JPH06101935A - Refrigerating cycle - Google Patents

Abstract

PURPOSE:To obtain a refrigerating cycle free from impairing the heat exchanging efficiency of an evaporator by passing the refrigerant of liquid phase through nearly all capillary tubes of the evaporator. CONSTITUTION:In an evaporator 2 included in a refrigerating cycle, the refrigerant of gas-liquid phase is injected from a compressor and sent through a condenser, an expansion valve and an inlet pipe 4 into an inlet flow diverter 10, where the refrigerant is separated into an upper gas phase and a lower liquid phase. At that time, the refrigerant of the upper gas phase is sent through a bypass 6 connected between the upper part of the inlet flow diverter 10 and the upper part of an outlet flow diverter 11 and then through an outlet pipe 5 back into the compressor. Therefore, there is no possibility of the refrigerant of gas phase entering the capillary tubes 3 for conducting heat exchange with air and the refrigerant of liquid phase is allowed to flow into the capillary tubes 3 and after heating for evaporation is sent through the outlet flow diverter 11 and the outlet pipe 5 back into the compressor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an evaporator used in a refrigerating cycle such as an air conditioner.

[0002]

2. Description of the Related Art In recent years, with the trend toward compact air conditioners and the like, there is a demand for a compact heat exchanger that maintains high heat exchange efficiency as a heat exchanger used in the refrigeration cycle of the air conditioner. Has been done. Therefore, a conventional evaporator 2 _b, which is an example of the heat exchanger, is shown in FIGS.
Shown in. In this evaporator 2 _b , a plurality of capillaries 3 (refrigerant pipes) formed in a spiral shape using a metal such as copper are arranged in parallel in the vertical direction, and both ends of each of the capillaries 3 are inlet side flow dividers 10 and outlet side flow dividers. It is connected to the container 11. As a result, a predetermined total flow passage cross-sectional area for passing a predetermined amount of refrigerant is secured, and the distance between the inlet side flow divider 10 and the outlet side flow divider 11 is designed to be as short as possible. . According to _the above-mentioned conventional evaporator 2 _b , the refrigerant in the gas-liquid two-phase state discharged from _the compressor and passing through the condenser and the expansion valve (not shown) is introduced from the inlet pipe 4 below the inlet side flow divider 10 to the inlet side. It flows into the flow divider 10. The refrigerant flowing into the inlet-side flow divider 10 receives heat from the outside air and vaporizes when passing through the respective refrigerant pipes 3, and then joins in the outlet-side flow divider 11. Further, the combined refrigerant flows out from the outflow pipe 5 above the outlet flow divider 11 toward the compressor. In addition, the above-mentioned shunt 1
As shown in FIG. 5, inside 0 and the outlet side flow divider 11,
A variation (maximum value δ) occurs in the charging length of the connecting portion of each capillary tube 3 into the inlet side flow divider 10 or the outlet side flow divider 11. Such variations are unavoidable in the process of assembling the evaporator 2 _b , and also have a great influence on the balance of the amount of refrigerant divided into the capillaries 3. Therefore, in order to eliminate the influence of the variation in the charging length of each capillary tube 3, the insertion member 19 is provided in each of the inlet flow distributor 10 and the outlet flow distributor 11 of the evaporator 2 _b. 3 has insert member 1 at each tip
9 are connected so as not to project into the respective flow dividers.
Thus, the evaporator 2 _b having the structure shown in FIG. 5 is disclosed in, for example, Japanese Patent Laid-Open No. 3-31665.

[0003]

