EP0631095A2

EP0631095A2 - Refrigeration cycle and method of controlling the refrigeration composition ratio of the refrigeration cycle

Info

Publication number: EP0631095A2
Application number: EP94109583A
Authority: EP
Inventors: Kensaku Oguni; Kazumoto Urata; Masatoshi Muramatsu; Takeshi Endo; Hiroaki Matsushima
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1993-06-24
Filing date: 1994-06-21
Publication date: 1994-12-28
Anticipated expiration: 2014-06-21
Also published as: DE69422551T2; DE69432489D1; EP0631095B1; DE69432489T2; EP0838643A3; JPH0712411A; EP0838643B1; EP0631095A3; EP0838643A2; DE69422551D1

Abstract

The composition of a refrigerant within the refrigeration cycle in which a non-azeotrope refrigerant is used is controlled to a predetermined composition. Further, the amount of the refrigerant is detected, and the composition and amount of the refrigerant within the refrigeration cycle are displayed, facilitating the maintenance of the refrigerant. The refrigeration cycle includes a compressor (1), a heat-source-side heat exchanger (2), use-side heat exchangers (20a,20b), and a pressure reducing apparatus (7,21a,21b), in which cycle a non-azeotrope refrigerant is used as a refrigerant. The refrigeration cycle further includes a sensor (8), disposed in a pipe portion where a liquid phase is formed, for detecting the composition of the non-azeotrope refrigerant circulating within the refrigeration cycle, and devices (5,6,10) for controlling the composition to a predetermined composition, a sensor for detecting the amount of refrigerant and a device for displaying the amount of the refrigerant. Since the composition of the refrigerant circulating within the refrigeration cycle is detected and control appropriate for the detected composition is performed, it becomes possible to perform a stable operation even when the refrigerant leaks outside and the composition of the refrigerant varies.

Description

BACKGROUND OF THE INVENTION

Field of the Invention:

The present invention relates to a refrigeration cycle in which a non-azeotrope refrigerant is used as a working medium. More particularly, the present invention relates to a refrigeration cycle in which the composition ratio of the refrigerant circulating within the refrigeration cycle is controlled and a method of controlling the refrigeration composition ratio of the refrigeration cycle.

Description of the Related Art:

First, a case in which a non-azeotrope refrigerant is used as a working medium will be explained. The non-azeotrope refrigerant is a refrigerant in which two or more types of refrigerants having different boiling points are mixed, and has characteristics shown in Fig. 3. Fig. 3 is a vapor-liquid equilibrium diagram illustrating characteristics of a non-azeotrope refrigerant in which two types of refrigerants are mixed. The horizontal axis indicates the composition ratio X of a refrigerant having a low boiling point, and the vertical axis indicates temperature. With pressure as a parameter, a saturation vapor line and a saturation liquid line exist in a high temperature region indicated by pressure P_H when, for example, pressure is high and when,conversely, pressure is low, these lines exist in a low temperature region indicated by pressure P_L. The composition ratio X = 0 indicates that the refrigerant is formed of only a high-boiling-point refrigerant, and the composition ratio X = 1.0 indicates that the refrigerant is formed of only a low-boiling-point refrigerant. In a mixture refrigerant, as shown in Fig. 3, a saturation liquid line and a saturation vapor line are determined by the composition thereof. The area below the saturation liquid line indicates the supercooled state, and the area above the saturation vapor line indicates the superheated state. The portion surrounded by the saturation liquid line and the saturation vapor line is a two-phase state of liquid and vapor. In Fig. 3, X₀ denotes the composition ratio of a refrigerant sealed in a refrigeration cycle. Points P1 to P4 indicate the typical points of the refrigeration cycle, and point P1 indicates a compressor outlet portion; point P2 indicates a condenser outlet portion; point P3 indicates an evaporator inlet portion; and point P4 indicates a compressor inlet portion.
An explanation will be given below of problems relating to leakage out of the refrigeration cycle, to variations in the composition of a circulating refrigerant within the refrigeration cycle in a non-steady state such as at the start-up time of the refrigeration cycle, and to refrigeration cycle operation control.
The leakage of a refrigerant out of the refrigeration cycle is not none even in a hermetically sealed type air-conditioner or refrigerator. In Fig. 3, point A indicates the two-phase portion in the refrigeration cycle, in which the liquid of composition X_a1 and the vapor of composition X_a2 exist. If the mixture refrigerant should leak out of a heat-transfer tube of a heat exchanger or from a connection tube of a component, it would be a refrigerant of composition ratio X_a1 in the case of liquid leakage, and a refrigerant of composition ratio X_a2 in the case of vapor leakage. Therefore, the composition ratio of the refrigerant remaining within the refrigeration cycle differs depending upon whether liquid or vapor leaks.
Fig. 4 is an illustration of a problem caused by the leakage of a refrigerant to the outside. If liquid leaks, the remaining mixture refrigerant enters the state of X₁ in which the ratio of a low boiling-point refrigerant is large; if vapor leaks, the remaining mixture refrigerant enters the state of X₂ in which the ratio of a high boiling-point refrigerant is large. In Fig. 2, X₀ indicates the composition ratio of a refrigerant which is sealed in initially. If a state in which the composition is X₀ is compared with a state in which the composition is X₁ at the same pressure, the temperature when the composition is X₁ is lower. If, however, a state in which the composition is X₀ is compared with a state in which the composition is X₂ at the same pressure, the temperature when the composition is X₂ is higher.
Fig. 5 shows general characteristics of a refrigeration cycle with respect to the composition ratio of the low boiling-point refrigerant. When the composition ratio X becomes larger, and therefore heating and cooling performance improves.
If the refrigerant leaks out of the refrigeration cycle in which a non-azeotrope refrigerant is used as a working medium, as described above, the composition ratio of the refrigerant remaining within the refrigeration cycle changes from the initial composition ratio, i.e., from the designed composition ratio for the apparatus depending upon leaked portions. Even if there is no leakage to the outside, there is a possibility that the composition ratio of the refrigerant circulating within the refrigeration cycle may vary in the non-steady state of the refrigeration cycle.
Changes in the composition ratio of the refrigerant within the refrigeration cycle cause problems; for example, heating and cooling capacity is varied, or pressure or temperature becomes abnormal. Therefore, the refrigeration cycle must be controlled properly.
Since a chlorofluorocarbon refrigerant containing chlorine is considered to damage an ozone layer, a non-azeotropic mixture of a chlorofluorocalcium refrigerant containing no chlorine has been proposed as an alternative refrigerant. A consideration must be given to the mixture refrigerant in order to safeguard the earth environment.
The control of a refrigeration cycle in which a non-azeotropic mixture is used as a working medium is disclosed in, for example, Japanese Patent Unexamined Publication Nos. 59-129366, 61-213554, and 64-58964.
Japanese Patent Unexamined Publication No. 59-129366 discloses that an electrostatic capacitance sensor is used as a means for detecting the composition of a refrigerant circulating within the refrigeration cycle. Further, it is disclosed that the refrigeration cycle comprises a first liquid receiver and a second liquid receiver, an electric heater being disposed in the second liquid receiver. When the outdoor air temperature is low during a heating operation, the electric heater of the second liquid receiver is operated and controlled so that a set refrigerant concentration is reached.
Disclosed in Japanese Patent Unexamined Publication No. 61-213554 is an apparatus comprising a separator for separating a low-boiling-point refrigerant, a liquid receiver for storing a low-boiling-point refrigerant, and a control valve for returning the refrigerant from the liquid receiver, which apparatus controls the composition of the refrigerant on the basis of the temperature of an element to be cooled.
