JP2014085092A - Open showcase - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an open showcase capable of realizing high energy saving performance even when a wind velocity of air curtain is increased.SOLUTION: In an open showcase including a showcase body 101 having an opening face 9 facing an external space on its front face, and having an accommodation space 10 inside thereof, and forming air curtain at the opening face 9 by supplying cold air cooled by an evaporator 6 in a refrigerant circuit from a supply opening 12 formed on an upper edge portion of the opening face 9, and sucking the same from a suction port 13 formed on a lower edge portion of the opening face 9, the refrigerant circuit is constituted by successively connecting a low stage-side compressor 1, an auxiliary radiator 2, a high stage-side compressor 3, a high stage-side radiator 4, a pressure reducing device 5 and the evaporator 6, and a suction opening 16 for the ambient air exchanging heat with the auxiliary radiator 2 and the high stage-side radiator 4, is formed on a region at a vertical lower part with respect to the suction opening 13 of the front face.

Description

  The present invention relates to an open type open showcase, and more particularly to an open showcase in which an air curtain is formed on an open surface of a showcase body.

  2. Description of the Related Art Conventionally, an open-type open showcase that is installed in a supermarket or a convenience store and stores and displays beverages, foods, and the like is known. Such an open showcase has, for example, a blower outlet and a suction opening arranged so as to face each other on the inner wall of the storage space of the showcase body with one side opened, and the cooling air blown out from the blower outlet is supplied. The air curtain is formed on the open surface by sucking into the suction port. The air curtain prevents air outside the open showcase from flowing into the accommodation space through the open surface, thereby improving the cooling effect in the showcase body.

  In such an open-type open showcase, preventing the entry of outside air by the air curtain greatly contributes to the improvement of energy saving. However, in supermarkets and convenience stores, for example, air may be blown from the air conditioner installed around the open showcase to the open surface of the showcase body. When there is an airflow around such an open showcase, the air curtain on the open surface may collapse. As a result, the circulating air of the air curtain leaks to the outside of the showcase, and the air outside the showcase body flows into the housing space, which may cause a problem that the energy saving performance of the open showcase is impaired.

  Therefore, in order to prevent the air curtain from collapsing, the temperature in the housing space of the showcase body is detected by an internal temperature sensor provided in the housing space of the showcase body and in the vicinity of the open surface. There has been proposed a technique of changing the air flow rate of the internal fan so that the internal temperature detected by the internal temperature sensor approaches the optimal internal temperature (see, for example, Patent Document 1).

  Further, as a refrigeration apparatus for cooling at a lower temperature than the conventional one, a two-stage cycle refrigeration apparatus that performs a compression process in two stages, a low stage side and a high stage side, is used. In such a two-stage cycle refrigeration apparatus, for example, an auxiliary radiator is installed in front of the high-stage compressor, and the discharged refrigerant discharged from the low-stage compressor is radiated by the auxiliary radiator and cooled. In some cases, the driving efficiency is improved (see, for example, Patent Document 2).

JP 2008-164209 A JP 2005-326138 A

  According to the said patent document 1, the ventilation volume of the internal fan is increased or decreased based on the detected internal temperature. However, if the wind speed of the air curtain is excessive, the air curtain itself entrains the airflow outside the open surface, and as a result, the outside air flows into the housing space, and at the same time, the cold air inside the housing space moves outward. It will be leaked. As a result, the cooling load of the open showcase (that is, the amount of outside air intrusion) increases and the required cooling capacity also increases, so that the energy-saving performance of cooling in the accommodation space is impaired. Conventionally, the entrainment of air outside the open showcase by the air curtain itself has not been considered.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an open showcase capable of realizing high energy saving even when the air curtain wind speed is increased.

