KR102369304B1 - Control method of refrigeration system using ejector - Google Patents

Abstract

The present invention provides a technique for increasing temperature and pressure of a refrigerant flowing into a compressor, thereby preventing performance degradation that may occur in a low-temperature mode in a refrigeration cycle. The present invention discloses a control method of a refrigeration apparatus using an ejector, wherein a compressor, a condenser, a refrigerant tank, an expansion valve, an evaporator, an ejector, and an accumulator are connected with a flow pipe to form a steam cycle, and the ejector is connected to the refrigerant tank and the ejector are connected with a branch pipe where a heat exchanger and a flow rate control unit are disposed. The control method of the refrigeration apparatus using the ejector comprises: having a refrigerant flow along the steam cycle of the compressor, condenser, refrigerant tank, expansion valve, evaporator, ejector, and accumulator; measuring an indoor temperature in a room where the evaporator is disposed and an inlet temperature of the compressor; if the measured indoor temperature and the inlet temperature are less than a set value, controlling a flow rate control unit so that some of a high-temperature high-pressure liquid refrigerant introduced into the refrigerant tank is transferred to the branch pipe; increasing temperature of the high-temperature high-pressure liquid refrigerant flowing through the branch pipe in the heat exchanger and supplying the refrigerant to the ejector; mixing the high-temperature high-pressure liquid refrigerant whose temperature has been increased with a low-temperature low-pressure gaseous refrigerant introduced from the evaporator in the ejector and ejecting the mixture to the inlet of the compressor; measuring the temperature of the refrigerant introduced into an inlet of the compressor; and controlling the flow rate control unit to cause a flow of the high-temperature high-pressure liquid refrigerant whose temperature has been increased into the ejector to be adjusted according to the temperature of the refrigerant measured in the inlet.

Description

Control method of a refrigeration system using an ejector {Control method of refrigeration system using ejector}

The present invention relates to a method for controlling a refrigeration system using an ejector.

Vapor compression refrigeration systems are used as air conditioners, refrigerators, and heat pumps that lower the temperature of living spaces, vehicles, airplanes, and the like and remove moisture.

A refrigeration system typically consists of four main parts that are connected to each other through piping to form a closed loop system. The four main components are the compressor, condenser, expansion valve and evaporator. The refrigerant circulates through the four main components and operates as pressure and temperature increase or decrease.

The refrigerant circulates continuously in the refrigeration system. The main stages of the refrigeration cycle are compression of the refrigerant through a compressor, heat release in the condenser, throttling in the evaporator, and heat in the evaporator. absorption step. This process is also referred to as a vapor compression refrigeration system.

In the refrigeration cycle, the refrigerant flows into the compressor as a low-temperature, low-pressure gas, and the temperature and pressure rise, and then, discharged as a high-temperature and high-pressure gas, and flows into the condenser. The refrigerant is converted into a saturated liquid as heat is radiated from the condenser, and discharged as a high-temperature and high-pressure liquid and flows into the expansion valve. The refrigerant is reduced in pressure and temperature at the expansion valve. At this time, the refrigerant changes to a saturated state in which vapor and liquid are mixed. The refrigerant discharged from the expansion valve flows into the evaporator as a low-temperature, low-pressure liquid. The refrigerant absorbs heat from the room (refrigeration space) in the evaporator, lowers the room temperature, becomes a low-temperature, low-pressure gas, and flows into the compressor.

However, as the refrigerant cycle proceeded repeatedly, the temperature of the refrigerant discharged from the evaporator was introduced into the compressor at an extremely low temperature (-20°C). There was a problem in that the efficiency of the refrigeration cycle was lowered by the low-temperature refrigerant.

Republic of Korea Patent Registration No. 10-1174451 (2012.07.31.) Republic of Korea Patent Registration No. 10-0555944 (2006.02.21.)

The present invention provides a technique for increasing the temperature and pressure of a refrigerant flowing into a compressor.

