JPH06105145B2 - Refrigeration equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a refrigerating apparatus used in a showcase or the like, and in particular, a plurality of coolers are provided, and defrosting of the coolers is alternately performed for each cooler. Alternatively, the present invention relates to a refrigerating device which is sequentially operated.

[Conventional technology]

A refrigeration system used for cooling a showcase or the like is provided with a plurality of coolers so that the temperature in the cooling space does not rise during defrosting of the frost adhering to the coolers, and the defrosters are alternately or sequentially defrosted one by one. Then, while defrosting one unit, the temperature of the space to be cooled is maintained by the other coolers at the same temperature as during the cooling by all the coolers or at a temperature slightly higher than that.

FIGS. 5 and 6 show an example of an open type showcase. The cool air C chilled by the two coolers 2a and 2b arranged at the bottom of the showcase 1 is the showcase 1 After passing through the duct 3 behind, the air is rectified and discharged from the discharge port 4 toward the lower part of the showcase 1 as an air curtain. The discharged cool air C passes from the cool air suction port 5 to the bottom of the showcase 1 and is cooled by the fan 6 or the fans 6a and 6b.
sent to a, 2b and circulates as described above.

When defrosting the cooler 2a, as shown in FIG. 5, the damper 7 provided in the passage extending from both coolers 2a and 2b to the duct 3 is used to remove the passage on the cooler 2a side during defrosting. Only the cool air from the side of the cooler 2b that is not blocked and defrosted is sent to the duct 3. In addition, as shown in FIG. 6, the coolers 2a and 2b are provided with dedicated fans 6a and 6b, respectively.
Side fan 6a is stopped or decelerated, and the other cooler 2b side fan 6b is accelerated.

FIG. 7 shows a refrigerating cycle of a refrigerating apparatus used for the above showcase or the like, and a thick line in the figure shows a flow of the refrigerant during defrosting.

The refrigerating device 8 is arranged inside the showcase 2
The cooler 2a, 2b of the base and the cooler 2a, 2b installed on the outside
It is composed of a compressor 9 for supplying a refrigerant to the condenser, a condenser 10, a liquid receiver 11, pipes connecting them and various valves. That is, the above-mentioned various types are used for the refrigerant liquefaction line including the compressor 9, the condenser 10 connected to the discharge line of the compressor 9, and the liquid receiver 11 connected to the discharge line of the condenser 10. The coolers 2a and 2b are connected in parallel via the valve.

Then, during a normal cooling operation, the valves 12, 13, 14 are opened to supply the liquid refrigerant from the liquid receiver 11 to both the coolers 2a, 2b through the check valves 15a, 15b and the expansion valves 16a, 16b. Evaporate to generate cold. The refrigerant evaporated in the coolers 2a and 2b is sucked by the compressor 9 through the valves 13 and 14 and compressed, and the condenser 10 and the liquid receiver 1
Sent to 1 and circulates.

When shifting from normal operation to defrosting one cooler 2a, use the valve 17
Open a and close valves 12 and 13. Therefore, the liquid refrigerant from the liquid receiver 11 is introduced into the cooler 2a through the valve 17a without expanding, and the sensible heat of the liquid refrigerant removes frost from the cooler 2a. The liquid refrigerant after defrosting has the check valve 18 closed because the valve 13 is closed.
Liquid is passed through the check valve 15b and the expansion valve 16b on the side of the other cooler 2b through a to enter the cooler 2b and evaporates to generate cold, and the liquid is received from the valve 14 through the compressor 9 and the condenser 10. Reach vessel 11.

When defrosting the cooler 2b, open the valves 13 and 17b and open the other valves.
By closing 12, 14, 17a, the liquid refrigerant from the liquid receiver 11 does not expand and passes through the valve 17b, the cooler 2b, the check valve 18b, the expansion valve 16a, the cooler 2a, the valve 13, and the compressor 9 , Reaches the liquid receiver 11 via the condenser 10.

