JPH02203166A - Absorption type refrigerator - Google Patents

Abstract

PURPOSE:To improve the wettability of cooling in a heat transfer tube, to scatter refrigerant substantially uniformly to the heat transfer tube, and further to prevent refrigerant evaporating temperature from decreasing in an evaporator by mixing absorption liquid of a specific range by weight concentration in refrigerant scattered by the evaporator. CONSTITUTION:Since absorption liquid of a range of 0.2 - 4% by weight concentration is mixed in the refrigerant of an evaporator 4, the surface tension of the refrigerant is reduced. Thus, even if oil, etc. is adhered to the outer surface of a heat transfer tube 22A at the time of starting operating of an absorption refrigerator, wettability of the refrigerant on the outer surface of the tube 22A can be improved, the wettability on a tray 18A is improved to scatter the refrigerant substantially uniformly to the tube 22A, thereby preventing the refrigerant evaporating temperature from decreasing in the evaporator 4 when the absorption liquid concentration is high. Thus, the heat exchanging rate of the tube 22A is improved to improve refrigerating capacity. The absorption liquid concentration can be calculated by a controller 25 based on a signal from a specific weight detector 34 provided at the evaporator 4 at the time of operating the refrigerator, and a refrigerant control valve 31 and the absorption liquid control valve 33 are controlled based on the absorption liquid concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to an absorption refrigerator that uses water as a refrigerant and a lithium bromide solution, which is a salt solution, as an absorption liquid.

(b) Conventional technology For example, Japanese Patent Publication No. 62-48148 defines a specific concentration/liquid amount relationship between the absorption liquid concentration in the refrigerant liquid in the evaporator and the amount of refrigerant liquid in the evaporator. , Kirani determines the permissible concentration range based on this concentration/liquid volume relationship, detects the absorption liquid concentration and refrigerant liquid volume, and when the detected absorption liquid concentration exceeds the upper limit of the permissible concentration range, the refrigerant in the evaporator is An absorption refrigeration system is disclosed in which a part of the absorption solution is flowed to the absorption liquid cycle side, and a part of the absorption solution is mixed into the refrigerant liquid in the evaporator when the detected concentration of the absorption liquid becomes smaller than the lower limit of the allowable concentration range. ing.

8) Problems to be Solved by the Invention In the conventional technology described above, when the absorption liquid concentration is low, for example, 0.1 wt%, at the beginning of operation of the absorption refrigerator, the surface tension of the refrigerant liquid increases. , the dripping of the absorption liquid in the evaporator will not be uniform, and the wettability on the surface of the heat transfer tube of the evaporator will deteriorate, the heat exchange rate in the heat transfer tube will deteriorate, and there is a risk that the refrigerating capacity will decrease. Ta. Furthermore, when the concentration of the absorbent is high, the refrigerant evaporation temperature in the evaporator is lowered, evaporation of the refrigerant in the evaporator is suppressed, and the refrigerating capacity is lowered.

An object of the present invention is to maintain the absorption liquid concentration in the evaporator at a predetermined concentration and improve the refrigerating capacity.

2) Means for Solving the Problems In order to solve the above problems, the present invention provides an absorber (5), a regenerator (1), (2), a condenser (3), and an evaporator.
4) are connected to each other via piping, water is used as the refrigerant, lithium bromide solution is used as the absorption liquid, and the refrigerant is sprayed onto the heat exchanger tube (22A) of the heat exchanger provided in the evaporator.
The present invention provides an absorption refrigerator characterized in that the refrigerant sprayed in the evaporator (4) is mixed with an absorption liquid having a weight concentration in the range of 0.2% to 4%.