In the method of controlling a refrigeration system using an ejector according to an embodiment of the present invention, a compressor, a condenser, a refrigerant tank, an expansion valve, an evaporator, an ejector, and an accumulator are connected to a flow path to form a vapor cycle, and the refrigerant tank and the ejector In a refrigeration device using an ejector connected to a branch pipe in which a heat exchanger and a flow rate control unit are disposed, flowing the refrigerant along the vapor cycle of a compressor, a condenser, a refrigerant tank, an expansion valve, an evaporator, an ejector, and an accumulator, the evaporator is arranged measuring the indoor temperature and the inlet temperature of the compressor; if the measured indoor temperature and the inlet temperature are less than or equal to a set value, a portion of the refrigerant in a high-temperature, high-pressure liquid state introduced into the refrigerant tank flows through the branch pipe controlling the flow rate control unit, supplying the high-temperature and high-pressure liquid refrigerant flowing through the branch pipe to the ejector by increasing the temperature in the heat exchanger; Mixing the introduced low-temperature and low-pressure gaseous refrigerant in the ejector and ejecting it to the inlet of the compressor, measuring the temperature of the refrigerant introduced into the inlet of the compressor, and the temperature of the refrigerant measured at the inlet and controlling the flow of the refrigerant in a high-temperature, high-pressure liquid state with an increased temperature by controlling the flow rate controller to flow into the ejector.

The temperature of the refrigerant ejected from the ejector may be 10 °C to 30 °C.

In the step of controlling the refrigerant flowing into the ejector, if the temperature of the refrigerant measured at the inlet is lower than the set value, the flow of the refrigerant is increased, and if the temperature of the refrigerant measured at the inlet is higher than the set value It is possible to reduce the flow of the refrigerant.

In the step of mixing the refrigerant in the ejector and ejecting it to the inlet of the compressor, the high-temperature and high-pressure refrigerant whose temperature has risen through heat exchange with the heating medium in the heat exchanger and the low-temperature and low-pressure refrigerant discharged from the evaporator are introduced into the ejector, After mixing, the ejector may increase the pressure of the refrigerant whose temperature has risen to eject it into the inlet of the compressor.

According to the embodiment of the present invention, since the refrigerant flowing into the compressor is introduced in a state in which the temperature and pressure are increased, the performance, which is a disadvantage during low-temperature operation in the vapor compression refrigeration cycle using the compressor, is prevented from being reduced.

According to an embodiment of the present invention, the temperature of the high-temperature, high-pressure liquid refrigerant in the heat exchanger is increased by heat exchange with waste heat. By utilizing the waste heat and applying it to the refrigeration system, the performance during low-temperature operation is improved.

1 is a conceptual diagram showing a refrigeration apparatus using an ejector according to an embodiment of the present invention.
Figure 2 is a schematic view showing the ejector of Figure 1;
3 is a block diagram illustrating a control method of a refrigeration apparatus using the ejector of FIG. 1;
Figure 4 is a refrigerant flow diagram of the vapor compression cycle of Figure 3;
5 is a flow chart of the vapor compression cycle using the ejector of FIG.
Figure 6 is a vapor compression cycle Ph diagram using the ejector of Figure 5.
7 is a graph showing a change in the temperature of the compressor inlet according to the temperature of the ejector motive side of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. Throughout the specification, like reference numerals are assigned to similar parts.

Then, a method for controlling a refrigerating apparatus using an ejector according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7 .

1 is a conceptual diagram showing a refrigeration system using an ejector according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the ejector of FIG. 1, and FIG. 3 is a block showing a control method of the refrigeration system using the ejector of FIG. Figure 4 is a flow chart of the refrigerant of the vapor compression cycle of Figure 3, Figure 5 is a flow chart of the vapor compression cycle using the ejector of Figure 3, Figure 6 is a diagram of the vapor compression cycle Ph using the ejector of Figure 5, Figure 7 is a graph showing the change in the compressor inlet temperature according to the ejector motive side temperature of FIG. 4 .

