JPH01291078A - Refrigerating device - Google Patents

Abstract

PURPOSE:To effect the defrosting of a drain pan and an evaporator surely in a short period of time, by a method wherein a heat accumulating tank is provided in the discharging pipe of a compressor and a branch passage is provided at the outlet port side of a drain pan in a bypass passage through a changeover valve while the branch passage is connected to the downstream side of the changeover valve so as to be capable of effecting heat exchange in the heat accumulating tank. CONSTITUTION:A heat accumulating tank 40, filled with heat accumulating solution, is provided in the discharging pipe 6a of a compressor 1. A branch passage 50 is provided at the outlet port side of a drain pan heater 21 in a bypass passage 20 through an opening and closing mechanism 51 while the branch passage is connected to the downstream side of the opening and closing mechanism. The intermediate part of the branch pipe is arranged so as to be capable of effecting heat exchange between the heat accumulating solution of the heat accumulating tank. According to this method, hot gas, whose temperature is reduced by heat exchange in the drain pan heater, is heated again by heat exchange in the heat accumulating tank 40 to effect the defrosting of an evaporator by the hot gas. Accordingly, the defrosting of a drain pan as well as an evaporator may be effected surely and quickly, a time for defrosting may be shortened as a whole and a remarkable temperature change in a refrigerator or a chamber will never be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a refrigeration system, and more particularly, a hot gas bypass path, a drain pan heater that heats a drain pan with the hot gas bypassed to the bypass path, and a hot gas valve. The present invention relates to a refrigerating ailt comprising: defrosting the drain pan and the evaporator via the bypass path.

(Prior art) Conventionally, using a hot gas bypass path and a hot gas valve,
As shown in Japanese Patent Laid-Open No. 59-197784, a refrigeration system that enables defrosting of a drain pan and evaporator measures a certain amount of refrigerant during defrost operation, and circulates the measured refrigerant to the defrost circuit. It is known what made it so.

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 CB), and a hot gas bypass path (C) that bypasses the hot gas discharged from the compressor (A) to the evaporator CB).
a drain pan heater (E) that heats the drain pan (D) with hot gas bypassed by the drain pan heater (E), and the bypass path (C).
A hot gas valve (F) that bypasses the hot gas is provided at the downstream side of the condenser (G), and a pair of solenoid valves () If) (H2) and a valve between these solenoid valves (Hl) (H2) are provided. A refrigerant measuring section is provided, which is composed of a measuring device (I) installed in the hot gas bypass n (C), a drain pan heater (E), and a constant amount of refrigerant measured by this measuring section during defrosting operation. It flows through a defrost circuit formed by an evaporator (B) and a compressor (A) to defrost the drain pan (D) and evaporator (B).

Therefore, in the above-mentioned refrigeration system, when entering defrost operation, pump-down operation is first performed with the downstream solenoid valve (Hl) closed, and after pump-down, the upstream solenoid valve (H2) 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 (H2) 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, a certain amount of hot gas introduced into the bypass path heats the drain pan heater (E). After that, the evaporator (B) is further heated and defrosted, so the evaporator (B) is further defrosted using the hot gas whose temperature has been lowered by heat exchange as it passes through the drain pan heater (E). Therefore, the time required for defrosting the evaporator CB) becomes longer, and the temperature inside the refrigerator or room changes significantly.

However, the above-mentioned problems are particularly noticeable when the outside temperature is low. In other words, when the outside temperature is low, heat loss from the outside refrigerant piping system such as the compressor (A) and outdoor piping is disposed outside the refrigerator. is large, and when the outside temperature is low, the pressure of the refrigerant measured by the meter aa is low, so it is difficult for the entire amount of refrigerant measured by the meter to flow into the defrost circuit, and furthermore, during defrost operation, the electromagnetic Since the valve (H2) is in the open state, a portion of the hot gas circulating in the defrost circuit flows back into the metering section exposed to the outside air, condenses and accumulates in this metering section, and as a result, the defrost circuit is closed. The amount of refrigerant circulating becomes insufficient, and the overall defrost time becomes longer.

However, the present invention was developed in view of the above circumstances.
It is an object of the present invention to provide a refrigeration system that can reliably defrost a drain pan and an evaporator while shortening the defrosting time.

In addition, we are trying to shorten the defrost operation time at low outside temperatures when the defrost time is particularly long, so that the compressor is not overloaded during defrost operation at high outside temperatures when defrost takes a relatively short time. There is no refrigeration equipment provided.

(Means for Solving the Problems) Accordingly, the present invention provides a discharge pipe (8a) of a compressor (1).
A heat storage tank (40) storing a heat storage solution is attached, and the drain pan heater (
21), a branch path (
50), this branch path (50) is connected to the downstream side of the opening/closing mechanism (51) in the bypass path (20), and the intermediate part of the branch path (50) is connected to the heat storage tank (4).
0) is characterized in that it is disposed so as to be able to exchange heat with the heat storage solution.