  An open showcase according to the present invention includes a showcase body having an open space to the external space on the front surface and the inside as an accommodating space, a cold air inlet provided at a lower edge of the open surface, and an open surface A cold air outlet provided at the upper edge of the air passage, a circulation passage from the cold air inlet to the cold air outlet, a cooling fan for blowing air in the circulation passage, and a cooling device for cooling the air in the circulation passage The cooling device compresses and discharges the refrigerant in an open showcase in which the air blown from the cold air outlet is sucked from the cold air inlet by forming the air curtain by driving the cooling fan. A low-stage compressor, an auxiliary radiator that exchanges heat between the refrigerant discharged from the low-stage compressor and ambient air, and a high-pressure that compresses and discharges the refrigerant that exchanged heat with the auxiliary radiator Stage side compressor and high stage side compression A high-stage radiator that exchanges heat between the refrigerant discharged from the ambient air and the ambient air, a decompressor that decompresses the refrigerant that has exchanged heat with the high-stage radiator, and a refrigerant decompressed by the decompressor And a cooler that evaporates, and a suction port for ambient air that exchanges heat with the auxiliary radiator and the high-stage radiator is provided in a region vertically below the cool air suction port on the front surface.

  The present invention can provide an open showcase capable of realizing high energy saving even when the air curtain wind speed is increased.

It is the schematic which shows the structure of the open showcase which concerns on Embodiment 1 of this invention. It is a refrigerant circuit figure of the open showcase which concerns on Embodiment 1 of this invention. It is the schematic which shows the structure of the integrated radiator of the open showcase which concerns on Embodiment 1 of this invention. It is a figure which shows the relationship between enthalpy and pressure in an open showcase. It is a figure which shows the relationship between an intermediate pressure and a compressor input. It is the figure explaining the heat dissipation when a low stage side condensation temperature is lower than ambient temperature, and when it is high with the Mollier diagram. It is explanatory drawing of the relationship between the heat dissipation of an auxiliary radiator and COP. It is explanatory drawing of sufficient heat processing capability with respect to the emitted heat amount.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an open showcase according to the invention will be described with reference to the drawings.

Embodiment 1 FIG.
The open showcase according to Embodiment 1 is an open-type open showcase that is installed in a supermarket or a convenience store and stores and displays beverages, foods, and the like. This open showcase realizes a refrigeration apparatus that performs a vapor compression refrigeration cycle.

  FIG. 1 is a schematic diagram showing a main part of an open showcase according to Embodiment 1. FIG. As shown in FIG. 1, the open showcase 100 includes a showcase body 101 in the upper part and a machine room 102 in the lower part. The showcase body 101 accommodates an evaporator 6 as a cooler, and the machine room 102 accommodates compressors 1 and 3 and radiators 2 and 4. A refrigerant circuit, which will be described later, is configured by connecting these devices, and a refrigerant filled in the refrigerant circuit circulates to realize a vapor compression refrigeration cycle.

  The showcase body 101 has a box shape as a whole, and an open surface 9 is formed on one surface thereof. In the present embodiment, the open surface 9 is provided on the front side of the showcase body 101. Inside the showcase body 101, a storage space 10 is formed that can store beverages to be cooled, fresh food, and the like. A plurality of display shelves 11 for displaying fresh food and the like are arranged and attached in the storage space 10 in the vertical direction. Moreover, the blower outlet 12 opened along the upper periphery of the open surface 9 of the showcase main body 101 is formed, and the suction inlet 13 opened along the lower periphery of the open surface 9 is formed. The blower outlet 12 is opened toward the lower side so as to face the accommodation space 10. The suction port 13 is opened toward the upper side so as to face the accommodation space 10. That is, the blower outlet 12 and the suction inlet 13 are formed inside the open surface 9 so as to face each other.

  The showcase body 101 is provided with a circulation passage 14 extending from the inlet 13 to the outlet 12. The circulation passage 14 is a passage partitioned from the accommodation space 10. In the first embodiment, the circulation passage 14 is provided along the lower wall surface, the rear wall surface, and the upper wall surface that surround the housing space 10, and the longitudinal section thereof is a “U” shape. Yes. The circulation passage 14 is provided with an evaporator 6 and an internal fan 15. When the internal fan 15 is driven, the cold air that has passed through the evaporator 6 is blown downward from the air outlet 12 and descends along the opening surface 9, and is then sucked from the air inlet 13. As a result, a cold air curtain is formed on the open surface 9 of the showcase body 101.