First, referring to FIGS. 1 and 2 , the refrigeration apparatus 1 using an ejector according to the present embodiment includes a compressor 10 , a condenser 20 , an expansion valve 30 , an evaporator 40 , and an ejector 60 . , a refrigerant tank 70 , a branch pipe 80 , and a heat exchanger 90 , and increases the temperature and pressure of the refrigerant flowing into the compressor 10 to prevent the efficiency of the refrigeration system caused by the lowering of the evaporation temperature. The refrigerating device 1 using the ejector according to the present embodiment may further include a flow rate control unit 110 and an accumulator 120 .

The compressor 10 , the condenser 20 , the expansion valve 30 , and the evaporator 40 are connected by a flow path pipe 50 . The refrigerant flows through the compressor 10 , the condenser 20 , the expansion valve 30 , and the evaporator 40 through the flow path 50 and forms a vapor compression cycle. The evaporator 40 is located in the room (refrigeration space) R and absorbs heat in the room to lower the temperature. Here, the detailed configuration of the compressor 10 , the condenser 20 , the expansion valve 30 , and the evaporator 40 is the same as the configuration of the known vapor compression cycle, and thus a detailed description thereof will be omitted.

The refrigerant tank 70 has a predetermined space in which the refrigerant is accommodated. The refrigerant tank 70 is positioned between the condenser 20 and the expansion valve 30 and is coupled to the flow path pipe 50 . The refrigerant is accommodated in the flow pipe 50 and the refrigerant tank 70 , and the refrigerant flowing through the flow pipe 50 passes through the refrigerant tank 70 .

An inlet (not shown) connected to the flow path pipe 50 connected to the condenser 20 is formed at a predetermined position around the refrigerant tank 70 . An outlet (not shown) connected to the flow path pipe 50 connected to the expansion valve 30 is formed at the bottom of the refrigerant tank 70 . The high-temperature, high-pressure liquid refrigerant discharged from the condenser 20 may flow into the refrigerant tank 70 through the inlet and then flow in the direction of the expansion valve 30 through the outlet.

On the other hand, although not shown in the drawings, a sensor for detecting the reception state of the refrigerant may be disposed in the refrigerant tank 70 . If the refrigerant detected by the sensor is less than the set capacity, the control unit may notify the user.

The ejector 60 is positioned between the evaporator 40 and the compressor 10 and is coupled to the flow pipe 50 . The ejector 60 includes a diffuser unit 62 connected to the main body 61 to which the suction unit 612 and the nozzle unit 611 are connected.

A suction space 613 is formed inside the body 61 , and the nozzle part 611 is disposed on one side of the body 61 , and at least a part thereof is located in the suction space 613 . The suction part 612 protrudes from the lower surface of the body 61 . The nozzle part 611 and the suction part 612 are connected in the suction space 613 . The suction unit 612 is connected to the flow path pipe 50 connected to the evaporator 40 .

The diffuser unit 62 has a predetermined length and is penetrated inside the diffuser unit 62 in the longitudinal direction. The diffuser part 62 is disposed on the other side of the main body 61 and the inside is connected to the suction space 613 . One end of the nozzle unit 611 is located inside the diffuser unit 62 .

On the other hand, the inside of the diffuser part 62 is connected to the main body 61 and is connected to the inlet 621 and the inlet 621 having a smaller cross-sectional area as the distance from the main body 61 is increased, and the inner circumference diameter changes. It includes an absent mixing unit 622 and a jetting unit 623 connected to the mixing unit 622 and having an increased cross-sectional area as the distance from the mixing unit 622 increases. The ejection part 623 is connected to the compressor 10 .

Since the detailed configuration of the ejector 60 is the same as that of the known ejector, a detailed description thereof will be omitted.

The branch pipe 80 has one end separated from the outlet and coupled to the outer periphery of the refrigerant tank 70 to be connected to the inner space of the refrigerant tank 70 . The other end of the branch pipe 80 is connected to the nozzle part 611 .

The heat exchanger 90 includes a plate heat exchanger. The heat exchanger 90 has a first flow path part 91 and a second flow path part 92 formed therein. The heat exchanger 90 is positioned between the ejector 60 and the refrigerant tank 70 , and the first flow path 91 is connected to the branch pipe 80 . The second flow passage 92 is connected to a waste heat pipe 93 through which a heating medium maintaining a temperature of 60° C. to 80° C. flows. The heating medium may be waste heat generated in a device (automobile, power plant, etc.) in which the refrigeration device 1 using an ejector is mounted.

