JPH02106670A - Freezing device - Google Patents

Abstract

PURPOSE:To increase a heating calorie to defrost and shorten a defrosting time by a method wherein in case of defrosting operation, liquid refrigerant condensed by an evaporator is made to reversely flow to a compressor after evaporation by receiving heat in a heat accumulating tank. CONSTITUTION:Liquid refrigerant condensed by radiating in an outdoor heat exchanger 7 of low temperature having frost thereon passes through a second bypass pipe 24 and oppositely returns to a compressor 1. In this case, heat for accumulation is given to a heat accumulating tank 21 at a heat exchanger 25 of the second bypassing pipe 24. With this arrangement, the refrigerant is evaporated at the heat exchanger 25, becomes gas refrigerant and returns back to the compressor 1, so that liquid refrigerant separated by each of accumulators 22 and 33 from a circulating refrigerant and stored is eliminated. A decreasing of an amount of circulating refrigerant passing through the compressor 1 is restricted, so that it is possible to perform a higher compressing work at the compressor 1 than that of the prior art.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a refrigeration system having a defrosting operation function for removing frost that has grown on an evaporator.

(Prior Art) As a conventional example of a refrigeration system having a defrosting operation function as described above, there can be mentioned, for example, the system described in Japanese Utility Model Application Publication No. 60-10178. In the device configured as a separate type air conditioner, the four-way switching valve connected to the discharge pipe and suction pipe of the compressor sequentially connects the first gas pipe, indoor heat exchanger, first liquid pipe, and electric A refrigerant circulation circuit is constructed by connecting an expansion valve, a second liquid pipe, an outdoor heat exchanger, and a second gas pipe, and a defrost on-off valve is interposed between the discharge pipe and the second liquid pipe. Connected by bypass piping. Note that an accumulator is interposed in the suction pipe.

In the above device, heating operation is performed by closing the defrost on-off valve and recirculating the refrigerant discharged from the compressor from the indoor heat exchanger to the outdoor heat exchanger, and during this heating operation, it acts as an evaporator. Defrosting operation to remove frost that has grown on the outdoor heat exchanger is performed by opening the defrost on-off valve described above. At this time, most of the refrigerant discharged from the compressor is directly supplied to the outdoor heat exchanger from the discharge pipe through the bypass pipe and the second liquid pipe,
The gas is then returned to the compressor from the outdoor heat exchanger via the second gas pipe and the suction pipe. In this way, the high-temperature discharge refrigerant from the compressor is directly supplied to the outdoor heat exchanger to defrost the outdoor heat exchanger. (called defrost).

(Problem to be solved by the invention) By the way, in the above-mentioned positive cycle defrost, the amount of compression work in the compressor, which is the heat source for defrosting, becomes small, so that sufficient defrosting heat is provided to the circulating refrigerant. The problem is that it becomes impossible. The refrigerant discharged from the compressor radiates heat and condenses when passing through the cold outdoor heat exchanger covered with frost, and this condensed refrigerant is not re-evaporated before being returned to the compressor. First, because the gas refrigerant is separated from the gas refrigerant by the accumulation rake installed in the suction pipe, the amount of gas refrigerant circulating through the compressor decreases, resulting in a decrease in the compression work of the compressor. It's put away. In addition, the liquid refrigerant separated by the accumulator is sucked into the compressor little by little and evaporates inside the compressor, but since the compression work in the compressor is spent as the heat of evaporation, The amount of heat required for defrosting further decreases, resulting in the problem that it takes a long time to complete defrosting.

This invention has been made in view of the above, and an object thereof is to provide a refrigeration system that can shorten the defrosting operation time in the above-mentioned normal cycle defrost compared to the conventional one.