  Next, the refrigerant circuit of the open showcase 100 will be described in detail. FIG. 2 is a refrigerant circuit diagram of the open showcase according to Embodiment 1 of the invention. As shown in FIG. 2, the refrigerant circuit includes a low-stage compressor 1, an auxiliary radiator 2, a high-stage compressor 3, a high-stage radiator 4, an expansion valve 5 as a decompression device, and an evaporation as a cooler. The apparatus 6 is configured by sequentially connecting. The low-stage compressor 1 compresses and discharges the refrigerant. The auxiliary radiator 2 exchanges heat between the refrigerant discharged from the low-stage compressor 1 and the ambient air, and radiates the refrigerant. The high stage compressor 3 compresses and discharges the refrigerant radiated by the auxiliary radiator 2. The high stage side radiator 4 exchanges heat between the refrigerant discharged from the high stage side compressor 3 and the ambient air, and radiates (condenses) the refrigerant. The expansion valve 5 depressurizes the refrigerant radiated by the high stage side radiator 4. The evaporator 6 evaporates the refrigerant decompressed by the expansion valve 5.

  The high stage side radiator 4 and the auxiliary radiator 2 are configured as an integrated radiator 7. The detailed structure of the integrated radiator 7 will be described later. The integrated radiator 7 is provided with a radiator fan 8. The radiator fan 8 allows ambient air to pass through the integrated radiator 7, exchanges heat with the refrigerant passing through the heat transfer tube of the integrated radiator 7, and then transfers the air after heat exchange to the outside of the integrated radiator 7. Exhaust.

  Here, in the open showcase according to the first embodiment, the ambient air suction port 16 by the radiator fan 8 is vertically below the open surface 9 on the same side surface (front surface) as the open surface 9 on which the air curtain is formed. It is formed in a side region (that is, a region vertically below the suction port 13). According to such an arrangement, it is possible to suck in cool air leaking from the air curtain from the ambient air suction port 16, so that energy saving is improved.

  Next, the structure of the integrated radiator 7 will be described in more detail. FIG. 3 is a schematic diagram showing the configuration of the integrated radiator of the refrigeration apparatus according to Embodiment 1 of the present invention. In FIG. 3, the integrated radiator 7 is a plate fin tube type heat exchanger formed by passing a heat transfer tube 72 through a flat heat transfer fin 71. In addition, the high stage side heat radiator 4 and the auxiliary | assistant heat radiator 2 may be integrated by sharing the heat-transfer fin 71, and the heat-transfer fin 71 part may be divided | segmented. If integrated, the structure of the heat exchanger makes it easy to manufacture. In addition, when the heat transfer fins 71 are divided between the auxiliary radiator 2 and the high-stage side radiator 4 that are at a high temperature, the thermal insulation effect is increased, so that the auxiliary radiator 2 and the high-stage side heat dissipation are increased. Both units 4 can dissipate heat more efficiently.

  In the integrated radiator 7 according to the first embodiment, the auxiliary radiator 2 that cools the discharge gas of the low-stage compressor 1 is closer to the ambient air inlet 16 than the high-stage radiator 4. Has been placed. Thereby, the cool air leaked from the air curtain having a temperature lower than that of the ambient air can be positively utilized by the auxiliary radiator 2, and the amount of heat released from the auxiliary radiator 2 can be increased. Although mentioned later, since the input of the high stage side compressor 3 can be reduced, so that the heat radiation amount of the auxiliary radiator 2 is increased, a large energy saving effect can be obtained.

