JP2004028374A - Refrigerating equipment combined with absorption type and compression type - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating equipment that can be used for an air conditioner, economically and efficiently operated by selecting the optimal operation mode of a compression freezer. <P>SOLUTION: This freezing equipment is constituted by combining an absorption freezer RA having an evaporator E and the compression freezer RP constituted of a compressor M, a first condenser C1 and a second condenser C2, cooling by outside air or cooling water, and a use side evaporator Ec providing a freezing effect. The evaporator E of the absorption freezer RA has heat exchange relation with the second condenser C2 of the compression freezer RP, or it uses the second condenser C2 at the same time. A circuit 1 by-passing the first condenser C1 is provided to the compression freezer, and a control valve 10 is provided to the circuit 1. A circuit by-passing the compressor M is provided to the compression freezer RP. The by-pass circuit can be provided with a check valve V1 or a control valve, and the compressor M can be provided with a high-head compressor and a low-head compressor. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a refrigerating apparatus, and in particular, air that effectively utilizes a refrigerating effect from an absorption refrigerator or an absorption chiller / heater using exhaust heat from an engine, a turbine, various plants or the like as a heat source in combination with a compression refrigerator. The present invention relates to a refrigeration device that can be used as a harmony device.
[0002]
[Prior art]
Generally, in a cogeneration system, heat is discharged in the form of exhaust gas, hot water, or the like, along with power generation. Since the exhaust heat is not so high in temperature, it is classified as low potential energy and is often used for hot water supply or heating. Recently, absorption chillers have been operated with waste heat and used for cooling.
In the cogeneration system, the exhaust heat is obtained from exhaust gas and cooling water of a gas turbine or an engine, or cooling water of a fuel cell. In some cases, an absorption refrigerator is operated using only exhaust heat. However, as a combined cooling system, a method of saving the amount of high potential energy required for operation by using exhaust heat together with high potential energy has been proposed and adopted for the first time. I have.
[0003]
By the way, since the amount of exhaust heat changes according to the amount of power generation, the amount of supply is unstable, and it is difficult to take out the capacity according to the cooling load when operating the absorption refrigerator with only the exhaust heat. In order to solve this, a refrigerating apparatus that cools a circulating refrigerant by using cold heat of an absorption refrigerator as a heat radiation source of a compression refrigerator is known.
However, in the compression refrigerator of this refrigerator, the refrigerant vapor compressed by the compressor is condensed by a heat source side heat exchanger (condenser), and the condensate is supercooled by an evaporator of an absorption refrigerator. Regarding the absorption refrigeration effect, it is necessary to always use it while the compression chiller is running, regardless of the cooling load, and since it is used only for the subcooling, the ratio of the absorption refrigeration effect (ratio to the compression refrigeration effect) Therefore, there has been a problem that the power consumption of the motor driving the compressor cannot be significantly reduced.
[0004]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems of the prior art, and switches the operation mode of the compression refrigerator to an optimum one according to the amount of supplied exhaust heat and the cooling load, thereby achieving economical and efficient operation. Provided is a refrigeration apparatus that can be used as an air conditioner that can perform cooling.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, an absorption refrigerator having an evaporator, a compressor, a first condenser cooled by outside air or cooling water, a second condenser, and a utilization side evaporator exhibiting a refrigeration effect are provided. Wherein the evaporator of the absorption refrigerator is in a heat exchange relationship with the second condenser of the compression refrigerator or serves also as the second condenser. And a circuit for bypassing the first condenser is provided in the compression refrigerator, and a control valve is provided in the bypass circuit.
In the refrigerating apparatus, the compression refrigerator may be provided with a circuit that bypasses the compressor, and the bypass circuit may include a check valve or a control valve. The compression refrigerator may include a high-head compressor and a low-pressure compressor. It may have a head compressor.
[0006]
Further, in the present invention, in the operation method of the refrigeration apparatus, the compression chiller operates in the following operation modes (a) to (d), (a) operates the compressor, and operates the bypass circuit of the first condenser. Closed, condensed in the first condenser, not supercooled in the second condenser, (b) operating the compressor, closing the bypass circuit of the first condenser, condensing in the first condenser, In the second condenser, an operation mode in which the refrigerant liquid from the first condenser is supercooled or condensed, (c) the compressor is operated, the bypass circuit of the first condenser is opened, and the refrigerant vapor is passed through the second condenser. Operating modes in which at least two types of operation modes are selected: (d) an operation mode in which the compressor is stopped, the bypass circuit of the first condenser is opened, and refrigerant vapor is condensed in the second condenser. Operating method of a refrigeration system characterized by operating in a refrigerator A.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, an absorption refrigerator (which may be driven by cogeneration exhaust heat, but need not be driven) is used as a destination of the condensation heat of the compression refrigerator. In particular, the cooling load and the operation state of the absorption refrigerator are used. The outdoor condenser (first condenser) of the compression refrigerator can be bypassed in accordance with (such as the load on the absorption refrigeration effect). Various operation modes can be set by a combination of condenser bypass, compressor start / stop, etc., and by switching these operation modes according to the load, energy saving such as compressor stop or reduction of required power (head) of the compressor can be achieved. I'm trying.