However, the heating medium may also be heat driven by solar heat, renewable energy, and low-temperature heat sources.

The temperature of the heating medium is higher than the temperature of the refrigerant in the high-temperature, high-pressure liquid state flowing through the first flow path part 91 . The refrigerant in the high-temperature, high-pressure liquid state of the first flow passage part 91 and the heat medium of the second flow passage part 92 exchange heat with each other. The heat medium of the second flow path part 91 may increase by 30°C to 40°C. For example, when the evaporation temperature is 5°C and the condensation temperature is 35°C, it may rise from 35°C to 60°C to 80°C.

The flow rate control unit 110 is positioned between the refrigerant tank 70 and the heat exchanger 90 and is coupled to the branch pipe 80 . The flow rate controller 110 controls the refrigerant flow rate of the high-temperature, high-pressure liquid state flowing through the branch pipe 80 . The flow rate may vary depending on the temperature of the refrigerant in the low-temperature low-pressure gas state introduced into the suction space 613 .

The accumulator 120 is positioned between the ejector 60 and the compressor 10 and is coupled to the flow pipe 50 . Accordingly, the refrigerant ejected from the ejector 60 may be introduced into the compressor 10 via the accumulator 120 .

Meanwhile, sensors T1 and T2 for sensing temperature are respectively disposed at the inlets of the room R and the compressor 10 . The sensor T1 disposed in the room R and the sensor T2 disposed at the inlet of the compressor 10 are connected to the control unit. The control unit receives the signal from the sensor and operates the flow rate control unit 110 when the sensed temperature is within the set value of 10° C. and controls the heat medium to flow to the heat exchanger 90 . Here, the set value may vary depending on the device in which the refrigerating device 1 using the ejector is installed, the installation environment, and the like.

Next, a method of controlling the refrigerating apparatus using an ejector will be described with further reference to FIGS. 3 to 6 .

First, the refrigeration device 1 using the ejector includes a compressor 10 , a condenser 20 , a refrigerant tank 70 , an expansion valve 30 , an evaporator 40 , an ejector 60 , and an accumulator 120 through a flow path pipe. (50) to form a steam cycle, the refrigerant tank (70) and the ejector (60) are connected to the heat exchanger (90) and the branch pipe (80) in which the flow rate control unit (110) is disposed.

Referring to FIG. 3 , the control method of the refrigeration system using an ejector includes a compressor 10 , a condenser 20 , a refrigerant tank 70 , an expansion valve 30 , an evaporator 40 , an ejector 60 , and an accumulator The step of flowing the refrigerant along the vapor cycle of 120 (S10), the step of measuring the room temperature in which the evaporator 40 is disposed and the inlet temperature of the compressor 10 (S20), the measured room temperature and the inlet temperature are If it is less than the set value, controlling the flow control unit 110 so that some of the refrigerant in the high-temperature and high-pressure liquid state introduced into the refrigerant tank 70 flows through the branch pipe 80 (S30), the branch pipe 80 flows The high-temperature and high-pressure liquid refrigerant is supplied to the ejector 60 by increasing the temperature in the heat exchanger 90 (S40), and the high-temperature and high-pressure liquid refrigerant and the evaporator 40 are introduced into the ejector 60 Mixing the refrigerant in the low-temperature and low-pressure gas state in the ejector 60 and ejecting it to the inlet of the compressor 10 (S50), measuring the temperature of the refrigerant introduced into the inlet of the compressor 10 (S60) and the inlet and controlling the flow rate control unit 110 according to the temperature of the refrigerant measured in the step of controlling the high-temperature, high-pressure liquid refrigerant flowing into the ejector 60 (S70).

