JP2003056941A - Absorption water cooler/heater and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorption water cooler/heater capable of preventing crystallization of an absorbing solution (particularly, strong solution) from occurring without lowering cycle efficiency in partial loading, and to provide a control method. SOLUTION: The water cooler/heater comprises a low temperature solution heat exchanger (Lex) for exchanging heat between a weak solution (K3) delivered from an absorber (Ab) and a strong solution (K2) returned to the absorber (Ab), a flow control means (Vk) for controlling the flow rate of the strong solution flowing in a region toward a regenerator (Lg) side from the heat exchanger (Lex), a first temperature measuring means (AT) for measuring temperature (Tex) of the strong solution passing between the heat exchanger (Lex) and the absorber (Ab), and a control means (5). The control means (5) determines the crystallization temperature (tc) of the strong solution (K2) on the basis of the concentration of the strong solution (K2) in the vicinity of an inlet (Li) of the heat exchanger (Lex), and controls the flow rate of the strong solution by comparing the crystallization temperature (tc) and the temperature (Tex) of the strong solution measured by the means (AT).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an absorption chiller-heater.

[0002]

2. Description of the Related Art In a conventional absorption chiller-heater, for example, the relational parameters such as the circulating amount of the absorbing solution, the heat transfer area of the solution and cooling water,
Basic settings have been made to ensure high efficiency during rated operation. Therefore, there is still room for efficiency improvement in partial load operation, which occupies most of the actual usage conditions. In the absorption refrigeration cycle, the cycle efficiency improves as the concentration difference between the concentrated solution and the dilute solution increases. In order to improve the efficiency, the density range should be expanded as much as possible. And, the smaller the flow rate of the absorbing solution, the larger the concentration difference becomes, and the efficiency is improved. FIG. 7 shows the relationship between the cooling load (kW) (horizontal axis) and the concentration width (wt%) (vertical axis) measured using the solution flow rate as a parameter.
The density width of No. 5 is about twice the density width of the line B7 with a flow rate of 75%, and the line B7 has a density width of 120% or more of the line B10 with a flow rate of 100%.

FIG. 8 shows a load factor (horizontal axis) and a coefficient of performance (CO
The relationship of P) (vertical axis) is compared between the actual machine and the improvement simulation. A line showing an improvement simulation under the conditions where the concentration width is fixed at 5.4%, the heat transfer coefficient of the heat exchanger is constant, the load ratio is decreased, and the heat transfer area per unit flow rate of the absorbing solution is increased. With respect to Ci, when the load factor is 20%, the COP is improved by about 30%, and a large improvement can be expected with respect to the 10% improvement of the line Cj due to the decrease in the concentration width in the actual machine. However, the absorption solution flow rate is determined by the event, depending on the pressure of the low temperature regenerator and the absorber assumed at the rated load and the fixed solution flow resistance means such as the orifice installed between the low temperature regenerator and the absorber. Therefore, in the conventional absorption chiller-heater, it is unavoidable that the flow rate becomes larger than the ideal solution flow rate that traces Ci in FIG. 8 described above during the partial load operation.

Further, if the flow rate of the absorbing solution is excessively reduced to improve the efficiency, lithium bromide crystals are precipitated in the solution, which impedes the flow of the solution. Especially,
Between the low temperature regenerator having the highest solution concentration and the absorber, the low temperature solution heat exchanger exchanges heat between the concentrated solution and the dilute solution, and the temperature of the concentrated solution is lowered, so that crystals are likely to precipitate.

The inventor has established a technique for making the control of the flow rate of the absorbing solution during the partial load operation and avoiding the precipitation of crystals of the concentrated solution compatible with each other and applying the technique to an actual machine.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems of the prior art. The cycle efficiency does not decrease even under partial load, and the absorbing solution (especially concentrated solution) is used. It is an object of the present invention to provide an absorption chiller-heater and a control method capable of preventing the crystallization of water.