(Means for Solving the Problems) Therefore, in the refrigeration system of the present invention, the compressor 1 has a discharge side gas pipe 41, a condenser 15, and a liquid pipe 10 in which a pressure reducing mechanism 8 is interposed.
, the evaporator 7, and the suction side gas pipe 42 are sequentially connected to form a refrigerant circulation circuit, and the evaporator 7 side of the liquid pipe IO from the pressure reducing mechanism 8 and the discharge side gas pipe 41 are connected to each other by a discharge side bypass on-off valve. The refrigeration system is connected by a first bypass pipe 19 having 18 interposed therein, and further includes a heat storage tank 2I for storing heat dissipated outwardly from high-temperature parts such as the compressor 1 and the discharge side gas pipe 41. On the other hand, a suction side on-off valve 4 is interposed in the suction side gas pipe 42, and this suction side on-off valve 4
A second bypass pipe 24 is connected to the second bypass pipe 24, and a suction-side bypass on-off valve 23 is interposed therein, and the heat storage tank is connected to the compressor 1 side of the suction-side bypass on-off valve 23. 21 is provided, and the defrosting operation of the evaporator 7 is performed by opening the discharge-side bypass on-off valve 18 and the suction-side bypass on-off valve 23 and by opening the suction-side on-off valve 4. A defrosting operation control means 40 is provided which performs the defrosting operation by closing the valve.

(Function) In the above refrigeration system, the circulating refrigerant during defrosting operation is
The heat is returned from the evaporator 7 to the compressor 1 through the second bypass pipe 24, and at this time, the amount of heat stored in the heat storage tank 21 is provided in the heat exchange section 25 of the '7242 bypass pipe 24. Therefore, the liquid refrigerant condensed in the evaporator 7 is evaporated in the heat exchanger 25 and turned into gas refrigerant, which is returned to the compressor 1, so that the amount of circulating refrigerant in the compressor 1 is prevented from decreasing. As a result, the amount of compression work applied to the circulating gas refrigerant in the compressor 1 is increased compared to the conventional one, and the amount of compression work expended as the amount of heat of evaporation of the liquid refrigerant inside the compressor 1 is reduced. As a result, the amount of heat for defrosting becomes larger than before, so the defrosting time is shortened.

(Example) Next, a specific example of the refrigeration apparatus of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a refrigerant circuit diagram of a refrigeration system according to an embodiment of the present invention, which is configured as a multi-type air conditioner by connecting the first to fourth indoor units A to D to one outdoor unit X. It shows.

A compressor 1 is installed inside the outdoor unit Pipe 5 and second gas pipe 6 are connected. An outdoor heat exchanger 7 is connected to the first gas pipe 5, and a liquid pipe 10 in which a first electric expansion valve 8 and a liquid receiver 9 are successively installed is further connected to the outdoor heat exchanger 7. has been done. This liquid pipe■0
The tip is branched into four liquid branch pipes 12...12 each having a second electric expansion valve 11...11 interposed therein, and the tip of the second gas pipe 6 is also branched correspondingly to the above. , branched into four gas branch pipes 14...14 each having a gas branch pipe muffler 13...13 interposed therebetween. Between the liquid branch pipes 12...12 and the gas branch pipes 14...14, each indoor heat exchanger installed in the first to fourth indoor units A-D (first indoor unit -A (only A is shown) are connected to form a refrigerant circulation circuit.

A discharge pipe muffler 16 and a first on-off valve 17 are sequentially interposed in the discharge pipe 2 in the refrigerant circulation circuit from the compressor 1 side, and between the discharge pipe muffler 16 and the first on-off valve 17. A first bypass pipe 19 in which a second on-off valve (discharge-side bypass on-off valve) 18 is interposed is branched from the first bypass pipe 19 , and this first bypass pipe 19 is located outside the liquid pipe 10 more than the first electric expansion valve 8 . It is connected to the heat exchanger 7 side.

