JP2004150776A - Absorption refrigerating machine and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorption refrigerating machine performing a minus temperature operation for ice storage heat at night and a plus temperature operation for air conditioning in the daytime and to provide its operation method. <P>SOLUTION: This absorption refrigerating machine is provided with a regenerator G, a condenser C, an absorber A and an evaporator E, adds solute to refrigerant liquid to be sprayed to a heat transmission part of the evaporator E and makes it to antifreeze solution. This absorption refrigerating machine is provided with a control mechanism LS retaining the fixed amount of the solute in the refrigerant liquid retained in the evaporator E, adjusting the refrigerant liquid amount retained in a liquid sump of the evaporator by a refrigerant liquid amount introduced from the condenser and controlling the solute concentration of the refrigerant liquid of the evaporator E. This absorption refrigerating machine is provided with an auxiliary absorber and an auxiliary regenerator enabling a two-stage concentration cycle and a cycle conversion mechanism converting the two-stage concentration cycle effective or ineffective. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an absorption refrigerator, and particularly to an absorption refrigerator that uses negative heat to store ice heat during the night by using exhaust heat or the like, and to operate at a plus temperature during the daytime for air conditioning. It relates to the driving method.
[0002]
[Prior art]
[Patent Document 1] JP-B-58-15703 [Patent Document 2] JP-A-6-347126 [Patent Document 3] JP-A-7-139844 [Patent Document 4] JP-A-11-304275 [Patent] Reference 5: Japanese Patent Application Laid-Open No. H11-304276 Patent Document 6: Japanese Patent Application Laid-Open No. H11-304277 In an absorption refrigerator using water as a refrigerant, when the temperature of the refrigerant is 0 ° C. or less, the refrigerant is prevented from freezing. Therefore, it is conventionally known to lower the freezing temperature by mixing an absorbent into the refrigerant of the evaporator (Japanese Patent Publication No. 58-15703).
Japanese Patent Application Laid-Open No. Hei 6-347126 discloses that the concentration of the evaporator is kept constant by keeping the absorbent held in the evaporator constant and keeping the liquid level constant. In addition, it is particularly important to have two sets of evaporators / absorbers, and to cool the absorber paired with the evaporator containing the absorbent with the other evaporator to avoid the crystal concentration of the absorber. Japanese Unexamined Patent Publication Nos. Hei 11-304275, Hei 11-304276 and Hei 11-304277 each disclose a double effect with two single-effect machines and use one evaporator in combination with an evaporator containing an absorbent. It has been described respectively to cool the absorber which results in avoiding the crystal concentration of the absorber.
However, these refrigerators are exclusively for taking out minus temperature, and the concentration of the absorbent in the evaporator is kept almost constant to prevent freezing. The efficiency at the time of temperature removal is only slightly improved.
[0003]
[Problems to be solved by the invention]
In view of the above prior art, the present invention improves efficiency in accordance with the temperature at which brine is taken out from an evaporator, and in particular, significantly improves efficiency when a minus temperature taking out operation is changed to a plus temperature taking out operation. It is an object of the present invention to provide an absorption refrigerator capable of performing the above-mentioned method and an operation method thereof.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a refrigerating machine, a condenser, an absorbing machine, and an evaporator, in which a solute is added to a refrigerant liquid sprayed to a heat transfer section of the evaporator to form an antifreezing liquid. In the machine, while maintaining a constant amount of solute in the refrigerant liquid held in the evaporator, while adjusting the amount of refrigerant liquid held in the liquid reservoir of the evaporator by the amount of refrigerant liquid introduced from the condenser An absorption refrigerator having a control mechanism for controlling the solute concentration of the refrigerant liquid in the evaporator.
In the absorption refrigerator, an auxiliary absorber and an auxiliary regenerator that enable a two-stage concentration cycle can be provided, and a cycle change mechanism that changes the two-stage concentration cycle to valid or invalid can be provided.
[0005]
According to the present invention, in the method for operating an absorption refrigerator, the control target temperature of the brine to be cooled by the evaporator is at least two values, and the liquid reservoir of the evaporator is adjusted in accordance with the control target temperature. And controlling the solute concentration of the refrigerant liquid to operate the absorption refrigerator.
In the method of operating the absorption refrigerator, the control target temperature of the brine includes an operation mode in which the temperature of the brine cooled by the evaporator is a minus temperature, and an operation mode in which the brine temperature is adjusted to a temperature suitable for air conditioning. The solute concentration of the refrigerant liquid in the liquid reservoir of the evaporator can be controlled by the operation mode, and the control of the solute concentration of the refrigerant liquid detects the liquid level in the liquid reservoir of the evaporator. The liquid level switch or the operating position of the liquid level switch to be adjusted is provided and performed, and the liquid level switch or the operating position to be used can be selected by an operation mode corresponding to the control target temperature.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in detail.