[0007]

The absorption chiller-heater of the present invention comprises a dilute solution delivered from the absorber (Ab) and the absorber (A).
The flow rate of the concentrated solution flowing through the low temperature solution heat exchanger (Lex) for exchanging heat with the concentrated solution returning to b) and the region (L12a) on the regenerator (Lg) side of the low temperature solution heat exchanger (Lex) is Adjusting flow rate control means and low temperature solution heat exchanger (Le
x) and the temperature of the concentrated solution flowing through the absorber (Ab) (T
ex) is provided with a first temperature measuring means and a control means, and the control means determines the crystal temperature of the concentrated solution from the concentrated solution concentration near the inlet (Li) of the low temperature solution heat exchanger (Lex). Then, the crystal temperature is compared with the concentrated solution temperature (Tex) measured by the first temperature measuring means, and if the concentrated solution temperature is higher than the crystal temperature by a predetermined value or more (with respect to the crystal temperature A control signal for decreasing the flow rate of the concentrated solution is output to the flow rate control means, and when the temperature is not higher than a predetermined value (there is no room for the crystal temperature), a control signal for increasing the flow rate of the concentrated solution is output. It is configured to output to the flow rate control means (claim 1: FIG. 1, FIG. 2, FIG. 3).

The control means of the absorption chiller-heater (1) of the present invention having such a configuration causes the first solution temperature measuring means to pass between the low temperature solution heat exchanger (Lex) and the absorber (Ab). The process of measuring the temperature of the concentrated solution and the low temperature solution heat exchanger Le
x) the step of determining the crystal temperature of the concentrated solution from the concentration of the concentrated solution, and the crystal temperature and the first temperature measuring means (A).
T) comparing the concentrated solution temperature measured by
When the concentrated solution temperature is higher than the crystal temperature by a predetermined value or more (if there is a margin to the crystal temperature), the flow rate of the concentrated solution is decreased and it is not higher than the predetermined value (no margin to the crystal temperature) And the step of controlling to increase the flow rate of the concentrated solution (claim 3: FIG. 1, FIG. 2).

According to the present invention having the above-mentioned structure, the concentration solution flow rate can be reduced and a wide concentration range can be obtained without producing crystals, so that the efficiency of the absorption chiller-heater can be improved.

Further, the absorption chiller-heater (2) of the present invention is a low temperature solution heat exchanger (Lex) for exchanging heat between the dilute solution sent from the absorber (Ab) and the concentrated solution returned to the absorber (Ab). )
And a regenerator (L) rather than the low temperature solution heat exchanger (Lex).
Flow rate suppressing means (Vk) for suppressing the flow rate of the concentrated solution flowing in the region g), and the first for measuring the temperature of the concentrated solution flowing between the low temperature solution heat exchanger (Lex) and the absorber (Ab). Temperature measuring means (AT), and the diluted solution line (L14) through which the diluted solution sent from the absorber (Ab) flows is the line (14s) flowing through the low temperature solution heat exchanger (Lex).
To a bypass line (14b) for bypassing, and the bypass line (14b) is provided with a flow rate control means (Vb) and has a control means (A5),
The control means (A5) determines the crystal temperature of the concentrated solution from the concentration of the concentrated solution near the inlet (Li) of the low temperature solution heat exchanger (Lex), and the crystal temperature and the first temperature measuring means (AT) are used. By comparing with the measured concentrated solution temperature, if the concentrated solution temperature is higher than the crystal temperature by a predetermined value or more (if the concentrated solution temperature has a margin with respect to the crystal temperature), the bypass line (14b) A control signal for reducing the bypass flow rate flowing through the flow controller is output to the flow rate control means (Vb), and when the temperature is not higher than a predetermined value (the concentrated solution temperature has no margin with respect to the crystal temperature), the control signal for increasing the bypass flow rate. Is output to the flow rate control means (Vb) (claim 2:
(FIGS. 4, 5, and 6).

The control means of the absorption chiller-heater (2) of the present invention having the above-mentioned structure uses the first temperature measuring means (AT) for the low temperature solution heat exchanger (Lex) and the absorber (Ab). ), Measuring the temperature of the concentrated solution flowing between the two), determining the crystallization temperature of the concentrated solution from the concentration of the concentrated solution near the inlet of the low temperature solution heat exchanger (Lex), Of the concentrated solution temperature measured by the temperature measuring means (AT), and if the concentrated solution temperature is higher than the crystal temperature by a predetermined value or more (the concentrated solution temperature has a margin with respect to the crystal temperature). A control step of decreasing the bypass flow rate flowing through the bypass line (14s) and increasing the bypass flow rate when the temperature is not higher than a predetermined value (the concentrated solution temperature has no margin with respect to the crystal temperature); (Claim 4: FIG. 4, 6).

