bis-trifluoromethyl-sulfide, or helium) to the C₃H_mF_n refrigerant is used. Thus, the operating pressure of refrigerant can be higher than that when using the single component refrigerant of the C₃H_mF_n refrigerant. Consequently, while reducing the influence of the pressure loss of refrigerant on the operation of the refrigeration apparatus (20), the actual operational efficiency of the refrigeration apparatus (20) can be improved.

0048In the thirteenth aspect of the invention, the refrigerant mixture made by adding carbon dioxide which is so-called "high-pressure refrigerant," to the HFO-1234yf is used. Thus, the operating pressure of refrigerant can be higher than that when using the single component refrigerant of the C₃H_mF_n refrigerant. Consequently, while reducing the influence of the pressure loss of refrigerant on the operation of the refrigeration apparatus (20), the actual operational efficiency of the refrigeration apparatus (20) can be improved.

0049In the sixteenth aspect of the invention, as the refrigerant of the refrigeration apparatus (20) which increases the pressure loss of refrigerant during the operation when the indoor units (51) are installed apart from the outdoor unit (22), the refrigerant mixture is used, in which the proportion of the C₃H_mF_n refrigerant is equal to or greater than 70% by mass and equal to or less than 94% by mass, and the proportion of the HFO refrigerant is equal to or greater than 6% by mass and equal to or less than 30% by mass. Thus, even if the indoor units (51) are installed apart from the outdoor unit (22), the pressure loss of refrigerant during the operation does not significantly increase, thereby not significantly degrading the actual operational efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

0050<ul id="ul0002" list-style="none" compact="compact"><li>[<figref idref="f0001">FIG. 1] FIG. 1</figref> is a schematic configuration diagram of a refrigeration apparatus of a first embodiment.</li><li>[<figref idref="f0002">FIG. 2] FIG. 2</figref> is a schematic configuration diagram of a refrigeration apparatus of a second embodiment.</li><li>[<figref idref="f0003">FIG. 3] FIG. 3</figref> is a schematic configuration diagram of a refrigeration apparatus of a variation of the second embodiment.</li></ul>

DESCRIPTION OF REFERENCE CHARACTERS

0051<dl id="dl0001" compact="compact"><dt>10</dt><dd>Refrigerant Circuit</dd><dt>20</dt><dd>Refrigeration Apparatus</dd><dt>22</dt><dd>Outdoor Unit</dd><dt>30</dt><dd>Compressor</dd><dt>51</dt><dd>Indoor Unit</dd></dl>

DESCRIPTION OF EMBODIMENTS

0052Embodiments of the present invention will be described in detail hereinafter with reference to the drawings.

<<First Embodiment>>

0053A first embodiment of the present invention will be described. The first embodiment is an air conditioning system (20) including a refrigeration apparatus of the present invention. As illustrated in <figref idref="f0001">FIG. 1</figref>, the air conditioning system (20) of the first embodiment includes an outdoor unit (22) and three indoor units (51 a, 51b, 51c). Note that the number of the indoor units (51) is set forth merely for purposes of examples, and not a plurality of indoor units but a single indoor unit may be provided.

0054The air conditioning system (20) includes a refrigerant circuit (10) filled with refrigerant to perform a refrigeration cycle. The refrigerant circuit (10) includes an outdoor circuit (9) accommodated in the outdoor unit (22); and an indoor circuit (17a, 17b, 17c) accommodated in each of the indoor units (51). The indoor circuits (17a, 17b, 17c) are connected to the outdoor circuit (9) in parallel with each other through a fluid-side communication pipe (18) and a gas-side communication pipe (19).

0055The refrigerant circuit (10) is filled with refrigerant mixture which contains a single type of C₃H_mF_n refrigerant (refrigerant represented by Molecular Formula 1: C₃H_mF_n (note that "m" and "n" are integers equal to or greater than 1 and equal to or less than 5, and a relationship represented by an expression m + n = 6 is satisfied) and having a single double bond in a molecular structure), and one or more types of HFC refrigerants; and in which the proportion of the C₃H_mF_n refrigerant is equal to or greater than 70% by mass and equal to or less than 94% by mass, and the proportion of the HFC refrigerant is equal to or greater than 6% by mass and equal to or less than 30% by mass. In the specification of the present application, the "HFC refrigerant" means hydrofluorocarbon refrigerant which does not contain the C₃H_mF_n refrigerant.

