WO2000052398A1 - Refrigerating device - Google Patents

Abstract

A refrigerating circuit (10), comprising a compressor (11), a four-way switching valve (12), an outdoor heat exchanger (13), an expansion valve (14), and an indoor heat exchanger (15) connected in order to each other, wherein an R32 is filled therein, and heat transfer tubes of the indoor heat exchanger (15) are formed of heat transfer tubes having an inner diameter of 4.7 to 5.9 mm, and the heat transfer tubes of the outdoor heat exchanger (13) are formed of heat transfer tubes having an inner diameter of 5.4 to 6.7 mm.

Description

 Details

Technical field

 The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus using a single refrigerant of R32 or a mixed refrigerant containing R32. Background art

 Until now, R22 has been often used as a suitable refrigerant for refrigeration systems such as air conditioners. However, because of the large ozone depletion potential of R22, it is scheduled to be completely abolished by the Montreal Protocol in 2002. Therefore, various refrigerants such as R407C, R410A or R134a are being developed as alternative refrigerants to replace R22.

 Solution 1

 However, as shown in Figure 10, each of the above alternative refrigerants has a low ozone depletion potential, but a global warming potential (GWP) equivalent to that of R22. Therefore, the above alternative refrigerants cannot be said to be sufficiently satisfactory from the viewpoint of preventing global warming.

 In addition, if the above alternative refrigerant is used, the COP of the refrigeration system will be lower than before, so the load on thermal power plants etc. will increase with the increase in power consumption, apart from the direct global warming effect due to refrigerant discharge And indirectly contribute to global warming. Therefore, the development of an alternative refrigerant that truly suppresses global warming has been desired.

 Therefore, development of a single refrigerant of R32 or a mixed refrigerant containing a large amount of R32 is being promoted as an alternative refrigerant having a small GWP.

However, simply charging a single R32 refrigerant or a mixed R32 refrigerant into the R22 refrigeration system does not make it possible to fully utilize the characteristics of R32 and prevent global warming. Can't get enough. Therefore, there is a long-awaited need for a refrigeration system that effectively utilizes the characteristics of R32 in order to prevent global warming. The present invention has been made in view of the above, and an object of the present invention is to provide a refrigeration apparatus that can effectively prevent the global warming by effectively utilizing the characteristics of R32. . Disclosure of the invention

 In order to achieve the above object, the present invention provides a heat exchanger with a heat transfer tube having a smaller diameter than before, so as to reduce the amount of refrigerant charged in a refrigerant circuit while maintaining the same device performance as before. And

 Specifically, the invention of the first aspect uses a compressor (11), an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat source so as to form a vapor compression refrigeration cycle using R32 as a refrigerant. It is intended for a refrigeration system equipped with a refrigerant circuit (10) having an exchanger (15). The heat transfer tube of the indoor heat exchanger (15) is formed by a heat transfer tube having an inner diameter of 5.9 mm or less.

 Another invention uses a refrigerant as R32 to form a vapor compression refrigeration cycle, a compressor (11), an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger. It is intended for a refrigeration system equipped with a refrigerant circuit (10) having (15). The heat transfer tube of the indoor heat exchanger (15) is formed by a heat transfer tube having an inner diameter of 4.7 mm to 5.9 mm.

 In addition, from the viewpoint of reducing the refrigerant charging amount, it is more preferable that the heat transfer tube of the indoor heat exchanger (15) is formed of a heat transfer tube having an inner diameter of 5.3 mm or less.

 Another invention relates to a compressor (11), an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger that form a vapor compression refrigeration cycle using R32 as a refrigerant. It is intended for a refrigeration system equipped with a refrigerant circuit (10) having (15). The heat transfer tube of the outdoor heat exchanger (13) is formed by a heat transfer tube having an inner diameter of 6.7 mm or less.

Another invention uses a refrigerant as R32 to form a vapor compression refrigeration cycle, a compressor (11), an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger. (15) It is intended for a refrigeration system equipped with a refrigerant circuit (10). The inside diameter of the heat transfer tube of the outdoor heat exchanger (13) is 5.4 mn! It is formed by a heat transfer tube that is ~ 6.7 mm.

 In addition, from the viewpoint of reducing the charged amount of the refrigerant, it is more preferable that the heat transfer tube of the outdoor heat exchanger (13) is formed by a heat transfer tube having an inner diameter of 6.1 mm or less.

 Another invention provides a compressor (75% by weight or more and less than 100% by weight) that uses a mixed refrigerant of R32 and R125 as a refrigerant to form a vapor compression refrigeration cycle. 11), a refrigeration system equipped with a refrigerant circuit (10) having an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger (15). The heat transfer tube of the indoor heat exchanger (15) is formed by a heat transfer tube having an inner diameter of 6.2 mm or less.