Disclosed in Japanese Patent Unexamined Publication No. 64-58964 is a mixture refrigerant composition variable refrigeration cycle in which the upper portion of the liquid receiver is connected to a refrigerant tank and the lower portion of the liquid receiver is connected to the refrigerant tank, which refrigeration cycle comprises a refrigerant tank capable of exchanging heat with a gas pipe through which a heat-source-side heat exchanger is connected to a use-side heat exchanger, a liquid receiver and the like.
As described above, in the refrigeration cycle in which a non-azeotrope refrigerant is sealed in, the composition ratio of the refrigerant within the refrigeration cycle may vary when the refrigerant leaks out of the refrigeration cycle or during the non-steady operation of the refrigeration cycle. The capacity of the refrigeration cycle can be varied by making the composition variable. Therefore, to obtain a high-capacity refrigeration cycle, it is important to control the refrigerant composition ratio within the refrigeration cycle so as to realize a stable operation. There has been a demand for a method of varying this composition ratio inexpensively. Further, it is necessary to use a refrigerant which does not contain chlorine and does not damage the ozone layer, in which a consideration is given to safeguard the earth environment.
For various problems of such refrigeration cycles using a non-azeotrope refrigerant, only the concentration of one of the non-azeotrope refrigerants is adjusted actively in the above-described prior art. Therefore, the prior art has the problem in that the width of the adjustment of the concentration is narrow.
Although in the above-described prior art a refrigeration cycle in which the composition of the mixture refrigerant during a cooling operation is varied from that during a heating operation, the prior art has the problem in that the composition of the mixture refrigerant cannot be varied in each of the cooling and heating operations. Further, in the prior art, no consideration is given to that the composition of the mixture refrigerant is detected to vary the composition. Also, in the prior art, no consideration is given to that a refrigerant which does not contains chlorine and does not damage the ozone layer is used. Mixture refrigerants which have been proposed recently have flammability to one degree or another. However, no consideration is given to the new problem of flammability. When a non-azeotrope refrigerant is sealed within the refrigeration cycle, there is a possibility that the composition ratio of the refrigerant may vary. However, no consideration is given to a method of sealing in the non-azeotrope refrigerant without varying the composition ratio.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an inexpensive refrigeration cycle in which a non-azeotrope refrigerant which does not damage the ozone layer is used, which can be operated stably,and in which the composition ratio of the non-azeotrope refrigerant can be varied widely.
It is another object of the present invention to provide a method of controlling the refrigerant composition ratio of a refrigeration cycle in which a refrigerant having a stable concentration can be sealed in when a non-azeotrope refrigerant which does not damage the ozone layer is sealed in the refrigeration cycle.
To achieve the above objects, according to one aspect of the present invention, there is provided a refrigeration cycle in which a non-azeotrope refrigerant which does not damage the ozone layer is used as a refrigerant, and in which a compressor, a heat-source side heat exchanger, a pressure reducing apparatus, and a use-side heat exchanger are connected in sequence. The refrigeration cycle comprises a device, disposed in a pipe portion where a liquid phase is formed, for detecting the composition of a non-azeotrope refrigerant circulating within the refrigeration cycle; a device for varying the composition of a refrigerant having a high-boiling-point refrigerant of the non-azeotropic mixture; a device for varying the composition of a refrigerant having a low-boiling-point refrigerant; and a control apparatus for controlling the devices for varying the composition of the non-azeotropic mixture. The composition of the non-azeotrope refrigerant is controlled on the basis of signals from the device for detecting the composition.
According to another aspect of the present invention, there is provided a refrigeration cycle comprising a compressor, a heat-source side heat exchanger, a use-side heat exchanger, and a pressure reducing apparatus, in which a non-azeotrope refrigerant which does not damage the ozone layer is used as the refrigerant. The refrigeration cycle comprises a device for detecting the composition of a non-azeotrope refrigerant circulating within the refrigeration cycle; a device for detecting the amount of refrigerant within the refrigeration cycle; and a display device for displaying the composition of the non-azeotrope refrigerant, the amount of refrigerant within the refrigeration cycle, and a refrigerant maintenance operation.
According to a further aspect of the present invention, the composition ratio of a non-azeotrope refrigerant is controlled to a predetermined composition ratio when the non-azeotrope refrigerant is sealed in the refrigeration cycle.
According to the present invention, since a composition detecting sensor for detecting the composition of the refrigerant circulating within the refrigeration cycle is disposed in a liquid-state pipe in the refrigeration cycle, it is possible to detect the composition of the mixture refrigerant with a high degree of accuracy. Since control appropriate for the composition ratio in the refrigeration cycle is performed on the basis of the detected composition, a stable operation is possible even when the refrigerant leaks outside and the composition of the refrigerant circulating within the refrigeration cycle is varied from the designed composition of the refrigeration cycle. In addition, since the composition ratio can be controlled to a predetermined composition ratio when a non-azeotrope refrigerant is sealed in the refrigeration cycle, it is possible to reduce variations in the composition ratio during operation. Even when the circulation composition is varied in a non-steady operating state of the refrigeration cycle, it is possible to secure performance and reliability. In addition, it is possible to control the capacity of the refrigeration cycle to capacity commensurate with a cooling or heating load.
According to the present invention, the operation for maintaining the composition of the refrigerant within the refrigeration cycle is considerably simplified.
The above and further objects, aspects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended to limit the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic view of a refrigeration cycle having a control apparatus for controlling the composition of a non-azeotrope refrigerant;
Fig. 2 is a longitudinal sectional view of a refrigerant circuit for controlling the composition of the refrigerant;
Fig. 3 is a diagram illustrating the characteristics of a non-azeotrope refrigerant;
Fig. 4 is a diagram illustrating the relationship between the composition of the non-azeotrope refrigerant and temperature;
Fig. 5 is a diagram illustrating the characteristics of a refrigeration cycle in which a non-azeotrope refrigerant is used;
Fig. 6 is a diagram illustrating the characteristics of a non-azeotrope refrigerant;
Fig. 7 shows an example of the composition of three-type mixture refrigerant;
Fig. 8 is a sectional view of an electrostatic capacitance type composition ratio detecting sensor;
Fig. 9 is a diagram illustrating the relationship between the composition of the non-azeotrope refrigerant and the electrostatic capacitance value;
Fig. 10 is a flowchart illustrating the control of the composition of the non-azeotrope refrigerant;
Fig. 11 is a schematic view of a refrigeration cycle having a control apparatus for controlling the composition of the non-azeotrope refrigerant;
Fig. 12 is a diagram illustrating the characteristics of the non-azeotrope refrigerant;
Fig. 13 is a flowchart illustrating the control of the composition ratio of the non-azeotrope refrigerant;
Fig. 14 is a schematic view of a refrigeration cycle having a control apparatus for controlling the composition ratio of the non-azeotrope refrigerant;
Fig. 15 is a detailed view of a refrigerant separation circuit;
Fig. 16 is a flowchart illustrating the control of the composition ratio of the non-azeotrope refrigerant;
Fig. 17 is a schematic view of a refrigeration cycle having a sensor for detecting the composition ratio of the non-azeotrope refrigerant and a sensor for detecting the amount of the refrigerant;
Fig. 18 is a schematic view of a refrigeration cycle having a sensor for detecting the composition ratio of the non-azeotrope refrigerant and a sensor for detecting the amount of the refrigerant;
Fig. 19 is a schematic view of a refrigeration cycle having a composition ratio detecting sensor and a refrigerant amount sensor;
Fig. 20 is a diagram illustrating the composition within a refrigerant bomb; and
Fig. 21 is a schematic view of a refrigeration cycle having a composition ratio detecting apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be explained below with reference to the accompanying drawings.