0056Specifically, the refrigerant mixture of the first embodiment contains 2, 3, 3, 3-tetrafluoro-1-propene (HFO-1234yf) which is the C₃H_mF_n refrigerant; and HFC-32 (difluoromethane) which is the HFC refrigerant. The refrigerant mixture contains a single type of HFC refrigerant. In the first embodiment, the refrigerant mixture is used, in which the proportion of the HFO-1234yf is 78.2% by mass, and the proportion of the HFC-32 is 21.8% by mass. In such a case, global warming potential is equal to or less than 150. Note that a chemical Formula of the HFO-1234yf is represented by an expression CF₃ - CF = CH₂, and a chemical formula of the HFC-32 is represented by an expression CH₂F₂.

<Configuration of Outdoor Circuit>

0057The outdoor circuit (9) includes a compressor (30); an outdoor heat exchanger (11); an outdoor expansion valve (12); and a four-way switching valve (13).

0058The compressor (30) is, e.g., a hermetic high-pressure dome scroll-type compressor. Electric power is supplied to the compressor (30) through an inverter. A discharge side of the compressor (30) is connected to a second port (P2) of the four-way switching valve (13), and a suction side is connected to a first port (P1) of the four-way switching valve (13).

0059The outdoor heat exchanger (11) is a cross-fin type fin-and-tube heat exchanger. An outdoor fan (14) is provided near the outdoor heat exchanger (11). In the outdoor heat exchanger (11), heat is exchanged between outdoor air and refrigerant. One end of the outdoor heat exchanger (11) is connected to a third port (P3) of the four-way switching valve (13), and the other end is connected to the outdoor expansion valve (12). A fourth port (P4) of the four-way switching valve (13) is connected to a gas-side end of the outdoor circuit (9).

0060The outdoor expansion valve (12) is provided between the outdoor heat exchanger (11) and a fluid-side end of the outdoor circuit (9). The outdoor expansion valve (12) is an electric expansion valve with variable opening.

0061The four-way switching valve (13) is switchable between a first state in which the first port (P1) communicates with the fourth port (P4), and the second port (P2) communicates with the third port (P3) (state indicated by a solid line in <figref idref="f0001">FIG. 1</figref>); and a second state in which the first port (P1) communicates with the third port (P3), and the second port (P2) communicates with the fourth port (P4) (state indicated by a dashed line in <figref idref="f0001">FIG. 1</figref>).

<Configuration of Indoor Circuit>

0062In each of the indoor circuits (17a, 17b, 17c), an indoor heat exchanger (15a, 15b, 15c) and an indoor expansion valve (16a, 16b, 16c) are provided in the order from a gas-side end toward a fluid-side end.

0063The indoor heat exchanger (15a-15c) is a cross-fin type fin-and-tube heat exchanger. An indoor fan (not shown in the figure) is provided near the indoor heat exchanger (15a-15c). In the indoor heat exchanger (15a-15c), heat is exchanged between room air and refrigerant. In addition, the indoor expansion valve (16a-16c) is an electric expansion valve with variable opening.

Operation

0064An operation of the air conditioning system (20) will be described. The air conditioning system (20) can perform a cooling operation and a heating operation, and switches between the cooling operation and the heating operation by the four-way switching valve (13).

<Cooling Operation>

0065In the cooling operation, the four-way switching valve (13) is set to the first state. In such a state, when operating the compressor (30), high-pressure refrigerant discharged from the compressor (30) is condensed by releasing heat to outdoor air in the outdoor heat exchanger (11). The refrigerant condensed in the outdoor heat exchanger (11) is distributed to each of the indoor circuits (17a-17c). The pressure of the refrigerant flowing into the indoor circuit (17a-17c) is reduced by the indoor expansion valve (16a-16c), and then such refrigerant is evaporated by absorbing heat from room air in the indoor heat exchanger (15a-15c). Meanwhile, room air is cooled and supplied to a room.

