JP2009024944A - Absorption type water cooling and heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of an absorption type water cooling and heating apparatus, variably setting a preset temperature of load fluid. <P>SOLUTION: An absorption refrigerating cycle is formed by connecting the followings: regenerators 12, 16 for heating a diluted solution to generate refrigerant steam and a concentrated solution; a condenser 18 for condensing the refrigerant steam generated in the regenerators; an evaporator 20 for performing heat exchange between the refrigerant liquid condensed by the condenser and load fluid to cool the load fluid; an absorber 22 for absorbing the refrigerant evaporated in the evaporators in the concentrated solution generated in the regenerators; and a solution circulating pump 24 for sending the diluted solution generated in the absorber to the regenerators. A refrigerant passage 36 connecting the condenser and the evaporator to each other is provided with a liquid refrigerant proportional valve 38 for adjusting a refrigerant flow rate. A control means 40 controls the valve opening of the liquid refrigerant proportional valve so that the detected temperature of the evaporator reaches a target temperature of the evaporator, and variably sets the target temperature of the evaporator according to the preset temperature of the load fluid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an absorption chiller / heater, and more particularly to an absorption chiller / heater equipped with a liquid refrigerant proportional valve that controls the flow rate of liquid refrigerant sent to the evaporator according to the evaporator temperature.

  An absorption chiller / heater forms an absorption refrigeration cycle by connecting a regenerator, a condenser, an evaporator, an absorber, and the like. For example, the liquid refrigerant and the load fluid are exchanged in the evaporator to exchange the liquid refrigerant. The load fluid is cooled by latent heat of vaporization.

  In such an absorption chiller / heater, as described in Patent Document 1, a liquid refrigerant proportional valve is provided in the refrigerant flow path between the condenser and the evaporator, and the liquid is proportional to the detected temperature of the evaporator. It is known that the flow rate of refrigerant to the evaporator is controlled by controlling the valve opening degree of the refrigerant proportional valve, thereby controlling the latent heat of vaporization and the cooling amount of the load fluid.

  For example, when the temperature of the absorber decreases due to a decrease in the cooling water temperature and the absorption capacity increases, thereby reducing the pressure and temperature of the evaporator, the liquid refrigerant is changed according to the decrease in the evaporator temperature. The liquid refrigerant flow rate is increased by increasing the valve opening of the proportional valve. Then, since the solution density | concentration in an absorber falls, the absorptive power of an absorber becomes small, evaporator temperature becomes high and it becomes predetermined evaporator temperature.

  In this way, the flow rate of the liquid refrigerant to the evaporator is adjusted by controlling the valve opening of the liquid refrigerant proportional valve so that the detected temperature becomes the target temperature (evaporator target temperature) while detecting the evaporator temperature. Therefore, the absorbing power in the absorber is kept constant.

JP-A-8-247469

  However, the technique described in Patent Document 1 leaves room for improvement in improving the cooling efficiency in the absorption chiller / heater that variably sets the set temperature (target temperature) of the load fluid. .

  That is, for example, when the valve opening degree is controlled while the evaporator target temperature is kept constant even though the set temperature of the load fluid is changed, the evaporator target temperature is increased when the set temperature rises. Will be set lower than necessary. Then, the valve opening degree is suppressed to be lower than necessary, and the refrigerant is stored in the refrigerant storage chamber. As a result, the solution cycle concentration is kept high. As the solution cycle concentration is lower, the amount of heat input to the regenerator is less and the efficiency as a chiller / heater is increased. Therefore, the efficiency may be suppressed in an operation where the set temperature of the load fluid is high.

  Then, this invention makes it a subject to improve the efficiency of the absorption-type cold / hot water machine which variably sets the preset temperature of load fluid.

  In order to solve the above problems, an absorption chiller / heater of the present invention includes a regenerator that heats a dilute solution to generate refrigerant vapor and a concentrated solution, and a condenser that condenses the refrigerant vapor generated in the regenerator. The evaporator liquid that cools the load fluid by exchanging heat between the refrigerant liquid condensed by the condenser and the load fluid, and the diluted solution generated by the regenerator absorbs the refrigerant evaporated by the evaporator to produce a dilute solution An absorption refrigeration cycle is formed by connecting an absorber that absorbs the diluted solution generated in the absorber to a regenerator, and is provided in a refrigerant flow path that connects the condenser and the evaporator. A liquid refrigerant proportional valve that adjusts the refrigerant flow rate and a control unit that detects the temperature of the evaporator and controls the valve opening degree of the liquid refrigerant proportional valve so that the temperature becomes the evaporator target temperature. The control means variably sets the evaporator target temperature according to the set temperature of the load fluid.