[0008]
Next, the present invention will be described in detail with reference to the drawings.
1 and 2 are flow configuration diagrams showing connection examples of components on the compression refrigerator side of the refrigeration apparatus of the present invention, and FIG. 3 is a Mollier diagram in each operation mode using FIG. In the figure, RA is an absorption refrigerator, RP is a compression refrigerator, M is a compressor, M1 is a high head compressor, M2 is a low and high head compressor, Ec is an evaporator, C1 is a first condenser, and C2 is a second condenser. Two condensers, V1 is a check valve, V2 is a control valve (expansion valve), V3 is an expansion valve (throttle device), 1 is a bypass circuit, 2 is a controller, 3 to 6 are temperature or pressure sensors, and 7 is a liquid. A pump, 8 is a check valve, 9 is a medium flow path, and 10 is a control valve, and each device is configured to control operation and stop by a signal from a temperature or pressure sensor.
[0009]
Next, the operation of the refrigeration apparatus of the present invention will be described with reference to FIGS.
In the present invention, various operation modes ((1) to (4) below) can be performed by a combination of a condenser bypass, a compressor start / stop, and the like. By switching these operation modes according to the load, the compressor is stopped or the compressor is stopped. Energy saving is achieved by reducing the required power (head) of the machine.
{Circle around (1)} Mode 1 (first condenser single mode) is an operation mode when the absorption refrigeration effect transfer medium (such as cold water) is not supplied to the second condenser C2, such as when the absorption refrigerator RA is stopped. The operation is similar to that of a normal compression refrigerator.
The refrigerant is compressed by the compressor M [11 → 12 in the Mollier diagram in FIG. 3 (a)], and then condensed and supercooled in the first condenser (air-cooled condenser) C1 (diagram 12 → 13). In this mode, the control valve 10 is closed to prevent refrigerant from flowing through the bypass circuit 1. The liquefied refrigerant passes through the second condenser C2 (here, no heat exchange is performed) and then expands in the expansion device V3 (diagrams 13 to 14). Subsequently, the refrigerant which has evaporated and overheated by removing the heat of the medium to be cooled by the evaporator Ec (diagram 14 → 11) is sucked into the compressor M again to form a refrigeration cycle.
[0010]
{Circle around (2)} In mode 2 (first and second condenser combined mode), in the above-described mode 1, the absorption refrigeration effect transfer medium (such as cold water) is supplied from the absorption refrigerator RA to the second condenser C2. In the operation mode in which heat exchange is performed with the refrigerant, the cold heat obtained by the absorption refrigerator RA is used for supercooling the refrigerant.
The refrigerant condensed and supercooled in the first condenser C1 (diagrams 22 to 23) is supercooled by the absorption refrigeration effect in the second condenser C2 (diagrams 23 to 24). Also in this mode, the control valve 10 is closed to prevent the refrigerant from flowing through the bypass circuit 1. Subsequently, the refrigerant expands in the expansion device V3 (diagrams 24 → 25), and takes heat in the evaporator Ec to evaporate and overheat (diagrams 25 → 26 → 21).
In this mode, the same amount of cold heat can be used in the evaporator Ec by using the cold heat obtained by operating the absorption refrigerator with the exhaust heat for supercooling the refrigerant (diagram 23 → 24) (diagram). 25 → 26).
[0011]
{Circle around (3)} In mode 3 (second condenser alone mode), the control valve 10 is opened, and the refrigerant is condensed and supercooled only by the cold heat obtained by the absorption refrigerator RA without using the first condenser C1. . When the temperature of the cooling medium of the first condenser C1 is almost equal to the temperature of the absorption refrigeration effect transfer medium, a part of the refrigerant vapor may be condensed in the first condenser C1 (at this time, the flow rate of the cooling medium is adjusted). May be used).
Since the absorption refrigeration transfer medium (such as cold water) can be lower than the cooling medium temperature, the condensation pressure of the refrigerant decreases. That is, in this mode, the required head of the compressor M can be made lower (diagrams 31 → 32) than when the air-cooled condenser C1 is used (diagrams 31 → 33).
The refrigerant compressed by the compressor M passes through the bypass circuit 1 and the control valve 10, enters the second condenser C2, and is condensed and supercooled by the absorption refrigeration effect (diagram 32 → 34). The same applies hereinafter.