Fig. 1 illustrates a refrigeration cycle in which a plurality of indoor machines are connected to one outdoor machine in accordance with a first embodiment of the present invention. Referring to Fig. 1, reference numeral 1 denotes a compressor; reference numeral 2 denotes an outdoor heat exchanger; reference numeral 3 denotes an outdoor air blower; reference numeral 4 denotes a four-way valve; reference numeral 5 denotes an accumulator; reference numeral 6 denotes a receiver; and reference numeral 7 denotes an outdoor refrigerant control valve which acts as a pressure reducing mechanism during a heating operation. Reference numeral 8 denotes a sensor for detecting the composition of a non-azeotrope refrigerant; reference numeral 10 denotes a refrigerant tank; reference numeral 11 denotes a cooling unit; reference numerals 12, 13 and 14 denote open/close valves; reference numerals 15, 16 and 17 denote pipes; reference numerals 91, 92, 93 and 94 denote check valves which constitute an outdoor machine. Reference numerals 20a and 20b denote indoor heat exchangers; reference numerals 21a and 21b denote indoor refrigerant control valves which act as a pressure reducing mechanism during a cooling operation; reference numerals 22 and 23 denote refrigerant distribution units; and reference numerals 24 and 25 denote pipes for connecting indoor machines to outdoor machines. The illustration of the indoor air blower is omitted.
Next, a detecting apparatus in which an electrostatic capacitance sensor 8 for detecting the composition of a non-azeotrope refrigerant is used, and a control apparatus for controlling the open/ close valves 12, 13 and 14 are disposed on the outdoor side. In Fig. 1, the illustration of the control system of the refrigeration cycle is omitted. A refrigerant which does not contain chlorine and does not damage the ozone layer is used as the refrigerant. In this embodiment, an example in which HFC32 and HFC134a are used as the non-azeotrope refrigerant will be explained.
Next, the flow of the refrigerant will be explained. During a cooling operation, the refrigerant discharged from the compressor flows in the following order: the four-way valve 4 → the outdoor heat exchanger 2 → the check valve 93 → the composition sensor 8 → the outdoor refrigerant control valve 7 → the check valve 92 → the receiver 6. The refrigerant is distributed by a refrigerant distribution unit; a part of the refrigerant flows in the order: the indoor refrigerant control valve 21a → the indoor heat exchanger 20a, and the other flow in the order: the indoor refrigerant control valve 21b → the indoor heat exchanger 20b. They merge in a distribution unit 22 and flow in the order: the pipe 24 → the four-way valve 4 → the accumulator 5, and return to the compressor. At this time, the indoor heat exchangers 20a and 20b act as evaporators and a cooling operation is performed.
On the other hand, during a heating operation, the refrigerant discharged from the compressor flows in the following order: the four-way valve 4 → the pipe 24 → the distribution unit 22. A part of the refrigerant flows in the order: the indoor heat exchanger 20a → the indoor refrigerant control valve 21a, and the other flow in the order: the indoor heat exchanger 20b → the indoor refrigerant control valve 21b. They merge in a distribution unit 23 and flow in the order: the pipe 25 → the receiver 6 → the check valve 94 → the composition sensor 8 → the outdoor control valve 7 → the check valve 91 → the outdoor heat exchanger 2 → the four-way valve 4 → the accumulator 5, and return to the compressor. At this time, the indoor heat exchangers 20a and 20b act as condensers and a heating operation is performed.
The details of the low-boiling-point refrigerant separation circuit of Fig. 1 are shown in Fig. 2. In Fig. 2, a cooling unit 11 is a double-pipe heat exchanger. When a liquid refrigerant is stored in a refrigerant storage tank 10, the open/ close valves 12 and 13 are opened. In this case, the liquid in the bottom of the receiver 6 flows out through the open/close valve 12, and the liquid is formed into a low-temperature refrigerant by the pressure reducing effect of the open/close valve 12 and guided into the inner pipe of the cooling unit 11. On the other hand, gas inside the receiver 6 flows out through the open/close valve 13 and is guided into the outer pipe of the cooling unit 11. The low-temperature refrigerant gas of the inner pipe exchanges heat with the gas of the outer pipe, and the low-temperature refrigerant is gasified and guided into the accumulator 5 through the pipe 15. The condensed liquefied refrigerant of the outer pipe is guided into the refrigerant storage tank 10. When a predetermined amount of liquid refrigerant is stored in the refrigerant storage tank 10, the open/ close valves 12 and 13 are closed. The above operation and effect make it possible to store the liquid refrigerant in the refrigerant storage tank 10. To discharge the liquid refrigerant from the refrigerant storage tank 10, the open/close valve 14 is opened so that the liquid refrigerant can be discharged to the accumulator 5 through the pipe 15.
The composition varying effect will be explained below.
The state of the refrigerant inside the receiver, which is made clear by the experiment conducted by the inventors of the present invention, will now be explained using a cooling operation as an example. Gas and liquid flow into the receiver 6 from the pipe 17, and the gas rises in the liquid layer inside the receiver 6, forming a gas layer. Then, the gas is condensed by the inner wall of the receiver 6 and liquefied. Thereafter, the gas is formed into only liquid in an outlet pipe 16 and flows out. The experimental results show that when the refrigerant dryness of the inlet is great, the liquid disappears inside the receiver 6, and when the refrigerant dryness is small, the receiver 6 is filled with the liquid. The experiment also revealed that the variation of the dryness with respect to the variation in the amount of liquid is 0.01 or less. That is, the dryness of the refrigerant which flows into the receiver is very small.
Fig. 6 illustrates changes of the state of the refrigerant in a refrigerant passage from the condenser to the receiver when a non-azeotrope refrigerant is used as a thermal medium. The horizontal axis indicates the composition ratio X of the low-boiling-point refrigerant, i.e., HFC32, and the vertical axis indicates temperature, with pressure being constant. The state X = 0 indicates a state in which only HFC134a is contained in the refrigerant, and the state X = 1 indicates a state in which the refrigerant is formed of only HFC32. In the non-azeotrope refrigerant, as shown in the figure, the temperature of the saturation vapor differs from that of the saturation liquid at the same pressure. The composition ratio X₀ indicates the composition ratio of the refrigerant sealed in the refrigeration cycle. Point A indicates the state of the inlet of the condenser; point B indicates the condensation start point; point C indicates the state of the inside of the receiver; and point D indicates the state of the outlet of the cooling unit. Point C, as described above, indicates that the flow rate of the liquid is very small. Point E indicates the liquid state inside the receiver, and the composition ratio of HFC32 is X₁. Point F indicates the gas state, and the composition ratio of HFC32 is X_g. It can be seen that the composition ratio of gas at point F is greater than the composition ratio X₀ of the refrigerant sealed in the refrigeration cycle, and the composition ratio in the refrigeration cycle can be varied by taking out gas.