[Problems to be Solved by the Invention]

However, in the above-mentioned one, since the sensible heat of the liquid refrigerant is used for defrosting the cooler, the amount of heat is small, and when a cover for energy saving is attached to the opening of the showcase etc. If the temperature around the showcase in cold regions or winter is low,
It may not be possible to completely defrost the cooler. In addition, the defrosting time of the cooler becomes long, the time for cooling with only one of the other coolers becomes long, the temperature of the cooled space easily rises, and the electricity cost is reduced without fully utilizing the efficiency of the refrigerator. It takes.
Further complicated piping and many valves are required, the structure becomes complicated, and a large space for installing them in the showcase is required, which reduces the product display volume of the showcase and maintains the showcase. Etc. were difficult.

Therefore, an object of the present invention is to provide a refrigerating apparatus that can shorten the defrosting time of a cooler to improve cooling efficiency and suppress an increase in temperature of a cooled space such as a showcase.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a liquefaction of a refrigerant including a compressor, a condenser connected to a discharge line of the compressor, and a liquid receiver connected to a discharge line of the condenser. With respect to the line, a plurality of coolers are connected in parallel, and in a refrigerating device that defrosts each cooler alternately or sequentially, between the compressor and the liquid receiver, bypassing the condenser. A high pressure superheated refrigerant vapor of the refrigeration cycle is provided with a bypass line for introducing the high pressure superheated refrigerant vapor into the receiver via a hot gas bypass valve, and the high pressure superheated refrigerant vapor stored in the receiver via the bypass line, It is characterized in that a defrost heat source introduction line for introducing the combined steam with the saturated refrigerant vapor stored in the liquid receiver via the condenser to each of the coolers is provided.

[Action]

Therefore, since the latent heat of condensation of the combined steam of the high-pressure superheated refrigerant vapor and the saturated refrigerant vapor is used for the defrosting heat source, the defrosting heat source is large compared to the case where a liquid refrigerant with a small enthalpy is used for the defrosting heat source, and the cooling is performed. Defrosting of the cooler can be completed completely in a short time, and moreover, compared with using high-temperature overheated refrigerant vapor for the defrosting heat source, heat shock can be prevented and the cooler and refrigerant pipes can be damaged. Therefore, the temperature rise in the cooled space can be suppressed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1 and 2 show the outline of the refrigeration cycle of the refrigeration system. The thick lines in the figures show the flow of the refrigerant during normal cooling operation, and FIG. 2 shows the removal of one of the coolers. The flow of the refrigerant when performing frost is shown respectively.

The refrigerating apparatus 20 includes two coolers 21a and 21b installed in a cooled space such as a showcase, and a compressor 22 installed outside the cooled space and supplying a refrigerant to the coolers 21a and 21b. It comprises a condenser 23, a liquid receiver 24, a pipe connecting them, and various valves.

That is, with respect to the refrigerant liquefaction line consisting of the compressor 22, the condenser 23 connected to the discharge line of the compressor 22, and the liquid receiver 24 connected to the discharge line of the condenser 23 The coolers 21a and 21b are connected in parallel via the valve. Further, between the compressor 22 and the liquid receiver 24, by bypassing the condenser 23, the high-pressure superheated refrigerant vapor of the refrigeration cycle, via the hot gas bypass valve 30 for adjusting the pressure in the refrigeration cycle, A bypass line 32 that is introduced into the liquid receiver 24 is provided. Further, the combined steam of the high-pressure superheated refrigerant vapor stored in the liquid receiver 24 via the bypass line 32 and the saturated refrigerant vapor stored in the liquid receiver 24 via the condenser 23 The defrosting heat source introduction line 33 introduced into each of the coolers 21a, 21b is connected between each of the coolers 21a, 21b and the compressor 22 via three-way valves 29a, 29b.

Then, during a normal cooling operation, the refrigerant gas compressed by the compressor 22 and having a high temperature and high pressure is radiated by the condenser 23 to liquefy most of the refrigerant gas and sent to the liquid receiver 24 in a gas-liquid mixed state. Among the refrigerant introduced into the liquid receiver 24 in the gas-liquid mixed state, the liquid refrigerant is stored in the lower part of the liquid receiver 24, and the gaseous saturated refrigerant vapor is stored in the upper part of the liquid receiver 24. The liquid refrigerant stored in the liquid receiver 24 passes through the valve 26 from the liquid receiver 24 and is further cooled by passing through the valves 27a, 27b and the expansion valves 28a, 28b or the refrigerant flow rate control valves in the preceding stages of both the coolers 21a, 21b. It is introduced into the vessels 21a and 21b and evaporates to generate cold. The evaporated refrigerant gas returns to the compressor 22 and circulates through the three-way valves 29a and 29b.