Thus, the efficiency of the absorption chiller-heater can be improved by reducing the flow rate of the concentrated solution and widening the concentration range by the flow rate suppressing means. When the concentrated solution has a low temperature that cannot afford the crystal precipitation temperature, control is performed by increasing the bypass flow rate to reduce the heat transfer amount in the low temperature solution heat exchanger (Lex) and lower the liquid temperature of the concentrated solution. To prevent crystallization.

In measuring the temperature of the concentrated solution flowing between the low temperature solution heat exchanger and the absorber, a temperature sensor (CT) measures the refrigerant condensation temperature (TC) of the condenser (Cd).
d) is measured, and based on this, the refrigerant condensing pressure (PCd)
To decide. Then, the outlet temperature (Tg) of the regenerator (Lg) near the absorber (Ab) is measured, and the concentrated solution concentration is calculated from the regenerator outlet temperature (Tg) and the refrigerant condensing pressure (PCd). You can ask. Alternatively, the refrigerant condensing pressure (PCd) of the condenser (Cd) is measured by a pressure sensor, and the concentrated solution concentration is calculated from the pressure and the outlet temperature (Tg) of the regenerator (Lg) near the absorber (Ab). It can also be calculated and obtained. Furthermore, a low temperature solution heat exchanger (L
ex) and absorber (Ab) between the concentrated solution passage lines (L
12a) may be provided with a concentration sensor that measures the concentration of the concentrated solution.

The flow rate controlling means (Vk) is not limited to the flow rate adjusting valve, but may be any "variable resistance" means capable of changing the fluid resistance, and a pump, a variable orifice, or the like can be applied.

Similarly, a valve, a pump, an orifice, a throttle, etc. can be applied to the flow rate suppressing means (Vb).

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a series type absorption chiller-heater 1 of the first embodiment. The absorption chiller / heater 1 includes a high temperature regenerator Hg, a low temperature regenerator Lg, and a condenser C.
A general main device is constituted by d, the evaporator Ev, and the absorber Ab, and the entire structure is constituted by a piping line, a control device, and the like for operating these main devices.

The absorber Ab and the high temperature regenerator Hg are composed of a diluted absorption solution K obtained by absorbing the vaporous refrigerant solution in the absorber Ab.
3 are communicated with each other by a dilute solution line L14 that conveys 3 to the high temperature regenerator Hg. Pump Pa to the dilute solution line L14
, A low temperature solution heat exchanger Lex is installed on the absorber Ab side of the line L14, and a high temperature solution heat exchanger Hex is installed on the high temperature regenerator Hg side.

The high temperature regenerator Hg and the low temperature regenerator Lg are concentrated solution lines L5 for carrying the concentrated absorption solution K1 which is heated in the high temperature regenerator Hg and evaporated and separated from the refrigerant solution.
Is communicated by. Further, they are communicated with each other by a refrigerant vapor line L21 that conveys the evaporated and separated refrigerant vapor. A fuel line Lq for supplying a quantity of heat Q to a burner Bu for heating the dilute solution K3 is attached to the high temperature regenerator Hg via a valve Vq. The concentrated solution line L5 is provided with a high temperature solution heat exchanger Hex which is thermally shared with the line L14.

The low temperature regenerator Lg and the condenser Cd are connected by a refrigerant line L7, and the condenser Cd has a condensation temperature TCd of the refrigerant.
A temperature sensor CT for measuring is attached. The temperature sensor CT is connected by a signal line 18 to a control device 5 which is a device portion of a control means described in detail later.