If the temperature of the absorption refrigeration effect transfer medium is higher than the cooling medium temperature, it is desirable not to use this mode.
[0012]
{Circle around (4)} In mode 4 (second condenser direct condensation mode), when the cooling heat obtained by the absorption refrigerator RA is sufficient, the compressor M is stopped and the refrigerant is circulated naturally or circulated by the liquid pump 7.
The refrigerant (diagram 41 → 42) that has passed through the check valve V1 (or the control valve is opened) passes through the bypass circuit 1 and the control valve 10, and enters the second condenser C2. An absorption refrigeration effect is supplied to the second condenser C2, and the refrigerant is condensed and supercooled by exchanging heat with the absorption refrigeration effect (diagram 42 → 43). Subsequently, the refrigerant is pressurized by the liquid pump 7 (diagram 43 → 44), expanded by the expansion device V3 (diagram 44 → 45), and takes heat in the evaporator 4 to evaporate and overheat (diagram 44 → 45). FIG. 45 → 41).
In this mode, since the compressor M is not operated, the required power can be greatly reduced. When the second condenser C2 is at a high position and a sufficient liquid head is obtained, for example, when the absorption refrigerator RA is installed on the roof of a building, the liquid pump 7 is omitted and the refrigerant is naturally circulated. You can also.
[0013]
(2) In 'Mode 2' (first and second condenser combined mode), the control valve 10 is kept closed and the expansion valve V2 at the refrigerant outlet of the first condenser C1 is opened, so that the refrigerant vapor and the condensate The refrigerant may be guided to the second condenser C2 in the two-phase state. At this time, the refrigerant flow in the first condenser C1 becomes active, and the heat transfer deterioration due to the condensed refrigerant liquid is also eliminated, the heat transfer becomes very good, the condensing pressure is remarkably reduced, and the compression power can be reduced. .
The operation is intermediate between mode 2 and mode 3.
(3) 'Mode 3' (first and second condenser combined mode) adjusts the control valve 10 so that a part of the refrigerant vapor is bypassed and condensed in the second condenser C2, and the remainder is dispersed in the first condenser. Condensed at C1, and the condensate is led to a second condenser C2.
The pressure of the first condenser C1 can be made lower than that in the case of full condensation, and the power can be slightly reduced. It can be used when there is excess absorption refrigeration effect.
The operation is intermediate between mode 2 and mode 3.
[0014]
(4) 'Mode 4' (first condenser direct condensation mode) is to stop the absorption chiller RA and the compressor M when the outside air temperature is lower than the chilled water temperature obtained by the absorption chiller RA, and to stop the refrigerant. Condensed in one condenser C1 and circulated by natural circulation or liquid pump 7.
In this mode, the refrigerant (diagram 41 → 42) passing through the check valve V1 (or the control valve is opened) is condensed and supercooled by exchanging heat with the outside air in the first condenser C1 (diagram). 42 → 43).
Subsequently, the refrigerant is pressurized by the liquid pump 7 (diagram 43 → 44), then expanded by the expansion device V3 (diagram 44 → 45), and takes heat in the evaporator Ec to evaporate and overheat (diagram 44 → 45). FIG. 45 → 41).
[0015]
Next, an example of switching between the operation modes will be described.
Stopping supply of refrigeration effect from absorption chiller RA (stop absorption chiller) or absorption refrigeration effect transfer medium temperature> First condenser cooling medium (cooling water, outside air) temperature or absorption refrigeration transfer medium temperature> First condenser outlet When the refrigerant temperature is (3), the operation is in the mode 1 and the operation in the mode 4 or 4 'is continued when the compressor M is stopped and the pressure M on the suction side of the compressor M is equal to or lower than a predetermined value. When the side pressure 6 is too low, the control valve 10 may be throttled to adjust the pressure. Also, in the compressor M operating state (minimum rotation speed in the case of the variable compressor speed), the compressor M suction side pressure decreases. If it has passed, a transition can be made to mode 4.
When the compressor M suction side pressure 6 rises too much, the compressor M shifts to the operation of the compressor M (mode 2 or 3), and the compressor M relation is controlled by the suction pressure 6, but the target of the cooling medium of the evaporator Ec is changed. Control may be performed based on the difference between the temperature and the detected temperature (compressor operation at target temperature <detected temperature).
When the outside air temperature is lower than the cold water temperature of the absorption chiller RA, the absorption chiller RA may be stopped and the operation may be performed in the mode 4 'for supplying outside air to the first condenser C1.