[0007] Incidentally, the above in the conventional evaporator 2 _b, the refrigerant flowing in the gas-liquid two-phase state in the inlet side diverter 10 from the inflow pipe 4, the upper fill side under the influence of gravity In the flow divider 10, a gas-phase refrigerant and a liquid-phase refrigerant may be vertically separated. The thus separated gas-phase refrigerant has a problem that the amount of heat received from the air flowing outside the capillary tube 3 is smaller than that of the liquid-phase refrigerant by the latent heat, so that the heat exchange efficiency of the evaporator 2 _b is impaired. It was Therefore, an object of the present invention is to pass the liquid-phase refrigerant through almost all capillaries without allowing the refrigerant in the vapor phase to pass through any of the capillaries (refrigerant tubes) of _the evaporator as much as possible. It is to provide a refrigeration cycle that does not impair.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is, in essence, that the refrigerant discharged from the compressor flows through the condenser and the refrigerant expansion mechanism. The side shunt and the outlet shunt from which the refrigerant flows out of the inlet shunt are connected via a plurality of refrigerant pipes arranged in parallel in the vertical direction, and the air flowing around the refrigerant tub is used. In a refrigeration cycle including an evaporator for heating a refrigerant in a refrigerant pipe, the refrigeration cycle is characterized in that an upper portion of the inlet side flow divider and an upper portion of the output side flow divider are connected by a bypass pipe. There is. When most of the refrigerant that has flowed into the inlet-side flow divider is a liquid-phase refrigerant, not only the vapor-phase refrigerant but also the liquid-phase refrigerant passes through the bypass pipe from the upper part of the outlet-side flow divider. It may flow out and may not flow through the plurality of refrigerant pipes.
This impairs the heat exchange efficiency of the evaporator. On the contrary, when a refrigerant containing a large amount of vapor-phase refrigerant flows into the inlet-side flow divider, the entire amount of the vapor-phase refrigerant cannot flow out from the bypass pipe to the upper portion of the outlet-side flow divider, so This refrigerant flows through the plurality of refrigerant tubes, which also causes a problem of impairing the heat exchange efficiency of the evaporator. In order to solve such a problem, in the present invention, in addition to the structure of the main means, a throttle valve is provided in the bypass pipe,
A configuration is adopted in which the valve opening of the throttle valve is controlled based on the temperature difference between the temperature of the refrigerant pipe and the temperature of the outlet flow divider. Further, generally, when the refrigeration cycle is started, the inside of the evaporator suddenly has a low pressure, and most of the refrigerant inside the evaporator becomes a gas-phase refrigerant. Therefore, when the plurality of refrigerant tubes are, for example, capillaries having an extremely small inner diameter, a liquid sealing phenomenon may occur in the capillaries, which may prevent the gas-phase refrigerant from flowing. In order to solve such a problem, the present invention has, in addition to the configuration of the main means or the configuration described above, the valve opening degree at the initial operation of the refrigerant expansion mechanism, as compared with the valve opening degree at the time of steady operation. Provide a refrigeration cycle that is designed to be large.

[0005]

In the refrigeration cycle according to the present invention, the refrigerant discharged from the compressor and passed through the condenser and the refrigerant expansion mechanism flows into the inlet side flow divider of the evaporator. Here, the inflowing refrigerant is vertically separated into a gas-phase refrigerant and a liquid-phase refrigerant by the action of gravity. Then, the vapor-phase refrigerant flows through the bypass pipe, passes through the upper part of the outlet flow divider, and flows out of the evaporator. Therefore, the refrigerant in the liquid phase does not flow into the plurality of refrigerant pipes provided between the inlet-side flow divider and the outlet-side flow divider, and flows around the respective refrigerant pipes. Heated by air. Therefore, it is possible to prevent the heat exchange efficiency of the evaporator from being lowered by the vapor phase refrigerant.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. 1 is a schematic configuration diagram showing a refrigeration cycle according to an embodiment of the present invention, FIG. 2 is a front view showing the appearance of an evaporator provided in the refrigeration cycle, and FIG. 3 is provided in the refrigeration cycle. It is a front view which shows another example of the evaporator. However, Figure 4
And the evaporator 2 _{b of the} conventional refrigeration cycle shown in FIG.
The same reference numerals are used for the elements common to and the detailed description thereof is omitted. Refrigeration cycle 1 according to the present embodiment
As shown in FIG. 1, the compressor 13 discharges a high-temperature and high-pressure gas-phase refrigerant, and the refrigerant from the compressor 13 and a blower 17
A condenser 14 for converting the refrigerant into a high-temperature and high-pressure liquid-phase refrigerant by exchanging heat with the outdoor air from the condenser 1;
An expansion valve 15 (an example of a refrigerant expansion mechanism) that expands the liquid-phase refrigerant from 4 into a low-temperature low-pressure vapor-phase refrigerant, and a refrigerant that has become a gas-liquid two-phase flow by evaporating a part of the liquid-phase refrigerant. An evaporator 2 is provided which converts the refrigerant into a low-temperature low-pressure gas-phase refrigerant by heat exchange with room air from the blower 18. The compressor 13, the condenser 14, the expansion valve 15 and the evaporator 2 are connected to each other via a refrigerant pipe 20. Evaporator 2 of the refrigeration cycle 1, as shown in FIG. 2, the conventional evaporator 2 _b and the basic structure is substantially the same, characteristic differences between the conventional evaporator 2 _b has a plurality Above the capillary tube 3, and the upper part of the inlet side flow distributor 10 and the upper part of the output side flow distributor 11 into which the gas-liquid two-phase refrigerant from the expansion valve 15 flows in via the inflow pipe 4. The bypass pipe 6 has an extremely large inner diameter and a very short pipe length.