 Another invention provides a compressor (75% by weight or more and less than 100% by weight) that uses a mixed refrigerant of R32 and R125 as a refrigerant to form a vapor compression refrigeration cycle. 11), a refrigerating system equipped with a refrigerant circuit (10) having an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger (15). The inside diameter of the heat transfer tube of the indoor heat exchanger (15) is 4.7 mn! It is formed by heat transfer tubes that are ~ 6.2 mm.

 It is more preferable that the heat transfer tube of the indoor heat exchanger (15) is formed of a heat transfer tube having an inner diameter of 5.5 mm or less from the viewpoint of reducing the amount of refrigerant to be charged.

 Another invention provides a compressor (75% by weight or more and less than 100% by weight) that uses a mixed refrigerant of R32 and R125 as a refrigerant to form a vapor compression refrigeration cycle. 11), a refrigeration system equipped with a refrigerant circuit (10) having an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger (15). The heat transfer tube of the outdoor heat exchanger (13) is formed by a heat transfer tube having an inner diameter of 7.1 mm or less.

Another invention provides a compressor (75% by weight or more and less than 100% by weight) that uses a mixed refrigerant of R32 and R125 as a refrigerant to form a vapor compression refrigeration cycle. 11), a refrigerant circuit having an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger (15) 0

 Four

 It is intended for refrigeration equipment equipped with (10). The heat transfer tube of the outdoor heat exchanger (13) is formed by a heat transfer tube having an inner diameter of 5.4 mm to 7.1 mm.

 In addition, from the viewpoint of reducing the amount of refrigerant to be charged, it is more preferable that the heat transfer tube of the outdoor heat exchanger (13) is formed by a heat transfer tube having an inner diameter of 6.3 mm or less.

 In each of the above inventions, the diameter of the heat transfer tube of the outdoor heat exchanger (13) or the indoor heat exchanger (15) is smaller than in the past.

 In addition, R32 / R125 mixed refrigerant containing R32 single refrigerant or R32 in an amount of 75% by weight or more and less than 100% by weight is regarded as a refrigerant and has a characteristic of R22. Low pressure loss. As a result, even if the inner diameter of the heat transfer tube becomes smaller, the pressure loss of the refrigerant is maintained at the same level as before.

 On the other hand, the smaller the inner diameter of the heat transfer tube, the smaller the amount of refrigerant charged in the refrigerant circuit (10). Therefore, the refrigerant charge is reduced while maintaining the performance equivalent to that of the conventional refrigeration system using R22. Therefore, in addition to the low global warming potential of R32, the global warming effect is significantly reduced by reducing the refrigerant charge of the refrigerant circuit (10). Effect of one invention

 According to the present invention, by reducing the diameter of the heat transfer tube of the outdoor heat exchanger (13) or the indoor heat exchanger (15) as compared with the conventional device using R22, the same performance as the conventional device can be obtained. The refrigerant charge in the refrigerant circuit (10) can be reduced while maintaining the pressure. As a result, the R32 single refrigerant or the R32 mixed refrigerant can be used more effectively than before, and the global warming effect is reduced by reducing the global warming potential of the refrigerant itself and reducing the refrigerant charge. Can be greatly reduced. Therefore, it is possible to provide a device suitable for global environmental protection.

 Further, the heat exchanger can be downsized by reducing the diameter of the heat transfer tube. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a refrigerant circuit diagram of the air conditioner. Figure 2 is a Mollier diagram.

 Figure 3 is a table showing the results of calculating the ratio of the inner diameter of the heat transfer tubes.

 FIG. 4 is a sectional view of a grooved tube.

 Figure 5 is a Mollier diagram.

 FIG. 6 is a table showing calculation results of the inner diameter ratio of the liquid side pipe.

 FIG. 7 is a diagram showing the pipe diameter of the gas side pipe and the liquid side pipe for R22 with respect to the rated cooling capacity.

 FIG. 8 is a diagram showing a small diameter ratio of the gas side pipe and the liquid side pipe to the rated cooling capacity. FIG. 9 is a diagram showing the relationship between the R22 copper tube and the R32 copper tube.

 Figure 10 is a table showing global warming potential. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

 Configuration of an air conditioner 1

 As shown in FIG. 1, the refrigeration apparatus according to the present embodiment is an air conditioner (1) formed by connecting an indoor unit (17) and an outdoor unit (16). The refrigerant circuit (10) of the air conditioner (1) uses a single refrigerant of R32 (hereinafter referred to as "32 single refrigerant") as a refrigerant, or 75% by weight or more and 100% by weight. % Of mixed refrigerant of R32 and R125 (R32 mixed rich refrigerant, hereinafter referred to as R32 / R125 mixed refrigerant) is used as the refrigerant.

 The refrigerant circuit (10) is a refrigerant circuit forming a vapor compression refrigeration cycle, and is a compressor (11), a four-way switching valve (12), an outdoor heat exchanger (13), and an expansion mechanism. The expansion valve (14) and the indoor heat exchanger (15) are sequentially connected via a gas pipe (31) and a liquid pipe (32), which are refrigerant pipes.