In Figs. 1 and 2, a gas refrigerant having a large composition ratio of HFC32 taken out from the upper portion of the receiver 6 is liquefied in the cooling unit 11 and stored in the tank 10. As a result, the composition ratio of the refrigerant within the refrigeration cycle becomes smaller than X₀. When the composition ratio of the refrigerant within the refrigeration cycle is smaller than X₀, it is possible to return the refrigerant having a large composition ratio of HFC32 to the refrigeration cycle by opening the open/close valve 14.
As described above, the refrigerant composition ratio in the main refrigeration cycle can be varied by taking out or returning the gas refrigerant inside the receiver.
Although the above-described embodiment describes a case in which a mixture refrigerant of two types of refrigerants, i.e., HFC32 and HFC134a, are used as a refrigerant, the present invention may be applied to a mixture refrigerant of more than two types. For example, the present invention may be applied to a three-type mixture refrigerant of HFC32, HFC125 and HFC134a shown in Fig. 7. The numeric values shown in Fig. 7 indicates weight percentage(%) of HFC32, HFC125 and HFC134a, and a mixture refrigerant of various weight percentages may be considered. Of HFC32, HFC125 and HFC134a, the boiling points of HFC32 and HFC125 are higher than that of HFC134a, and therefore the present invention utilizing the difference between the boiling points of mixed refrigerants may be applied. HFC32 and HFC125 exhibit azeotropic characteristics which can be regarded as a single refrigerant, and the above-described mixture refrigerant can be assumed as a mixture refrigerant of the azeotrope refrigerant of HFC32 and HFC125, and HFC134a. The composition varying function of the present invention may be exhibited for a mixture refrigerant of HFC32, HFC125 and HFC134a. In Figs. 1 and 2, gas in the upper portion of the receiver 6 is a low-boiling-point refrigerant having a large refrigerant composition ratio, whose compositions of HFC32 and HFC125 from among the three types of refrigerants are large. The gas having large compositions of HFC32 and HFC125, taken out from the upper portion of the receiver 6, is liquefied by the cooling unit 11 and stored in the tank 10. As a result, regarding the composition ratio of the refrigerant within the refrigeration cycle, the composition ratios of low-boiling-point refrigerants, i.e., HFC32 and HFC125, are small, and the composition ratio of the high-boiling-point refrigerant, i.e., HFC134a, is large. Regarding the composition ratio within the refrigeration cycle, it is possible to return the composition ratio of the HFC32 and HFC125 to the original state by opening the open/close valve 14. As stated above, it is possible to vary the composition of the refrigerant in the case of a three-type mixture refrigerant.
Next, an explanation will be given of an embodiment of the electrostatic capacitance type sensor 8 for detecting the composition of a mixture refrigerant. Fig. 8 is a sectional view of the electrostatic capacitance type composition detecting sensor 8 shown in Fig. 1. In Fig. 8, reference numeral 53 denotes an outer tube electrode, and reference numeral 54 denotes an inner tube electrode, both of which are hollow tubes. The inner tube electrode 54 is fixed at its both ends by stoppers 55a and 55b in which a circular groove is provided in the central portion of the outer tube electrode 53. The outer diameter of the stoppers 55a and 55b is nearly the same as the inner diameter of the outer tube electrode 53, and the side opposite to the inner tube electrode holding side is fixed by the refrigerant introduction pipe 59 having an outer diameter nearly the same as the inner diameter of the outer tube electrode 53. In addition, the refrigerant introduction pipe 59 is fixed to the outer tube electrode 53.
As a result, the inner tube electrode 54 is fixed to the central portion of the outer tube electrode 53. An outer-tube electrode signal line 56 and an inner-tube electrode signal line 57 are connected to the outer tube electrode 53 and the inner tube electrode 54 in order to detect an electrostatic capacitance value. A signal line guide tube 58 (e.g., a hermetic terminal) for guiding the inner-tube electrode signal line 57 to the outside of the outer tube electrode 53 and for preventing the refrigerant inside from escaping to the outside, are disposed outside the inner-tube electrode signal line 57. In the stoppers 55a and 55b, at least one through passage having a size smaller than the inner diameter of the inner tube electrode 54 is disposed in the central portion thereof, and at least one passage for the refrigerant is disposed at a place between the inner tube electrode 54 and the outer tube electrode 53, so that the flow of the mixture refrigerant flowing through the inside is not obstructed.
Next, an explanation will be given of a method of detecting the composition of a mixture refrigerant by using the electrostatic capacitance type composition ratio detecting sensor 8. Fig. 9 illustrates the relationship between the composition ratio of the refrigerant and the electrostatic capacitance value when the electrostatic capacitance sensor is used. Fig. 9 illustrates measured values obtained when HFC134a is used as a high boiling-point refrigerant and HFC32 is used as a low boiling-point refrigerant from among the mixture refrigerant and they are sealed in the composition ratio detecting sensor shown in Fig. 8 as gas and liquid, respectively. The horizontal axis indicates the composition ratio of the HFC32, and the vertical axis indicates the electrostatic capacitance value which is an output from the composition ratio detecting sensor 8.
In Fig. 9, a comparison of the electrostatic capacitance value of gas of each refrigerant with that of liquid of each refrigerant shows that the liquid refrigerant has a larger value, and the difference between the electrostatic capacitance value of gas and that of liquid is large, in particular, in the HFC134a. This indicates that the electrostatic capacitance value varies when the dryness of the refrigerant varies. In contrast, a comparison between the electrostatic capacitance values of HFC134a and HFC32 shows that HFC32 has a larger electrostatic capacitance value for both liquid and gas. This indicates that only a gas or liquid refrigerant exists in the composition ratio detecting sensor 8, and when the composition of the refrigerant varies, the electrostatic capacitance value varies.
However, since the inside of the composition ratio detecting sensor 8 enters a two-phase state of gas and liquid, the electrostatic capacitance value varies due to the dryness of the refrigerant in addition to the composition ratio of the mixture refrigerant, it becomes impossible to detect the composition ratio. Therefore, when the composition ratio of the mixture refrigerant is detected by using the composition ratio detecting sensor 8, it is necessary to dispose the composition ratio detecting sensor 8 in a portion where the refrigerant is always gas or liquid in the refrigeration cycle. In this embodiment, since the check valves 91 to 94 are arranged, the refrigerant passing through the composition ratio detecting sensor 8 is in a liquid state. Means other than the electrostatic capacitance type may be used for the composition ratio detecting means.
Next, Fig. 10 is a flowchart illustrating a method of controlling the refrigeration cycle shown in Fig. 1. When a predetermined condition is satisfied after the refrigeration cycle is started, the composition ratio is determined on the basis of a signal from the composition ratio detecting sensor 8. A check is made to determine whether the detected composition ratio X is greater than the composition ratio X₀ of the refrigerant sealed in the refrigeration cycle. When $X > (X₀ + α)$
, the open/ close valves 12 and 13 are opened. When the condition $(X₀ - α) ≦ X ≦ (X₀ + α)$
is satisfied, the open/ close valves 12 and 13 are closed. When the detected composition ratio $X < (X₀ - α)$
, the open/close valve 14 is opened, and when $(X₀ - α) ≦ X ≦ (X₀ + α)$
is satisfied, the open/close valve 14 is closed. a is the tolerance.
Therefore, it is possible to control the composition of the refrigerant within the refrigeration cycle to X₀ or thereabouts, making it possible to prevent the pressure on the high pressure side from abnormally increasing and making a stable operation possible. Since the composition ratio of the non-azeotrope refrigerant can be varied, it becomes possible to vary the heating and cooling capacity as shown in Fig. 3.
