JPH01291079A - Refrigerating device - Google Patents

Abstract

PURPOSE:To effect optimum defrosting regardless of an atmospheric condition, by a method wherein a branch passage is provided in the suction pipe of a compressor provided with a heat accumulating tank in the discharging pipe thereof through a changeover valve equipped with a control means and is connected to the downstream side of the changeover valve so as to be capable of effecting heat exchange in the heat accumulating tank while an atmospheric condition detecting means is provided. CONSTITUTION:When a low atmospheric temperature is detected by an atmospheric temperature detector 52 or a discharging gas temperature detector 54 upon effecting defrosting operation, suction gas is distributed into a compressor 1 from an evaporator 4 through a changeover valve 51 and a branch passage 50 while the suction gas is heated by a heat accumulating tank 40. Accordingly, hot gas from the compressor can be heated and the high-temperature hot gas can be introduced into the evaporator 4 whereby the evaporator can be defrosted in a short period of time even when heat loss is generated in the compressor or the like by the low temperature atmosphere. On the other hand, when a high atmospheric temperature is detected, heating of suction gas in the heat accumulating tank through the branch passage is stopped whereby unnecessary heating is eliminated and the overload operation of the compressor may be avoided. Accordingly, the optimum defrosting may be effected regardless of an atmospheric condition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a refrigeration system, and more specifically, a refrigeration system that includes a hot gas bypass path and a hot gas valve that bypasses the bypass path. The present invention relates to a refrigeration system that performs a defrost operation.

(Prior art) Conventionally, using a hot gas bypass path and a hot gas valve,
A refrigeration system that defrosts an evaporator using the stored heat of the hot gas introduced through the bypass path is known as disclosed in Japanese Patent Laid-Open No. 197764/1983.

As shown in FIG. 5, this refrigeration system includes a hot gas bypass path (C) that bypasses the hot gas discharged from the compressor (A) to the evaporator (B), and the bypass path (
Hot gas valve (F) bypassing hot gas to C)
Equipped with.

In addition, the method described in this publication measures a certain amount of refrigerant prior to defrost operation so that proper defrost can be performed regardless of the operating conditions (differences in cooling capacity, etc.) immediately before shifting to defrost operation. It is designed to circulate measured refrigerant through the defrost circuit, and the condenser (G)
On the downstream side of the refrigerant metering section, a refrigerant metering section consisting of a pair of solenoid valves (Hl) (H2) and a meter (I) interposed between these solenoid valves (Hl) (H2) is installed. A certain amount of refrigerant measured by this metering section is passed through the defrost circuit formed by the hot gas bypass path (C), the evaporator (B), and the compressor (A) to defrost the evaporator (B). I try to do it.

In addition, a drain pan heater (E) for heating the drain pan (D) is provided in the middle of the hot gas bypass path (C).

Therefore, in the above-mentioned refrigeration system, when entering defrost operation, pump-down operation is first performed with the downstream solenoid valve (H2) closed, and after pump-down, the upstream solenoid valve (Hl) is closed. In order to close the refrigerant and introduce the refrigerant measured by the metering section between the two electromagnetic valves into the defrost circuit, after the pump-down operation is completed, the hot gas valve (F) is switched and the bypass path is closed. (C)
is communicated with the compressor (A), and the solenoid valve (Hl) on the downstream side is opened, and the pressure difference between the high-pressure metering section and the low-pressure defrost circuit on the evaporator (B) side causes the metering section to open. Refrigerant is introduced into the defrost circuit.

(Problem to be Solved by the Invention) In the above-mentioned refrigeration system, the evaporator (B) is heated by the hot gas introduced into the bypass path (C) to perform defrosting. In case 1, the time required to defrost the evaporator (B) is longer than that under high outside air conditions, and the temperature control inside the refrigerator or room is sacrificed for practical use.

In other words, when the outside temperature is low, there is a large heat loss from the compressor (A) and the external refrigerant piping system installed outside the cabinet, such as the outdoor piping, and the temperature of the hot gas discharged from the compressor (A) decreases. The temperature of the hot gas itself is lowered, and the temperature of the hot gas flowing into the evaporator (B) is also lowered, so it takes a long time to thaw the evaporator (B).

In addition, especially in the case where the above-mentioned measuring section is provided, when the outside air temperature is low, the pressure of the refrigerant measured by the measuring section becomes low, so it is difficult for the entire amount of refrigerant measured by the measuring section to flow out into the defrost circuit. During defrost operation, the solenoid valve (H2) is open, so some of the hot gas circulating in the defrost circuit flows back into the metering section exposed to the outside air and condenses in this metering section. As a result, the amount of refrigerant circulating through the defrost circuit becomes insufficient, resulting in an even longer defrost time overall.