0066The refrigerant evaporated in the indoor circuit (17a-17c) joins the refrigerant evaporated in the other indoor circuit (17a-17c), and then is returned to the outdoor circuit (9). In the outdoor circuit (9), the refrigerant returned from the indoor circuits (17a-17c) is recompressed in the compressor (30), and then such refrigerant is discharged. During the cooling operation, the opening of the indoor expansion valve (16a-16c) is adjusted so that the degree of superheat of refrigerant at an outlet port of the indoor heat exchanger (15a-15c) is a constant value (e.g., 5°C).

<Heating Operation>

0067In the heating operation, the four-way switching valve (13) is set to the second state. In such a state, when operating the compressor (30), high-pressure refrigerant discharged from the compressor (30) is distributed to each of the indoor circuits (17a-17c). The refrigerant flowing into the indoor circuit (17a-17c) is condensed by releasing heat to room air in the indoor heat exchanger (15a-15c). Meanwhile, room air is heated and supplied to a room. The refrigerant condensed in the indoor heat exchanger (15a-15c) joins the refrigerant condensed in the other indoor heat exchanger (15a-15c), and then is returned to the outdoor circuit (9).

0068In the outdoor circuit (9), the pressure of the refrigerant returned from the indoor circuits (17a-17c) is reduced by the outdoor expansion valve (12), and then such refrigerant is evaporated by absorbing heat from outdoor air in the outdoor heat exchanger (11). The refrigerant evaporated in the outdoor heat exchanger (11) is recompressed in the compressor (30), and then such refrigerant is discharged. During the heating operation, the opening of the indoor expansion valve (16a-16c) is adjusted so that the degree of supercool of refrigerant at the outlet port of the indoor heat exchanger (15a-15c) is a constant value (e.g., 5°C).

Advantages of First Embodiment

0069In the present embodiment, the HFO-1234yf and the HFC-32 are mixed at a predetermined ratio, thereby increasing an operating pressure of refrigerant. This reduces an influence of a pressure loss of refrigerant during circulating in the refrigerant circuit (10) on the operation of the air conditioning system (20), thereby improving an actual operational efficiency of the air conditioning system (20). Thus, problems arisen when using the single component refrigerant of the C₃H_mF_n refrigerant can be solved.

0070In the refrigerant mixture, the proportion of the HFO-1234yf may be equal to or greater than 70% by mass and equal to or less than 94% by mass, and the proportion of the HFC-32 may be equal to or greater than 6% by mass and equal to or less than 30% by mass. Refrigerant mixture containing, e.g., the HFO-1234yf of 77.4% by mass and the HFC-32 of 22.6% by mass may be used. In the refrigerant mixture, the proportion of the HFO-1234yf may be preferably equal to or greater than 77% by mass and equal to or less than 87% by mass, and the proportion of the HFC-32 may be preferably equal to or greater than 13% by mass and equal to or less than 23% by mass. More preferably, the proportion of the HFO-1234yf may be equal to or greater than 77% by mass and equal to or less than 79% by mass, and the proportion of the HFC-32 may be equal to or greater than 21% by mass and equal to or less than 23% by mass. In this respect, the same is true for a second embodiment and other embodiments.

0071In the air conditioning system (20) of the present embodiment, the indoor circuits (17a-17c) of the indoor units (51a-51c) are connected to the outdoor circuit (9) of the outdoor unit (22) through the communication pipes (18, 19). The indoor units (51) of the air conditioning system (20) may be installed apart from the outdoor unit (22). In such a case, the pressure loss of refrigerant during circulating in the refrigerant circuit (10) increases. In the present embodiment, as refrigerant of the air conditioning system (20), which may cause the increase in the pressure loss of refrigerant during the operation, the refrigerant mixture is used, in which the proportion of the HFO-1234yf is 78.2% by mass, and the proportion of the HFC-32 is 21.8% by mass. Thus, even if the indoor units (51) are installed apart from the outdoor unit (22), the pressure loss of refrigerant during the operation does not significantly increase, thereby not significantly degrading the actual operational efficiency.