In the present invention, to prevent freezing even at a refrigerant temperature of 0 ° C. or less, solutes added to the refrigerant liquid in the evaporator to form an antifreeze liquid include an absorbent used for absorbing the refrigerant in the absorption refrigerator, or ethylene glycol, Propylene glycol or the like can be used.
When taking out the minus temperature, the solute concentration of the antifreeze in the refrigerant is increased to a concentration at which the refrigerant does not freeze, and when taking out at the plus temperature, the concentration is made thin.
In the present invention, the solute concentration of the antifreeze held in the evaporator is kept constant, and the solute concentration is changed by increasing or decreasing the amount of the refrigerant. As a specific example, the concentration of the solute can be changed by controlling the amount of the refrigerant held by the evaporator by the liquid level.
[0007]
The relationship between the efficiency of the absorption refrigerator and the solute concentration of the evaporator is that when the solute concentration of the antifreeze in the evaporator is high, the heat transfer becomes worse, for example, the viscosity of the refrigerant increases, and the heat conductivity decreases. In order to extract the brine temperature, it is necessary to lower the temperature of the refrigerant. In addition, since the vapor pressure drop (boiling point rise) becomes large, the saturated vapor temperature becomes further lower, and a stronger absorbent capacity is required than in the case of a low concentration refrigerant, and the concentration on the absorption solution side becomes higher. Due to the crystal limit of the absorption solution, the solution concentration of the concentrated solution is limited, the concentration range of the absorption solution cycle is reduced, and the efficiency is further reduced.
When extracting the plus temperature, the refrigerant temperature rises even if the heat transfer coefficient is the same, but by reducing the solute concentration in the refrigerant, the heat transfer is improved, the refrigerant temperature further rises, and the vapor pressure drops Therefore, the saturated vapor temperature further increases, the concentration on the absorption solution side further decreases, the cycle width of the cycle can be increased, and the efficiency increases.
[0008]
Also, the relationship between the efficiency of the absorption refrigerator and the cycle change is that when taking out minus temperature, it is necessary to greatly increase the absorption capacity, the concentration of the absorber is high, and in the same cycle as when taking out plus temperature. When attempting to regenerate the absorbing solution, the required temperature of the heat source becomes very high. When the heat source temperature is limited, for example, when the heat source temperature is 100 ° C. or less, a two-stage concentration cycle is required to remove the negative temperature, and a low COP is obtained. Can be approximately doubled. Efficiency can be further improved by performing it in combination with the concentration of the above evaporator.
Similarly, improvement can be achieved by switching between a double-effect cycle and a double-effect cycle incorporating two-stage absorption.
Next, the present invention will be described with reference to the drawings.
[0009]
FIG. 1 is a flowchart showing an example in which the present invention is applied to a single-effect absorption refrigerator.
In FIG. 1, G is a regenerator, C is a condenser, A is an absorber, E is an evaporator, XL is a solution heat exchanger, SP is a solution pump, RP is a refrigerant pump, V1 is a control valve, and LS is a liquid level. It is a detector. In FIG. 1, the dilute solution that has absorbed the refrigerant is sent from the absorber A to the regenerator G through the heated side of the solution heat exchanger XL. In the regenerator G, the concentrated solution is heated and concentrated by a heat source such as hot water or steam, and the concentrated solution passes through the heating side of the solution heat exchanger XL and returns to the absorber A. On the other hand, the refrigerant vapor generated in the regenerator G enters the condenser C, is cooled and becomes a condensed liquid, and accumulates in a refrigerant tank (a liquid reservoir or a separate reservoir) below the condenser. The refrigerant liquid stored in the tank is introduced into the evaporator E by adjusting the valve V1 so that the liquid level becomes a target value by a signal of the liquid level detector LS provided in the evaporator E. The evaporator E contains a certain amount of solute that turns the refrigerant liquid into an antifreeze. By adjusting the liquid level, the amount of the refrigerant is adjusted, and the target solute concentration of the antifreeze is obtained. The refrigerant is sprinkled from the upper part of the evaporator E to the heat transfer portion, and takes heat from the brine to be cooled, and a part of the refrigerant evaporates and is absorbed by the absorbing solution of the absorber A.
[0010]
When taking out the minus temperature, the solute concentration of the antifreeze liquid is made high, and when it is taking out the minus temperature, the liquid level is set to the L1 position. When the temperature is positive, the liquid level is controlled by L2.