However, the present invention was developed in view of the above circumstances.
Under low outside air conditions, increasing the temperature of the intake gas to the compressor increases the temperature of the discharged hot gas, shortening the defrost time, and under high outside air conditions, where defrosting takes a relatively short time, it is unnecessary. To provide a refrigeration system that avoids overload operation of a compressor due to excessive heating of intake gas, and thereby performs proper defrost operation regardless of outside air conditions.

(Means for Solving the Problems) Accordingly, the present invention provides a discharge pipe (6a) of a compressor (1).
A heat storage tank (40) storing a heat storage solution is attached, and a switch tJt (
The branch road (50) is branched via the branch road (51).
50) in the opening/closing mechanism (5) in the suction pipe (6c).
1), and a detecting means for detecting outside air conditions, the middle part of the branch path (50) being disposed in the heat storage tank (40) so as to be able to exchange heat with the heat storage solution; The present invention is characterized in that an opening/closing control means for the opening/closing mechanism (51) for introducing suction gas into the branch path (50) when defrosting is performed under low outside air conditions is provided.

The outside air condition detection means includes an outside air temperature detector (52) that detects low outside air conditions when the detected value is less than a predetermined value.
) and a discharge gas temperature detector (54).

(Function) When defrost operation is performed using the above refrigeration equipment,
Outside air temperature detector (52) and discharge gas temperature detector (54)
When it is detected that the outside air is low, the opening/closing mechanism (51)
The suction gas flowing out from the evaporator (4) and being sucked into the compressor (1) is branched and sent to the branch path (5o) via the
The suction gas is heated in a heat storage tank (40) and sent to a compressor (1).
will be returned to. By heating the suction gas, the temperature of the hot gas discharged from the compressor (1) is also increased, and the temperature of the hot gas discharged from the compressor (1) is also increased.
In step 4), this hot gas with a high temperature can be introduced, and defrosting can be completed in a short time even when the outside air is low.

On the other hand, outside temperature detection! (52) and discharge gas temperature detector (
54), when high outside air is detected, the branch path (S
Heating of the suction gas in the heat storage tank (4o) via the heat storage tank (4o) is stopped, unnecessary heating of the suction gas is eliminated, and the compressor (
1) Overload operation can be prevented.

(Example) The one shown in Figure 1 is a refrigeration system for marine containers, which includes a compressor (1), an air-cooled condenser (2), and a water-cooled condenser (3).
), an evaporator (4), and a temperature-sensitive expansion valve (
5), and these devices are connected by refrigerant piping (6),
The air inside the refrigerator is cooled by the evaporator (4).

In FIG. 1, (7) is a dryer, (8) is a liquid indicator, (9) is an accumulator, (10) is a drain pan installed below the evaporator (3), and (11) is a drain pan installed below the evaporator (3).
) is a fan attached to the evaporator (3), and (12) is a fan attached to the air-cooled condenser (2).

In the refrigeration unit A configured as above, the hot gas discharged from the compressor (1) is inserted into the middle of the discharge pipe (6a) extending from the discharge side of the compressor (1).
Connect the inlet side of a hot gas bypass path (20) that bypasses each of the condensers (2), (3) and the temperature-sensitive expansion valve (5) to the evaporator (4), and connects the inlet side of the hot gas bypass path (20) to the outlet side thereof. is connected to a flow divider (13) provided on the inlet side of the evaporator (4). In addition, a drain pan heater (21) disposed along the drain pan (10) is located in the middle of the bypass path (20).
) so that the drain pan (10) can also be heated, but this drain pan heater (21) does not necessarily need to be provided.

Further, the hot gas bypass path (20) and the discharge pipe (
A hot gas valve (22) consisting of a proportional control valve is installed at the connection site with the water-cooled condenser (3).
That is, in the embodiment shown in FIG. 1, a command to stop the freezing or refrigeration operation and a command to start the defrost operation is provided downstream of the liquid indicator (8) and upstream of the expansion valve (5). The first on-off valve (3
0), and a metering tank (31) is provided upstream of the first on-off valve (30), and the closing operation of the on-off valve (30) enables pump down operation, and the metering tank (31) is provided with a metering tank (31). 31) and the condensers (2) and (3), and on the upstream side of the metering tank (31), in FIG. 1, the liquid indicator (8) and the metering tank ( 31), a second on-off valve (32) consisting of a solenoid valve forming a measuring part (33) for measuring a certain amount of refrigerant to be used for defrosting out of the refrigerant confined in the liquid reservoir part is provided. ing.

Therefore, in the embodiment shown in the figure, a closed cylindrical heat storage tank (40) storing a heat storage solution is provided near the compressor (1), and the discharge pipe (40) is provided in the heat storage tank (40). 6a) on the upstream side of the hot gas valve (22).