The low temperature regenerator Lg and the absorber Ab are communicated with each other by a concentrated solution line L12 which conveys the concentrated concentrated solution K2 further concentrated in the low temperature regenerator Lg. A low temperature solution heat exchanger Lex that is thermally shared with the line L14 is provided in the concentrated solution line L12. Concentrated solution line L
An adjusting valve Vk of a flow rate control means for adjusting the flow rate of the concentrated solution K2 is interposed between the low temperature solution heat exchanger Lex 12 and the low temperature regenerator Lg, and is provided between the adjusting valve Vk and the low temperature regenerator Lg. A temperature sensor BT, which is a second temperature measuring means for measuring the temperature Tg of the concentrated solution K2 flowing through the line L12, is provided. The control valve Vk and the temperature sensor BT are connected to the control device 5 by a control line 19 and a signal line 16, respectively.

The temperature sensor AT which is the first temperature measuring means for measuring the temperature Tex of the concentrated solution K2 flowing through the line L12a in the region L12a between the low temperature solution heat exchanger Lex and the absorber Ab of the line L12 is provided. It is provided. The temperature sensor AT is connected to the control device 5 via a signal line 21.

The control device 5 controls the condensing pressure PCd of the refrigerant and the concentrated solution concentration DK2 near the inlet Li of the low temperature solution heat exchanger Lex from the crystal temperature tc at which the concentrated solution K2 precipitates crystals.
Is determined and the crystal temperature tc is compared with the concentrated solution temperature Tex measured by the temperature sensor AT. The controller 5 also outputs a control signal for decreasing the flow rate vK2 of the concentrated solution K2 to the adjustment valve Vk if the concentrated solution temperature Tex is equal to or higher than a predetermined value of the crystal temperature tc of the concentrated solution K2 and there is a margin for crystal precipitation. , Again, concentrated solution temperature Tex
Has a function of outputting a control signal for increasing the flow rate vK2 of the concentrated solution K2 to the adjusting valve Vk if there is no room for crystal precipitation below a predetermined temperature below the crystal temperature tc of the concentrated solution K2.

FIG. 2 shows the functions of the control device 5 in a block configuration. The calculation unit 51 includes a temperature sensor C
It is connected to the first interface If1 communicating with T, and is configured to have a function of calculating the refrigerant condensing pressure PCd from the refrigerant condensing temperature TCd from the temperature sensor CT. The arithmetic unit 51 can be omitted if a means for directly measuring the refrigerant condensing pressure PCd is provided.

The arithmetic unit 52 communicates with the second interface If2 communicating with the temperature sensor BT, and the concentrated solution temperature Tg from the temperature sensor BT and the refrigerant condensing pressure PC.
It is configured to have a function of calculating the concentrated solution concentration DK2 together with d. The calculation unit 53 has a concentrated solution concentration D
It has a function of calculating the crystal precipitation temperature tc from K2 according to a known formula.

The comparison means 54 communicates with the third interface If3 communicating with the temperature sensor AT, and combines the concentrated solution temperature Tex from the temperature sensor AT and the crystal precipitation temperature tc so that the concentrated solution temperature Tex has a margin. Is configured to have a function of calculating whether or not

The valve opening determining unit 55 has a function of determining the valve opening for increasing or decreasing the concentrated solution flow rate vK2, that is, the opening of the flow rate adjusting valve Vk based on the result calculated by the comparing means 54. Is configured. Interface 5
6 outputs the output signal of the valve opening determination unit 55 to the valve Vk.
It has a function of transmitting and transmitting to.

Absorption chiller / heater 1 constructed as shown in FIGS. 1 and 2.
The operation control means will be described with reference to the flowchart shown in FIG. In step S1, the condensation temperature TCd of the refrigerant in the condenser Cd is measured. In step S2, the condensation pressure PCd is calculated from the condensation temperature TCd.

In step S3, the temperature Tg of the concentrated solution K2 discharged from the low temperature regenerator Lg is measured. In step S4, the concentrated solution concentration DK2 is calculated from the condensation pressure PCd and the concentrated solution temperature Tg near the inlet Li of the low temperature solution heat exchanger Lex. In step S5, the crystal precipitation temperature tc is calculated from the concentrated solution concentration DK2. Step S
4 and step S5 are steps for determining the crystal temperature.

In step S6, the low temperature solution heat exchanger Le is used.
Concentrated solution K2 at the outlet of x, that is, low temperature solution heat exchanger L
temperature T of the concentrated solution K2 flowing between ex and the absorber Ab
ex is measured by the temperature sensor AT. Step S6 is a step of measuring the temperature of the concentrated solution K2.