Specifically, the discharge side of the compressor (11) and the first port (12a) of the four-way switching valve (12) are connected by a first gas side pipe (21). The second port (12b) of the four-way switching valve (12) and the outdoor heat exchanger (13) are connected by the second gas side pipe (22). Outdoor The heat exchanger (13) and the expansion valve (14) are connected by the first liquid side pipe (25). The expansion valve (14) and the indoor heat exchanger (15) are connected by the second liquid side pipe (26). The indoor heat exchanger (15) and the third port (12c) of the four-way switching valve (12) are connected by a third gas side pipe (23). The fourth port (12d) of the four-way selector valve (12) and the suction side of the compressor (11) are connected by a fourth gas side pipe (24).

 Compressor (11), 1st gas side pipe (21), 4-way switching valve (12), 2nd gas side pipe (22), outdoor heat exchanger (13), 1st liquid side pipe (25), expansion The valve (14) and the fourth gas side pipe (24) are housed in an outdoor unit (16) together with an outdoor blower (not shown). On the other hand, the indoor heat exchanger (15) is housed in an indoor unit (17) together with an indoor blower (not shown). A part of the second liquid-side pipe (26) and the third gas-side pipe (23) constitutes a so-called communication pipe that connects the outdoor unit (16) and the indoor unit (17).

 —Composition of heat exchanger 1

 Since R32 single refrigerant or R32 / R125 mixed refrigerant has a greater refrigeration effect per unit volume than R222, the required amount of refrigerant circulation to achieve the specified capacity is R2. Less than 2 Therefore, in the case of the R32 single refrigerant or the R32 / R125 mixed refrigerant, when the inner diameter of the heat transfer tube of the heat exchanger is fixed, the refrigerant circulation amount is reduced. It is smaller than 2.

 In general, when the inside diameter of the heat transfer tube of the heat exchanger is reduced, the performance of the entire device is reduced due to a decrease in heat transfer area and an increase in refrigerant pressure loss. However, when using R32 single refrigerant or R32 / R125 mixed refrigerant, the refrigerant-side heat transfer coefficient in the heat transfer tube is larger than R22, so the pressure loss in the tube is equivalent to R22. Even if it is increased to the extent, it is possible to exhibit the same or better performance as R22 as a whole.

By the way, the portion of the refrigerant circuit (10) having the largest amount of refrigerant is the outdoor heat exchanger (13). Therefore, by reducing the diameter of the heat transfer tube of the outdoor heat exchanger (13), the amount of refrigerant charged can be effectively reduced. In addition, the outdoor heat exchanger (13) and the indoor heat exchanger (15) will be reduced in size by reducing the diameter of the heat transfer tubes, so that the outdoor unit (16) and the indoor unit (17) will be made more compact. Is also possible. _ ^ Therefore, in this air conditioner (1), the diameter of the heat transfer tubes of the outdoor heat exchanger (13) and the indoor heat exchanger (15) is reduced until the pressure loss in the tubes reaches the same level as R22. I decided that. Specifically, in this air conditioner (1), considering the amount of change in the refrigerant saturation temperature corresponding to the pressure loss in the heat transfer tube, the outdoor heat exchange was performed so that the amount of change in temperature would be equal to R22. The inner diameter of the heat transfer tubes of the heat exchanger (13) and the indoor heat exchanger (15) was set.

 Basic principle of heat transfer tube configuration

 Next, the basic principles of the heat transfer tubes of the outdoor heat exchanger (13) and the indoor heat exchanger (15) will be specifically described.

 Here, as shown in FIG. 2, the outdoor heat exchanger (T) is set so that the saturation temperature change amount △ Te corresponding to the pressure loss of the evaporative refrigerant becomes equal to the saturation temperature change amount of R 22 in the conventional device. 13) Set the heat transfer tubes of the indoor heat exchanger (15). That is,

 Um Te = Const. (1)

And here,

 ΔΡ: Piping pressure loss (kPa)

 L: Piping length (m)

 G: Refrigerant circulation rate (kg / s)

A: Channel cross-sectional area (m ² )

 λ: loss factor

 d: Piping inner diameter (m)

ps: Compressor suction refrigerant density (kg / m ³ )

圧力損失 ΔΡは、 次式の円管の摩擦損失の式を用いて算出する。 L G² 、 And The above-mentioned saturation temperature change amount ΔΤ e is expressed by the following equation.

Pressure loss ΔΡ is calculated using the following equation for friction loss of a circular pipe. LG ² ,

 ΔΡ2 λ

When the d 2- sA ² cooling capacity Q = Gx Ah constant, G ²

△ poc OC (Ah ² -psd ⁵ P sd ⁵ )

Δh: Freezing effect (kJ / kg)

Becomes Therefore, T P, and from the above equations (2) and (4), the pressure loss ΔΡ is

ATeo X (Ah ² * p sd ⁵ ) -1 is represented.