Further, when the pressure inside the liquid receiver 24 decreases, high-pressure superheated refrigerant vapor is introduced from the compressor 22 into the liquid receiver 24 through the bypass line 32 via the hot gas bypass valve 30, and the liquid receiver 24
The pressure of the refrigerant is kept at an appropriate value.

Next, when defrosting the one cooler 21a, the valve 26 is closed, and the one-way valve 29a is operated to operate the high-pressure superheated refrigerant vapor and the saturated refrigerant vapor stored in the upper part inside the receiver 24. Refrigerant gas consisting of the combined steam of the above is supplied from the defrosting heat source introduction line 33 from the direction opposite to the cooler 21a. At this time, the pressure reducing valve 25
The pressure of the liquid refrigerant on the coolers 21a, 21b side is lowered to facilitate introduction of the refrigerant gas from the opposite direction.

This refrigerant gas is saturated refrigerant vapor that has not condensed in the condenser 23 and high-pressure superheated refrigerant vapor that enters the receiver 24 from the compressor 22 through the bypass line 32 via the hot gas bypass valve 30 in the receiver 24. The combined refrigerant is the refrigerant at approximately point A in the Mollier diagram shown in FIG. 3, and is used in the conventional example B
It has a larger enthalpy Ai than the enthalpy Bi of the liquid refrigerant at the point, and it is possible to complete the defrosting in a short time. When the refrigerant at point C in the Mollier diagram shown in FIG. 3, that is, the high-pressure superheated refrigerant vapor compressed by the compressor 22 is used as the defrosting heat source, the high-temperature and high-pressure refrigerant directly enters the cooler. Therefore, the heat shock may damage the cooler or the refrigerant pipe, but since the refrigerant at the point A, which is lower in temperature than the point C, is used, heat shock can be prevented and the cooler or the refrigerant pipe can be damaged. Absent. In addition, since the temperature rise of the cooled space can be suppressed, the heat load on the cooler on the non-defrosting side is reduced, and the cooling capacity can be sufficiently exerted.

The liquid refrigerant that has condensed by performing heat exchange by melting frost on the outer surface in the cooler 21a enters the other cooler 21b from the check valve 31a through the valve 27b and the expansion valve 28b and evaporates to generate cold. The temperature of the space to be cooled does not rise even if the one cooler 21a is defrosted.

The evaporated refrigerant gas is sucked into the compressor 22 through the other three-way valve 29b as in the normal operation. Further, since the refrigerant gas condenses in the cooler 21a, when the pressure in the receiver 24 decreases, the high-pressure superheated refrigerant vapor from the compressor 22 via the hot gas bypass valve 30 to the receiver 24 from the bypass line 32. By being guided, the pressure in the refrigeration cycle is adjusted, and defrosting can be performed more efficiently.

It should be noted that the valve 27a can be defrosted without any trouble even in the open state.

Thus, in the refrigerating apparatus 20 of the present invention, the cooler 21a
As a heat source for defrosting, since high-pressure superheated refrigerant vapor and saturated refrigerant vapor with a large amount of heat are used, the defrosting time can be shortened to about 1/5 of that of the conventional case, and only one cooler 21b can be used. Since the operating time of is reduced, the temperature rise in the space to be cooled can be suppressed and the operating time of the two coolers 21a and 21b can be lengthened, so that the efficiency of the refrigeration system can be fully exerted and the operating expenses such as electricity bills can be reduced. You can save money.

Further, in the present embodiment, when entering the defrosting operation from the normal operation,
Only the valve 26 at the outlet of the receiver 24 and one of the three-way valve 29a or the three-way valve 29b need be operated, the mechanism is simplified, and the flow of the refrigerant near the coolers 21a and 21b is simplified. Since the space for arranging pipes and valves is small, installation in the showcase is easy and workability such as maintenance is improved.

It should be noted that switching can be performed by combining normal valves without using the three-way valves 29a, 29b, and the check valves 31a, 31b may also use normal valves.