In step S7, does the concentrated solution temperature Tex have a margin with respect to the crystal temperature tc due to the crystal temperature tc from step S5 and the concentrated solution temperature Tex from step S6? Weigh and compare. This step S7 is a step of comparing the crystal temperature tc with the concentrated solution temperature Tex.

In step S8, since the temperature Tex of the concentrated solution K2 is insufficient with respect to the crystal temperature tc, the concentrated solution flow rate vK2 is increased. Then, the process returns to step S1. In step S9, since the temperature Tex of the concentrated solution K2 has a margin with respect to the crystallization temperature tc and the flow rate of the concentrated solution can be reduced, the concentrated solution flow rate vK2 is reduced.
At this time, the decrease in the concentrated solution amount vK2 is controlled such that the rise in the refrigerant evaporation temperature in the evaporator Ev is kept within a range of conditions in which cold water of 7 ° C. necessary for the cooling load Ref passing through the evaporator Ev is obtained, for example. To do. Then, step S
Return to 1.

A refrigerant condensing pressure PCd measuring sensor may be provided instead of the refrigerant condensing temperature TCd measuring means of the condenser Cd. In that case, the arithmetic unit 51 for obtaining the refrigerant condensing pressure from the refrigerant condensing temperature in the control unit 5 in FIG. 2 can be omitted. Further, step S2 of calculating the refrigerant condensing pressure PCd from the refrigerant condensing temperature TCd in FIG.
Can be omitted.

Further, the low temperature solution heat exchanger Lex and the absorber A are used.
A concentration sensor that measures the concentration of the concentrated solution may be provided on the concentrated solution line L12a between the point b and the point b. In that case, the refrigerant condensing pressure calculation unit 51 and the concentrated solution concentration calculation unit 52 for obtaining the refrigerant condensing pressure PCd from the refrigerant condensing temperature TCd are
It can be omitted from the control device 5 of FIG. Further, step S2 of calculating the refrigerant condensing pressure PCd from the refrigerant condensing temperature TCd.
And step S4 of calculating the concentration of the concentrated solution can be omitted from the flowchart of FIG.

In this way, the efficiency is improved by causing the optimum necessary amount of concentrated solution flow according to the magnitude of the load to flow through the absorber Ab.

FIG. 4 shows the construction of the series type absorption chiller-heater 2 of the second embodiment. Absorption chiller / heater 2
In general, a high temperature regenerator Hg, a low temperature regenerator Lg, a condenser Cd, an evaporator Ev and an absorber Ab constitute a general main device, and the overall configuration is constituted by a piping line and a control device for operating these main devices. Has been done.

The parts different from the first embodiment shown in FIGS. 1 and 2 will be mainly described below, and the devices having the same functions will be described by using the same reference numerals.

The absorber Ab and the high temperature regenerator Hg are composed of a diluted absorption solution K obtained by absorbing the vaporous refrigerant solution in the absorber Ab.
3 are communicated with each other by a dilute solution line L14 that conveys 3 to the high temperature regenerator Hg. Pump Pa to the dilute solution line L14
Is installed, the low temperature solution heat exchanger Lex is installed on the absorber Ab side of the line L14, and the high temperature solution heat exchanger Hex is installed on the high temperature regenerator side.

A branch point B1 is provided between the pump Pa of the line L14 and the low temperature solution heat exchanger Lex.
A bypass line 14b that bypasses the low temperature solution heat exchanger Lex is branched into a line L14 which is a region of a line L14 that passes through the low temperature solution heat exchanger Lex from the branch point B1 and joins at a confluence point G1.

A regulating valve Vb for regulating the bypass flow rate is interposed in the bypass line 14b, and the regulating valve Vb is connected by a control line 20 to a control device A5 which is a device part of control means described later. FIG. 5 shows the vicinity of the low temperature solution heat exchanger Lex. In the figure, the confluence point G1 and the regulating valve Vb are combined to form a three-way valve V3B. Other configurations and functions are the same as those in FIG.

The high temperature regenerator Hg and the low temperature regenerator Lg are concentrated solution lines L5 for carrying the concentrated absorption solution K1 which is heated in the high temperature regenerator Hg and evaporated and separated from the refrigerant solution.
Is communicated by. Further, they are communicated with each other by a refrigerant vapor line L21 that conveys the evaporated and separated refrigerant vapor.