 Therefore, from the above formulas (1) and (5) and the values of R22 and R32, the ratio of the inner diameter of the heat transfer tube for R32 to the heat transfer tube for R22, that is, the small diameter ratio of the heat transfer tube, is given by the following formula. You can ask for it.

'ΔΤΊ'

, X (Ah ₂ 2 ² * P s _99D 99 Λ D (<ι X (Ah ₉ ² -p S

^{P 22 5 22 "22 ΔΡ 32} 32) 32n - d u 3o2 9 5)

△

図 3は、 上記（6)式に各物性値を代入した計算結果を示す。 なお、 本計算では、 蒸発温度 Teを 2°C、 凝縮温度 Tcを 49°Cと仮定し、 蒸発器出口のスーパ一ヒート S H= 5 d e g、 凝縮器出口のサブクール S C = 5 d e gとした。

FIG. 3 shows a calculation result obtained by substituting each physical property value into the above equation (6). In this calculation, the evaporation temperature Te was assumed to be 2 ° C and the condensing temperature Tc was assumed to be 49 ° C, and the superheat SH at the evaporator outlet was set to 5 ° and the subcool SC at the condenser outlet was set to 5 °.

 From the above calculation results, it was found that the diameter of the heat transfer tube for the R32 single refrigerant was reduced to about 0.76 times that of the heat transfer tube for R22. Further, it was found that the diameter of the heat transfer tube for the R32 / R125 mixed refrigerant can be reduced to about 0.76 to 0.8 times that of the heat transfer tube for R22. The same calculation was performed for other alternative refrigerants for reference, but it was found that the effect of reducing the diameter as compared to R32 could not be obtained (see Fig. 3).

 In this air conditioner (1), based on such a principle, a heat transfer tube having the following inner diameter was used in comparison with the heat transfer tube for: 22.

In other words, when a single R32 refrigerant is used, the heat transfer tubes of the indoor heat exchanger (15) must be The diameter is 4.7mn! The heat transfer tube of the outdoor heat exchanger (13) is formed of a heat transfer tube with an inner diameter of 5.4 mm to 6.7 mm.

 On the other hand, when the R32 / R125 mixed refrigerant is used, the inside diameter of the heat transfer tube of the indoor heat exchanger (15) is 4.7mn! The heat transfer tube of the outdoor heat exchanger (13) has an inner diameter of 5.4mn! It was decided to be formed of 7.1 mm heat transfer tube.

 When the inner diameter of each heat transfer tube is smaller than the above numerical range, the refrigerant pressure is further reduced, but the refrigerant pressure loss becomes excessive. On the other hand, if the inner diameter of each heat transfer tube is larger than the above numerical range, the refrigerant pressure loss is reduced and the efficiency of the device is improved, but the effects of R32, such as the effect of reducing the refrigerant charge, should be fully utilized. Becomes difficult.

 Therefore, in the present embodiment, the inner diameters of the heat transfer tubes of the outdoor heat exchanger (13) and the indoor heat exchanger (15) are set within the above numerical ranges.

 It should be noted that the above numerical range may be further limited depending on the use conditions of the apparatus and the like, in order to more remarkably exhibit the characteristics of R32.

 For example, when using a single R32 refrigerant, the heat transfer tube of the indoor heat exchanger (15) is formed of a heat transfer tube with an inner diameter of 4.9 mm-5.7 mm, and the heat transfer tube of the outdoor heat exchanger (13) The inner diameter of the heat transfer tube is 5.6mn! It may be formed of a heat transfer tube of up to 6.5 mm.

 Furthermore, when a single R32 refrigerant is used, the heat transfer tube of the indoor heat exchanger (15) is formed of a heat transfer tube having an inner diameter of 5.1 mm to 5.5 mm, and the heat transfer tube of the outdoor heat exchanger (13) is used. The heat transfer tube may be formed of a heat transfer tube having an inner diameter of 5.8 mm to 6.3 mm.

 When using the R32 / R125 mixed refrigerant, the heat transfer tube of the indoor heat exchanger (15) is formed of a heat transfer tube with an inner diameter of 4.9 mm to 6.0 mm, and the heat transfer tube of the outdoor heat exchanger (13) is used. The heat transfer tube may be formed of a heat transfer tube having an inner diameter of 5.6 mm to 6.9 mm.

 Furthermore, when using a 32 / R 125 mixed refrigerant, the inside diameter of the heat transfer tube of the indoor heat exchanger (15) is 5.2mn! The heat transfer tube of the outdoor heat exchanger (13) may be formed of a heat transfer tube with an inner diameter of 5.9 mm to 6.6 mm.

Here, the inner diameter of the heat transfer tube means the inner diameter of the tube after expansion in the case of a smooth inner surface tube. In addition, as shown in Fig. 4, in the case of an inner grooved tube, the inner diameter of the heat transfer tube is calculated from the outer diameter after expansion. It means the value obtained by subtracting twice the bottom thickness, that is, the inner diameter di = do-2 t.