Variation of First Embodiment

0072A first variation of the first embodiment is an air conditioning system (20) only for heating. Unlike the first embodiment, in the air conditioning system (20), a four-way switching valve (13) is not provided in an outdoor circuit (9). A discharge side of a compressor (30) is connected to a gas side of each of indoor circuits (17a-17c). A suction side of the compressor (30) is connected to a gas side of an outdoor heat exchanger (11). In the air conditioning system (20), only a heating operation is performed, in which an indoor heat exchanger (15a-15c) is operated as a condenser, and the outdoor heat exchanger (11) is operated as an evaporator.

<<Second Embodiment>>

0073A second embodiment of the present invention will be described. The second embodiment is a hot-water supply system (20) including the refrigeration apparatus of the present invention.

0074As illustrated in <figref idref="f0002">FIG. 2</figref>, the hot-water supply system (20) of the present embodiment includes a hot-water storage unit (23) and a heat source unit (22). Both of the hot-water storage unit (23) and the outdoor unit (22) are installed outside a room, and are connected together through pipes to form a circulation path (21) which will be described later.

0075The hot-water storage unit (23) includes a hot-water storage tank (25) which is an elongated cylindrical hermetic container. A water supply port (26), a hot-water outlet port (27), a water discharge port (28), and a hot-water inlet port (29) are formed in the hot-water storage tank (25). The water supply port (26) and the water discharge port (28) are formed in a bottom section of the hot-water storage tank (25). The hot-water outlet port (27) is formed in a top section of the hot-water storage tank (25). The hot-water inlet port (29) is formed in an upper section of a side wall of the hot-water storage tank (25).

0076An outlet end of a water supply path (31) for supplying city water to the hot-water storage tank (25) is connected to the water supply port (26) of the hot-water storage tank (25). A plurality of branched water supply paths (32a, 32b) are connected to the water supply path (31). Each of the branched water supply paths (32a, 32b) is connected to a mixing valve (35a, 35b). On the other hand, an inlet end of a hot-water supply path (36) is connected to the hot-water outlet port (27) of the hot-water storage tank (25). A plurality of branched hot-water supply paths (37a, 37b) are connected to the hot-water supply path (36). Each of the branched hot-water supply paths (37a, 37b) is connected to the mixing valve (35a, 35b). The single branched water supply path (32a, 32b) and the single branched hot-water supply path (37a, 37b) are connected to the mixing valve (35a, 35b).

0077Three ports are formed in the mixing valve (35a, 35b). In the mixing valve (35a, 35b), a first port is connected to the branched water supply path (32a, 32b); a second port is connected to the branched hot-water supply path (37a, 37b); and a third port is connected to a utilization-side flow path (39) extending toward a utilization side such as a bathtub (33) of a bath, a kitchen, and a washstand. The mixing valve (35a,35b) mixes water flowing into the first port with water flowing into the second port to send such water through the third port.

0078An inlet end of the circulation path (21) is connected to the water discharge port (28) of the hot-water storage tank (25), and an outlet end of the circulation path (21) is connected to the hot-water inlet port (29). The circulation path (21) is provided so as to cross between the hot-water storage unit (23) and the outdoor unit (22).

0079A pump mechanism (34) which is a so-called "circulation pump" is provided in the circulation path (21). A water-heat exchanger (43) which will be described later is connected to the circulation path (21). The circulation path (21) is configured so that water sent from the hot-water storage unit (23) by the pump mechanism (34) is returned to the hot-water storage unit (23) after passing through the heat source unit (22).

0080The heat source unit (22) includes a refrigerant circuit (10) in which a compressor (30), an air-heat exchanger (42), the water-heat exchanger (43), an expansion valve (12) are provided. The refrigerant circuit (10) is filled with refrigerant mixture containing HFO-1234yf of 78.2% by mass and HFC-32 of 21.8% by mass. An outdoor fan (14) is provided near the air-heat exchanger (42).

0081In the refrigerant circuit (10), a discharge side of the compressor (30) is connected to the water-heat exchanger (43), and a suction side of the compressor (30) is connected to the air-heat exchanger (42). The expansion valve (12) is arranged between the air-heat exchanger (42) and the water-heat exchanger (43).

0082The compressor (30) has variable operational capacity. The air-heat exchanger (42) is a cross-fin type fin-and-tube heat exchanger. The expansion valve (12) is an electric expansion valve with variable opening.