A fuel line Lq for supplying a heat quantity Q to a burner Bu for heating a dilute solution is attached to the high temperature regenerator Hg via a valve Vq. The concentrated solution line L5 is provided with a high temperature solution heat exchanger Hex which is thermally shared with the line L14.

The low temperature regenerator Lg and the condenser Cd are communicated with each other through a refrigerant line L7, and the condenser Cd has a condensation temperature TCd of the refrigerant.
A temperature sensor CT for measuring is attached. The temperature sensor CT is communicated with the control device A5 via a signal line 18. The low temperature regenerator Lg and the absorber Ab are the low temperature regenerator Lg.
Is connected by a concentrated solution line L12 that conveys the concentrated concentrated solution K2 that has been further concentrated.

In the concentrated solution line L12, the line L14
A low temperature solution heat exchanger Lex that is thermally shared with is interposed. Between the low temperature solution heat exchanger Lex and the low temperature regenerator Lg of the concentrated solution line L12, the adjusting valve Vk of the flow control means for adjusting the flow rate of the concentrated solution K2 is provided, and the adjusting valve Vk and the low temperature regenerator Lg are provided. Solution K flowing through line L12 between
A temperature sensor BT, which is a second temperature measuring unit that measures the temperature Tg of 2, is provided. The temperature sensor BT is connected to the control device A5 via a signal line 16.

The line L12 is located in the region line L12a between the low temperature solution heat exchanger Lex and the absorber Ab in the line L12.
A temperature sensor AT, which is a first temperature measuring means for measuring the temperature Tex of the concentrated solution K2 flowing through a, is provided.
The temperature sensor AT is connected to the control device A5 via a signal line 21.

The control device A5 controls the condensing pressure PCd of the refrigerant and the concentrated solution concentration DK2 in the vicinity of the inlet Li of the low temperature solution heat exchanger Lex from the crystal temperature t at which the concentrated solution K2 precipitates crystals.
It has a function of determining c and comparing the crystal temperature tc with the concentrated solution temperature Tex measured by the temperature sensor AT. The controller A5 also controls the concentrated solution temperature Te
If x is a predetermined value or more than the crystal temperature tc of the concentrated solution K2 and there is a margin for crystal precipitation, the regulating valve Vb interposed in the bypass line 14b is adjusted to the valve closing side to control the low temperature solution heat exchanger Le.
A signal is output so as to increase the dilute solution flowing in x to increase the amount of heat received from the concentrated solution K2 flowing in the line L12. Further, if the concentrated solution temperature Tex is less than a predetermined value than the crystal temperature tc of the concentrated solution K2 and there is no margin in crystal precipitation, the adjustment valve Vb is adjusted to the valve opening side to adjust the rare solution flowing to the low temperature solution heat exchanger Lex. A signal is output so as to reduce the amount of heat received from the concentrated solution K2 flowing through the line L12.

The functional configuration of the control device A5 is substantially the same as the block configuration of FIG. 2 in the first embodiment. In the present embodiment, the control target of the valve opening / closing determining unit 55 in FIG. 2 is a state in which the flow rate adjusting valve Vb of the present embodiment is replaced with the flow rate adjusting valve Vk of the first embodiment.

The operation control means of the absorption chiller-heater 2 constructed as shown in FIG. 4 will be described with reference to the flow chart shown in FIG. In the following steps, the flow rate of the concentrated solution K2 is adjusted by adjusting valve Vk.
It is performed on the assumption that it is properly adjusted by.

In step S11, the condensation temperature TCd of the refrigerant in the condenser Cd is measured. In step S12, the condensation pressure PCd is calculated from the condensation temperature TCd. In step S13, the temperature Tg of the concentrated solution K2 discharged from the low temperature regenerator Lg is measured.

In step S14, the condensation pressure PCd and the temperature T of the concentrated solution near the inlet Li of the low temperature solution heat exchanger Lex are increased.
The concentration DK2 of the concentrated solution is calculated from g and calculated. In step S15, the crystal precipitation temperature tc is calculated from the concentrated solution concentration DK2. Step S14 and Step S15
Is the step of determining the crystal temperature.