In the above refrigeration apparatus, an outside air temperature detector (52) is provided, and when the temperature detected by the detector (52) is lower than a predetermined value, the opening/closing mechanism (61) is configured to introduce hot gas into the branch path (50). ) may be provided, and a discharge gas temperature detector (54) for detecting the temperature of the discharge gas may be provided.
), and opening/closing control means for the opening/closing mechanism (51) that introduces hot gas into the branch path (50) when the temperature detected by the detector (54) is below a predetermined value may be provided.

(Function) When the defrost operation is performed by the above-mentioned refrigeration system, the hot gas introduced into the bypass path (20) causes
The drain pan (
lO) was heated and defrosted, and the hot gas whose temperature was lowered by heat exchange in the drain pan heater (21) passed through the branch path (50) and was heated in the heat storage tank (40). Thereafter, the gas is sent to the evaporator (4), and therefore, the evaporator (4) is defrosted by the heated hot gas.

In addition, the device is equipped with an outside air temperature detector (52) and an opening/closing control means for operating the opening/closing mechanism (51) based on the detection result from the detector (52), or a discharge gas temperature detector (64). In the case where the opening/closing control means for operating the opening/closing mechanism (51) based on the detection result from the detector (54) is provided, the drain pan heater (21) is activated only when the outside temperature is low and the defrost time becomes long. The hot gas whose temperature has been lowered by the heat exchange is transferred to the branch path (
50) and is heated in the heat storage tank (40), and when the outside temperature is high, the hot gas that has passed through the drain pan heater (21) is directly directed to the evaporator (4) without passing through the heat storage tank (40). It is sent to.

(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 system configured as described above, a discharge pipe (6a) extending from the discharge side of the compressor (1) is provided in the middle of the discharge pipe (6a) to carry the hot gas discharged from the compressor (1) to each of the condensers. (2) (3) Connect the inlet side of a hot gas bypass path (20) that bypasses the temperature-sensitive expansion valve (5) to the evaporator (4), and connect the outlet side to the evaporator (4). (4) is connected to the flow divider (13) provided on the inlet side of the bypass passage (20), and a drain pan heater (21) disposed along the drain pan is interposed in the middle of the bypass path (20). The drain pan heater (
21) by hot gas passing through the drain pan (10)
I'm trying to heat it up.

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 drain pan heater (21) in the bypass passage (20), and a three-way solenoid valve constituting an opening/closing mechanism for the branch passage (50) is connected to this branch part. While installing a switching valve (51),
After passing the intermediate part of this branching path (50) through the inside of the heat storage tank (40), the branching path (50) is connected to the bypass path (
20) 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) in the bypass path (20) to the branch path (50), and when the outside air temperature is 0° C. or higher, the controller (53) turns off the switching valve (51) to close the branch path (50), and at the same time, the upstream side of the switching valve (51) in the bypass path (20) is turned off in the bypass path (20). The switching valve (51
).

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 (8).

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, for measurement in the metering section (33), the first on-off 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 turned into a hot gas valve (20). This is done by switching to the gas bypass path (20) and closing the second on-off valve (32), and supplying the thus measured refrigerant to the defrost circuit requires a certain period of time (approximately 20 seconds) after metering. rear,
This is done by opening the first on-off valve (30).

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

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) and when passing through the drain pan heater (21), the drain pan (10) is heated to defrost the drain pan (10), and the drain pan heater (21) is As shown in FIG. 3, the temperature of the hot gas passing through the drain pan heater (21
) When the outside temperature is below 0°C, the switching valve (5) is activated by the controller (53).
1), the inlet side of the branch passage (50) is connected to the upstream side of the switching valve (51) in the bypass passage (20), and therefore the hot gas whose temperature has decreased is As it is sent to the branch path (50) and passes through the heat storage tank (40), the temperature rises again due to heat exchange with the heat storage solution, as is clear from FIG. Then, the hot gas whose temperature has become high in this way is sent to the evaporator (4), heats the evaporator (4), and defrosts the evaporator (4).

On the other hand, when the outside air temperature is 0° C. or higher, the switching valve (51) is turned off by the controller (53), the branching path (50) is closed, and the switching valve (51) in the bypass path (20) is closed. The upstream side of is connected to the downstream side of the switching valve (51) in the bypass passage (21), so the hot gas that has passed through the drain pan heater (21)
The heat storage solution is directly sent to the evaporator (4) without passing through the branch path (50), in other words, without undergoing heat exchange with the heat storage solution, heating the evaporator (4), and evaporating. Vessel (4)
Therefore, in a high outside temperature state of 0° C. or higher, where defrosting does not take much time, heat exchange in the heat storage tank (40) is not performed, so the compressor (
1) can be suppressed to that extent, and the drive of the compressor (
1) can be prevented from becoming overloaded.