In addition, the absorber (5), regenerators (1), (2), condenser (3), and evaporator (4) with heat transfer tubes (22A) are connected to each other via piping, and the refrigerant is water and absorption liquid. In an absorption refrigerator using a lithium bromide solution, an absorption liquid feed pipe (32) is provided between the absorber (5) and the evaporator (4) to guide the absorption liquid from the absorber to the evaporator. Liquid feed pipe (32)
An absorption liquid control valve (33) is provided in the middle of the evaporator (
4) and the absorber (5) from the evaporator pipe) to the absorber (
A refrigerant feed pipe (30) is provided to guide the refrigerant to the refrigerant feed pipe (30), a refrigerant control valve (31) is provided in the middle of the refrigerant feed pipe (30), and a detector (34) for detecting the specific gravity of the refrigerant is provided in the evaporator (4). ), further input a signal from this detector (34), and determine the specific gravity,
Alternatively, the absorption liquid concentration of the refrigerant is calculated from the density, and the absorption liquid adjustment valve (33) and the refrigerant adjustment valve (3) are operated based on the absorption liquid concentration.
1) to reduce the weight concentration of the absorbing liquid in the refrigerant of the evaporator to 0.
．． The present invention provides an absorption refrigerating machine characterized in that it is equipped with a control device (35) that controls the temperature within the range of 2% to 4%.

Furthermore, an evaporator (4) having an absorber 5), a regenerator (1), (2), a condenser (3), and a heat transfer tube (22A).
In an absorption refrigerator that uses water as the refrigerant and lithium bromide solution as the absorption liquid, the absorber (5) is connected to the evaporator (4) between the absorber (5) and the evaporator (4). ) is provided, and an absorption liquid control valve (33) is provided in the middle of this absorption liquid feed pipe (32),
An evaporator (4) is provided between the evaporator (4) and the absorber (5).
) to the absorber (5), and a refrigerant control valve (3) is provided in the middle of this refrigerant feed pipe 30).
1), a pressure detector (37) for detecting the internal pressure and a temperature detector (38) for detecting the refrigerant evaporation temperature are provided in the evaporator (4).
Furthermore, a temperature sensor (38) and a pressure sensor (37) are provided.
), calculates the refrigerant evaporation temperature from the internal pressure of the evaporator (4), and controls the refrigerant control valve based on the difference between the calculated refrigerant evaporation temperature and the detected refrigerant evaporation temperature,
The present invention provides an absorption refrigerator characterized in that it is equipped with a control device that controls the weight concentration of the absorption liquid in the refrigerant of the evaporator (4) within a range of 0.2% to 4%.

(e) The weight concentration of the absorption liquid in the refrigerant of the action evaporator <4) is in the range of 0.2% to 4%, and the surface tension of the refrigerant decreases, so that when the absorption refrigerator starts operating, etc. Even if oil or the like adheres to the outer surface of the heat exchanger tube (22A), the wettability of the refrigerant on the outer surface of the heat exchanger tube (22A) is improved, and the refrigerant flows almost uniformly on the outer surface of the heat exchanger tube (22A). Furthermore, it is possible to prevent a decrease in the refrigerant evaporation temperature in the evaporator (4) and improve the heat exchange rate in the heat exchanger tubes (22A).

Also, when the absorption refrigerator is operating, the specific gravity of the refrigerant is detected by the specific gravity detector (34) provided in the evaporator (4), and the refrigerant absorption liquid calculated by the control device (35) based on this specific gravity is detected. Based on the concentration, the absorption liquid control valve (33) of the absorption liquid feed pipe (32) and the refrigerant control valve (31) of the refrigerant feed pipe (30) are
〉 is controlled, and when the absorption liquid concentration is high, the refrigerant feed pipe (
The refrigerant is sent to the absorber (5) via the absorber (5) and the absorbent concentration decreases.When the absorbent concentration is low, the absorbent feed pipe (30)
2), the absorption liquid is sent to the evaporator (4), and the weight concentration of the absorption liquid in the refrigerant is controlled in the range of 0.2% to 4%, and the refrigerant on the outer surface of the heat transfer tube (22A) is The wettability of the heat exchanger tube (22A) is improved, and the heat exchange rate in the heat exchanger tube (22A) can be improved.