In step S16, the low temperature solution heat exchanger L
A temperature sensor AT measures the temperature Tex of the concentrated solution K2 at the outlet of ex, that is, the concentrated solution K2 flowing between the low temperature solution heat exchanger Lex and the absorber Ab. Step S16 is a step of measuring the temperature of the concentrated solution K2.

In step S17, the crystallization temperature tc from step S15 and the concentrated solution temperature Te from step S16.
Depending on x, does the concentrated solution temperature Tex have a margin with respect to the crystal temperature tc? Weigh and compare. This step S17
Is a step of comparing the crystallization temperature tc with the concentrated solution temperature Tex.

In step S18, since the temperature Tex of the concentrated solution K2 is insufficient with respect to the crystal temperature tc, the flow rate adjusting valve Vb is opened to reduce the flow rate of the rare solution flowing through the low temperature solution heat exchanger Lex. This allows the concentrated solution K
2 Heat release is suppressed to prevent crystal precipitation. Then, the process returns to step S11.

In step S19, since the temperature Tex of the concentrated solution K2 has a margin with respect to the crystallization temperature tc and the temperature of the concentrated solution K2 can be lowered, the flow rate adjusting valve Vb is closed to heat the low temperature. Increase the dilute solution flow rate through the solution heat exchanger Lex. Then, the process returns to step S11.

As described above, heat transfer from the concentrated solution K2 to the low temperature solution heat exchanger Lex is controlled to maintain a state in which crystal precipitation does not occur in the concentrated solution K2 and maintain high efficiency operation.

An example in which a refrigerant condensing pressure PCd measuring sensor is provided instead of the refrigerant condensing temperature TCd measuring means of the condenser Cd, and a concentrated solution passage line L12a between the low temperature solution heat exchanger Lex and the absorber Ab is provided. The example of providing the concentration sensor for measuring the concentration of is similar to that of the first embodiment.

It should be noted that the illustrated first and second embodiments are merely examples, and are not intended to limit the technical scope of the present invention. For example, although the double-effect absorption chiller-heater is shown in the illustrated embodiment, a single-effect, single double-effect, triple-effect absorption chiller-heater may be used. Also,
Although the series flow type absorption chiller-heater is used in the illustrated embodiment, it is also applicable to various types such as a parallel flow type, a reverse flow type, a series parallel flow type, and a reverse parallel flow type. .

[0057]

The effects of the present invention are listed below. (1) According to the present invention, a flow rate adjusting means is provided between the low temperature regenerator and the absorber so that an optimum concentrated solution flow rate is obtained in consideration of the solution crystal precipitation temperature which is a factor of flow rate reduction calculated from the concentrated solution temperature and the concentration. Since the temperature is adjusted, the temperature difference between the concentrated solution and the diluted solution can be kept large especially under partial load, and high efficiency can be maintained. (2) By providing a bypass line on the dilute solution line passing through the low temperature solution heat exchanger to adjust the amount of heat transferred from the dilute solution to the dilute solution, maintain the dilute solution temperature so that crystal precipitation does not occur. In particular, it is possible to maintain high efficiency by keeping a large temperature difference between the concentrated solution and the dilute solution under partial load.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a series flow type absorption chiller / heater according to a first embodiment of the present invention.

FIG. 2 is a block configuration diagram showing details of a control device in FIG.

FIG. 3 is a flowchart showing the operation of the first embodiment.

FIG. 4 is a configuration diagram showing a series flow type absorption chiller / heater according to a second embodiment of the present invention.

5 is a view showing a low temperature solution heat exchanger and piping in FIG.

FIG. 6 is a flowchart showing the operation of the second embodiment.

FIG. 7 is a diagram showing a relationship between a solution concentration width and a cooling load with a circulating solution flow rate as a parameter.

FIG. 8 is a diagram showing a relational characteristic between a load factor and a coefficient of performance of a conventional absorption chiller-heater, and a relational characteristic obtained by simulation for improving the coefficient of performance by improvement.