  Moreover, in the integrated radiator 7 of this Embodiment, the auxiliary radiator 2 which cools the discharge gas of the low stage compressor 1 which becomes high temperature is arrange | positioned in the upper part (vertical upper side) of a heat exchanger, and high stage The side radiator 4 is disposed in the lower part (vertically below). Thereby, the heat radiation of the auxiliary radiator 2 does not interfere with the high-stage radiator 4 side, that is, the heat transfer fluid warmed by the auxiliary radiator 2 moves to the high-stage radiator 4 side. In addition, both the auxiliary radiator 2 and the high-stage radiator 4 can efficiently dissipate heat.

  As the heat radiation amount of the auxiliary radiator 2 is increased, the input of the higher stage compressor 3 can be reduced. However, as a means for increasing the heat radiation amount of the auxiliary radiator 2, water spraying to the auxiliary radiator 2 may be performed. Cooling to the wet bulb temperature is possible by the vaporization heat of the sprinkled water, and the heat radiation amount of the auxiliary radiator 2 can be increased. For securing water, if drain water generated in the evaporator 6 is used, there is no need for replenishment, and further, drainage work of drain is unnecessary, which improves the product power.

Note that the refrigerant used in the open showcase 100 configured as described above is CO _{2 in} this embodiment. In the open showcase 100 according to the present embodiment, the refrigerant circuit is never opened, and thus the amount of refrigerant leakage is small. Therefore, a conventional HFC refrigerant having a high global warming potential is not a problem, but a refrigerant having a small influence on global warming, that is, CO ₂ , HFO refrigerant, HC refrigerant, ammonia, water or the like is desirable.

Next, a characteristic operation of the open showcase 100 of the present embodiment will be described. The CO ₂ refrigerant compressed and discharged by the low-stage compressor 1 is cooled by the auxiliary radiator 2 in the integrated radiator 7 and then sucked into the high-stage compressor 3 and further compressed. The CO ₂ refrigerant compressed and discharged by the high-stage compressor 3 is radiated and condensed by the high-stage radiator 4 in the integrated radiator 7 and then decompressed by the expansion valve 5 to the evaporator 6. Inflow. The CO ₂ refrigerant flowing into the evaporator 6 evaporates and returns to the low stage compressor 1.

  Here, in the refrigeration apparatus of the present embodiment, the low stage side high pressure (that is, the low stage side compressor 1 and the high stage side compressor 3 are determined by the capacity ratio of the low stage side compressor 1 and the high stage side compressor 3. Adjust the intermediate pressure between). In this embodiment, the operating capacity is variable so that the number of revolutions of the motor for driving the compressor can be controlled. However, the low-stage high pressure is determined by the excluded volume ratio of the low-stage compressor 1 and the high-stage compressor 3. May be adjusted.

  FIG. 4 is a diagram showing the relationship between enthalpy and refrigerant pressure in an open showcase. In the open showcase 100 of the present embodiment, the refrigeration capacity ΔH (heat exchange amount of the evaporator 6) is determined for the cooling load that changes according to the ambient air temperature and the air curtain wind speed, and the determined refrigeration The refrigerant flow rate Gr is controlled by the low-stage compressor 1 so as to output the capacity. Therefore, if the operating speed of the high-stage compressor 3 is increased from a certain operating state to increase the capacity of the high-stage compressor 3, the high-stage suction pressure decreases and the low-stage high pressure also decreases. There is a relationship. Conversely, if the capacity of the high-stage compressor 3 is reduced, the low-stage high pressure increases.

  Further, as is apparent from FIG. 4, when the operating speed of the high stage side compressor 3 is increased and the low stage side high pressure is reduced, the input of the high stage side compressor 3 increases (WH1 <WH2). The input of the low-stage compressor 1 becomes small (WL1> WL2).

  Therefore, the horizontal axis is the low-stage high pressure (intermediate pressure) and the vertical axis is the total input for the entire two-stage cycle showcase, with the input of the high-stage compressor 3 (enthalpy difference) and the input of the low-stage compressor 1 When respective graphs of (enthalpy difference) and their total input are created, the graph is as shown in FIG. As shown in FIG. 5, when the compressor inputs on the high stage side and the low stage side are substantially the same, the total input becomes the smallest, COP (= refrigeration capacity / (high stage compressor input + low stage side). It can be seen that the compressor input)) is maximized.