Therefore, the evaporator 2 of the refrigerant 1 having the above-mentioned structure
According to the method, according to the inflow pipe 4, the inlet-side flow divider 10 in the gas-liquid two-phase state is provided.
The refrigerant flowing into the inside is vertically separated into a gas phase and a liquid phase in the inlet side flow divider 10 due to the influence of gravity. Therefore, the gas-phase refrigerant in the upper part of the inlet side flow distributor 10 flows through the bypass pipe 6 having a pressure loss extremely smaller than that of the capillary tube 3 to reach the upper part of the outlet side flow distributor 11, and further from the outlet pipe 5 to the compressor. Return to the suction side of 13. Therefore, the refrigerant in the gas phase does not flow into any of the capillaries 3, the refrigerant in the liquid phase is diverted to all the capillaries 3, and the refrigerant in each of the capillaries 3 absorbs heat by exchanging heat with indoor air. After changing to the gas phase,
Merge in the outlet flow divider 11. Further, the refrigerant from each capillary tube 3 merges with the refrigerant from the bypass tube 6, and then returns from the outflow tube 5 to the compressor 13. As described above, since the liquid-phase refrigerant capable of receiving a larger amount of heat than the vapor-phase refrigerant flows through all the capillaries 3, the heat exchange efficiency of the condenser 2 is not impaired. ， Maintained in high efficiency. Generally, depending on the operating conditions of the refrigeration cycle 1, as described above, the dryness of the refrigerant flowing into the inlet side flow divider 10 in the gas-liquid two-phase state changes. Then, for example, when the degree of dryness of the refrigerant flowing into the inlet-side flow divider 10 is too low, the amount of vapor-phase refrigerant in the inlet-side flow divider 10 becomes extremely small. Therefore, not only the vapor-phase refrigerant but also the liquid-phase refrigerant passes through the bypass tubes 6 and bypasses the respective capillary tubes 3. As a result, the heat exchange efficiency of the evaporator 2 deteriorates. On the contrary, when the dryness of the refrigerant flowing into the inlet-side flow divider 10 is too large, the amount of the vapor-phase refrigerant in the inlet-side flow divider 10 becomes extremely large, which causes a part of the vapor-phase refrigerant. Flowing into the capillary tube 3 of the above and impairs the heat exchange efficiency of the evaporator 2.

Therefore, in order to eliminate the above-mentioned inconvenience, an evaporator _2a as shown in FIG. 3 is adopted. In this evaporator 2 _a , a throttle valve 7 which is provided in the bypass pipe 6 for controlling the amount of refrigerant flowing through the bypass pipe 6 and a surface of the uppermost capillary 3 on the outlet flow distributor 11 side are provided with the capillaries. Capillary temperature sensor 8 for detecting the surface temperature of 3 and the output side flow divider 11 provided on the surface of the output side flow divider 11.
And an outlet-side shunt temperature sensor 9 for detecting the surface temperature of the. Further, based on the temperature difference between the surface temperature of the capillary tube 3 and the surface temperature of the outlet flow divider 11, the control circuit 16 (see FIG. 1) for controlling the operation of the refrigeration cycle 1 detects It is configured to control the valve opening of the throttle valve 7. Specifically, the heat given to the refrigerant from the indoor air is used as sensible heat when the refrigerant is in the gas phase, and is used as latent heat and sensible heat when the refrigerant is in the liquid phase. As a result, when a certain amount of heat is applied, the temperature of the vapor phase refrigerant rises significantly. On the other hand, the liquid-phase refrigerant does not reach such a high temperature due to the action of the latent heat. Therefore, the temperature difference between the respective temperatures detected by the capillary temperature sensor 8 and the outlet-side shunt temperature sensor 9 is a predetermined temperature (when the vapor phase refrigerant flows only in the uppermost capillary tube 3). Based on the temperature difference, the opening degree of the throttle valve 7 is controlled so as to be less than the temperature difference between the capillary temperature and the outlet flow divider temperature at this time. Therefore, according to the evaporator _2a , even when the dryness of the gas-liquid two-phase refrigeration cycle that has flowed into the inlet side flow divider 10 changes due to a change in the operating conditions of the refrigeration cycle 1, whichever capillary tube 3 Also, the liquid-phase refrigerant can be circulated in all the capillaries 3 without circulating the gas-phase refrigerant. As a result, the heat exchange efficiency of the evaporator _2a is not impaired even under the above-mentioned operating conditions. Further, the control circuit 16 is configured to make the valve opening degree of the expansion valve 15 larger than the valve opening degree during the steady operation for a certain time in the initial operation of the refrigeration cycle 1. Therefore, according to the control circuit 16, most of the refrigerant that has flowed from the expansion valve 15 into the inlet side flow divider 10 at the beginning of the operation of the refrigeration cycle 1 becomes a liquid-phase refrigerant. As a result, the evaporator 2 in which the refrigerant is rapidly vaporized by the activation of the compressor 13
A sufficient amount of liquid-phase refrigerant can be fed into ( _2a ). As a result, the inside of each of the capillaries 3 is not filled with the vapor-phase refrigerant, and the liquid sealing phenomenon that stops the flow of the refrigerant does not occur in these capillaries 3 and the operation state of the refrigeration cycle 1 is quickly performed. It is possible to shift to the state of steady operation. Incidentally, in the evaporators 2 and _2a of the above-mentioned respective embodiments,
The bypass pipe 6 which connects the upper part of the inlet-side flow divider 10 and the upper part of the outlet-side flow divider 11 is provided above all the capillaries 3, but the present invention is not limited to this. For example, when the number of the capillaries 3 arranged in parallel in the vertical direction is large, even when the above-mentioned bypass pipe 6 is arranged slightly below the uppermost capillaries 3, it is almost the same as each of the above-described embodiments. The same effect will be produced.