Furthermore, during operation of the absorption refrigerator, the refrigerant evaporation temperature is calculated based on the signal from the pressure detector (37) provided in the evaporator (4), and the refrigerant evaporation temperature and the refrigerant temperature detector (38) are calculated.
), the absorption liquid control valve (33) and the refrigerant control valve (31) are controlled based on the difference between the refrigerant evaporation temperature and the refrigerant evaporation temperature detected by the refrigerant. is sent to the absorber (5) via the refrigerant feed pipe 30), and the concentration of the absorption liquid decreases.Also, when the concentration of the absorption liquid of the refrigerant decreases and the above temperature difference becomes small, the absorption liquid becomes the absorption liquid. The absorption liquid is sent to the evaporator (4) via the feed pipe (32), and the weight concentration of the absorption liquid in the refrigerant is controlled within the range of 0.2% to 4%. The wettability is improved and it becomes possible to improve the heat exchange rate in the evaporator.

(F) Example Hereinafter, an example of the present invention will be described in detail based on the drawings.

The one shown in Figure 1 is a dual-effect absorption refrigerator, with water (H, O) used as the refrigerant and lithium bromide (L) used as the absorbent (absorbing liquid).
iBr) solution. Here, the lithium bromide solution contains a small amount of octyl alcohol as a surfactant, for example.

In Figure 1, (1) is a high temperature regenerator equipped with a gas burner (IB), (2) is a low temperature regenerator, (3) is a condenser, (4) is an evaporator, (5) is an absorber, ( 6) is a low temperature heat exchanger, (7) is a high temperature heat exchanger, (8) or 12) is an absorption liquid piping, (15) is an absorption liquid pump, (16> or 1)
8) is a refrigerant pipe, <19) is a refrigerant pump, (20) is a gas pipe connected to a gas burner (IB), (21) is a heating amount control valve, and (22) is a cold water pipe, each of which is connected to the first The piping is connected as shown in the figure. A refrigerant distribution tray (18) is provided on the refrigerant outlet side of the refrigerant pipe (18).
A) is provided, and a heat exchanger tube (22A) which is an evaporator heat exchanger for a cold water pipe (22) is provided below this tray (18A). Also, (25) is a cooling water pipe, and an absorber heat exchanger (26) is installed in the middle of this cooling water pipe (25).
), and a condenser heat exchanger <27).

Furthermore, in FIG. 1, a refrigerant feed pipe (30 )
A refrigerant control valve (31) is provided in the middle of this refrigerant conveyance or pipe 30). Also, absorption liquid piping (8)
Absorption liquid pump (15) discharge side and refrigerant distribution 'If (18)
An absorption liquid feed pipe (32) is installed between the suction side of the refrigerant pump (19) and an absorption liquid control valve (33) is provided in the middle of this absorption liquid feed pipe (32). . or,(
34) is a specific gravity detector that is attached to the refrigerant reservoir (4A) of the evaporator (4) and detects the specific gravity of the refrigerant accumulated in the refrigerant reservoir (4A). Furthermore, (35> is a specific gravity detector (3
4), refrigerant control valve (31), and absorption liquid control valve (33)
This control device (35) operates based on the signal from the specific gravity detector (34), calculates the absorption liquid concentration in the refrigerant, and controls the refrigerant control valve based on the absorption liquid concentration. (31) and an absorption liquid control valve (33), and each control valve (31) and (33) is controlled by a control device (35).