  Thus, when the compression ratios of the low-stage compressor 1 and the high-stage compressor 3 are substantially equal, the total input (input of the high-stage compressor 3 + input of the low-stage compressor 1) is The operation efficiency of the entire two-stage cycle is optimized. Therefore, in the open showcase of the present embodiment, the capacity of the high-stage compressor 3 is set so as to target a low-stage high pressure (hereinafter referred to as optimum intermediate pressure) in which the compression ratios of the high-stage side and the low-stage side are substantially the same. Control is going to be done. Thereby, the effect that the COP of the two-stage cycle showcase is maximized is obtained. In the present embodiment, the case where the capacity control of the high-stage compressor 3 is performed will be described. However, the present invention is not limited to this, and the compression ratio of the low-stage compressor 1 and the high-stage compressor 3 What is necessary is just to adjust the capacity | capacitance ratio of the capacity | capacitance of the low stage side compressor 1 and the capacity | capacitance of the high stage side compressor 3 so that a compression ratio may become equivalent.

  Here, the high pressure on the high stage side varies depending on the ambient air temperature for heat exchange with the high stage radiator 4. If the ambient temperature rises, the high stage side high pressure rises and the optimum intermediate pressure also rises. On the other hand, if the ambient temperature decreases, the optimum intermediate pressure similarly decreases. Thus, the optimum intermediate pressure changes with the ambient temperature.

  As described above, in the present embodiment, the capacity control of the high-stage compressor 3 is performed with the optimal intermediate pressure at which the compression ratios of the high-stage side and the low-stage side are substantially the same as the target. The saturation temperature will be lower than the ambient temperature. Specifically, when the internal temperature is 5 ° C, the saturation temperature of the optimum intermediate pressure is about 15 ° C when the ambient temperature is 27 ° C. As described above, since the optimum intermediate pressure changes with the ambient temperature, the saturation temperature of the optimum intermediate pressure is located in a temperature region lower than the ambient temperature.

  However, in this embodiment, the cold air leaking from the air curtain by the auxiliary radiator 2 can be used. Even at the optimum intermediate pressure saturation temperature of 15 ° C, the cold air temperature (inside temperature) of 5 ° C is lower, so it is possible to condense the refrigerant in the auxiliary radiator 2, greatly increasing the heat dissipation and obtaining an energy saving effect. It is done.

In particular, since the refrigerant CO ₂ of the present embodiment has a large specific heat ratio and a high discharge temperature, the heat radiation by the auxiliary radiator 2 is effective and the energy saving effect is large. Furthermore, although there is a possibility that the discharge temperature of the high stage compressor will rise excessively, since the discharge temperature can be lowered by the heat radiation of the auxiliary radiator 2, high reliability can be obtained.

(Difference in heat dissipation of auxiliary radiator 2 when low-stage condensation temperature is lower and higher than intake air temperature of auxiliary radiator 2)
Next, the heat radiation amount of the auxiliary radiator 2 will be considered. When the capacity of the high-stage compressor 3 is controlled with the optimum intermediate pressure as a target, and the cold air leaking from the air curtain cannot be used, the saturation temperature of the optimum intermediate pressure becomes lower than the intake air temperature. Since the auxiliary radiator 2 is a radiator that radiates heat to the surroundings, even if the refrigerant discharged from the low-stage compressor 1 exchanges heat with the ambient air in the auxiliary radiator 2, the refrigerant is only lowered to the ambient temperature. Absent. Also, when the low-stage condensation temperature is lower than the ambient temperature and when it is higher than the ambient temperature, even when the refrigerant at the discharge temperature is lowered to the same ambient temperature by the auxiliary radiator 2, the heat radiation amount is different.

