JPS63204074A - Refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a temperature-type automatic countermeasure for an oil return pipe of a flooded evaporator.

(Prior art) Conventionally, in refrigeration equipment, for example,
As disclosed in Japanese Patent No. 671, an oil return pipe is provided to return part of the refrigerant and oil present at a predetermined height from the cooling pipe inside the flooded evaporator to the suction pipe of the pressure am. By returning the refrigerant with a high oil concentration at the top of the liquid level to the compressor, the efficiency of oil recovery in the refrigeration circuit is increased.A temperature-sensitive cylinder of a thermostatic automatic expansion valve is attached to the oil return pipe, and the temperature-sensitive cylinder of the temperature-type automatic expansion valve is installed in the oil return pipe. There is a known system that attempts to control the degree of superheat to be constant by adjusting the opening degree of an automatic expansion valve and controlling the liquid level inside the evaporator within an appropriate range.

(Problems to be solved by the invention) By the way, when refrigerant and oil flow together in refrigerant piping,
As shown in Figure 3, the refrigerant flows near the center of the pipe (solid line arrow in the figure), and the oil flows in an annular shape with an almost uniform thickness along the pipe wall (a) (dashed line arrow in the figure). ) is known to be.

When trying to detect the temperature of superheated gas refrigerant by attaching a temperature sensing cylinder (b) to the oil return pipe, the thickness of the oil film inside the pipe wall (a) changes depending on the amount of oil recovered. There is a problem that a difference occurs in the heat transfer coefficient due to the oil film, and the relationship between the refrigerant temperature detected by the temperature sensing tube (b) and the actual refrigerant humidity changes.

That is, the actual refrigerant temperature when the refrigerant temperature detected by the temperature sensing tube (b) is a constant value to and the oil rising rate is different, for example, the actual refrigerant temperature t5 when the oil rising rate is 5% (solid line in the figure). Comparing the actual refrigerant temperature t1 when the oil rising rate is 1% (dashed line in the figure), the oil film is thicker when the oil rising rate is 5%, and the heat transfer coefficient due to the flow of the oil film is Since the refrigerant temperature t5 is approximately proportional to the thickness of the refrigerant, the refrigerant temperature t5 is lower than the refrigerant temperature t1. In other words, on the automatic expansion valve side, when the oil rise rate is high, the apparent degree of superheat is detected to be higher than the actual degree of superheat of the refrigerant, so the opening degree is adjusted to be larger than the appropriate opening degree. The refrigeration system is likely to fall into wet operation, and when it becomes wet operation, the oil flow i increases as well as the refrigerant flow rate, increasing the detection error of the refrigerant temperature, and further increasing the wet operation, which can create a vicious cycle.

The present invention has been made in view of the above, and its purpose is to reduce the temperature detection error of the superheated gas refrigerant in the thermosensor when the oil rising rate increases with an appropriate configuration, thereby increasing the oil rising rate. The objective is to prevent wet operation due to an increase in the temperature and to perform stable superheat degree control.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention includes a compressor (1), a condenser (2), as shown in FIGS.
, a refrigeration system equipped with a refrigeration circuit formed by sequentially connecting a thermostatic automatic expansion valve (4) and a flooded evaporator (5) having a cooling pipe (6) therein is assumed.

An oil return pipe (8) returns a part of the refrigerant and oil present at a predetermined height inside the evaporator (5) to the suction pipe (7a) of the pressure-a machine (1). shall be established. Furthermore, separating means (11) is provided in the oil return pipe (8) to separate the flows of refrigerant and oil, and has a refrigerant passage (14) through which the refrigerant flows and an oil passage (15) through which oil flows, The temperature sensing tube (4a) of the thermostatic automatic expansion valve (4) for measuring the temperature of the gas refrigerant is attached to the refrigerant passage (14).

(Function) With the above configuration, in the present invention, during operation of the refrigeration system, part of the refrigerant and oil from the evaporator (5) passes through the oil return pipe (8) to the suction pipe (7a) of the compressor (1). ). Then, the temperature of the superheated gas refrigerant flowing through the oil return pipe (8) is detected by the temperature sensing cylinder, and the opening degree of the automatic expansion valve (4) is adjusted according to the degree of superheat, thereby performing constant superheat degree control. . At that time, the separation means (
11), the mixed flow of refrigerant and oil in the oil return pipe (8) is separated, and the refrigerant flows into the refrigerant passage (14) side, and the refrigerant flows into the oil passage (1).
Since the oil is diverted to the 5) side, the refrigerant passage (14)
Almost no oil film is formed inside. And the refrigerant passage (
Since the temperature sensing tube (4a) is attached to 14), the temperature value of the superheated gas refrigerant detected by the temperature sensing tube (4a) is not affected by changes in the oil rising rate. Therefore, since the opening degree of the automatic expansion valve (4) is appropriately adjusted according to the exact temperature of the superheated gas refrigerant, it is possible to effectively prevent wet operation due to an increase in the rate of oil rise, and to maintain stable overheating. control can be performed.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

FIG. 1 shows a refrigerant system of a refrigeration system according to an embodiment of the present invention, in which (1) is a compressor, (2) is a condenser that condenses and liquefies the refrigerant, and (3) is a refrigerant that is liquefied in the condenser. (4) is an automatic expansion valve that automatically adjusts its opening according to the degree of superheating of the refrigerant; (5) is an evaporator that evaporates the refrigerant; - (5) are sequentially connected by refrigerant piping (7) so that refrigerant can flow therein, thereby forming a refrigeration circuit. Here, the evaporator (5) is equipped with a cold W pipe (6) through which water flows, and the cold f! It has a liquid-filled structure in which the entire J pipe (6) is immersed in refrigerant liquid, and cold water is obtained by heat exchange with the refrigerant.