A second embodiment of a refrigeration cycle in accordance with the present invention is shown in Fig. 11. Fig. 11 also shows a refrigeration cycle in which the composition ratio of a non-azeotrope refrigerant is variable, and principally the amount of a high-boiling-point refrigerant is varied. Components in Fig. 11 having the same reference numerals as those in Fig. 1 designate identical components. In Fig. 11, reference numeral 30 denotes a refrigerant tank; reference numerals 31 and 32 denote open/close valves; and reference numerals 33 and 34 denote pipes. The direction of flow of the refrigerant during heating and cooling operations is the same as in Fig. 1. It is possible to make the liquid refrigerant in the bottom portion of the accumulator 5 flow out to a tank 30 via an open/close valve 31 and to make the refrigerant in the tank 30 return to the main refrigeration cycle via the open/close valve 32.
Fig. 12 shows changes of the refrigerant in a system from the evaporator to the accumulator 5. The horizontal axis indicates the composition ratio X of the low-boiling-point refrigerant, i.e., HFC32, and the vertical axis indicates temperature, with pressure being constant. The state X = 0 indicates that the refrigerant is formed of only HFC134a, and the state X = 1 indicates that the refrigerant is formed of only HFC32. In the non-azeotrope refrigerant, the temperature of saturation vapor is different from that of saturation liquid even at the same pressure as shown in the figure. X₀ indicates the composition ratio of HFC32 in the refrigerant sealed in the refrigeration cycle. Point G indicates the inlet state of the evaporator, and point H indicates the state inside the accumulator 5. Since the refrigerant inside the accumulator 5 has been passed through the evaporator, the dryness of the refrigerant is great, and point H is close to the vapor line. Therefore, the states of liquid and gas at point H are indicated by points J and I. At point J, the high-boiling-point refrigerant composition ratio of HFC134a is high, and at point I, the composition ratio of the low-boiling-point refrigerant approaches X₀.
Therefore, by guiding the liquid refrigerant removed from the accumulator 5 into the tank 30, it is possible to decrease the composition ratio of HFC134a within the main refrigeration cycle. The liquid refrigerant can be stored in the accumulator 5 by increasing the opening of the indoor refrigerant control valve 21a or 21b in the case of a cooling operation.
Next, Fig. 13 is a flowchart for controlling the refrigeration cycle shown in Fig. 11. When a predetermined condition is satisfied after the refrigeration cycle is started, the composition ratio is determined on the basis of a signal from the composition sensor. A check is made to determine whether the detected composition ratio X is greater than the composition ratio X₀ of the refrigerant sealed in the refrigeration cycle. When $X > (X₀ + α)$
, the open/close valve 32 is opened. When the condition $(X₀ - α) ≦ X ≦ (X₀ + α)$
is satisfied, the open/close valve 32 is closed. When the detected composition ratio $X < (X₀ + α)$
and $X < (X₀ - α)$
, the open/close valve 31 is opened. When $(X₀ - α) ≦ X ≦ (X₀ + α)$
is satisfied, the open/close valve 14 is closed. α is the tolerance.
Therefore, it is possible to control the composition of the refrigerant within the refrigeration cycle to X₀ or thereabouts, making a stable operation possible. Since the composition ratio of the non-azeotrope refrigerant can be varied, it becomes possible to vary the heating and cooling capacity as shown in Fig. 3.
Next, a third embodiment of the refrigeration cycle in accordance with the present invention is shown in Fig. 14. Fig. 14 also shows a refrigeration cycle in which the composition ratio of the non-azeotrope refrigerant can be varied, and the functions of the embodiment shown in Figs. 1 and 11 are integrated. Components in Fig. 14 having the same reference numerals as those in Fig. 11 designate identical components. Reference numeral 40 denotes a refrigerant tank; reference numerals 41 and 43 denote open/close valves; and reference numerals 42 and 44 denote pipes. The refrigerant tank 40 is formed integral with the accumulator 5 as shown in Fig. 14, so that heat can be exchanged between the refrigerant tank 40 and the accumulator 5. The direction of flow of the refrigerant during heating and cooling operations is the same as in Fig. 1. In Fig. 14, it is possible to make the liquid refrigerant in the bottom portion of the accumulator 5 flow out to the tank 40 via the open/close valve 43 and and stored therein.
Further, the gas refrigerant inside the receiver 6 can be condensed and liquefied by making the liquid refrigerant flow into the tank 40 via the open/close valve 41 and exchanging heat with the accumulator 5. It is also possible to make the liquid refrigerant in the bottom portion of the tank 40 flow out into the accumulator 5 via the open/close valve 43 so that the liquid refrigerant is returned to the main refrigeration cycle. Therefore, by opening the open/close valve 41, it is possible to release gas having a large composition ratio of HFC32 from the main refrigeration cycle and decrease the composition ratio of HFC32. On the other hand, by opening the open/close valve 43, it is possible to release the liquid refrigerant having a large composition ratio of HFC134a from the main refrigeration cycle and decrease the composition ratio of HFC134a.
Fig. 15 is a detailed view of the receiver 6, the accumulator 5 and the tank 40, all of which are shown in Fig. 14. Components in Fig. 15 having the same reference numerals as those in Fig. 14 designate identical components. A pipe 34 through which the accumulator 5 is connected to the compressor 1 is formed into a U-shape inside the accumulator 5, and the end portion thereof is open in the upper portion of the accumulator 5. A hole 36 for returning oil circulating within the refrigeration cycle is disposed in the bottommost portion of the U-shape, and a hole 35 for making a part of gas flow out is disposed in the topmost portion of the U-shape. A pipe 42 and the open/close valve 41 are connected to each other at an appropriate position in the upper portion of the receiver 6 and at an appropriate position in the upper portion of the refrigerant tank 40. Further, a pipe 44 and the open/close valve 43 are connected to each other at appropriate positions of the lower portion of the accumulator 5 and the refrigerant tank 40. Although the refrigerant tank 40 is formed integral in the lower portion of the accumulator 5 in Fig. 15, the refrigerant tank 40 may be arranged in any way if heat can be exchanged between the accumulator 5 and the refrigerant tank 40.
Fig. 16 is a flowchart for controlling the refrigeration cycle shown in Fig. 14. When a predetermined condition is satisfied after the refrigeration cycle is started, the composition ratio is determined on the basis of a signal from the composition ratio detecting sensor. A check is made to determine whether the detected composition ratio X is greater than the composition ratio X₀ of the refrigerant sealed in the refrigeration cycle. When $X > (X₀ + α)$
, the open/close valve 41 is opened. When the condition $(X₀ - α) ≦ X ≦ (X₀ + α)$
is satisfied, the open/close valve 41 is closed. When the detected composition ratio $X < (X₀ + α)$
and $X < (X₀ - α)$
, the open/close valve 43 is opened. When $(X₀ - α) ≦ X ≦ (X₀ + α)$
is satisfied, the open/close valve 43 is closed. Therefore, it is possible to control the composition of the refrigerant within the refrigeration cycle to X₀ or thereabouts, making a stable operation possible. Since the composition ratio of the non-azeotrope refrigerant can be varied, it becomes possible to vary the heating and cooling capacity as shown in Fig. 3.
Next, a description will be given of a fourth embodiment of the refrigeration cycle of the present invention with reference to Fig. 17.