Referring to FIG. 4 , in the vapor compression cycle of the refrigeration system using the ejector, the refrigerant flows through the flow path pipe 50 through the compressor 10, the condenser 20, the refrigerant tank 70, the expansion valve 30, and the evaporator ( 40), the ejector 60 and the accumulator 120 flow (S10). The flow rate control unit 110 blocks the refrigerant in the high temperature and high pressure liquid state of the refrigerant tank 70 from flowing to the branch pipe 80 .

As the vapor compression cycle continues to operate, the refrigerant lowers the temperature of the room (R). In addition, the sensors T1 and T2 continuously measure the inlet temperatures of the room R and the compressor 10, respectively (S20).

Next, a vapor compression cycle using the ejector of the refrigeration system using the ejector described above will be described with reference to FIG. 5 .

If the temperature measured by the operation of the vapor compression cycle is less than the set value (temperature), the control unit controls the flow rate control unit 110 and the heat exchanger 90 to operate (S30).

The vapor compression cycle (compressor, condenser, refrigerant tank, expansion valve, evaporator, ejector, accumulator) operates, and the high-temperature, high-pressure liquid refrigerant in the refrigerant tank 70 by the operation of the flow rate control unit 110 is transferred to the branch pipe 80 ) to flow through the first flow path 91 . And the heat medium flows in the second flow path part 92 . The temperature of the refrigerant in the high-temperature and high-pressure liquid state of the first flow path part 91 is increased by heat exchange with the heat medium of the second flow path part 92 .

The high-temperature and high-pressure liquid refrigerant having an elevated temperature is introduced into the suction space 613 through the nozzle unit 611 and is introduced into the suction space 613 through the suction unit 612 together with the refrigerant in the low-temperature, low-pressure gaseous state and the diffuser unit. It is mixed while flowing through the inside of (62) (S40).

The refrigerant in the low-temperature, low-pressure gaseous state and the high-temperature, high-pressure liquid refrigerant in which the temperature has risen are mixed and ejected through the ejection unit 623 (S50).

The refrigerant in the low-temperature and low-pressure gas state has a higher temperature than when it flows into the suction space 613 , and the refrigerant in the high-temperature and high-pressure liquid state has a lower temperature than when it flows into the suction space 613 . The refrigerant (low-temperature, low-pressure gas + high-temperature, high-pressure liquid with increased temperature) mixed therewith flows into the accumulator 120 while maintaining the temperature at 10°C to 30°C. And the refrigerant ejected by the structure of the ejection unit 623 flows into the accumulator 120 in a state in which the pressure is increased.

The refrigerant passing through the accumulator 120 flows into the compressor 10 to become a refrigerant in a high-temperature, high-pressure gaseous state. Since the refrigerant (low-temperature, low-pressure gas + high-temperature, high-pressure liquid) passes through the ejector 60 and flows into the compressor 10 with the temperature and pressure increased, the compression efficiency is improved. Accordingly, an effect of improving the efficiency of the refrigeration cycle occurs.

The sensor T2 measures the temperature of the inlet (S60).

The flow rate control unit 110 adjusts the refrigerant flow rate of the high temperature and high pressure liquid state flowing through the branch pipe 80 to control the temperature of the refrigerant flowing into the compressor 10 . That is, when the temperature of the refrigerant flowing into the compressor 10 is low (less than 10° C.), the flow rate control unit 110 increases the refrigerant flow rate of the high temperature and high pressure liquid state flowing through the branch pipe 80 . Conversely, when the temperature of the refrigerant flowing into the compressor 10 is high (over 30° C.), the flow rate controller 110 reduces the refrigerant flow rate of the high-temperature and high-pressure liquid state flowing through the branch pipe 80 ( S70 ).

Accordingly, as shown in FIG. 6 , by increasing the pressure and temperature of the refrigerant entering the compressor 10 by utilizing the ejector 60 and heat exchange, the power consumption of the compressor 10 is reduced, thereby increasing the COP of the cycle. can

Referring to FIG. 7 , the Y-axis is the temperature of the ejection unit 623 of the ejector 60 , and the X-axis is the flow rate distribution ratio of the flow control unit 100 . And D is the ejection part 623 side temperature of the ejector 60, E shows the temperature of the inlet side of the flow rate control unit (110).