(8) has one end opened in the wall of the evaporator (5) at a predetermined height from the cooling pipe (6), and
5) and the suction pipe (7a), an oil return pipe (10) connects the oil return pipe (8) to allow the flow of refrigerant and the liquid pipe (7b) in the refrigeration circuit. This is a heat exchanger (10) for heating the refrigerant in the oil return pipe (8) through heat exchange with a liquid refrigerant to increase the degree of superheating of the refrigerant.

Further, (11) is an oil separator installed in the oil return pipe (8), and as shown in FIG. A main pipe section (13G) disposed in and extending in the lateral direction is connected to an oil return pipe (8),
A first pipe that divides the flow of the oil return pipe (8) into two upper and lower flows.
A refrigerant passage that is connected to the T-joint (13) and the upper branch pipe (13a) of the first T-joint (13) and has a shape that is raised, bent approximately horizontally, and further bent vertically downward. (14) and the 1st T! ! An oil extractor 1 (15) connected to the branch pipe section (13b) on the lower side of the hand (13) and having a shape of hanging down, bent in a substantially horizontal direction, and further bent in a vertically upward direction; and the first T-joint. A second T is arranged in a shape symmetrical to that of (13) and makes the separate flows merge into the refrigerant passage (14) and oil passage (15).
The refrigerant passage (14) is connected to the upper part and the oil passage (15) is connected to the lower part through the first and second T-joints (13) and (16). 14).

(15) are connected in parallel to form a substantially rectangular closed ring shape. Also, the confluence pipe part (16) of the second T joint (16)
c) the suction of the compressor (1) via the oil return pipe (8);
! j (7a).

And, directly above the second Tll1 hand (16) on the outer wall of the refrigerant passage (14) of the oil separator (11), there is a temperature sensing cylinder of the automatic expansion valve (4) for detecting the temperature of the superheated gas refrigerant. (4a) is attached in contact with the wall surface.

In addition, in order to equalize the fluid resistance of the refrigerant passage (14) and the oil passage (15), two TI hands (13) and (1
6) are attached so as to be point-symmetrical to each other within the rectangle. Further, the substantially horizontal portions of the oil return pipe (8) and the oil separator (11) have a certain downward slope relative to the suction pipe (7a) of the compressor (1) in order to prevent backflow of oil. It is designed to have the following.

In addition, in Fig. 1, <5a) and (5b) are the evaporators (
5) is formed on the upper part of the suction pipe (7a) of the pressure machine (1).
are two small spaces connected to each other, the two small spaces (
5a) and (5b) have the ability to separate and remove oil and liquid refrigerant in the refrigerant sucked into the compressor (1) as much as possible, and suck the gas refrigerant with less moisture into the suction pipe (7a). It is something that you have.

In Figures 1 and 2, during operation of the refrigeration system, the refrigerant compressed by the compressor (1) is condensed and liquefied in the condenser (2), stored in the liquid receiver (3), and then Expansion valve (4)
Under the expansion action of
From the two small spaces at the top (5a>, (5b)
Return a) to transtemal pressure IFj1 (1). At that time, the area near a predetermined height from the cooling pipe (6) of the evaporator (5) is the liquid level of the refrigerant, and the area near the liquid level contains a lot of oil with a light specific gravity.
Also, due to heat exchange with water, mixing with the vaporized refrigerant occurs, resulting in a forming phenomenon, and since the oil return pipe (8) is opened in the container wall at the part that comes in contact with that part, the oil has a high proportion of oil. The refrigerant flows through the oil return pipe (8), undergoes heat exchange in the heat exchanger (10), becomes a superheated gas refrigerant, and passes through the oil separator (11) with oil to the compressor (1).
into the suction pipe (7a).

In the oil separator (11), the flow of refrigerant flowing near the center of the oil return pipe (8) (solid line arrow in the figure) and the flow of oil flowing in an annular shape along the pipe wall (dashed line in the figure) arrow)
When the mixed flow hits the branch point of the first TII1 hand (13), the oil flows to the lower branch pipe (13b) of the first T joint (13) due to the difference in self weight, and the light gas refrigerant mostly flows to the upper branch pipe (13a). ), so almost only the gas refrigerant is separated and flows into the refrigerant passage (14). Therefore, the oil separator (11) has the function of separating the flow of refrigerant and oil in the oil return pipe (8) into the refrigerant passage (14) and the oil passage (15). . Next, the degree of superheat of the refrigerant is detected by the temperature sensing cylinder (4a) attached to the refrigerant passage (14), and the following constant superheat degree control is performed according to the degree of superheat.