 As the heat transfer tube, various heat transfer tubes such as a copper tube and an aluminum tube can be used. The external heat exchanger (13) and the indoor heat exchanger (13) according to the present embodiment are a type of air heat exchanger for performing heat exchange with air, which is a plate fin tube heat exchanger composed of copper tubes and aluminum fins. The heat transfer tubes are made of copper tubes.

 ー Composition of refrigerant piping

 Also, in this air conditioner (1), in order to reduce the amount of refrigerant charged, the diameter of the refrigerant pipes of the refrigerant circuit (10) as well as the heat exchanger tubes of the heat exchangers (13, 15) has been reduced. I am trying.

 As described above, when the R32 single refrigerant or the R32 / R125 mixed refrigerant is used as it is in the R22 refrigerant pipe, the pressure loss of the refrigerant is reduced. Therefore, even if the inside diameter of the liquid side pipe (32) of the refrigerant circuit (10) is reduced to increase the pressure loss in the pipe to the same level as when R22 is used, the performance of the device is maintained at the same level as before. Is done. Therefore, in this air conditioner (1), the liquid side pipe (32) is reduced in diameter until the pressure loss in the pipe becomes R22, so that the refrigerant circuit (10) is maintained while maintaining the performance of the apparatus. Refrigerant charge was reduced.

 On the other hand, if the gas side pipe (31), especially the fourth gas side pipe (24), which is the suction pipe for the compressor (11), is reduced in diameter, the amount of refrigerant charged will not be reduced so much, but the suction The efficiency of the equipment is greatly reduced due to the effect of the increased pressure loss. Such a reduction in the efficiency of the equipment indirectly leads to an increase in the effect of global warming.

 Therefore, in the present air conditioner (1), the gas side pipe (31) is the same as the conventional R22 gas side pipe, and only the liquid side pipe (32) is smaller than the conventional R22 liquid side pipe. Was also reduced in diameter.

 Basic principle of the configuration of one refrigerant pipe

 Next, the basic principle of the liquid side pipe (32) will be described.

Here, the liquid-side piping (32) is sized so that the ratio of the pressure drop of the liquid-side piping (32) to the pressure drop of the refrigerant from the condenser outlet to the evaporator inlet accounts for the same amount as in R22. Design (32). That is, the following equation is established using the symbols shown in FIG. (Pco-Pvi) + (Pvo-Pbi)

 Nishi onst.

 (Pco-Pei) where

 P: Pressure loss in piping (kPa)

 L: Piping length (m)

 G: Refrigerant circulation (kg / s)

A: Channel cross-sectional area (m ² )

 λ: loss factor

 d: Piping inner diameter (m)

s: Compressor suction refrigerant density (kg / m ³ )

Where each term of the numerator in the above equation (7) is calculated using the following equation for friction loss of a circular pipe,

^ΔΡ + 2 "^ · '· ( ⁸ ) Here, the capacity Q = GxAh is fixed, and the following equation is derived from the above equation (8).

APoc G ²

oc (Ah ² -p sd ⁵ ) " ¹

β sd ⁵

Δh: Freezing effect (kJ / kg)

 Therefore, the following equation is derived.

(Pco-Pvi) + (Pvo -Pbi) c (厶h ² 'p _s .d ⁵⁾ one ¹ (10) Then, from equation (7) and (10), the following equation is derived.

(Pco-Pvi) + (Pvo-Pbi) (Ah ² -ps'd ⁵ ) — ¹

(Pco-Pei) ― (HP-LP)… ¹ )

Therefore, from the above formulas (7) and (11) and the physical properties of R22 and R32, the ratio of the small diameter of the liquid side pipe (32) of R32 to the liquid side pipe of R22 is calculated as follows. be able to.

 FIG. 6 shows a calculation result obtained by substituting each physical property value into the above equation (12). In this calculation, the evaporation temperature Te was 2 ° C, the condensation temperature Tc was 49 ° C, the superheat SH was 5 deg, and the subcool SC was 5 deg.

 From the above calculation results, it was found that the liquid side pipe (32) of the R32 single refrigerant can be reduced to about 0.76 times the diameter of the liquid side pipe for R22. It was also found that the R32 / R125 mixed refrigerant can be reduced in diameter to about 0.76 to 0.8 times if the composition of R32 is contained at 75% by weight or more. . For reference, similar calculations were performed for other alternative refrigerants, but it was found that the effect of reducing the diameter as compared to R32 could not be obtained (see Fig. 6).

 FIG. 7 is a diagram showing the pipe diameter (outer diameter) of the gas side pipe and the liquid side pipe in the conventional apparatus using R22 for each cooling capacity rating.

 In this air conditioner (1), depending on the rated cooling capacity, the gas side pipe (31) uses the same diameter as the R22 gas side pipe, while the liquid side pipe (32) uses the above. Use a pipe with a smaller diameter than the liquid side pipe for R22.

