JP3257666B2 - Open showcase driving method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an open showcase provided with a main cooler and an auxiliary cooler in order to suppress the formation of frost on a cooler and improve the cooling durability.

[0002]

2. Description of the Related Art Conventionally, as a method of preventing frost formation on a cooler and improving cooling continuity, a method in which a fin pitch is changed between the windward side and the leeward side of one cooler, for example, a windward side is used. There are widely known a cross-fin type in which a fin is 16 mm and a leeward side thereof is a half of 8 mm, and a type in which an auxiliary coil having a wide fin pitch, that is, a so-called dehumidifying coil is installed on the windward side of a cooler.

[0003] In each of these methods, precooling of circulating cold air is performed at a front stage on the windward side to remove moisture,
It is intended to prevent frost formation on the main cooling section and the cooler on the leeward side. Therefore, the cooling of the circulating cool air, that is, the main heat exchange, is performed by the cooling unit or the cooler on the downwind side.

[0004]

By adopting the above-mentioned method, the cooling duration in summer can be extended to 4 to 6 hours, but the business hours of a general supermarket are from 10:00 to 20:00 or It is 21:00,
Even if a case having a cooling durability of 6 hours was used, it was necessary to perform defrosting at least once during business hours.

[0005] On the other hand, in a large store, it is premised that products are sold out on the same day, but recently, chilled meat, sashimi, fillets, fried fish and the like in a semi-frozen state may be displayed.
Even a single defrosting operation during business hours can cause serious damage to these semi-frozen products, which poses a serious problem in a store aimed at freshness.

The present invention has been made in view of the above circumstances, and has as its object the ability to maintain the cooling duration for 12 hours or more, eliminating the need to perform a defrosting operation during business hours, and An object of the present invention is to provide a driving method of an open showcase that can display goods without any problem.

[0007]

In order to solve the above-mentioned problems, according to the present invention, a storage chamber having an open front surface is formed in a main body constituted by a heat insulating wall, and an opening of the storage chamber is stored in the storage chamber. In an open showcase that cools a storage room by covering it with an air curtain of cold air blown downward from an air outlet provided at an upper front end of the room, a main cooler is provided in a duct defined by the storage room. And an auxiliary cooler on the leeward side with respect to the main cooler,
An evaporating pressure adjusting valve is provided in the suction pipe of both coolers or the suction pipe of the main cooler, and the evaporating pressure adjusting valve adjusts the evaporating pressure of the high-pressure liquid refrigerant when the two coolers are simultaneously operated, The cool air cooled by the main cooler is further cooled by the auxiliary cooler, and in particular, the heat exchange amount of the main cooler is set to be equal to or larger than the heat exchange amount of the auxiliary cooler. And the evaporation pressure regulating valve is provided in a suction pipe of a main cooler.

As described above, the main cooler is provided on the leeward side and the auxiliary cooler is provided on the leeward side to operate simultaneously, so that even if the cooling capacity of the main cooler is reduced due to frost, the leeward side is provided. By the auxiliary cooler, the cool air can be cooled to a predetermined temperature. In addition, by installing an evaporation pressure adjusting valve in the suction pipe, it is possible to prevent the refrigerator from starting and stopping and causing a sudden change in the low pressure of the refrigerator when the control valve is turned ON and OFF, which causes frost on the cooler. And frost formation on the cooler can be largely suppressed.

[0009]

Preferred embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a sectional side view of an open showcase provided with a main cooler and an auxiliary cooler.

[0010] The open showcase 1 comprises a heat insulating wall 2
A multi-stage storage room 4 having an open front is formed in a main body 3 composed of a main body 3 and an outer-layer duct 5 and an inner-layer duct 6 are provided on the back of the main body 3, and a main cooler 7 and an auxiliary are provided in the inner-layer duct 6. A cooler 8 is provided. The outer-layer duct 5 and the inner-layer duct 6 are provided with an outer-layer fan 9 and an inner-layer fan 10 for circulating cool air in each duct, respectively. Further, immediately before the main cooler 7, a defrost heater 11 is provided.

At the upper front end position of the main body 3, a cool air outlet 12 having a honeycomb structure is provided over the entire longitudinal direction of the case, from which cool air from each of the inner and outer ducts is rectified and blown downward as an air curtain. The front opening of the case is covered and the inside of the storage room 4 is cooled.
In addition, a suction port 13 communicating with each of the inner and outer ducts is provided in a lower front portion of the main body 3, and cool air sucked by the outer layer fan 9 and the inner layer fan 10 from the suction port 13 is supplied to the outer layer duct 5 and the inner layer duct. 6 respectively.

The cold air flowing through the outer layer duct 5 acts as a heat insulating layer, and then blows out from the outlet 12 to be sucked into the inlet 1.
Cycle to 3. The cool air flowing into the inner layer duct 6 is cooled by the main cooler 7 and further cooled by the auxiliary cooler 8 to a predetermined temperature, and is blown out from the outlet 12 and circulated in the same manner as described above.

Next, FIG. 2 is an explanatory diagram showing a piping system of the main cooler 7 and the auxiliary cooler 8 in the refrigeration cycle. The high-pressure side of the main cooler 7 and the auxiliary cooler 8 is connected via expansion valves 24 and 25 to high-pressure pipes 22 and 23 branched on the downstream side of the liquid solenoid valve 21. On the other hand, the main cooler 7
Is joined to a suction pipe 28 of the auxiliary cooler 8 via an evaporating pressure control valve 27, and then connected to a compressor (not shown).