That is, when the load on the evaporator (5) decreases and the liquid level rises during operation of the refrigeration system, the part with high liquid refrigerant density comes into contact with the opening of the oil return pipe (8), and the oil return pipe (8
), a wet refrigerant containing a large amount of liquid refrigerant flows through the heat exchanger (
10) The temperature of the superheated gas refrigerant that has passed through decreases. Then, the opening degree of the automatic expansion valve (4) is reduced according to the temperature of the superheated gas refrigerant detected in the wet part (4a), so the liquid level in the evaporator (5) decreases and the oil return pipe ( 8) allows a refrigerant containing an appropriate amount of liquid refrigerant to flow.

Moreover, when the load on the evaporator (5) increases and the liquid level falls, the part with low density of the liquid refrigerant comes into contact with the opening of the oil return pipe (8), and the oil return pipe (8) is filled with liquid. The refrigerant with less refrigerant flows and the temperature of the superheated gas refrigerant that has passed through the heat exchanger (10) increases. Then, an automatic expansion valve (4) is installed according to the temperature of the superheated gas refrigerant detected by the sensor ffiM (4a).
Since the opening degree of the evaporator (5) is adjusted to a large extent, the liquid level of the evaporator (5) rises, and refrigerant containing an appropriate amount of liquid refrigerant flows into the oil return pipe (8). As described above, the liquid level position of the evaporator (5) is maintained within an appropriate range, and superheat degree constant control is performed.

Therefore, in the above embodiment, the oil separator (11) prevents the flow of refrigerant and oil in the oil return pipe (8) from the refrigerant passage (
14) and an oil passage (15), and the refrigerant passage (1
Since the temperature sensing tube (4a) is attached to the tube 4), there is no oil film inside the pipe, and unlike the conventional method, the temperature sensing tube (4a)
The temperature value of the superheated gas refrigerant detected in is not affected by changes in the oil rising rate. Therefore, since the opening degree of the automatic expansion valve (4) is appropriately adjusted according to the exact degree of superheating of the gas refrigerant, the above-mentioned wet operation can be effectively prevented, and the evaporator (5) Liquid level control and superheat constant control can be performed stably.

In addition, in the oil separator (11), the oil separated into the oil passage (15) joins the gas refrigerant in the gas passage (14) at the second TO hand (16), and passes through the oil return pipe (8) to the compressor. (1)
Since the oil flows into the suction pipe (7a) of the oil, the efficiency of oil recovery is not impaired.

In addition, in the above embodiment, two Ts are used as the oil separator (11).
Although we use a combination of piping using ellipses (13) and <16>, it is also possible to use a collision type or centrifugal type oil separator such as those commercially available as cartridges. effect can be obtained.

(Effects of the Invention) As explained above, according to the present invention, an oil return pipe is provided for returning part of the refrigerant and oil from the evaporator of the refrigeration device to the pressure am suction pipe, and the flow in the oil return pipe is By separating the flow into the refrigerant flow and the oil flow, and installing a temperature-sensing tube of a thermostatic automatic expansion valve in the path where the refrigerant flows, the temperature of the superheated gas refrigerant can be accurately detected, and the oil flow It is possible to effectively prevent wet operation due to an increase in the rising rate and perform stable superheat degree control.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, with FIG. 1 being an overall configuration diagram thereof, and FIG. 2 being a partially enlarged view of an oil separator. FIG. 3 is an explanatory diagram of a refrigerant temperature detection error in a conventional temperature-sensing cylinder mounting section. (1)... Compressor, (2)... Condenser, (4)...
・Automatic expansion valve, (4a)...Temperature cylinder, (5)...Evaporator, (6)...Cooling pipe, (7a)...Suction pipe, (
8)...Oil return pipe, (11)...Oil separator (oil separation means), (14)...Refrigerant passage, (15)...Oil passage. Patent applicant Daikin Industries, Ltd. representative
Attorney Patent Attorney 1) Hiroshi Figure 3 Figure 2 15 (Oil passage)

Claims (1)

[Claims] (1) A refrigeration circuit consisting of a compressor (1), a condenser (2), a thermostatic automatic expansion valve (4), and a flooded evaporator (5) having an internal cooling pipe (6) connected in sequence. In the refrigeration system, a part of the refrigerant and oil present at a predetermined height inside the evaporator (5) is transferred to the compressor (1).
An oil return pipe (8) is provided to return the oil to the suction pipe (7a), and the oil return pipe (8) is provided with an oil return pipe (8) that separates the flow of refrigerant and oil so that the refrigerant passage (14) through which the refrigerant flows is connected to the oil return pipe (8). A separating means (11) having an oil passage (15) through which gas flows is interposed, and a temperature sensing tube (4a) of the automatic expansion valve (4) for detecting the temperature of the gas refrigerant is provided in the refrigerant passage (14). A refrigeration device characterized in that it is installed.