 FIG. 8 is a diagram showing the ratio of the inner diameter dg of the gas side pipe to the inner diameter d1 of the liquid side pipe, that is, the inner diameter ratio (= the inner diameter dg of the gas side pipe / the inner diameter d1 of the liquid side pipe). In this air conditioner (1), gas side piping (31) and liquid side piping (32) having the following inner diameter ratios are used according to the rated cooling capacity.

That is, when the rated cooling capacity is more than 5 kW and less than 9 kW, use the gas side pipe (31) and the liquid side pipe (32) so that the above inner diameter ratio becomes 2.1 to 3.5. . When the rated cooling capacity is 5 kW or less or greater than 9 kW, the above inner diameter ratio is 2.6 Use gas-side piping (31) and liquid-side piping (32) so as to satisfy 3.5.

 When the rated cooling capacity is 5 kW or less, the liquid side piping (32) is not suspicious.

Use 2mm to 4.2mm piping. Cooling rating is greater than 5 kW and 22.

When the power is less than 4 kW, use a pipe with an inner diameter of 5.4 mm to 7.0 mm as the liquid side pipe (32). If the rated cooling capacity is 22.4 kW or more, use a pipe with an inner diameter of 7.5 mm to 9.8 mm as the liquid side pipe (32).

 When the inner diameter ratio or the inner diameter of the liquid side pipe (32) is smaller than the above numerical range, the refrigerant performance is further reduced, though the refrigerant charging amount is further reduced. On the other hand, when the inner diameter ratio or the inner diameter of the liquid side pipe (32) is larger than the above numerical range, the effect of reducing the refrigerant charge is reduced although the refrigerant pressure loss is reduced and the device performance is improved.

 Therefore, in the present embodiment, the gas-side pipe (31) and the liquid-side pipe (32) are set within the above numerical ranges so that the refrigerant filling amount can be sufficiently reduced while maintaining the performance of the apparatus. .

 It should be noted that the above numerical range may be further limited depending on the use conditions of the apparatus and the like in order to more effectively utilize the characteristics of R32.

 For example, when the rated cooling capacity is greater than 5 kW and less than or equal to 9 kW, the above inner diameter ratio may be set to 2.4 to 3.2. When the rated cooling capacity is 5 kW or less or greater than 9 kW, the above inner diameter ratio may be 2.8-3.3.

 Further, when the rated cooling capacity is greater than 5 kW and 9 kW or less, the inner diameter ratio may be set to 2.6 to 3.0. When the rated cooling capacity is 5 kW or less or larger than 9 kW, the above inner diameter ratio may be set to 2.9 to 3.1.

 The inner diameter of the liquid side pipe (32) is 3.5 mπ when the rated cooling capacity is 5 kW or less. Up to 3.9 mm, 5.7 mm to 6.7 mm when the rated cooling capacity is greater than 5 kW and less than 22.4 kW, and 7.8 mm when the rated cooling capacity is 22.4 kW or more It may be 9.5 mm.

Furthermore, the inner diameter of the liquid side pipe (32) should be 3.6 mm to 3.8 mm when the cooling capacity is 5 kW or less, and the cooling capacity should be greater than 5 kW and less than 22.4 kW. 6. Omn! When the rated cooling capacity is 22.4 kW or more, it may be 8.1 mm to 9.1 mm.

 By the way, copper pipes have been often used as refrigerant pipes because of their low cost and easy handling. Since various standard products are available for copper tubes, the cost of the refrigerant pipes (31, 32) can be reduced by using existing standard products. Therefore, in order to reduce the cost of the equipment, by combining standard products so as to have the above-mentioned inner diameter ratio, both the liquid side pipe (32) and the gas side pipe (31) should be composed of only standard products. Is preferred.

 Fig. 9 compares the specifications of the copper pipe for R22 (JISB 8607) with the specifications of the high-pressure compliant pipe for R32 proposed by the Japan Refrigeration and Air Conditioning Industry Association (Nichirei).

 The optimum inner diameter ratio calculated from the above calculation results is 0.76 for the R32 single refrigerant, and 0.80 for the R32 / R125 mixed refrigerant containing 75% by weight of R32. From FIG. 9 above, it was found that within the range of ± 10% of the optimal inner diameter ratio, the combination of standard products can easily realize the inner diameter ratio.

 For example, if a 99.5 mm standardized pipe is used for R22, an 8. Omm standardized pipe can be used instead of R32. Thus, the present embodiment is a form that can be easily realized by combining standard products.

 Operation of the air conditioner (1)

 The operation of the air conditioner (1) will be described based on the refrigerant circulation operation in the refrigerant circuit (10).

 During cooling operation, the four-way switching valve (12) is set to the solid line side shown in Fig. 1. That is, in the four-way switching valve (12), the first port (12a) and the second port (12b) communicate with each other, and the third port (12c) and the fourth port (12d) communicate with each other.