  FIG. 6 is a diagram illustrating the amount of heat released when the low-stage condensation temperature is lower and higher than the ambient temperature using the Mollier diagram. FIG. 6 (1) shows the heat dissipation enthalpy difference when the condensation temperature is higher than the ambient temperature, and FIG. 6 (2) shows the heat dissipation enthalpy difference when the condensation temperature is lower than the ambient temperature.

(1) When the low-stage condensation temperature is higher than the ambient temperature The temperature of the refrigerant discharged from the compressor (temperature at point a) is, for example, 80 ° C to 90 ° C, the ambient temperature is 20 ° C, and the condensation temperature is 25 ° C. Think about the case. Since the radiator is a radiator that dissipates heat to the surroundings, as shown in FIG. 6 (1), the refrigerant (point a) at 80 ° C. to 90 ° C. is exchanged with the surroundings in the radiator, It falls to 25 degreeC (point b) which is a condensation temperature with a gas state. And it is condensed and liquid state is maintained while maintaining 25 ° C. (point c). Since the ambient temperature is 20 ° C., the refrigerant can further dissipate heat and drop to 20 ° C. (point d) in the liquid state. Thus, since condensation is performed when the condensation temperature is higher than the ambient temperature, it is possible to perform cooling with a phase change, and it is possible to increase the heat radiation amount as compared with the case of performing cooling without a phase change.

(2) When the low-stage condensation temperature is lower than the ambient temperature The temperature of the refrigerant discharged from the low-stage compressor 1 (the temperature at point a) is, for example, 80 ° C to 90 ° C, and the ambient temperature is 20 ° C and the low stage Consider the case where the side condensation temperature is 10 ° C. Since the auxiliary radiator 2 is a radiator that dissipates heat to the outside air, as described above, the refrigerant of 80 ° C. to 90 ° C. can reach a maximum ambient temperature of 20 ° C. by heat exchange with the outside air in the auxiliary radiator 2. It only goes down. That is, as shown in FIG. 6 (2), the refrigerant (point a) at 80 ° C. to 90 ° C. becomes 20 ° C. (point b) in the gas state in the auxiliary radiator 2. That is, when the lower stage condensation temperature is lower than the ambient temperature, the auxiliary radiator 2 cannot perform cooling with phase change, and performs gas cooling without phase change. That is, the auxiliary radiator 2 is used in the gas cooling region.

  Here, since the heat radiation from the point a to the point b in FIG. 6 (2) is a heat radiation in a gas state, even if the temperature is lowered to the same ambient temperature 20 ° C., the heat is condensed and lowered to 20 ° C. (1 ) Cannot increase the amount of heat released by the auxiliary radiator 2. Therefore, if the low-stage condensation temperature is lower than the ambient temperature, even if the air volume of the radiator fan 8 of the auxiliary radiator 2 is increased or a radiator with a large heat transfer area is adopted as the auxiliary radiator 2, The amount of heat released from the auxiliary radiator 2 cannot be increased, and at most, the amount of heat dissipated before the discharged refrigerant is reduced to the outside temperature while being in a gas state.

  In summary, in the present embodiment, the cold air leaking from the air curtain can be used in the auxiliary radiator 2 and the cold air temperature is lower than the saturation temperature of the optimum intermediate pressure. It is possible to condense. Therefore, the heat dissipation amount can be greatly increased to obtain an energy saving effect.

(Relationship between heat dissipation of auxiliary radiator 2 and COP)
FIG. 7 is an explanatory diagram of the relationship between the heat dissipation amount of the auxiliary radiator and the COP. FIG. 7 shows a Mollier diagram of a two-stage cycle. In configuring the two-stage cycle, the case where the heat dissipation amount in the auxiliary radiator 2 is Qsub1 is compared with the case where Qsub2 is set (Qsub1 <Qsub2). As shown in FIG. 7, when the refrigeration capacity ΔH is constant, θh1 <θh2 is satisfied. Therefore, the input (enthalpy difference) of the high-stage compressor 3 can be reduced when Qsub2 is used compared to the case where Qsub1 is set. Yes (WH1> WH2). That is, if the suction temperature of the high-stage compressor 3 is low, the compressor power is reduced even with the same boost amount. Therefore, the input of the high stage side compressor 3 can be made smaller when Qsub2 is used compared to the case where the heat dissipation amount of the auxiliary radiator 2 is Qsub1.