In Fig. 17, reference numeral 1 denotes a compressor; reference numeral 2 denotes an outdoor heat exchanger; reference numeral 3 denotes an outdoor air blower; reference numeral 4 denotes a four-way valve; reference numeral 5 denotes an accumulator; reference numeral 6 denotes a receiver; reference numeral 7 denotes an outdoor refrigerant control valve; reference numeral 8 denotes a sensor for detecting the composition ratio of a non-azeotrope refrigerant; reference numerals 91, 92, 93 and 94 denote check valves which are disposed in outdoor machines. Reference numerals 20a and 20b denote indoor heat exchangers; reference numerals 21a and 21b denote indoor refrigerant control valves; reference numerals 22 and 23 denote refrigerant distribution units; and reference numerals 24 and 25 denote pipes through which the indoor side is connected to the outdoor side. An electrostatic capacitance type liquid level sensor 60 for detecting the liquid level of the refrigerant inside the receiver 6 is disposed inside the receiver 6. In addition, disposed are the electrostatic capacitance sensor 8 for detecting the composition ratio of the non-azeotrope refrigerant, the electrostatic capacitance type liquid level sensor 60 for detecting the liquid level of the refrigerant, a liquid-level detection apparatus, a computation apparatus for computing the composition of a refrigerant, a computation apparatus for computing the amount of the refrigerant, and a display apparatus.
In this embodiment, a refrigerant which does not contain chlorine and does not damage the ozone layer is used as a working medium. Examples of such refrigerants include a mixture refrigerant of HFC32 and HFC134a, which is a non-azeotrope refrigerant. An example in which this refrigerant is used will be explained below.
The flow of the refrigerant of this embodiment will be explained. During a cooling operation, the refrigerant discharged from the compressor flows in the following order: the four-way valve 4 → the outdoor heat exchanger 2 → the check valve 93 → the composition ratio detecting sensor 8 → the outdoor refrigerant control valve 7 → the check valve 92 → the receiver 6. The refrigerant is distributed by the distribution unit 23. A part of the refrigerant flows in the order: the indoor refrigerant control valve 21a → the indoor heat exchanger 20a, and the other flows in the order: the indoor refrigerant control valve 21b → the indoor heat exchanger 20b. They merge in the distribution unit 22, flow in the order: the pipe 24 → the four-way valve 4 → the accumulator 5, and return to the compressor. The indoor heat exchangers 20a and 20b act as evaporators, and a cooling operation is performed. During a heating operation, on the other hand, the refrigerant discharged from the compressor flows in the order: the four-way valve 4 → the pipe 24 → the distribution unit 22. A part of the refrigerant flows in the order: the indoor heat exchanger 20a → the indoor refrigerant control valve 21a, and the other flows in the order: the indoor heat exchanger 20b → the indoor refrigerant control valve 21b. They merge in the distribution unit 23, and flow in the following order: the pipe 25 → the receiver 6 → the check valve 94 → the composition ratio detecting sensor 8 → the outdoor refrigerant control valve 7 → the check valve 91 → the outdoor heat exchanger 2 → the four-way valve 4 → the accumulator 5, and return to the compressor. In this case, the indoor heat exchangers 20a and 20b act as condensers, and a heating operation is performed.
When the refrigerant sealed in the refrigeration cycle leaks outside and the composition ratio of the non-azeotrope refrigerant varies, the composition of the refrigerant within the refrigeration cycle can be detected by the composition ratio detecting sensor 8 as stated before. Since there is a correlation between the the liquid level of the receiver 6 and the amount of the refrigerant within the refrigeration cycle, it is possible to detect the amount of refrigerant within the refrigeration cycle by the liquid level sensor disposed inside the receiver 6 as shown in Fig. 17. In this embodiment, since an electrostatic capacitance type sensor is used as a liquid level sensor, the signal from the liquid level sensor 60 varies even when the composition ratio of the refrigerant varies. However, it is possible to correct the signal from the liquid level sensor 60 on the basis of the composition ratio detected by the composition ratio detecting sensor 8.
With the refrigeration cycle constructed as described above, it is possible to easily maintain the refrigeration cycle even when the refrigerant sealed in the refrigeration cycle leaks outside and the composition ratio of the non-azeotrope refrigerant varies. More specifically, it is possible to selectively display the amount of refrigerant within the refrigeration cycle, the composition ratio of the refrigerant, a display of whether the type and amount of the refrigerant are normal or not, the type of the refrigerant to be added, and the amount of the refrigerant to be added, facilitating a maintenance operation to a greater extent.
A fifth embodiment of the present invention will be explained below. Fig. 18 shows an example in which a valve 61 for sealing in a refrigerant is added to the refrigeration cycle shown in Fig. 17. The valve 61 is disposed on the inlet side of the accumulator 5 of the refrigeration cycle. Reference numeral 62 denotes a bomb for a low-boiling-point refrigerant; and reference numeral 63 denotes a bomb for a high-boiling-point refrigerant. When the refrigerant within the refrigeration cycle becomes deficient, the low-boiling-point refrigerant bomb 62 is connected to the refrigerant sealing-in valve 61 and the refrigerant is sealed in when the refrigerant to be added is a low-boiling-point refrigerant. When, however, the refrigerant to be added is a high-boiling-point refrigerant, there is a case in which the pressure in the refrigerant bomb is lower than that inside the refrigeration cycle. In such a case, the refrigeration cycle is operated, and the opening of the indoor refrigerant control valve 21a or 21b is decreased during a cooling operation so that the pressure on the low pressure side of the refrigeration cycle is decreased less than the pressure of the refrigerant bomb 63. As a result, it becomes possible to seal in a refrigerant. In the case of a heating operation, the opening of the outdoor refrigerant control valve may be decreased.
Next, a description will be given of the operation when the above-described refrigeration cycle is used. Fig. 19 shows an example in which the refrigerant sealing-in valve 61 is added to the refrigeration cycle of Fig. 17. The refrigerant sealing-in valve 61 is disposed on the inlet side of the accumulator 5 of the refrigeration cycle. In Fig. 19, reference numeral 64 denotes a refrigerant bomb in which a non-azeotrope refrigerant is sealed in. The refrigerant bomb 64 is provided with a valve 65 for taking out the refrigerant from the upper portion of the bomb and a valve 67 for taking out the refrigerant from the lower portion of the bomb.
Fig. 20 illustrates the internal state of the refrigerant bomb 64. Gas having the composition at point K and liquid having the composition at point L in the figure coexist inside the refrigerant bomb 64. Therefore, it is possible to take out a refrigerant having a large composition ratio of a low-boiling-point refrigerant by taking out gas, and by taking out liquid, it is possible to take out a refrigerant having a large composition ratio of a high-boiling-point refrigerant. In a case in which the refrigerant is sealed in the refrigeration cycle, by using the above-described characteristics, the refrigerant is taken out from the valve 65 in Fig. 19 when a low-boiling-point refrigerant is sealed in, and a refrigerant is taken out from the valve 67 in Fig. 19 when a high-boiling-point refrigerant is sealed in.
Next, a sixth embodiment of the present invention will be explained with reference to Fig. 21.