In this state, the gas refrigerant discharged from the compressor (11) flows through the first gas side pipe (21), the four-way switching valve (12), and the second gas side pipe (22), and passes through the outdoor heat exchanger. Condensed in (13). The liquid refrigerant flowing out of the outdoor heat exchanger (13) flows through the first liquid side pipe (25), and is expanded. In (14), the pressure is reduced to a gas-liquid two-phase refrigerant. The two-phase refrigerant flowing out of the expansion valve (14) flows through the second liquid side pipe (26), exchanges heat with the indoor air in the indoor heat exchanger (15), evaporates, and cools the indoor air. The gas refrigerant flowing out of the indoor heat exchanger (15) flows through the third gas-side pipe (23), the four-way switching valve (12), and the fourth gas-side pipe (24), and flows to the compressor (11). Inhaled o

 On the other hand, during the heating operation, the four-way switching valve (12) is set to the broken line side shown in FIG. In other words, the four-way switching valve (12) is in a state where the first port (12a) and the fourth port (12d) communicate with each other, and the second port (12b) and the third port (12c) communicate with each other. .

 In this state, the gas refrigerant discharged from the compressor (11) flows through the first gas-side pipe (21), the four-way switching valve (12), and the third gas-side pipe (23), and passes through the indoor heat exchanger. (15). The refrigerant flowing into the indoor heat exchanger (15) exchanges heat with the indoor air to condense and heat the indoor air. The liquid refrigerant flowing out of the indoor heat exchanger (15) flows through the second liquid side pipe (26) and is decompressed by the expansion valve (14) to become a gas-liquid two-phase refrigerant. The two-phase refrigerant flowing out of the expansion valve (14) flows through the first liquid side pipe (25) and evaporates in the outdoor heat exchanger (13). The gas refrigerant flowing out of the outdoor heat exchanger (13) flows through the second gas pipe (22), the four-way switching valve (12), and the fourth gas pipe (24), and is sucked into the compressor (11). Is done.

 Effects of one embodiment—

 According to this embodiment, R32 single refrigerant or R32 / R125 mixed refrigerant is used as the refrigerant, and the heat transfer tubes of the outdoor heat exchanger (13) and the indoor heat exchanger (15) are used. Since the diameter was made smaller than before, it became possible to reduce the amount of refrigerant charged while maintaining the performance of the device, and to reduce the effect of global warming.

 In addition, by reducing the diameter of the heat transfer tubes, the cost and size of the outdoor heat exchanger (13) and the indoor heat exchanger (15) can be reduced and the indoor unit (17) and the outdoor unit (16) can be reduced. ) Can be reduced in size.

In addition, by forming the liquid-side pipe (32) with a relatively small-diameter pipe, it is possible to further reduce the amount of refrigerant charged in the refrigerant circuit (10) while maintaining the same operating efficiency as before. became. Therefore, the characteristics of R32, which have a small global warming potential and a small pipe pressure loss, can be fully utilized, and the global warming effect can be greatly reduced. Other Embodiment 1

 In the above-described embodiment, the so-called heat pump type air conditioner capable of selectively performing the cooling operation and the heating operation is described. It may be a cooling only machine. In addition, the present invention is applied to a heating-only machine by setting the inner diameter of the liquid side pipe (32) and the gas side pipe (31) or the ratio of the inner diameter to each of the heating rated capacity corresponding to the cooling rated capacity. It is also possible to do so.

 The gas side pipe (31) and the liquid side pipe (32) need not necessarily be formed of copper pipes, but may be formed of other pipes such as SUS pipes, aluminum pipes, and iron pipes.

 The outdoor heat exchanger (13) and the indoor heat exchanger (15) are not limited to the air heat exchanger, but may be a liquid-liquid heat exchanger such as a double tube heat exchanger.

 By reducing the diameter of the heat transfer pipe, gas side pipe (31), and liquid side pipe (32) of the outdoor heat exchanger (13) and the indoor heat exchanger (15), the internal volume of the refrigerant circuit (10) is reduced. (The internal volume of the part through which the refrigerant passes). Therefore, the amount of air, moisture, impurities and the like mixed in the refrigerant circuit (10) becomes smaller than before, and the opportunity for the refrigerating machine oil to come into contact with moisture and the like is reduced. Therefore, according to the present embodiment, the deterioration of the refrigerating machine oil is less likely to occur than before. Therefore, when synthetic oil such as ether oil or ester oil is used as the refrigerating machine oil, the superiority of the present embodiment is more remarkably exhibited.

 The refrigeration apparatus of the present invention is not limited to a refrigeration apparatus in a narrow sense, but is a refrigeration apparatus in a broad sense including a refrigeration apparatus, a dehumidifier, and the like, as well as the air conditioner described above.