On the other hand, a branch passage (50) is branched from the outlet side of the accumulator (9) in the suction pipe (6c) of the compressor (1), and an opening/closing mechanism for the branch passage (50) is configured in this branch portion. A switching valve (51) consisting of a three-way solenoid valve is installed, and after passing the middle part of this branching passage (50) through the heat storage tank (40), the branching passage (50) is connected to the suction pipe ( 6c
) is connected to the downstream side of the switching valve (51).

Therefore, the operation of the switching valve (51) is performed by the opening/closing control means of the switching valve (51) based on the detection result of the outside air temperature detector (52) provided near the air-cooled condenser (2). Specifically, when the outside air temperature detected by the outside air temperature detector (52) is 0° C. or less using a controller (53) described later as the control means, the controller (53) The switching valve (5)
1) is turned on to connect the upstream side of the switching valve (51), that is, the outlet side of the accumulator (9) to the branch path (50).
and when the outside temperature is 0° C. or higher, the controller (53) turns off the switching valve (51) to close the branch passage (50) and close the accumulator (9). The outlet side of the suction pipe (6c) is directly connected to the suction pipe (6c).

In the above configuration, the defrost circuit includes the compressor (1), the hot gas valve (21), the hot gas bypass path (20), the drain pan heater (21), and the evaporator (
4), formed by an accumulator (9).

Further, the hot gas valve (21) adjusts the valve opening degree to the hot gas bypass path (20) from 0 to 100 in proportion to the voltage.
By controlling the amount of hot gas bypassed to the evaporator (4), the capacity can be adjusted to enable freezing and refrigeration operations, and during defrost operation, the entire amount of hot gas is bypassed to the hot gas bypass. Road (20)
PID control is performed by a controller (53) having a built-in computer.

In addition, in total 4 in the measuring section (33), the first opening valve (30) is closed in response to a defrost operation start command, first a pump down operation is performed, and after that, the hot gas valve (20) is closed. This is done by switching the refrigerant to the hot gas bypass path (20) and closing the second on-off valve (32), and supplying the refrigerant thus measured to the defrost circuit requires a certain period of time (approximately 20 seconds) after metering. )After,
This is done by opening the first on-off valve (30).

Therefore, the command to start the defrost operation is mainly performed by the air pressure switch (APS) and the defrost timer, and the end of the defrost operation is mainly performed by detecting the intake gas temperature at the outlet side of the evaporator (4). This is done by the thermostat (TH), and the end of the pump down operation, which is done by the defrost operation start command, is controlled by the low pressure switch (LPS).
).

In Fig. 1, (HPS) is a high voltage switch, (HF
O2) is a high pressure control switch, (OPS) is a hydraulic protection switch, and (WPS) is a water pressure switch.

Next, a defrost operation of the refrigeration system having the above configuration will be explained.

In response to a defrost operation start command from the air pressure switch (APS), a pump-down operation is performed with the first on-off valve (30) closed, and the pressure on the low-pressure gas pipe side falls below a predetermined value, causing the low pressure Switch (LPS)
When the pump-down operation is completed, the second on-off valve (32) closes, the first on-off valve (32) opens, and the bypass passage ( 20) communicates with the discharge side of the compressor (1), and a certain amount of refrigerant metered by the metering section (33) is introduced into the defrost circuit.

The hot gas discharged from the compressor (1) is
From the bypass path (20) to the drain pan heater (2
1), is supplied to the evaporator (4), and then returned to the compressor (1).

By the way, during such a defrost operation, if the outside air temperature is low at 0° C. or lower, the switching valve (51) is turned on by the controller (53), so that the evaporator (4) and the accumulator are connected to the branch path (50). (9) and is returned to the compressor (1).
) and passes through the heat storage tank (40), as shown in Figure 3, the temperature increases due to heat exchange with the heat storage solution compared to the one without a heat storage tank (dotted line). It is.

Then, the suction gas is returned to the compressor (1) in a state where its temperature has been increased, and the temperature of the hot gas discharged from the compressor (1) is also increased. Therefore, when the outside air temperature is low, the compressor (1) and the hob gas bypass path (20)
Even if the heat loss is large, or even if the amount of hot gas circulated is reduced due to backflow recondensation to the metering section (33), high-temperature hot gas is supplied to the evaporator (4). Therefore, defrosting in the evaporator (4) can be accelerated.

On the other hand, when the outside air temperature is high outside temperature of 0° C. or higher, the switching valve (51) is turned off by the controller (53), the branching path (50) is closed, and the suction in the heat storage tank (40) is The compressor (1
). Therefore, in a high outside temperature state of 0° C. or higher where defrosting does not take much time, unnecessary heating of the suction gas is not performed, and the drive of the compressor (1) can be suppressed to that extent. ) can prevent overload operation.