[0009]

The present invention is constructed as described above. This allows the liquid-phase refrigerant to pass through most of the refrigerant tubes of the evaporator. As a result, the heat exchange efficiency of the evaporator is not impaired. In the case where the throttle valve is provided in the bypass pipe and the valve opening of the throttle valve is controlled based on the temperature difference between the temperature of the refrigerant pipe and the temperature of the outlet flow divider, the operating conditions of the refrigeration cycle are Even if the temperature changes, it is possible to pass the liquid-phase refrigerant through most of the refrigerant tubes according to this operating condition. Furthermore, in the case of a configuration in which the valve opening at the beginning of operation of the refrigerant expansion mechanism is made larger than the valve opening at the time of steady operation, a large amount of liquid-phase refrigerant is stored in the evaporator, which rapidly becomes a low pressure at the beginning of operation. Can be flowed into. As a result, it is possible to quickly shift the evaporator to the normal operation state.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a refrigeration cycle according to an embodiment of the present invention.

FIG. 2 is a front view showing an appearance of an evaporator provided in the refrigeration cycle.

FIG. 3 is a front view showing another example of the evaporator provided in the refrigeration cycle.

FIG. 4 is a front view showing the external appearance of an evaporator provided in a conventional refrigeration cycle, which is an example of the background of the present invention.

5 is a front sectional view showing the inside of the evaporator shown in FIG.

[Explanation of symbols]

1 ... Refrigeration cycle 2, 2 _a , 2 _b ... Evaporator 3 ... Capillary pipe (refrigerant pipe) 6 ... Bypass pipe 7 ... Throttle valve 8 ... Capillary temperature sensor 9 ... Outflow shunt temperature sensor 10 ... Inflow shunt 11 ... Outflow side flow divider 13 ... Compressor 14 ... Condenser 15 ... Expansion valve (refrigerant expansion mechanism) 16 ... Control circuit

Claims (3)

[Claims] 1. An inlet-side flow divider into which a refrigerant discharged from a compressor and passed through a condenser and a refrigerant expansion mechanism flows, and an outlet-side flow divider from which a refrigerant flows out of the inlet-side flow divider are arranged in parallel in a vertical direction. In a refrigeration cycle equipped with an evaporator that is connected through a plurality of deployed refrigerant pipes and that heats the refrigerant in the refrigerant pipes by the air that flows around the refrigerant pipes, in the upper part of the inlet side flow divider and the outlet side. A refrigeration cycle characterized in that the upper part of the flow divider is connected by a bypass pipe. 2. A throttle valve is provided in the bypass pipe, and the valve opening of the throttle valve is controlled based on the temperature difference between the temperature of the refrigerant pipe and the temperature of the outlet flow divider. Refrigeration cycle described in. 3. The refrigeration cycle according to claim 1, wherein the valve opening degree of the refrigerant expansion mechanism at the initial operation is larger than the valve opening degree at the time of steady operation.