0083The water-heat exchanger (43) is a so-called "plate-type heat exchanger," and includes a plurality of first flow paths (43a) and a plurality of second flow paths (43b) which are separated from each other. The water-heat exchanger (43) is configured so that heat is exchanged between fluid in the first flow path (43a) and fluid in the second flow path (43b). The first flow path (43a) is connected to the circulation path (21). Water taken from the bottom section of the hot-water storage tank (25) flows into the first flow path (43a). On the other hand, the second flow path (43b) is connected to the refrigerant circuit (10), and is arranged between the compressor (30) and the expansion valve (12). High-temperature high-pressure refrigerant discharged from the compressor (30) flows into the second flow path (43b).

Operation

0084A water boiling operation of the hot-water supply system (20) of the second embodiment will be described. The water boiling operation is performed by operating the compressor (30) and the pump mechanism (34).

0085When operating the compressor (30), a vapor compression refrigeration cycle is performed by circulating refrigerant in the refrigerant circuit (10). In the refrigerant circuit (10) in which the refrigerant cycle is performed, refrigerant is compressed in the compressor (30), and then releases heat to water of the first flow path (43a) in the water-heat exchanger (43). Subsequently, the pressure of the refrigerant is reduced by the outdoor expansion valve (12), and such refrigerant absorbs heat from outdoor air in the air-heat exchanger (42). The water-heat exchanger (43) is operated as a radiator, and the air-heat exchanger (42) is operated as an evaporator.

0086Meanwhile, when operating the pump mechanism (34), water in the hot-water storage tank (25) circulates through the circulation path (21). In the circulation path (21), water taken through the water discharge port (28) of the hot-water storage tank (25) is heated by refrigerant in the first flow path (43a) of the water-heat exchanger (43), and then is returned to the hot-water storage tank (25) through the hot-water inlet port (29). The water heated in the water-heat exchanger (43) flows into the hot-water storage tank (25) to increase a hot-water amount.

Variation of Second Embodiment

0087A variation of the second embodiment will be described. As illustrated in <figref idref="f0003">FIG. 3</figref>, in such a variation, a floor heating path (48) in which a floor heating radiator (41) is provided is connected to a hot-water storage tank (25). An inlet end of the floor heating path (48) is connected to a hot-water outlet port (27) of the hot-water storage tank (25), and an outlet end is connected to a hot-water return port (24) of the hot-water storage tank (25). A pump mechanism (8) is provided upstream of the floor heating path (48). As in the second embodiment, the refrigerant mixture containing the HFO-1234yf of 78.2% by mass and the HFC-32 of 21.8% by mass is used in the refrigerant circuit (10).

0088In the floor heating path (48), when operating the pump mechanism (8), hot-water flowing out through the hot-water outlet port (27) of the hot-water storage tank (25) is supplied to the floor heating path (48). Subsequently, the hot-water is used for heating a room, and then such hot-water is cooled. The water cooled in the floor heating path (48) is returned to the hot-water storage tank (25) through the hot-water return port (24). In the floor heating path (48), water circulates between the hot-water storage tank (25) and the floor heating path (48).

<<Other Embodiments>>

0089The foregoing embodiments may have the following configurations.

0090In the foregoing embodiments, the C₃H_mF_n refrigerant used for the refrigerant mixture may be refrigerant other than the HFO-1234yf. Specifically, instead of using the HFO-1234yf, any of the following may be used: 1, 2, 3, 3, 3-pentafluoro-1-propene (referred to as "HFO-1225ye," and a chemical formula thereof is represented by an expression CF₃ - CF = CHF); 1, 3, 3, 3-tetrafluoro-1-propene (referred to as "HFO-1234ze," and a chemical formula thereof is represented by an expression CF₃ - CH = CHF); 1, 2, 3, 3-tetrafluoro-1-propene (referred to as "HFO-1234ye," and a chemical formula thereof is represented by an expression CHF₂ - CF = CHF); 3, 3, 3-trifluoro-1-propene (referred to as "HFO-1243zf," and a chemical formula thereof is represented by an expression CF₃ - CH = CH₂); 1, 2, 2-trifluoro-1-propene (a chemical formula thereof is represented by an expression CH₃ - CF = CF₂); and 2-fluoro-1-propene (a chemical formula thereof is represented by an expression CH₃ - CF = CH₂).