Referring to Fig. 21, reference numeral 1 denotes a compressor; reference numeral 2 denotes an outdoor heat exchanger; reference numeral 3 denotes an outdoor air blower; reference numeral 4 denotes a four-way valve; reference numeral 5 denotes an accumulator; reference numeral 6 denotes a receiver; reference numeral 7 denotes an outdoor refrigerant control valve; reference numeral 8 denotes a sensor for detecting the composition of a non-azeotrope refrigerant; reference numerals 91, 92, 93 and 94 denote check valves which are disposed in an outdoor machine; reference numerals 20a and 20b denote indoor heat exchangers; reference numerals 21a and 21b denote indoor refrigerant control valves; reference numerals 22 and 23 denote refrigerant distribution units; reference numerals 24 and 25 denote pipes through which the indoor side is connected to the outdoor side; reference numerals 81 and 82 denote pipes; reference numerals 83 and 84 denote open/close valves; reference numeral 80 denotes a detection display apparatus for detecting and displaying the composition ratio of a non-azeotrope refrigerant; and reference numeral 85 denotes an electrostatic capacitance sensor. The detection display apparatus 80 is provided, in addition to the electrostatic capacitance sensor 85, with a computation apparatus for computing the composition of a refrigerant and a display apparatus for displaying the composition thereof. In this embodiment, HFC32 and HFC134a are used as the non-azeotrope refrigerant.
Next, the flow of the refrigerant will be explained. During a cooling operation, the refrigerant discharged from the compressor flows in the following order: the four-way valve 4 → the outdoor heat exchanger 2 → the check valve 93 → the outdoor refrigerant control valve 7 → the check valve 92 → the receiver 6. The refrigerant is distributed by the distribution unit 23. A part of the refrigerant flows in the order: the indoor refrigerant control valve 21a → the indoor heat exchanger 20a, and the other flows in the order: the indoor refrigerant control valve 21b → the indoor heat exchanger 20b. They merge in the distribution unit 22, flow in the order: the pipe 24 → the four-way valve 4 → the accumulator 5, and return to the compressor. In this case, the indoor heat exchangers 20a and 20b act as evaporators, and a cooling operation is performed. During a heating operation, on the other hand, the refrigerant discharged from the compressor flows in the following order: the four-way valve 4 → the pipe 24 → the distribution unit 22. A part of the refrigerant flows in the order: the indoor heat exchanger 20a → the indoor refrigerant control valve 21a, and the other flows in the order: the indoor heat exchanger 20b → the indoor refrigerant control valve 21b. They merge in the distribution unit 23, flow in the following order: the pipe 25 → the receiver 6 → the check valve 94 → the outdoor refrigerant control valve 7 → the check valve 91 → the outdoor heat exchanger 2 → the four-way valve 4 → the accumulator 5, and return to the compressor. In this case, the indoor heat exchangers 20a and 20b act as condensers, and a heating operation is performed.
When the composition of the refrigerant is to be detected, the sensor 85 of the detection display apparatus 80 is connected between the open/ close valves 83 and 84, and the refrigerant is made to flow through the sensor 85 while a cooling or heating operation is being performed. As described above, a refrigerant take-out section for detecting the composition of the refrigerant is disposed in the refrigeration cycle, and the composition ratio can be detected by the detection display apparatus 80 which is disposed separately from the refrigeration cycle system. As a result, there is no need to dispose a composition ratio sensor in the refrigeration cycle, and therefore the refrigeration cycle can be constructed at a low cost.
If no refrigerant has been sealed in the refrigeration cycle, first the cycle is evacuated to a vacuum by a vacuum pump, and then refrigerants may be sealed in according to the descending order of their boiling points, each by a predetermined amount. When such operation has been completed, it is possible to bring the composition ratio of the non-azeotrope refrigerant within the refrigeration cycle close to a set value.
According to the present invention, it is possible to vary the composition ratio of the refrigerant within the refrigeration cycle in which a non-azeotrope refrigerant is sealed in by using an inexpensive apparatus and to stabilize the composition ratio of the non-azeotrope refrigerant.
Further, since the composition ratio of the refrigerant within the refrigeration cycle in which a non-azeotrope refrigerant is sealed in can be detected and since the amount of refrigerant within the refrigeration cycle can be detected, it becomes possible to display types of refrigerants to be added and deleted and the amount of the refrigerant to be added and deleted, greatly facilitating the operation of maintaining the refrigerant of the refrigeration cycle. In addition, since the composition ratio of the refrigerant sealed in the refrigeration cycle is controlled, a highly efficient operation of the refrigeration cycle is possible.
Many different embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments described in this specification. To the contrary, the present invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the claims. The following claims are to be accorded the broadest interpretation, so as to encompass all such modifications and equivalent structures and functions.

Claims

A refrigeration cycle in which a compressor, a heat-source-side heat exchanger, a refrigerant pressure reducing apparatus, and a use-side heat exchanger are connected in sequence through a pipe, and a non-azeotrope refrigerant is used as a working refrigerant, said refrigeration cycle comprising:
flow control means for causing a refrigerant to be always in a liquid phase, disposed in at least a part of said pipe; and
detecting means for detecting the composition of a non-azeotrope refrigerant, disposed in the pipe portion where the refrigerant is formed into a liquid phase by said flow control means.
A refrigeration cycle according to claim 1, further comprising composition ratio control means for controlling the composition of the non-azeotrope refrigerant within the refrigeration cycle on the basis of the composition of the non-azeotrope refrigerant detected by said detecting means.
A refrigeration cycle according to claim 1, wherein said non-azeotrope refrigerant is a non-azeotrope refrigerant in which a refrigerant which does not damage an ozone layer is mixed.
A refrigeration cycle according to claim 2, wherein said non-azeotrope refrigerant is a non-azeotrope refrigerant in which a refrigerant which does not damage an ozone layer is mixed.
A refrigeration cycle according to claim 1, wherein said control means comprises storing means for prestoring the designed composition ratio of a non-azeotrope refrigerant to be sealed in the refrigeration cycle; and comparing means for comparing a designed composition ratio stored in said storing means with a composition ratio detected by said detecting means.
A refrigeration cycle according to claim 2, wherein said control means comprises storing means for prestoring the designed composition ratio of a non-azeotrope refrigerant to be sealed in the refrigeration cycle; and comparing means for comparing a designed composition ratio stored in said storing means with a composition ratio detected by said detecting means.
A refrigeration cycle according to claim 3, wherein said control means comprises storing means for prestoring the designed composition ratio of a non-azeotrope refrigerant to be sealed in the refrigeration cycle; and comparing means for comparing a designed composition ratio stored in said storing means with a composition ratio detected by said detecting means.
A refrigeration cycle according to claim 4, wherein said control means comprises storing means for prestoring the designed composition ratio of a non-azeotrope refrigerant to be sealed in the refrigeration cycle; and comparing means for comparing a designed composition ratio stored in said storing means with a composition ratio detected by said detecting means.
A refrigeration cycle according to claim 1, wherein said detecting means for detecting the composition of a non-azeotrope refrigerant is an electrostatic capacitance type sensor.
A refrigeration cycle in which a compressor, a heat-source-side heat exchanger, a refrigerant pressure reducing apparatus, and a use-side heat exchanger are connected in sequence through a pipe, a liquid receiver is disposed in the middle of a high-pressure liquid connection pipe through which said heat-source-side heat exchanger is connected to said use-side heat exchanger, and a non-azeotrope refrigerant is used as a working refrigerant, said refrigeration cycle comprising:
flow control means for causing a refrigerant to be always in a liquid phase, disposed in at least a part of said pipe;
detecting means for detecting the composition of the non-azeotrope refrigerant, disposed in the pipe portion where the refrigerant is formed into a liquid phase by said flow control means;
a cooling unit for guiding out a gas refrigerant in the upper portion of said liquid receiver, and cooling and liquefying it;
a tank for storing the liquefied refrigerant; and
a return pipe line for returning the refrigerant from said tank to the refrigeration cycle.