Further, the cooling rated capacity in the above embodiment means the capacity of the evaporator, and is not limited to the capacity of the air conditioner at the time of cooling. The cooling capacity rating is that the connecting pipe length is 5 m and the indoor unit and outdoor unit When the height difference is 0 m, the ability to be exhibited under the specified JIS conditions (indoor dry bulb temperature of 27 ° C, indoor wet bulb temperature of 19 ° C, outdoor dry bulb temperature of 35 ° C) is there. Industrial applicability

 As described above, the refrigeration apparatus of the present invention is useful when a refrigerant having a small ozone depletion coefficient is used, and is suitable for a refrigeration apparatus that can truly prevent global warming.

Claims

The scope of the claims 1. Using R32 as a refrigerant, it has a compressor (11), an outdoor heat exchanger (13), a pressure reducing mechanism (14), and an indoor heat exchanger (15) to form a vapor compression refrigeration cycle. A refrigeration system having a refrigerant circuit (10),  A refrigeration system in which the heat transfer tubes of the indoor heat exchanger (15) are formed by heat transfer tubes having an inner diameter of 5.9 mm or less. 2. Compressor (11), outdoor heat exchanger (13), pressure reducing mechanism (14), and indoor heat exchanger (15) to form a vapor compression refrigeration cycle using R32 as refrigerant Refrigerant circuit (10) a refrigeration apparatus comprising:  A refrigerating apparatus in which the heat transfer tubes of the indoor heat exchanger (15) are formed by heat transfer tubes having an inner diameter of 4.7 mm to 5.9 mm. 3. The refrigeration apparatus according to claim 1 or 2,  A refrigeration unit in which the heat transfer tubes of the indoor heat exchanger (15) are formed by heat transfer tubes with an inner diameter of 5.3 mm or less. 4. The compressor (11), the outdoor heat exchanger (13), the pressure reduction mechanism (14), and the indoor heat exchanger (15) are combined so that a vapor compression refrigeration cycle is formed using R32 as a refrigerant. Refrigerant circuit having (10) a refrigeration apparatus comprising:  A refrigeration system in which the heat transfer tubes of the outdoor heat exchanger (13) are formed by heat transfer tubes having an inner diameter of 6.7 mm or less. 5. It has a compressor (11), an outdoor heat exchanger (13), a pressure reduction mechanism (14), and an indoor heat exchanger (15) to form a vapor compression refrigeration cycle using R32 as a refrigerant. Refrigerant circuit (10) a refrigeration apparatus comprising: A refrigeration unit in which the heat transfer tubes of the outdoor heat exchanger (13) are formed by heat transfer tubes having an inner diameter of 5.4 mm to 6.7 mm. 6. The refrigeration apparatus according to claim 4 or 5,  The heat transfer tube of the outdoor heat exchanger (13) is a refrigeration unit formed by a heat transfer tube with an inner diameter of 6.1 mm or less. 7. More than 75% by weight and less than 100% by weight; Compressor (11), outdoor heat exchanger (1 3) A refrigeration system including a refrigerant circuit (10) having a pressure reducing mechanism (14) and an indoor heat exchanger (15),  The heat transfer tube of the indoor heat exchanger (15) is a refrigeration unit formed by a heat transfer tube having an inner diameter of 6.2 mm or less. 8. Compressor (11), outdoor heat exchanger (1 3 ), A refrigeration apparatus including a refrigerant circuit (10) having a pressure reducing mechanism (14) and an indoor heat exchanger (15),  A refrigeration system in which the heat transfer tubes of the indoor heat exchanger (15) are formed by heat transfer tubes having an inner diameter of 4.7 mm to 6.2 mm. 9. The refrigeration apparatus according to claim 7 or 8,  The heat transfer tubes of the indoor heat exchanger (15) are refrigeration units formed by heat transfer tubes with an inner diameter of 5.5 mm or less. 10. Compressor (11), outdoor heat exchanger so as to form a vapor compression refrigeration cycle using a refrigerant mixture of R32 and R125 of 75% by weight or more and less than 100% by weight as a refrigerant (13) A refrigeration apparatus comprising a refrigerant circuit (10) having a pressure reducing mechanism (14) and an indoor heat exchanger (15),  The heat transfer tube of the outdoor heat exchanger (13) is a refrigeration unit formed by a heat transfer tube having an inner diameter of 7.1 mm or less. 1 1. A compressor (11) and an outdoor heat exchanger (13) are used to form a vapor compression refrigeration cycle, using a mixed refrigerant of R32 and R125 of 75% by weight or more and less than 100% by weight as a refrigerant. ), A refrigeration apparatus including a refrigerant circuit (10) having a pressure reducing mechanism (14) and an indoor heat exchanger (15),  A refrigeration system in which the heat transfer tubes of the outdoor heat exchanger (13) are formed by heat transfer tubes having an inner diameter of 5.4 mm to 7.1 mm. 12. The refrigeration apparatus according to claim 10 or 11,  The heat transfer tubes of the outdoor heat exchanger (13) are refrigeration units formed by heat transfer tubes with an inner diameter of 6.3 mm or less.