0091In the foregoing embodiments, instead of using the HFC-32, HFC-125 may be used. In such a case, the proportion of the HFC-125 in the refrigerant mixture is preferably equal to or greater than 10% by mass and equal to or less than 30% by mass, and more preferably equal to or greater than 10% by mass and equal to or less than 20% by mass. The C₃H_mF_n refrigerant may be the HFO-1234yf as in the foregoing embodiments, or may be refrigerant other than the HFO-1234yf.

0092In the foregoing embodiments, the HFC refrigerant may be refrigerant other than the HFC-32 and the HFC-125. Specifically, the HFC refrigerant includes HFC-134 (1, 1, 2, 2-tetrafluoroethane); HFC-134a (1, 1, 1, 2-tetrafluoroethane); HFC-143a (1, 1, 1-trifluoroethane); HFC-152a (1, 1-difluoroethane); HFC-161 (fluoroethane); HFC-227ea (1, 1, 1, 2, 3, 3, 3-heptafluoropropane); HFC-236ea (1, 1, 1, 2, 3, 3-hexafluoropropane); HFC-236fa (1, 1, 1, 3, 3, 3-hexafluoropropane); and HFC-365mfc (1,1, 1, 3, 3-pentafluorobutane).

0093In the foregoing embodiments, more than two types of HFC refrigerants may be used for the refrigerant mixture. Specifically, refrigerant mixture containing the HFC-125 and the HFC-32 may be used as the HFC refrigerant. The C₃H_mF_n refrigerant may be the HFO-1234yf as in the foregoing embodiments, or may be refrigerant other than the HFO-1234yf.

0094In the foregoing embodiments, refrigerant mixture containing the C₃H_mF_n refrigerant and hydrocarbons may be used. Specifically, as hydrocarbon refrigerant used for the refrigerant mixture, methane, ethane, propane, propene, butane, isobutene, pentane, 2-methylbutane, or cyclopentane may be used. A single type of or multiple types of hydrocarbon refrigerant(s) may be used. As in the foregoing embodiments, refrigerant mixture containing methane, ethane, propane, or propene increases the operating pressure of refrigerant. Thus, while reducing the influence of the pressure loss of refrigerant on the operation of the refrigeration apparatus (20), the actual operational efficiency of the refrigeration apparatus (20) can be improved. In this respect, the same is true for refrigerant mixture containing the C₃H_mF_n refrigerant and dimethyl ether; refrigerant mixture containing the C₃H_mF_n refrigerant and bis-trifluoromethyl-sulfide; refrigerant mixture containing the C₃H_mF_n refrigerant and helium; and refrigerant mixture containing the HFO-1234yf and carbon dioxide, which will be described below.

0095In the foregoing embodiments, the refrigerant mixture containing the C₃H_mF_n refrigerant and dimethyl ether may be used.

0096In the foregoing embodiments, the refrigerant mixture containing the C₃H_mF_n refrigerant and bis-trifluoromethyl-sulfide may be used.

0097In the foregoing embodiments, the refrigerant mixture containing the C₃H_mF_n refrigerant and helium may be used.

0098In the foregoing embodiments, the refrigerant mixture containing the HFO-1234yf and carbon dioxide may be used.

0099In the foregoing embodiments, the refrigeration apparatus (20) of the present invention may be applied to, e.g., a refrigeration apparatus for cooling food (refrigerators or freezers); a refrigeration apparatus in which an air conditioner is combined with a refrigerator or a freezer; and a refrigeration apparatus with a humidity adjusting function, in which heat of refrigerant circulating in a heat exchanger is used for heating/cooling adsorbent. In addition, in the embodiments, the heat source of the refrigerant circuit (10) is air, but such a heat source may be a water heat source or an underground heat source.

0100The foregoing embodiments have been set forth merely for purposes of preferred examples in nature, and are not intended to limit the scope, applications, and use of the invention.

INDUSTRIAL APPLICABILITY

0101As described above, the present invention is useful for the refrigeration apparatus in which the refrigeration cycle is performed.