  In the open showcase 100 of the present embodiment, since COP = refrigeration capacity / (input of the high-stage compressor 3 + input of the low-stage compressor 1), the input of the high-stage compressor 3 is reduced. As a result, the COP can be increased.

  By arranging the above contents, the COP can be maximized by the operation control in which the compression ratio of the high-stage compressor 3 and the compression ratio of the low-stage compressor 1 are substantially the same, and the auxiliary radiator 2 As the amount of heat released increases, the value of COP can be increased.

  Next, the required heat treatment capacity with respect to the heat radiation amount will be described. In the integrated radiator 7 of the present embodiment, if the heat radiation amount of the auxiliary radiator 2 is increased, an energy saving effect can be obtained, but the required heat treatment capacity is maintained by the high-stage heat radiator 4 with respect to the total heat radiation amount. There is a need. If the high-stage radiator 4 does not have sufficient heat treatment capacity, the high-stage high pressure is high, so it is better to reduce the proportion of the auxiliary radiator 2 and assign it to the high-stage radiator 4 to save energy. Becomes larger. Further, when the high stage side high pressure is excessively increased, the auxiliary radiator 2 must be assigned to the high stage side radiator 4 in order to ensure reliability.

  Therefore, if the high-stage side radiator 4 occupies the proportion of the integral heat radiator 7 that achieves the required heat treatment capacity and all the rest is assigned to the auxiliary radiator 2, the effect of the auxiliary radiator 2 in the two-stage cycle can be obtained. You can make the most of it.

  FIG. 8 is an explanatory diagram of a sufficient heat treatment capacity with respect to the heat radiation amount. As shown in FIG. 8, the heat radiation amount is the heat exchange amount (refrigeration capacity) of the cooler + the compressor input. For example, in the case of a single-stage cycle showcase with COP = 2, since the refrigeration capacity is “2” with respect to the compressor input “1”, the heat release amount is “3”. Therefore, the heat treatment capacity of the radiator is generally designed to be about 1.5 times that of the cooler.

  Further, in the cooler, the refrigerant temperature (condensation temperature) and the ambient temperature of the radiator are used in order to set the temperature difference between the refrigerant temperature (evaporation temperature) and the medium to be cooled (internal air) to a desired temperature (for example, 10 ° C.). If the temperature difference between the two becomes the desired temperature (for example, 10 ° C.), the necessary heat treatment capability is obtained. In other words, in the integrated radiator 7 of the two-stage cycle showcase of the present embodiment, the temperature difference between the refrigerant temperature (condensation temperature) and the ambient temperature is expressed as the refrigerant temperature (evaporation temperature) of the cooler and the internal air temperature. If the temperature difference is less than (for example, 10 ° C. or less), a COP higher than that of the single stage cycle can be reliably obtained including the effect of the auxiliary radiator 2.

  The heat treatment capacity is represented by the product of the heat transfer area and the heat transfer rate of the heat exchanger, and the heat transfer rate is mainly determined by the heat transfer rate on the refrigerant side and the heat transfer rate on the air side. The cooler for low temperature equipment has a large pitch between the heat transfer tubes and fins and a smaller heat passage rate than the radiator from the viewpoint of improving the frost resistance, and therefore the heat transfer area of the cooler is larger than that of the radiator.

  The refrigeration apparatus of this embodiment can be widely applied to refrigeration or refrigeration equipment such as showcases, commercial refrigeration refrigerators, and vending machines that require non-fluorocarbons, reduction of chlorofluorocarbons, and energy saving of equipment.