The evaporating pressure control valve 27 adjusts the evaporating pressure of the high-pressure liquid refrigerant in the main cooler 7 to set the refrigerant evaporating temperature in the main cooler 7 and the auxiliary cooler 8 to an optimum state. And the evaporation pressure control valve 27
Thus, the cooling temperatures of the two coolers are appropriately set, and the heat exchange amount of the main cooler 7 is equal to or larger than the heat exchange amount of the auxiliary cooler 8. The amount of heat exchange and the cooling temperature in the cooler without the evaporating pressure control valve are set according to the size of the cooler itself, the fin pitch, the diameter and the number of coils, the capacity of the expansion valve (the branching of the refrigerant to both coolers). Ratio) or the like.

Further, the suction pipe 28 of the auxiliary cooler 8
An evaporation pressure control valve 29 can be provided as shown by a broken line in the figure. In this case, the evaporating pressure control valve 2 on the main cooler 7 side
Evaporation pressure control valve 29 on the auxiliary cooler 8 side of the set value of 7
May be reduced, for example, the main cooler 7 is set to 2.
8 kg / cm2, and the auxiliary cooler 8 is 2.2 kg / cm2.
It should be 2.

Here, when the interior of the storage room of the open showcase is kept at 0-1 ° C. suitable for storing fresh products, it is necessary to blow cool air of about −5 ° C. from the outlet 12 so that the cooler The evaporation temperature is usually set at -10 to -13C. On the other hand, in the present invention, the main cooler 7 has a fin pitch of about 12 mm, 40 、 ３ inch coils, and the evaporating temperature thereof is set to about -8 ° C., which is slightly higher than before, and the leeward auxiliary The cooler 8 has a fin pitch of 8 to 12 mm and 32 3/8 inch coils,
Its evaporation temperature is slightly lower than that of the main cooler 7 -10 to -13.
Set to ° C. That is, the main cooling (heat exchange)
Performed by the main cooler 7 on the windward side with a large heat exchange amount,
The shortage is supplemented by the auxiliary cooler 8. Further, the fin pitch of the main heat exchanger is increased in consideration of the influence of frost formation.

When the main cooler 7 and the auxiliary cooler 8 are operated at the same time in such a setting, the cool air temperature at the inlet of the main cooler 7 shown in the figure is 2.3 to 3.0 ° C. The cold air temperature at the outlet of the main cooler 7 (the inlet of the auxiliary cooler 8) is-
The cold air temperature at the outlet of the auxiliary cooler 8 indicated by 1.7 to -2.3 ° C. becomes -4.5 to -5.5 ° C.
A cool air temperature suitable to keep at ~ -1 ° C is obtained.

When the operation is performed in this manner, the amount of frost of the main cooler 7 naturally increases and the cooling capacity gradually decreases, but the amount of frost of the auxiliary cooler 8 is extremely small. Therefore, cool air for a long time to the specified -4.5.
It can be cooled to -5.5 ° C, and continuous operation for 12 hours or more is possible.

Further, when performing the defrosting operation, the defrost heater 11 provided immediately before the main cooler 7 is operated, so that the frost can be uniformly melted down to the auxiliary cooler 8 on the leeward side. A heater having a small capacity can be used, and the defrosting time can be shortened as compared with a case where both the coolers are uniformly frosted.

[0020]

According to the present invention, as described above, the main cooling
Auxiliary cooler compensates for lack of cooling without sudden heat exchange
The cooling capacity of the main cooler due to frost formation
Even if the air temperature drops, cool air is
It can be cooled to a predetermined temperature. Further, in particular suppress the frost formation amount on the intake pipe of the cooler provided evaporation pressure regulating valve
The amount of frost on the main cooler is extremely small,
12 hours or more in an environment of 70 ° C. and 70% humidity and 14 to 15 hours in an environment of a temperature of 25 ° C. and 60% humidity. The number of times of defrosting is less than twice a day. There is no need to perform defrosting inside, and high freshness management of the product can be performed.

Further, even if the continuous operation is performed for a long period of time, only the main cooler forms frost, and almost no frost forms on the auxiliary cooler. It suffices to simply install it on the upper side, maintenance becomes easy, and the defrosting time can be shortened.
Furthermore, since the number of times of defrosting itself is reduced by half compared to the conventional case, energy is saved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional side view of an open showcase showing a preferred embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a piping system of a main cooler and an auxiliary cooler in a refrigeration cycle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Open showcase 2 Insulated wall 3 Main body 4 Storage room 5 Outer duct 6 Inner duct 7 Main cooler 8 Auxiliary cooler 9 Outer fan 10 Inner fan 11 Defrost heater 12 Outlet 13 Suction port 21 Liquid solenoid valve 22 High pressure pipe 23 High pressure Piping 24 Expansion valve 25 Expansion valve 26 Suction pipe 27 Evaporation pressure control valve 28 Suction pipe 29 Evaporation pressure control valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F25D 11/00 101

Claims (3)

(57) [Claims] 1. A storage room having an open front surface is formed in a main body constituted by a heat insulating wall, and an opening of the storage room is blown downward from an outlet provided at an upper front end of the storage room. In an open showcase that cools the storage room by covering it with an air curtain of cool air, a main cooler and an auxiliary cooler leeward with respect to the main cooler are provided in a duct defined by the storage room. In addition to this, an evaporation pressure adjusting valve is provided in the suction pipe of both coolers or the suction pipe of the main cooler, and the evaporation pressure of the high-pressure liquid refrigerant when the two coolers are simultaneously operated is adjusted by the evaporation pressure adjusting valve. The method of operating an open showcase, wherein the cool air cooled by the main cooler is further cooled by the auxiliary cooler. 2. The method according to claim 1, wherein a heat exchange amount of the main cooler is set to be equal to or larger than a heat exchange amount of the auxiliary cooler. 3. The method of operating an open showcase according to claim 1, wherein the evaporation pressure regulating valve is provided in a suction pipe of a main cooler.