Furthermore, in the above device, a heat storage tank 21 is provided in the middle of the discharge piping 2, and external radiation from the discharge piping 2, which is maintained in a high temperature state by the circulation of the high temperature gas refrigerant discharged from the compressor 1, is provided. The amount of heat is stored in a heat storage agent filled in the heat storage tank 21. On the other hand, a first accumulator 22 is interposed in the suction pipe 3, and the four-way switching valve 4 side of the first accumulator 22 in the suction pipe 3 and the first gas pipe 5 are connected by a second bypass pipe 24 in which a third on-off valve (suction-side bypass on-off valve) 23 is interposed, and the first accumulator 22 A heat exchange section 25 disposed within the heat storage tank 21 is provided in the middle of the example, and the amount of heat stored in the heat storage agent is imparted to the refrigerant flowing through the heat exchange section 25. ing.

The compressor 1 includes a first compressor 31 whose rotation speed is variable by inverter control, and a second compressor 3 whose rotation speed is constant.
This is a composite type compressor called a twin converter, in which the first and second compressors 31 and 32 are connected in parallel and housed in a housing. They are interconnected via multors 33.33. Further, in the refrigerant VIi ring circuit, the discharge pipe 2 and the suction pipe 3 are connected to each other by a third bypass pipe 35 in which a fourth on-off valve 34 is interposed. This is to quickly equalize the pressure in the refrigerant circuit by opening the fourth on-off valve 34 after the operation is stopped. Furthermore, in FIG. 1, the liquid branch pipe 12 to which the first indoor unit A is connected is connected to the first bypass pipe 19 through a fourth bypass pipe 37 in which a fifth on-off valve 36 is interposed, and A parallel circuit including a sixth on-off valve 38 and a check valve 39 is installed in the gas branch pipe 14 to which the first indoor unit I-A is connected.
For example, a changing room in a bathroom when not in use can be used as a drying room for clothes after washing, and a drying unit for blowing warm air into the changing room can be connected instead of the indoor unit A. It is. In this case, in order to perform refrigerant circulation control for the drying unit that is different from that for the other indoor units B-D, the opening and closing operations of the fifth and sixth on-off valves 36 and 38 described above are performed. The details will be omitted, but the first indoor unit I-A is connected to the following, so the fifth on-off valve 36 is kept closed, the sixth on-off valve 38 is kept open, and the pressure equalization valve 1-A is kept closed. The refrigerant circulation control for heating operation and defrosting operation performed with the 4-on-off valve 34 closed will be explained.

Although not shown in each indoor unit A-D above,
Each of them is further provided with an indoor control device, and the outdoor unit X is also provided with an outdoor control device 40 that also functions as a defrosting operation control means, as shown in the figure.

Then, when the user turns on the operation switch with the cooling/heating selector switch on the indoor control device side set to the heating side,
By the outdoor control device 40, the four-way switching valve 4 is placed in the switching position shown by the solid line in the figure, and the first on-off valve 17 is opened, the second on-off valve 17 is opened,
The third on-off valve I8.23 is closed, compression s1 is activated, and heating operation is started. As a result, the refrigerant discharged from the compression a1 is transferred to the four-way switching valve 4, the second
It is supplied to each indoor heat exchanger 15 via the gas pipe 6, further passes through the outdoor heat exchanger 7 from the liquid pipe 10, and then via the first gas pipe 5, the four-way switching valve 4, and the suction pipe 3. It is returned to the compressor 1. In this case, the degree of superheating of the evaporative refrigerant is controlled by the first electric expansion valve 8. In addition, each second electric expansion valve 11...1
1, the amount of refrigerant distributed to each indoor heat exchanger 15 is controlled.
...This is done by controlling the opening degree of 11. The second electric expansion valve 11 corresponding to the indoor unit in the stop room is set to a predetermined stop opening (an opening that allows a small amount of refrigerant to flow in proportion to natural heat dissipation in order to prevent liquid from returning to the compressor 1). ).

In the heating cycle described above, a discharge pipe 2 and a second gas pipe 6 communicating with the discharge pipe 2 via a four-way switching valve 4 are used.
A discharge side gas pipe 41 is formed by the suction pipe 3, and a suction side gas pipe 42 is formed by the suction pipe 3 and the first gas pipe 5 communicating with the suction pipe 3 via the four-way switching valve 4. Valve 4 is
It also functions as a suction side on-off valve that closes the flow path through the suction side gas pipe 42 in the defrosting cycle described later.