  DESCRIPTION OF SYMBOLS 1 Low stage side compressor, 2 Auxiliary radiator, 3 High stage side compressor, 4 High stage side radiator, 5 Expansion valve, 6 Evaporator, 7 Integrated radiator, 8 Radiator fan, 9 Open surface, 10 Housing space, 11 display shelf, 12 air outlet, 13 suction port, 14 circulation passage, 15 internal fan, 16 suction port, 71 heat transfer fin, 72 heat transfer tube, 100 open showcase, 101 showcase body, 102 machine room

An open showcase according to the present invention includes a showcase body having an open space to the external space on the front surface and the inside as an accommodating space, a cold air inlet provided at a lower edge of the open surface, and an open surface A cold air outlet provided at the upper edge of the air passage, a circulation passage from the cold air inlet to the cold air outlet, a cooling fan for blowing air in the circulation passage, and a cooling device for cooling the air in the circulation passage The cooling device compresses and discharges the refrigerant in an open showcase in which the air blown from the cold air outlet is sucked from the cold air inlet by forming the air curtain by driving the cooling fan. A low-stage compressor, an auxiliary radiator that exchanges heat between the refrigerant discharged from the low-stage compressor and ambient air, and a high-pressure that compresses and discharges the refrigerant that exchanged heat with the auxiliary radiator Stage side compressor and high stage side compression A high-stage radiator that exchanges heat between the refrigerant discharged from the ambient air and the ambient air, a decompressor that decompresses the refrigerant that has exchanged heat with the high-stage radiator, and a refrigerant decompressed by the decompressor and a condenser for evaporating, an auxiliary radiator and high-stage radiator and inlet of ambient air to the heat exchanger, vertically below the areas than cold air suction port in the front, the auxiliary radiator, high-stage It is arranged in a region vertically above the side radiator .

Claims (7)

A showcase body having an open surface to the external space on the front surface and having the inside as a storage space, a cold air inlet provided at a lower edge portion of the open surface, and an upper edge portion of the open surface A cold air outlet, a circulation passage extending from the cold air inlet to the cold air outlet, a cooling fan for blowing air in the circulation passage, and a cooling device for cooling the air in the circulation passage. In an open showcase that drives the cooling fan to suck in the cold air blown out from the cold air outlet through the cold air inlet and forms an air curtain on the open surface.
The cooling device is
A low-stage compressor that compresses and discharges the refrigerant;
An auxiliary radiator that exchanges heat between the refrigerant discharged from the low-stage compressor and the ambient air;
A high-stage compressor that compresses and discharges the refrigerant that has exchanged heat with the auxiliary radiator;
A high-stage radiator that exchanges heat between the refrigerant discharged from the high-stage compressor and the ambient air;
A decompression device that decompresses the refrigerant that has exchanged heat with the high-stage radiator;
A cooler for evaporating the refrigerant decompressed by the decompression device,
An open showcase in which a suction port for ambient air for heat exchange with the auxiliary radiator and the high-stage radiator is provided in a region vertically below the cold air suction port on the front surface. The high-stage radiator and the auxiliary radiator are configured as an integrated radiator in which heat transfer fins are integrated,
The open showcase according to claim 1, further comprising a blower for heat dissipation that allows ambient air to pass through the integrated radiator.   The open showcase according to claim 1, wherein the auxiliary radiator is disposed closer to the ambient air inlet than the high-stage radiator.   The open showcase according to any one of claims 1 to 3, wherein the auxiliary radiator is disposed in a region vertically above the high-stage radiator.   The capacity ratio between the capacity of the low stage compressor and the capacity of the high stage compressor is adjusted so that the compression ratio of the low stage compressor and the compression ratio of the high stage compressor are equal. The open showcase according to any one of claims 1 to 4, wherein:   In the high stage side radiator, the temperature difference between the refrigerant flowing through the high stage side radiator and the ambient air is equal to or less than the temperature difference between the refrigerant flowing through the cooler and the medium to be cooled by the cooler. The open showcase according to claim 1, which has a heat treatment ability to be The open showcase according to claim 1, wherein the refrigerant is CO ₂ .

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