[0016]
Next, in modes 2, 2 ', 3 and 3' in which the compressor M and the absorption refrigerator RA are operated, in the operation in mode 2, the outlet temperature of the second condenser C2 of the absorption refrigeration effect transfer medium 4 or the compression refrigerator. When the outlet temperature 5 of the second condenser C2 of the refrigerant is equal to or lower than a predetermined value, the control valve 10 is opened to set the mode 3.
In the mode 3 operation, when the second condenser C2 outlet temperature 4 of the absorption refrigeration effect transfer medium or the second condenser C2 outlet temperature 5 of the compression refrigeration refrigerant is equal to or higher than a predetermined value, the control valve 10 is closed, and the mode 2 is set. I do. During the transition, the temperature is differentiated to prevent frequent transitions.
The control valve 10 may be adjusted so as to have a predetermined value between 2 and 3 (mode 3 ′), or the expansion valve may be adjusted so as to have a predetermined value between 2 and 3. V2 may be adjusted (mode 2 ').
[0017]
FIG. 2 shows a case where two compressors are provided in parallel in FIG. 1 (high-head compressor M1 and low-head compressor M2), and the operation mode is almost the same as that of FIG. In 1 or 2, when the outside air temperature is low and in the mode 3, the high head compressor M1 is stopped and the low head compressor M2 is operated.
The low-head compressor M2 consumes less power and saves energy.
In addition, even in the case of one compressor in FIG. 1, a method of operating with a different compression ratio using a screw compressor, a scroll compressor, or the like is also effective for energy saving.
The absorption refrigerator is not particularly limited, such as single-effect, double-effect, and single-effect, and is not limited by the working medium of the absorption refrigerator. The form of the heat source is not particularly limited, such as hot water, steam, fuel, or exhaust gas, and is not limited to exhaust heat, and may be an absorption refrigerator using an inexpensive fuel as a heat source. Each device constituting one compression refrigerator may be a plurality of devices.
Although described as a compression refrigerator, a mode in which heating operation is performed by a heat pump by switching pipes may be employed. At this time, heat may be supplied to the heat pump using the absorption refrigerator as a chiller / heater, or an exhaust heat source may be supplied directly to the heat pump.
[0018]
【The invention's effect】
In the present invention, a bypass circuit is provided in the first condenser and the compressor of the compression refrigerator, and the refrigerant flow (operation mode) is switched according to the load, thereby effectively utilizing the cold heat from the absorption refrigerator. Thus, the power consumption of the compressor can be reduced.
[Brief description of the drawings]
FIG. 1 is a flow configuration diagram showing an example of a connection example of a compression refrigerator of a refrigerator of the present invention.
FIG. 2 is a flow configuration diagram showing another example of the connection example of the compression refrigerator of the refrigeration apparatus of the present invention.
FIG. 3 is a Mollier diagram in each operation mode using the apparatus of FIG. 1;
[Explanation of symbols]
RA: absorption refrigerator, RP: compression refrigerator, M: compressor, M1: high head compressor, M2: low and high head compressor, Ec: evaporator, C1: first condenser, C2: second condenser , V1: check valve, V2: control valve (expansion valve), V3: expansion valve (throttle device), 1: bypass circuit, 2: controller, 3-6: temperature or pressure sensor, 7: liquid pump, 8 : Check valve, 9: medium flow path, 10: control valve

Claims (4)

A refrigerating apparatus combining an absorption refrigerator having an evaporator, a compressor, a first condenser for cooling with outside air or cooling water, a second condenser, and a compression refrigerator having a utilization side evaporator exhibiting a refrigerating effect. The evaporator of the absorption refrigerator has a heat exchange relationship with the second condenser of the compression refrigerator, or also serves as the second condenser. A refrigeration apparatus comprising: a circuit for bypassing one condenser; and a control valve in the bypass circuit. The refrigeration apparatus according to claim 1, wherein the compression chiller is provided with a circuit that bypasses the compressor, and the bypass circuit has a check valve or a control valve. The refrigeration apparatus according to claim 1, wherein the compression refrigerator has a high-head compressor and a low-head compressor. 4. The method of operating a refrigeration system according to claim 1, 2, or 3, wherein the compression chiller operates in the following operation modes (a) to (d); An operation mode in which the bypass circuit is closed, the first condenser is condensed, and the second condenser is not supercooled, (b) the compressor is operated, the bypass circuit of the first condenser is closed, and the first condenser is closed. An operation mode in which the refrigerant is condensed and the refrigerant liquid from the first condenser is supercooled or condensed in the second condenser, (c) the compressor is operated, the bypass circuit of the first condenser is opened, and the second condenser is opened. And (d) an operation mode in which the compressor is stopped, the bypass circuit of the first condenser is opened, and the refrigerant vapor is condensed in the second condenser. An operation method of a refrigeration apparatus, wherein the operation method is operated in an operation mode.

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