In the evaporator E, a certain amount of solute is retained in the refrigerant, but the retained amount may change during long-time operation. A pipe having a valve for entering and exiting the solution from the absorber A to the evaporator E (not shown) may be provided to facilitate seasonal maintenance adjustment.
[0011]
FIG. 2 shows a cycle of the absorption refrigerator of FIG. 1 on a During diagram. FIG. 2 (a) is a cycle diagram at a minus temperature, and FIG. 2 (b) is a cycle diagram at a plus temperature. The crystal line indicated by the broken line is a mixture of LiBr and CaCl ₂ at a ratio of 2: 1 to the absorbent used as a solute (the crystal concentration can be shifted to be higher by several% to 10% than in the case of LiBr alone). ).
When taking out the minus temperature, it approaches the crystal line, so the circulation amount of the solution is increased, and the concentration of the concentrated solution is reduced even slightly. At the plus temperature, there is room for the crystal line, so the amount of circulating solution is reduced and the concentration range is widened to improve cycle efficiency. The increase and decrease of the solution circulation amount is performed by adjusting the number of rotations of the solution pump SP by adjusting the frequency of the power supply by the inverter.
[0012]
FIG. 3 is a flow configuration diagram showing another example of the absorption refrigerator of the present invention, which is a two-stage concentration / single-effect mixer by switching the cycle, and includes an evaporator E, an absorber A, a regenerator G, and a condenser C. , An auxiliary absorber AX, an auxiliary regenerator GX, a low-temperature heat exchanger XL, and a high-temperature heat exchanger XH.
In FIG. 3, the cycle of the solution can be changed by the valves V2 and V3. The solid arrow in FIG. 3 indicates the case of the two-stage concentration cycle corresponding to the minus temperature extraction.
In FIG. 3, when the minus temperature is taken out by the evaporator, the refrigerant which is the antifreeze liquid is sprinkled from the upper part of the evaporator E to the heat transfer portion, and the heat is taken from the brine as the medium to be cooled, and a part of the refrigerant is removed. Evaporate. The concentrated solution guided to the absorber A absorbs the refrigerant vapor from the evaporator E while being cooled by the cooling water, and becomes a dilute solution. The dilute solution from the absorber A is sent to the auxiliary regenerator GX through the valve V2, and is heated and concentrated by a heat source such as hot water to become a concentrated solution, and returns to the absorber A.
[0013]
The refrigerant vapor generated in the auxiliary regenerator GX is absorbed by the absorption solution in the auxiliary absorber AX. The dilute solution in the auxiliary absorber AX is sent to the regenerator G by the solution pump SPX, and reduced by heating with a heat source such as hot water to become a concentrated solution, and returns to the auxiliary absorber AX through the valve V3. The refrigerant vapor generated in the regenerator G enters the condenser C, is cooled and becomes condensed liquid, and is stored in a refrigerant tank (liquid reservoir) below the condenser C. The refrigerant liquid stored in the tank is introduced into the evaporator E by adjusting the valve V1 so that the liquid level becomes a target value in accordance with a signal from the liquid level detector LS provided in the evaporator E. The evaporator E contains a certain amount of solute to be made into an antifreeze in the refrigerant. By adjusting the liquid level to L1 with a small amount of the refrigerant, the target concentration of the antifreeze is increased.
[0014]
When the plus temperature is taken out by the evaporator E, the valves V2 and V3 are switched, the solution is flowed in the direction of the dashed arrow, and the auxiliary absorber AX and the auxiliary regenerator GX are removed to form a single effect cycle. That is, the dilute solution from the absorber A passes through the low-temperature solution heat exchanger XL, and is then guided to the regenerator G via the high-temperature heat exchanger XH by the valve V2. The concentrated solution heated and concentrated in the regenerator G passes through the heating side of the high-temperature heat exchanger XH, and is guided to the absorber A via the low-temperature solution heat exchanger XL by the valve V3.
The refrigerant vapor generated in the regenerator G is cooled in the condenser C to become a condensed liquid, and accumulates in the lower refrigerant tank. The refrigerant liquid stored in the tank is introduced into the evaporator E by adjusting the valve V1 so that the liquid level becomes the target value L2 based on a signal from the liquid level detector LS provided in the evaporator E. The solute concentration in the evaporator is reduced due to the large amount of refrigerant. The refrigerant is sprinkled from the upper part of the evaporator E to the heat transfer portion, and takes heat from the brine to be cooled, and a part of the refrigerant evaporates and is absorbed by the absorbing solution of the absorber A.