The operation of the absorption refrigerator will be explained below. Here, when the absorption refrigerator is in operation, the refrigerant and the absorption liquid circulate through each pipe as in the conventional absorption refrigerator. The refrigerant accumulated in the refrigerant reservoir (4A) flows through the refrigerant pipe (18) and is sprayed from the tray (18A) to the heat transfer tube (22A), and the cold water flowing inside the heat transfer tube (22) is caused by the heat of vaporization of the refrigerant. It can be cooled completely. Here, when starting operation for the first time after installing the absorption chiller, each control valve (31) and (33) are closed, and when the refrigerant reservoir (4A) is full and the load is 100%, The absorption liquid is mixed into the refrigerant so that the concentration of the absorption liquid in the refrigerant is, for example, 1% by weight. Then, by mixing the absorption liquid into the refrigerant as described above, the heat exchanger tube (22
Even if there is oil etc. on the outer surface of the heat exchanger tube (
22A) The wettability of the refrigerant on the outer surface is improved, and the refrigerant flows over almost the entire outer surface of the heat exchanger tube (22A). In addition, the wettability of the refrigerant distribution tray (18A) is improved, and the heat transfer tube (2
Refrigerant is almost uniformly distributed to 2A). As a result, the heat exchange efficiency in the heat exchanger tube (22A) is improved. As is clear from the experimental results of the refrigerating capacity with respect to the weight concentration of the absorption liquid (hereinafter referred to as absorption liquid concentration) in Figure 2, when 1% of the absorption liquid is mixed in the refrigerant, the refrigerating capacity of the pure refrigerant increases. 100
%, the freezing capacity increases to 103%. When the absorption liquid concentration is in the range of 0.2% to 4%, the refrigerating capacity becomes higher than in the case of pure refrigerant.

In addition, after the absorption refrigerating machine starts operating, if the absorption liquid concentration in the refrigerant decreases and becomes lower than 0.2%, the specific gravity detector (3
The control device (35) operates based on the signal from 4),
A signal is output to the absorption liquid control valve (33), and the absorption liquid control valve (
33) opens slightly. Then, the absorption liquid is transferred to the absorption liquid feed pipe (
32) to the refrigerant pipe (18), and is discharged together with the refrigerant from the refrigerant pump (19) and sprayed onto the heat exchanger tubes (22A). Therefore, the concentration of the absorption liquid in the refrigerant in the refrigerant reservoir (4A) increases. Thereafter, the control device (35) operates based on the signal from the specific gravity detector (34) and calculates the concentration of the absorbent, and when the concentration of the absorbent in the refrigerant becomes 0.2% or higher and higher than 4%. In this case, the control device (35) operates and the absorption liquid control valve (33) closes, stopping the absorption liquid from being mixed into the refrigerant. Further, the refrigerant control valve (31) opens based on a signal from the control device (35), and the refrigerant mixed with the absorption liquid flows to the absorber (5) via the refrigerant feed pipe (30), and the absorption liquid is returned to the absorber (5) and the concentration of the absorbent decreases. Then, when the absorption liquid concentration decreases and becomes lower than 0.2%, the absorption liquid control valve (33) opens in the same way as above and the absorption liquid is sent to the evaporator (4>. By keeping the concentration between 0.2% and 4%, the wettability of the refrigerant in the heat exchanger tube (22A) is improved and the refrigerant in the tray (1
8A) to the heat exchanger tubes (22A) can be uniformly distributed.

In addition, the absorption liquid control valve (33)
, and by changing the opening degree of the refrigerant control valve (31), the absorber (5)
The amount of absorption liquid flowing from to the evaporator (4) and the evaporator <4
) by controlling the amount of refrigerant containing the absorption liquid flowing from the absorber (5) to the absorption liquid concentration to approximately 1%, the wettability in the heat transfer tube (22A) is further improved. Refrigerant distribution from the tray (18A) becomes more uniform.

According to the above embodiment, since the absorption liquid with a weight concentration in the range of 0.2% to 4% is mixed in the refrigerant of the evaporator (4), the surface tension of the refrigerant decreases, and the absorption refrigerating machine Even if oil or the like adheres to the outer surface of the heat exchanger tube (22A) at the start of operation, it is possible to improve the wettability of the refrigerant on the outer surface of the heat exchanger tube (22A). The wettability is improved, and the refrigerant can be almost uniformly distributed to the heat transfer tubes (22A). Furthermore, the drop in refrigerant evaporation temperature in the evaporator (4) that occurs when the absorption liquid concentration is high is suppressed, and the transfer is improved. Heat pipe (2
The heat exchange rate in 2A) is improved, and the refrigeration capacity can be improved.