Further, each indoor heat exchanger 15 functions as a condenser, the outdoor heat exchanger 7 functions as an evaporator, and the first electric expansion valve 8 functions as a pressure reducing mechanism.

In the cooling operation, the four-way switching valve 4 is switched to the switching position shown by the broken line in the figure, and the refrigerant discharged from the compressor 1 is transferred to the outdoor heat exchanger 7, which serves as a condenser, as shown by the broken line arrow in the figure. This is done by circulating the water from the air to the indoor heat exchangers 15, which serve as evaporators. At this time, the first electric expansion valve 8 is fully opened, and each of the second electric expansion valves 11 . . . 11 controls the degree of superheating of the refrigerant. Note that the second electric expansion valve 11 corresponding to the indoor unit in the room where cooling is stopped is fully opened.

If the frost that has grown on the outdoor heat exchanger 7 increases while the heating operation is continued, for example, the outdoor heat exchanger 7
Since the temperature of the outdoor heat exchanger 7 decreases with the amount of frost formed above, the temperature of the outdoor heat exchanger 7 is detected, and a defrost signal is generated when the detected temperature becomes below the reference temperature. In response to the defrost signal, the outdoor control device 40 controls each on-off valve 17. as shown in FIG.
18.23, the opening/closing control of the four-way switching valve 4, and the opening degree control of each electric expansion valve 8.11.

That is, the second on-off valve 18 and the third on-off valve 23 are opened approximately simultaneously with the generation of the defrost signal, and then,
After some delay, the first on-off valve 17 is closed, and the four-way switching valve 4 is switched to the switching position shown by the broken line in FIG.
, the second electric expansion valves 8 and 11 are respectively fully opened.

As a result, the refrigerant discharged from the compressor 1 is transferred to the first bypass pipe 1, as shown by the dashed line arrow in FIG.
9 and is directly supplied to the outdoor heat exchanger 7. The refrigerant that has passed through the outdoor heat exchanger 7 is then transferred from the first gas pipe 5 to the second gas pipe 5.
The water is returned to the compressor 1 through the bypass pipe 24.

In the refrigerant circulation cycle during the above-mentioned defrosting operation, the liquid refrigerant condensed by dissipating heat to the frosted, low-temperature outdoor heat exchanger 7 is returned to the compressor l through the second bypass pipe 24. The amount of heat stored in the heat storage tank 21 is applied to the heat exchange section 25 of the second bypass pipe 24. As a result, it evaporates in the heat exchange section 25, becomes a gas refrigerant, and is returned to the compressor 1. Therefore, no liquid refrigerant is separated and stored in each accumulator 22, 33 from the circulating refrigerant, and a decrease in the amount of circulating refrigerant passing through the compressor 1 is suppressed, so the compressor 1 performs a larger compression work than before. It will be carried out. In addition, the amount of compression work consumed as heat of evaporation of the liquid refrigerant inside the compressor 1 decreases, and as a result, the gas refrigerant discharged from the compressor 1 retains sufficient heat for defrosting. Since the refrigerant circulation cycle is maintained in this state, the defrosting operation time required to complete defrosting is shorter than in the past. Also, as mentioned above, compression 8! ! ■
By operating in such a way that liquid does not return to the compressor 1, liquid compression in the compressor 1 is prevented, resulting in an apparatus with improved reliability.

Furthermore, in the above case, at the start of the defrosting operation, the indoor side is communicated with the suction pipe 3 via the four-way switching valve 4, and as a result, the refrigerant that had been supplied to each indoor side during the heating operation until then is As a result, a larger amount of circulating refrigerant can be secured in the defrosting cycle, and the amount of heat held by the refrigerant indoors at the start of the defrosting operation is utilized as the amount of defrosting heat. Furthermore, the defrosting time can be shortened.