[0015]
FIG. 4 is a flow configuration diagram in FIG. 3 in which a continuous cycle change is performed by a two-stage concentration and single-effect mixer.
In FIG. 4, the cycle change is performed by the valves V2 ′ and V3 ′, and the solution is caused to flow in the arrow direction by the valves V2 ′ and V3 ′, so that the valves V2 and V3 of FIG. The same cycle as in the case of the arrow is performed. Further, by switching the valves V2 'and V3', the solution can be cycled from the absorber A → the auxiliary absorber AX → the regenerator G → the auxiliary regenerator GX → the absorber A, and the heat source input change of the valve V4. Thus, the direction can be changed from the single-effect cycle (V4 fully closed) to the two-stage concentration cycle direction (V4 open direction).
[0016]
FIG. 5 is a flow diagram of a mixer for two-stage concentration and double effect by cycle switching.
FIG. 5 shows an example in which a two-stage concentration cycle is incorporated in a double-effect cycle. When the temperature is lowered to minus temperature, the solution is flowed in the direction indicated by the solid line at valves V3 'and V5, and the two-stage concentration cycle is performed. To prevent the heat source temperature required for the double effect cycle from becoming too high even when the solution concentration becomes high.
On the other hand, when the temperature is increased, the solution is flowed in the direction of the dashed arrow at the valves V3 'and V5 to remove the two-stage concentration function and increase the efficiency as a complete double-effect cycle.
Note that the same switching as in FIG. 4 for FIG. 3 can be provided for FIG.
[0017]
【The invention's effect】
According to the present invention, using an exhaust heat or the like, a negative temperature operation is performed in order to store ice heat at night, and an absorption chiller that operates at a positive temperature for air conditioning in the daytime, from the negative temperature extraction operation. Efficiency could be greatly improved when the operation became positive temperature extraction operation.
[Brief description of the drawings]
FIG. 1 is a flow configuration diagram showing an example of an absorption refrigerator of the present invention.
FIG. 2 is a During diagram of the refrigeration cycle of the absorption refrigerator of FIG. 1, where (a) is at minus temperature and (b) is at plus temperature.
FIG. 3 is a flow diagram showing another example of the absorption refrigerator of the present invention.
FIG. 4 is a flow diagram showing another example of the absorption refrigerator of the present invention.
FIG. 5 is a flow diagram showing another example of the absorption refrigerator of the present invention.
[Explanation of symbols]
G: regenerator, C: condenser, A: absorber, E: evaporator, GL: high temperature regenerator, AX: auxiliary absorber, GX: auxiliary regenerator, XL: low temperature side heat exchanger, XM: medium temperature side Heat exchanger, XH: High-temperature side heat exchanger, SP, SPX: Solution pump, RP: Refrigerant pump, V1-V5, V2 ', V3': Control valve, LS: Liquid level detector

Claims (5)

In an absorption refrigerator having a regenerator, a condenser, an absorber, and an evaporator, and a solute added to a refrigerant liquid sprayed to a heat transfer portion of the evaporator to make an antifreeze liquid, the refrigerant liquid held in the evaporator The amount of the solute is kept constant, and the amount of the refrigerant liquid held in the liquid reservoir of the evaporator is adjusted by the amount of the refrigerant liquid introduced from the condenser to control the solute concentration of the refrigerant liquid in the evaporator. An absorption refrigerator having a control mechanism. The absorption refrigerator according to claim 1, further comprising an auxiliary absorber and an auxiliary regenerator that enable a two-stage enrichment cycle, and a cycle changing mechanism that changes the two-stage enrichment cycle to valid or invalid. Characteristic absorption refrigerator. 3. The method for operating an absorption refrigerator according to claim 1, wherein the control target temperature of the brine cooled by the evaporator is at least two values, and the liquid storage portion of the evaporator is adjusted in accordance with the control target temperature. An operation method of an absorption refrigerator, wherein the operation is performed by controlling a solute concentration of a refrigerant liquid. The control target temperature of the brine has an operation mode in which the temperature of the brine cooled by the evaporator is a minus temperature, and an operation mode in which the temperature of the brine is adjusted to a temperature suitable for air conditioning. The method according to claim 3, wherein the solute concentration of the refrigerant liquid in the liquid reservoir is controlled. The control of the solute concentration of the refrigerant liquid is performed by providing at least two operation positions of a liquid level switch or a liquid level switch for detecting and adjusting the liquid level in the liquid reservoir of the evaporator, and adjusting the temperature to the control target temperature. The method according to claim 4, wherein a liquid level switch or an operation position to be used is selected according to the operation mode.

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