A refrigeration cycle in which a compressor, a heat-source-side heat exchanger, a refrigerant pressure reducing apparatus, and a use-side heat exchanger are connected in sequence through a pipe, a liquid receiver is disposed in the middle of a high-pressure liquid connection pipe through which said heat-source-side heat exchanger is connected to said use-side heat exchanger, and a non-azeotrope refrigerant in which at least two types of refrigerants which do not damage the ozone layer are mixed is used as a working refrigerant, said refrigeration cycle comprising:
a refrigerant storage tank;
a refrigerant circuit for taking out a refrigerant gas in the upper portion of a liquid receiver and introducing it into the refrigerant storage tank;
a refrigerant circuit for taking out a liquid refrigerant in the lower portion of a liquid receiver and introducing it into the intake side of a compressor;
a heat exchanger for exchanging heat between the refrigerant gas taken out from the upper portion of the liquid receiver and the liquid refrigerant taken out from the lower portion of the liquid receiver; and
a refrigerant circuit for introducing the refrigerant from a refrigerant storage tank to the intake side of the compressor.
A refrigeration cycle in which a compressor, a heat-source-side heat exchanger, a refrigerant pressure reducing apparatus, an accumulator disposed on the intake side of said compressor, and a use-side heat exchanger are connected in sequence through a pipe, said refrigeration cycle comprising:
flow control means for causing a refrigerant to be always in a liquid phase, disposed in at least a part of said pipe;
detecting means for detecting the composition of the non-azeotrope refrigerant, disposed in the pipe portion where the refrigerant is formed into a liquid phase by said flow control means;
a tank for guiding out a refrigerant in the lower portion of said accumulator and storing it; and
a pipe line for returning the refrigerant from said tank to the main refrigeration cycle.
A refrigeration cycle in which a compressor, a heat-source-side heat exchanger, a refrigerant pressure reducing apparatus, a use-side heat exchanger, and an accumulator disposed on the intake side of said compressor are connected in sequence through a pipe, a liquid receiver is disposed in the middle of a high-pressure liquid connection pipe through which said heat-source-side heat exchanger is connected to said use-side heat exchanger, and a non-azeotrope refrigerant in which at least two types of refrigerants which do not damage the ozone layer are mixed is used as a working refrigerant, said refrigeration cycle comprising:
a refrigerant storage tank formed so as to be able to exchange heat with said accumulator;
a passage for guiding a liquid refrigerant from the lower portion of the accumulator; and
a refrigerant circuit for guiding gas to said refrigerant storage tank, which gas is in the upper portion of the liquid receiver disposed in the middle of a high-pressure liquid connection pipe through which said heat-source-side heat exchanger is connected to said use-side heat exchanger.
A refrigeration cycle, the main refrigeration cycle of which comprising: a compressor; a heat-source-side heat exchanger; a use-side heat exchanger; a refrigerant pressure reducing apparatus; a liquid receiver disposed in the middle of a high-pressure liquid connection pipe through which said heat-source-side heat exchanger is connected to said use-side heat exchanger; and an accumulator disposed on the intake side of said compressor, wherein a non-azeotrope refrigerant in which at least two types of refrigerants which do not damage the ozone layer are mixed is used as a working refrigerant, said refrigeration cycle comprising:
detecting means for detecting the composition of a non-azeotrope refrigerant;
a refrigerant storage tank formed so as to be able to exchange heat with said accumulator;
a passage for guiding a liquid refrigerant from the lower portion of the accumulator; and
a refrigerant circuit for guiding out gas in the upper portion of the liquid receiver to said storage tank.
A refrigeration cycle comprising:
a compressor;
a heat-source-side heat exchanger;
a use-side heat exchanger; and
a refrigerant pressure reducing apparatus, wherein a non-azeotrope refrigerant, in which a plurality of refrigerants which do not damage the ozone layer are mixed, is used as a refrigerant, said refrigeration cycle further comprising:
a first sensor for detecting the composition of the non-azeotrope refrigerant;
composition computing means for computing the composition of the non-azeotrope refrigerant in accordance with signals from said first sensor;
a second sensor for detecting the amount of the refrigerant within the refrigeration cycle;
refrigerant amount computing means for computing the amount of the refrigerant in accordance with signals from said second sensor;
a display apparatus for displaying at least the composition of the non-azeotrope refrigerant, the amount of the non-azeotrope refrigerant, the results of the determination of whether the composition and the amount of the non-azeotrope refrigerant are normal or abnormal, and the type and amount of the refrigerant to be added.
A refrigeration cycle in which a compressor, a heat-source-side heat exchanger, a refrigerant pressure reducing apparatus, and a use-side heat exchanger are connected in sequence through a pipe, and a non-azeotrope refrigerant is used as a working refrigerant, said refrigeration cycle comprising:
flow control means for causing a refrigerant to be always in a liquid phase, disposed in at least a part of said pipe;
detecting means for detecting the composition of the non-azeotrope refrigerant, disposed in the pipe portion where the refrigerant is formed into a liquid phase by said flow control means;
composition computing means for computing the composition of a non-azeotrope refrigerant in accordance with signals from said detecting means;
a sensor for detecting the amount of the refrigerant within the refrigeration cycle;
refrigerant amount computing means for computing the amount of the refrigerant in accordance with signals from said sensor;
a display apparatus for displaying the type and/or amount of the refrigerant;
atmosphere temperature detecting means for detecting the atmosphere temperature of the refrigeration cycle; and
control means for controlling so that the pressure on the low pressure side of the refrigeration cycle is lower than the saturation pressure of a high-boiling-point refrigerant on the basis of the type or amount of the refrigerant to be added, displayed on said display apparatus, when the high-boiling-point refrigerant is sealed in.
A refrigeration cycle according to claim 16, wherein a liquid take-out portion which is connected to a liquid portion within the refrigerant gas bomb in which a non-azeotrope refrigerant to be sealed in said refrigeration cycle is stored, and a gas take-out portion which is connected to a gas portion, and the take-out portions are connected to said refrigeration cycle through a valve.
A method of controlling the composition of a refrigerant in a refrigeration cycle comprising: a compressor; a heat-source-side heat exchanger; a use-side heat exchanger; and a refrigerant pressure reducing apparatus, in which cycle a non-azeotrope refrigerant is sealed in, said method comprising the step of:
sealing in refrigerants which form said non-azeotrope refrigerant according to the descending order of their boiling points, each by a predetermined amount.
A method of controlling the composition of a refrigerant in a refrigeration cycle comprising: a compressor; a heat-source-side heat exchanger; a use-side heat exchanger; and a refrigerant pressure reducing apparatus, in which cycle a non-azeotrope refrigerant is sealed in, said method comprising the step of:
decreasing the pressure on a low pressure side of the refrigeration cycle less than the saturation pressure of a high-boiling-point refrigerant and sealing in a high-boiling-point refrigerant when a refrigerant is added to the refrigeration cycle on the basis of the type and amount of the refrigerant to be added, displayed on a display apparatus for displaying the type and amount of the refrigerant.
A method of controlling the composition of a refrigerant in a refrigeration cycle comprising: a compressor; a heat-source-side heat exchanger; a use-side heat exchanger; and a refrigerant pressure reducing apparatus, in which cycle a non-azeotrope refrigerant is sealed in, said method comprising the step of:
evacuating the refrigeration cycle to a vacuum by a vacuum pump before a non-azeotrope refrigerant is sealed in; and
sealing in refrigerants according to the descending order of their boiling points.