In the above embodiment, the controller (53)
The switching valve (51) constituting the opening/closing mechanism of the branch path (50) based on the detection result of the outside temperature detector (52).
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 is installed in the suction pipe (6c) of the compressor (1) to estimate the outside air temperature from the temperature of the discharge gas flowing through the defrost circuit, and when the temperature detected by the detector (54) is lower than the set value, the The controller (53) turns on the switching valve (51) to open the branch path (5o).
Alternatively, hot gas may be introduced.

However, the temperature of the discharged gas is not stabilized until a predetermined period of time has elapsed after the start of the defrost operation. Therefore, in the above embodiment, as shown in the flowchart of FIG. ) is turned on, and the switching valve (Sl) is turned off 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 do so.

Further, in the above embodiment, the controller (53) controls the switching valve (51) based on the detection result of the outside air temperature detector (52). The hot gas may be constantly introduced into the branch path (50).

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

That is, a heat storage tank (40) storing a heat storage solution is attached to the discharge pipe (6a) of the compressor (1), and a bypass path (2
A branch path (50) is branched to the outlet side of the drain pan heater (21) in the bypass path (20) via an opening/closing mechanism (51), and this branch path (60) is connected to the opening/closing mechanism (51) in the bypass path (20). ), and by disposing the middle part of the branch path (50) in the heat storage tank (40) so as to be able to exchange heat with the heat storage solution, the heat in the drain pan heater (21) is The temperature of the hot gas whose temperature has decreased due to the exchange is raised again through heat exchange in the heat storage tank (40), and the evaporator is defrosted by the hot gas having a higher temperature, so that the drain pan and the evaporator can be defrosted. This can be done reliably and quickly, and the defrosting time can be shortened as a whole, so that large temperature changes within the chamber or indoors are not caused.

Furthermore, in the above refrigeration apparatus, an outside air temperature detector (52)
and an opening/closing control means for operating the opening/closing mechanism (51) based on the detection result from this detector (52), or a discharge gas temperature detector (54) and a Based on the detection result, the opening/closing machine ejl
(61), the hot gas whose temperature has been lowered by heat exchange in the drain pan heater (21) is transferred to the branch path (50) only when the outside temperature is low and the defrost time becomes longer. ) and is heated in the heat storage tank (40), while when the outside temperature is high, the hot gas that has passed through the drain pan heater (21) is heated in the heat storage tank (40) without passing through the heat storage tank (40). (
Since the heat is sent directly to the evaporator (4) without heat exchange at step 40), the driving of the compressor (1) can be suppressed to that extent, and therefore the overall temperature of the outside air is low, which requires a particularly long time for defrosting. While defrosting time can be shortened, it is also possible to reliably prevent the compressor from operating overload during defrosting at high outside temperatures, where defrosting takes a relatively short time.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant piping diagram showing an embodiment of the refrigeration system according to the present invention, Fig. 2 is an enlarged sectional view of the main parts, and Fig. 3 shows the temperature change of the refrigerant during defrosting by the refrigeration system according to the invention. FIG. 4 is a flowchart showing operational control during defrosting of another embodiment of the refrigeration system according to the present invention, 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 (10)... ... Drain pan (20) ... Bypass path (21) ... Drain pan heater (40) ... Heat storage tank (50) ... Branch path (51) ... Switching valve (open/close Mechanism) (52)...Outside air temperature detector (54)...Discharge gas temperature detector Fig. 2 5θ dθ

Claims (1)

[Claims] 1) Compressor (1), condenser (2), (3) and expansion mechanism (5)
) and an evaporator (4), the hot gas bypass path (20 ), a hot gas valve (22) that bypasses hot gas to the bypass path (20), and a drain pan heater (21) that heats the drain pan (10) with the hot gas bypassed to the bypass path (20). A refrigeration system is provided with a discharge pipe of the compressor (1) to enable defrosting of the drain pan (10) and the evaporator (4) by hot gas introduced via the bypass path (20). (6
A) is provided with a heat storage tank (40) storing a heat storage solution, and a branch path (50) is connected to the outlet side of the drain pan heater (21) in the bypass path (20) via an opening/closing mechanism (51). branch, and connect this branch path (50) to the downstream side of the opening/closing mechanism (51) in the bypass path (20), and connect the intermediate part of the branch path (50) to the heat storage tank (40), A refrigeration device characterized in that the refrigeration device is arranged to be able to exchange heat with the heat storage solution. 2) An outside air temperature detector (52) is provided, and the detector (52)
) is below a predetermined value, the branch path (
21) the opening/closing mechanism (51) for introducing hot gas into
The refrigeration system according to claim 1, further comprising opening/closing control means. 3) Discharge gas temperature detector (5) that detects the temperature of discharge gas
4), further comprising an opening/closing control means for the opening/closing mechanism (51) for introducing hot gas into the branch path (21) when the temperature detected by the detector (54) is below a predetermined value. 1. The refrigeration device according to 1.