Furthermore, when the absorption refrigerator is in operation, the concentration of the absorption liquid is calculated by the control device (35) based on the signal from the specific gravity detector (34) installed in the evaporator (4), and the concentration of the absorption liquid is calculated based on the concentration of the absorption liquid. Since the refrigerant control valve (31) and the absorption liquid control valve (33) can be fully controlled, the absorption liquid flowing from the absorber (5) to the evaporator (4) and the absorption liquid flowing from the evaporator (4) to the absorber (5) Adjust the refrigerant containing the liquid, and adjust the absorption liquid concentration from 0°2% to 4%.
By maintaining the temperature within this range, the refrigerating capacity of the absorption refrigerator during operation can be improved.

Here, in the above embodiment, the absorption liquid concentration was calculated based on the signal from the specific gravity detector (34), but the refrigerant liquid reservoir (4A
) is provided with, for example, an ultrasonic density sensor (which determines the concentration of the absorbent liquid based on ultrasonic density and temperature), and the control device (35) operates based on the signal from this sensor, and each of the control valves (31), Similar effects can be obtained when the control (33) is performed. Further, the opening and closing control of each of the control valves <31) and (33) may be performed at predetermined intervals using a timer.

In another embodiment, a pressure detector (37) for detecting the evaporation pressure is installed in the evaporator (4) as shown by the broken line in FIG.
A refrigerant temperature detector (4A) is installed in the refrigerant reservoir (4A).
A refrigerant evaporation temperature detector) (38) is provided to calculate the refrigerant temperature (refrigerant evaporation temperature) from the pressure inside the evaporator (4) and compare it with the actually measured refrigerant temperature. Here, in the case of pure refrigerant, there is no difference between the refrigerant temperature determined from the pressure of the evaporator (4) and the actually measured refrigerant temperature, but the temperature difference increases depending on the degree of mixing of the absorption liquid into the refrigerant. Then, the absorption liquid concentration in the refrigerant is 4
%, the temperature difference was 0.5°C. Therefore,
When the above temperature difference becomes larger than 045℃, the refrigerant control valve (31) is opened and the refrigerant containing the absorption liquid is transferred to the absorber <5>.
By returning it to Furthermore, it is possible to avoid a decrease in the heat exchange rate in the evaporator (4) due to an increase in the concentration of the absorbent. In addition, when the evaporation pressure and refrigerant temperature of the evaporator (4) are detected as described above and the refrigerant control valve <31) is controlled based on the difference between the calculated refrigerant temperature and the actually measured refrigerant temperature, the absorption Liquid control valve (
33) is a manual valve, and the absorption liquid control valve (33) is opened when the absorption refrigerator starts operating, and the absorption liquid concentration is between 0.2% and 4%.
By mixing the absorption liquid into the refrigerant so that the absorption liquid falls within the range of .

(G) Effects of the Invention The present invention is an absorption refrigerating machine configured as described above, in which the weight concentration of the refrigerant sprayed in the evaporator is 0.2% to 4%.
% of absorption liquid, the surface tension of the refrigerant decreases, and if oil, etc. adheres to the outer surface of the heat transfer tube of the evaporator when starting operation after installation of the absorption refrigerator, etc. It is also possible to improve the wettability of cooling in the heat exchanger tubes, to distribute the refrigerant almost uniformly to the heat exchanger tubes, and to prevent the refrigerant evaporation temperature from decreasing in the evaporator. , it is possible to improve the heat exchange rate in the evaporator and improve the refrigeration capacity.

Also, the absorption liquid concentration is calculated from the specific gravity or density of the refrigerant in the evaporator, and the absorption liquid control valve and the refrigerant control valve are controlled based on the absorption liquid concentration, and the weight concentration of the absorption liquid in the refrigerant is reduced to 0.2%. By controlling it within the range of 4% to 4%, even if the absorption liquid concentration changes during operation of the absorption refrigerator, it is possible to improve the wettability of the refrigerant in the heat transfer tubes of the evaporator, etc. It is possible to prevent the refrigerant evaporation temperature from decreasing in the container, and as a result, the power of the refrigeration source can be improved.