In the above embodiment, the controller (53)
Based on the detection result of the outside temperature detection n (52), the switching valve (51) that constitutes the opening/closing mechanism of the branch path (50)
However, the discharge gas temperature detector (54) that detects the temperature of the discharge gas is, for example, 2 in FIG.
As shown by the dotted chain line, it is provided in the discharge pipe (6a), or
Alternatively, it may be installed in the suction pipe (6c) of the compressor (1) to detect the suction gas temperature, which has a correlation with the discharge gas temperature, and the outside air temperature can be estimated from the temperature of the discharge gas flowing through the defrost circuit. When the temperature detected by the device (54) is lower than the set value, the controller (53)
Turn on the switching valve (51) to open the branch path (50).
) may introduce hot gas.

However, the temperature of the discharged gas does not stabilize until a predetermined period of time elapses after the start of the defrost operation, so that the state of the refrigerant circulating in the defrost circuit is not stabilized. At the start, the switching valve (51) is turned on, and the operation is started only when the discharge gas temperature (TO) detected by the discharge gas temperature detector (54) becomes higher than the set temperature (α°C). It is preferable to turn off the switching valve (51).

(Effects of the Invention) The refrigeration apparatus according to the present invention described above provides the following effects.

That is, when the defrost operation is performed, if the outside air temperature detector (52) or the discharge gas temperature detector (54) detects that the outside air is low, the branch path (50) is opened via the opening/closing mechanism (51). In addition, the suction gas flowing out from the evaporator (4) and being sucked into the compressor (1) is branched and flowed, and the suction gas returned to the compressor (1) can be heated in the heat storage tank (40).
The temperature of the hot gas discharged from the compressor (1) can also be increased, and this hot gas with increased temperature can be introduced into the evaporator (4). Even if heat loss occurs in the gas bypass passage (20) or the like, the evaporator (4) can be defrosted in a short time.

On the other hand, the outside air temperature detector (52) and the discharge gas temperature detector (
When high outside air is detected in the branch path (54), the branch path (54) is detected.
Heating of the suction gas in the heat storage tank (40) via the heat storage tank (40) is stopped, unnecessary heating of the suction gas is eliminated, and the compressor (
1) Overload operation can be avoided.

Therefore, it has become possible to perform proper defrosting regardless of outside air conditions.

[Brief explanation of the drawing]

FIG. 1 shows the freezing if! according to the present invention! 2 is an enlarged sectional view of the main parts, FIG. 3 is an explanatory diagram showing the temperature change of the refrigerant during defrosting, and FIG. 4 is another implementation of the refrigeration system according to the present invention. FIG. 5 is a flowchart showing operational control during defrosting, and FIG. 5 is a refrigerant piping diagram showing an example of a conventional refrigeration system. (1)... Compressor (2) (3)... Condenser (4)... Evaporator (5)... Expansion mechanism (20)... ...Hot gas bypass path (40)...
・Thermal storage tank (50)...Branch path (51)...Switching valve (opening/closing mechanism) (52)...Outside air temperature detector (54)...Discharge gas temperature detector (6a )...Discharge pipe (6c)...Suction pipe

Claims (1)

[Claims] 1) Compressor (1), condenser (2), (3) and expansion mechanism (5)
) and an evaporator (4), the hot gas bypass path (20 ) and a hot gas valve (22) for bypassing the hot gas in the bypass passage (20),
) by hot gas introduced through the evaporator (4)
A refrigeration system that enables defrosting of the compressor (1), in which a heat storage tank (40) storing a heat storage solution is attached to the discharge pipe (6a) of the compressor (1), and a heat storage tank (40) storing a heat storage solution is attached to the discharge pipe (6a) of the compressor (1). (6c), the branch path (50) is connected via the opening/closing mechanism (51).
branch, this branch path (50) is connected to the downstream side of the opening/closing mechanism (51) in the suction pipe (6c), and the intermediate part of the branch path (50) is connected to the heat storage tank (40), a detection means for detecting outside air conditions while being arranged to be able to exchange heat with the heat storage solution; and the opening/closing mechanism (51) for introducing suction gas into the branch path (50) when defrosting is performed under low outside air conditions. 1. A refrigeration system comprising: opening/closing control means. 2) The outside air condition detection means is an outside air temperature detector (52), and when the temperature detected by the detector (52) is below a predetermined value, it detects that the outside air condition is low. Refrigeration equipment. 3) The outside air condition detection means is a discharge gas temperature detector (54
2. The refrigeration system according to claim 1, wherein when the temperature detected by the detector (54) is lower than a predetermined value, a low outside air condition is detected.