FIG. 4 shows coolers 21a and 21b using the same refrigeration cycle.
In the example shown in FIG. 1, a plurality of units are installed in parallel, and at least two units adjacent to each other form a set and are arranged in one showcase or the like. When defrosting one of the coolers 21a and 21b, the valve 26 is closed in the same manner as the above-described circuit, and one of the three-way valve 29a is turned to rotate the high pressure superheated refrigerant vapor and the saturated refrigerant from the upper part of the liquid receiver 24. A vapor refrigerant gas formed by merging with vapor is introduced into the coolers 21a and 21b. The liquid refrigerant condensed in the coolers 21a and 21b is the other cooler 2
After entering the 1b and 21b to generate evaporated cold, it is sucked into the compressor 22 via the other three-way valve 29b.

Depending on the size of the showcase and the like, it is also possible to arrange three or more coolers as one set and sequentially defrost each cooler. An electromagnetic valve is generally used as each valve used in the refrigeration cycle, and opening / closing of the valve and defrosting operation are controlled by a timer, a computer, or the like.

〔The invention's effect〕

As described above, the present invention provides a plurality of refrigerant liquefaction lines each including a compressor, a condenser connected to a discharge line of the compressor, and a liquid receiver connected to a discharge line of the condenser. Connect the base cooler in parallel, between the compressor and the receiver,
A bypass line that bypasses the condenser and introduces the high-pressure superheated refrigerant vapor of the refrigeration cycle into the receiver via the hot gas bypass valve is provided, and the high-pressure superheat stored in the receiver via the bypass line. A defrost heat source introduction line for introducing the combined vapor of the refrigerant vapor and the saturated refrigerant vapor stored in the receiver via the condenser to each of the coolers is provided, and each cooler is defrosted alternately or sequentially. Therefore, since the latent heat of condensation of the combined steam of the high-pressure superheated refrigerant vapor and the saturated refrigerant vapor is used for the defrosting heat source, the defrosting heat source has big,
Defrosting of the cooler can be completed completely in a short time, and moreover, heat shock can be prevented and damage to the cooler and the refrigerant pipes can be made compared to using high-temperature overheated refrigerant vapor for the defrosting heat source. Moreover, since the temperature rise in the cooled space can be suppressed, the heat load on the cooler on the non-defrosting side is reduced, and the cooling capacity can be sufficiently exerted.

Further, since the time during which the cooler is stopped for defrosting is shortened, the operating time in all the coolers can be taken longer, the cooling efficiency of the refrigeration system can be sufficiently exhibited, and the operating cost can be reduced.

Moreover, since a bypass line is provided between the compressor and the receiver to bypass the condenser and introduce the high-pressure superheated refrigerant vapor of the refrigeration cycle into the receiver via the hot gas bypass valve, the refrigeration cycle The internal pressure is adjusted so that the pressure of the refrigerant in the liquid receiver can be maintained at an appropriate value, and defrosting can be performed more efficiently.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIGS. 1 and 2 are circuit diagrams showing a refrigerating cycle of a refrigerating apparatus, FIG. 3 is a Mollier diagram, and FIG. Circuit diagrams showing an example in which a large number of coolers are installed, FIGS. 5 to 7 show conventional examples, FIGS. 5 and 6 are sectional views showing the internal structure of a showcase, and FIG. It is a circuit diagram of a cycle. 20 …… Refrigerator, 21a, 21b …… Cooler, 22 …… Compressor, 2
3 …… Condenser, 24 …… Receiver, 25 …… Reducing valve, 26,27a, 27
b ... valve, 28a, 28b ... expansion valve, 29a, 29b ... three-way valve, 30
...... Hot gas bypass valve, 31a, 31b …… Check valve, 32…
… Bypass line, 33 …… Defrost heat source introduction line

Claims (1)

[Claims] 1. A plurality of cooling units for a refrigerant liquefaction line including a compressor, a condenser connected to a discharge line of the compressor, and a liquid receiver connected to a discharge line of the condenser. Connected in parallel, in a refrigerating device for defrosting each of the coolers alternately or sequentially, between the compressor and the receiver,
Bypassing the condenser and providing a bypass line for introducing high-pressure superheated refrigerant vapor of the refrigeration cycle to the liquid receiver via a hot gas bypass valve, and being stored in the liquid receiver via the bypass line. High-pressure superheated refrigerant vapor, and a defrosting heat source introduction line for introducing a combined steam of saturated refrigerant vapor stored in the receiver via the condenser into each of the coolers. apparatus.