Furthermore, the refrigerant evaporation temperature is calculated from the internal pressure of the evaporator, and the refrigerant control valve is controlled based on the difference between this refrigerant evaporation temperature and the measured refrigerant evaporation temperature, and the weight concentration of the absorption liquid in the refrigerant is reduced to 0.2%.
By controlling the refrigerant to a range of 4% to 4%, it is possible to improve the wettability of the refrigerant in the heat exchanger tubes using a relatively inexpensive detector, and to avoid a decrease in the heat exchange rate in the evaporator. can.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an absorption refrigerator showing an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between absorption liquid concentration and refrigerating capacity. (1)...High temperature regenerator, (2)...Low temperature regenerator,
(3)... Condenser, (4)... Evaporator, (5
)...Absorber, (30)...Refrigerant feed pipe, (3
1)...refrigerant control valve, (32)...absorption liquid feed pipe, 33)...absorption liquid control valve, (34)...specific gravity detector, (35)...control device, (37)...
・Pressure detector, (38)...Refrigerant temperature detector.

Claims (1)

[Scope of Claims] 1. An absorber, a regenerator, a condenser, and an evaporator having a heat transfer tube are connected to each other through piping, and water is used as a refrigerant and a lithium bromide solution is used as an absorption liquid. In an absorption refrigerating machine that sprays a refrigerant into the heat transfer tubes of a heat exchanger, an absorption liquid having a weight concentration of 0.2% to 4% is mixed into the refrigerant sprayed in the evaporator. refrigerator. 2. In an absorption refrigerator that uses water as a refrigerant and lithium bromide solution as an absorption liquid, the absorber, regenerator, condenser, and evaporator with heat transfer tubes are connected through piping. An absorption liquid feed pipe is provided between the absorber and the absorber to guide the absorption liquid from the absorber to the evaporator, and an absorption liquid control valve is provided in the middle of this absorption liquid feed pipe, and between the evaporator and the absorber, the absorption liquid is A refrigerant feed pipe is provided to guide the refrigerant to the refrigerant, a refrigerant control valve is provided in the middle of the refrigerant feed pipe, a detector is provided in the evaporator to detect the specific gravity or density of the refrigerant, and a signal is input from this detector. , calculate the absorption liquid concentration of the refrigerant from the specific gravity or density, control the absorption liquid control valve and the refrigerant control valve based on the absorption liquid concentration, and set the weight concentration of the absorption liquid in the refrigerant of the evaporator to 0.2.
An absorption refrigerating machine characterized in that it is equipped with a control device that controls the temperature within the range of % to 4%. 3. In an absorption refrigerator that uses water as the refrigerant and lithium bromide solution as the absorption liquid, the absorber, regenerator, condenser, and evaporator with heat transfer tubes are connected through piping. An absorption liquid feed pipe is provided between the absorber and the absorber to guide the absorption liquid from the absorber to the evaporator, and an absorption liquid control valve is provided in the middle of this absorption liquid feed pipe, and between the evaporator and the absorber, the absorption liquid is A refrigerant feed pipe is provided to guide the refrigerant to the refrigerant, a refrigerant control valve is provided in the middle of the refrigerant feed pipe, a pressure detector to detect the internal pressure and a temperature detector to detect the refrigerant evaporation temperature are provided in the evaporator, and a temperature detector is provided to detect the refrigerant evaporation temperature. Inputting signals from the detector and the pressure detector, calculating the refrigerant evaporation temperature from the internal pressure of the evaporator, and controlling the refrigerant control valve based on the difference between the calculated refrigerant evaporation temperature and the detected refrigerant evaporation temperature, The weight concentration of the absorption liquid in the refrigerant of the evaporator is set to 0.
An absorption refrigerating machine characterized by being provided with a control device that controls the temperature within a range of 2% to 4%.