When distributing the flow rate in the refrigerant tank 70, the temperature of the ejection part 623 of the ejector 60 can be adjusted by using the following [Equation 1].

[Equation 1]

A, B1 and B2 are constants according to the refrigerant inflow, and X is the flow rate distribution.

Accordingly, it can be seen that as the flow rate distribution ratio of the flow rate controller 110 increases, the temperature of the refrigerant ejected from the ejection unit 623 of the ejector 60 increases.

Therefore, according to this embodiment, since the refrigerant flowing into the compressor is introduced in a state in which the temperature and pressure are increased, the performance, which is a disadvantage during low-temperature operation in the vapor compression refrigeration cycle using the compressor, is prevented from being reduced.

In addition, the temperature of the high-temperature, high-pressure liquid refrigerant in the heat exchanger is increased by heat exchange with waste heat. By utilizing the waste heat and applying it to the refrigeration system, the performance during low-temperature operation is improved.

If the refrigeration system using an ejector is an automobile, its economic activity capacity is large by improving fuel efficiency and reducing carbon dioxide.

Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

1: Refrigeration system using ejector
10: compressor 20: condenser
30: expansion valve 40: evaporator
50: flow pipe 60: ejector
61: body 611: nozzle unit
612: suction unit 613: suction space
62: diffuser 621: inlet
622: mixing unit 623: ejection unit
70: refrigerant tank 80: branch pipe
90: heat exchanger 91: first flow path part
92: second flow passage 93: waste heat pipe
110: flow control unit 120: accumulator
130: control unit T1, T2: sensor
R: Indoor

Claims (4)

A compressor, a condenser, a refrigerant tank, an expansion valve, an evaporator, an ejector, and an accumulator are connected to a flow pipe to form a steam cycle, and the refrigerant tank and the ejector are connected to a branch pipe in which a heat exchanger and a flow rate control unit are disposed. at,
flowing the refrigerant along the vapor cycle of the compressor, condenser, refrigerant tank, expansion valve, evaporator, ejector and accumulator;
Measuring the room temperature in which the evaporator is disposed and the inlet temperature of the compressor;
When the measured indoor temperature and the inlet temperature are less than or equal to a set value, controlling the flow rate controller so that a portion of the refrigerant in a high-temperature and high-pressure liquid state flowing into the refrigerant tank flows through the branch pipe;
supplying the high-temperature, high-pressure liquid refrigerant flowing through the branch pipe to the ejector by increasing the temperature in the heat exchanger;
mixing the refrigerant in the high-temperature and high-pressure liquid state with the increased temperature and the refrigerant in the low-temperature and low-pressure gaseous state introduced into an ejector from the evaporator in the ejector and ejecting the refrigerant into an inlet of the compressor;
measuring the temperature of the refrigerant introduced into the inlet of the compressor; and
Controlling the flow rate control unit according to the temperature of the refrigerant measured at the inlet to adjust the high-temperature, high-pressure liquid refrigerant flowing into the ejector
A control method of a refrigeration system using an ejector comprising a. In claim 1,
A control method using a refrigeration device using an ejector, wherein the temperature of the refrigerant ejected from the ejector is 10°C to 30°C. In claim 1,
In the step of controlling the refrigerant flowing into the ejector,
When the temperature of the refrigerant measured at the inlet is lower than the set value, the flow of the refrigerant is increased, and when the temperature of the refrigerant measured at the inlet is higher than the set value, the flow of the refrigerant is decreased
A method of controlling a refrigeration system using an ejector. In claim 1,
In the step of mixing the refrigerant in the ejector and ejecting it to the inlet of the compressor,
The high-temperature, high-pressure refrigerant whose temperature has risen through heat exchange with the heating medium in the heat exchanger and the low-temperature and low-pressure refrigerant discharged from the evaporator are introduced into the ejector and mixed, and the ejector increases the pressure of the refrigerant whose temperature has risen to increase the pressure of the compressor. spouting into the inlet
A method of controlling a refrigeration system using an ejector.

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