By continuing the defrosting operation described above, the frost adhering to the outdoor heat exchanger 7 is removed, and after that, when the temperature of the outdoor heat exchanger 7 rises and the detected temperature exceeds the predetermined defrost end temperature, the defrost operation starts. The signal is stopped, and as a result, the outdoor control device 40 performs the switching as shown in FIG. 2, and the heating operation is restarted. That is, almost simultaneously with the stop of the defrost signal, the four-way switching valve 4 is switched and the first
, the second electric expansion valve 8.11 is opened, and then, after opening the first on-off valve 17, the second and third on-off valves 18.
Perform the valve closing operation in step 23. In this way, when switching between the heating cycle and the defrosting cycle, the answers are sequentially switched to suppress sudden pressure changes on the indoor side, thereby minimizing the switching noise on the indoor side and causing discomfort to the user. I try not to let it happen.

Although specific embodiments of the present invention have been described above, the above embodiments do not limit the present invention, and various modifications can be made within the scope of the present invention. For example, the heat storage tank 21 may be compressed. It is also possible to have a configuration in which the air conditioner is installed around the unit 1, and in the above description, a multi-type air conditioner in which a plurality of indoor units 1-A-D are connected is taken as an example.
The above can also be implemented in an air conditioner connected to one indoor unit, and although the above example shows an air conditioner that can cool and heat, it can also be implemented in an air conditioner that can only perform heating operation. It is possible. In this case, instead of the four-way switching valve 4, a two-boat on-off valve is provided in the suction side gas pipe. Furthermore, the present invention can also be applied to refrigeration devices other than air conditioners.

(Effects of the Invention) As described in item 1, in the refrigeration system of the present invention, the liquid refrigerant that condenses in the evaporator during defrosting operation is given heat stored in the heat storage tank, evaporates, and then returns to the compressor. be swept away. Therefore, a decrease in the amount of circulating refrigerant in the compressor is suppressed, and the amount of compression work applied to the circulating gas refrigerant in the compressor is increased compared to the conventional method, and the compression work is expended as heat of evaporation of the liquid refrigerant inside the compressor. Since the amount of heat is reduced, the amount of heat for defrosting becomes larger than before, and the time of defrosting operation is shortened.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram of a refrigeration system according to an embodiment of the present invention configured as a multi-type air conditioner, and FIG. 2 is a time chart of switching control to defrosting operation in the air conditioner. 1... Compressor, 4... Four-way switching valve (suction side on-off valve)
, 7... Outdoor heat exchanger (evaporator), 8... First electric expansion valve (pressure reduction mechanism), 10... Liquid pipe, 15... Indoor heat exchanger (condenser), 18... ...Second on-off valve (discharge side bypass on-off valve), 19...First bypass piping, 21.
...Thermal storage tank, 23...Third on-off valve (suction side bypass on-off valve), 24...Second bypass piping, 25...Heat exchange section, 40...Outdoor control device (defrosting operation control) means),
41...Discharge side gas pipe, 42...Suction side gas pipe.

Claims (1)

[Claims] 1. Compressor (1), discharge side gas pipe (41), condenser (
15), the liquid pipe (10) provided with the pressure reducing mechanism (8), the evaporator (7), and the suction side gas pipe (42) are connected in sequence to constitute a refrigerant circulation circuit, and the liquid pipe (10) ) on the evaporator (7) side and the discharge side gas pipe (
41) is connected to the compressor (1) and the discharge side gas pipe (41) by a first bypass pipe (19) provided with a discharge side bypass on-off valve (18).
A heat storage tank (2
1), a suction side on-off valve (4) is interposed in the suction side gas pipe (42), and this suction side on-off valve (4) is provided.
), connect a second bypass pipe (24) that bypasses the
A suction-side bypass on-off valve (23) is interposed in this second bypass pipe (24), and the heat storage tank (2) is located closer to the compressor (1) than the suction-side bypass on-off valve (23).
1), and the defrosting operation of the evaporator (7) is controlled by the discharge side bypass on-off valve (18) and the suction side bypass on-off valve (23). A refrigeration system characterized by being provided with a defrosting operation control means (40) that opens a valve and closes a suction side on-off valve (4).