[Explanation of symbols] Hg: High temperature regenerator Lg: low temperature regenerator Ab ... Absorber Cd: condenser Ev ... Evaporator K1 ... concentrated solution K2 ... concentrated solution K3 ... dilute solution Hex ... High temperature solution heat exchanger Lex ... low temperature solution heat exchanger 5 ... Control device L5: concentrated solution line L12 ... Concentrated solution line L14 ... Dilute solution line AT ・ ・ Temperature sensor (first temperature measuring means) BT ... Temperature sensor CT ・ ・ Temperature sensor

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Enjoji Keita             1-5-20 Kaigan, Minato-ku, Tokyo Tokyo Gas             Within the corporation F-term (reference) 3L093 AA05 BB11 BB22 BB42 CC01                       EE04 GG02 HH02 HH04 JJ02                       KK05

Claims (4)

[Claims] 1. A low temperature solution heat exchanger for exchanging heat between a dilute solution sent from an absorber and a concentrated solution returning to the absorber, and a concentrated solution flowing in a region closer to a regenerator than the low temperature solution heat exchanger. A flow rate control means for adjusting the flow rate, a first temperature measurement means for measuring the temperature of the concentrated solution flowing between the low temperature solution heat exchanger and the absorber, and a control means are provided, and the control means is for controlling the low temperature. The crystal temperature of the concentrated solution is determined from the concentration of the concentrated solution in the vicinity of the inlet of the solution heat exchanger, the crystal temperature is compared with the concentrated solution temperature measured by the first temperature measuring means, and the concentrated solution temperature is crystallized. When the temperature is higher than a predetermined value by a predetermined value or more, a control signal for decreasing the concentrated solution flow rate is output to the flow rate control means, and when the temperature is not higher than the predetermined value, a control signal for increasing the concentrated solution flow rate is output to the flow rate control means. An absorption chiller-heater characterized by being configured to do. 2. A low temperature solution heat exchanger for exchanging heat with a dilute solution sent from the absorber and a concentrated solution returning to the absorber, and a concentrated solution flowing in a region closer to the regenerator than the low temperature solution heat exchanger. A dilute solution sent from the absorber flows, comprising a flow rate suppressing means for suppressing the flow rate and a first temperature measuring means for measuring the temperature of the concentrated solution flowing between the low temperature solution heat exchanger and the absorber. The dilute solution line is branched into a line flowing through the low temperature solution heat exchanger and a bypass line bypassing the low temperature solution heat exchanger, the bypass line is provided with a flow rate control means, and has a control means. The crystal temperature of the concentrated solution is determined from the concentration of the concentrated solution in the vicinity of the inlet of the low temperature solution heat exchanger, the crystal temperature is compared with the concentrated solution temperature measured by the first temperature measuring means, and the concentrated solution temperature is If the temperature is higher than the crystallization temperature by a predetermined value or more, A control signal for reducing the bypass flow rate flowing through the bypass line is output to the flow rate control means, and a control signal for increasing the bypass flow rate is output to the flow rate control means when the temperature is not higher than a predetermined value. A characteristic absorption chiller / heater. 3. The control means of the absorption chiller-heater according to claim 1, wherein the first temperature measuring means measures the temperature of the concentrated solution flowing between the low temperature solution heat exchanger and the absorber, Determining the crystal temperature of the concentrated solution from the concentration of the concentrated solution near the inlet of the solution heat exchanger, and comparing the crystal temperature with the concentrated solution temperature measured by the first temperature measuring means,
Controlling the concentrated solution flow rate to decrease if the concentrated solution temperature is higher than the crystallization temperature by a predetermined value or more and increase the concentrated solution flow rate if not higher than the predetermined value. Control method of absorption chiller-heater. 4. The control means of the absorption chiller-heater according to claim 2, wherein the temperature of the concentrated solution flowing between the low temperature solution heat exchanger and the absorber is measured by the first temperature measuring means; Determining the crystal temperature of the concentrated solution from the concentration of the concentrated solution near the inlet of the solution heat exchanger, and comparing the crystal temperature with the concentrated solution temperature measured by the first temperature measuring means,
Controlling the bypass flow rate flowing through the bypass line if the concentrated solution temperature is higher than the crystallization temperature by a predetermined value or more, and increasing the bypass flow rate if it is not higher than the predetermined value. A method for controlling an absorption chiller-heater featuring.