  According to this, for example, if the set temperature of the load fluid increases, the target temperature of the evaporator increases correspondingly, and the target temperature of the evaporator is not constant but is variably set according to the set temperature of the load fluid. Can do. Therefore, if the set temperature of the load fluid increases, the valve opening can be increased to reduce the amount of refrigerant in the refrigerant storage chamber, and the cycle concentration of the solution can be lowered. As a result, the amount of heat input to the regenerator can be suppressed. The efficiency of the hot and cold water machine can be improved.

  In this case, it is desirable that the control means sets the evaporator target temperature to a value lower than the set temperature of the load fluid by a certain temperature. For example, if the temperature is about 2 ° C. lower than the set temperature of the load fluid, the cooling capacity is sufficiently obtained, so that the evaporator target temperature can be set to a value 2 ° C. lower than the set temperature of the load fluid.

  ADVANTAGE OF THE INVENTION According to this invention, the efficiency of the absorption-type cold / hot water machine which variably sets the preset temperature of load fluid can be improved.

  Hereinafter, an embodiment of an absorption chiller / heater to which the present invention is applied will be described. In addition, although this embodiment demonstrates as what is called a double effect absorption chiller / heater as an example, this invention is not limited to this, It is also possible to apply to a single effect or a triple effect absorption chiller / heater. is there.

  FIG. 1 is a diagram illustrating an overall configuration of an absorption chiller / heater according to the present embodiment. The absorption chiller / heater 10 includes a high temperature regenerator 12, a separator 14, a low temperature regenerator 16, a condenser 18, an evaporator 20, an absorber 22, a solution circulation pump 24, a high temperature and a low temperature solution. The heat exchangers 26, 28 and the like are connected by piping to form an absorption refrigeration cycle.

  The high temperature regenerator 12 heats a dilute solution made of, for example, water as a refrigerant and lithium bromide (LiBr) as an absorbent by a heat source given from the outside, and the separator 14 converts the heated dilute solution into a refrigerant vapor. And an intermediate concentrated solution. The high temperature solution heat exchanger 26 cools the separated intermediate concentrated solution by heat exchange with the diluted solution sent by the solution circulation pump 24, and the low temperature regenerator 16 separates the cooled intermediate concentrated solution by the separator 14. Reheated with the refrigerated refrigerant vapor to produce a concentrated solution. The low temperature solution heat exchanger 28 lowers the temperature by exchanging heat of this concentrated solution with the dilute solution sent by the solution circulation pump 24.

  Cooling water is passed through the condenser 18, whereby the refrigerant vapor is condensed, and the condensed liquid refrigerant is stored in a liquid refrigerant storage chamber 30 provided in the condenser 18. The evaporator 20 is provided with a liquid refrigerant distributor 32, and the liquid refrigerant flowing from the condenser 18 is dropped from the liquid refrigerant distributor 32 and sprayed onto the evaporator heat transfer tube. Thereby, the liquid refrigerant evaporates by taking heat from the load fluid such as water to be cooled flowing in the evaporator heat transfer tube, and the load fluid is cooled by the latent heat of evaporation.

  The absorber 22 absorbs the refrigerant evaporated by the evaporator 20 by dropping the concentrated solution generated by the low-temperature regenerator 16 and then heat-exchanged by the low-temperature solution heat exchanger 28 to generate a diluted solution. The solution circulation pump 24 sends the dilute solution generated by the absorber 22 to the high temperature regenerator 12 through the low temperature solution heat exchanger 28 and the high temperature solution heat exchanger 26.

  Further, the liquid refrigerant storage chamber 30 and the liquid refrigerant distributor 32 are connected via refrigerant flow paths 34 and 36, and the refrigerant flow path 36 is provided with a liquid refrigerant proportional valve 38 for adjusting the refrigerant flow rate. Yes. Furthermore, control means 40 is provided for controlling the valve opening degree of the liquid refrigerant proportional valve 38 so that the detected temperature becomes the evaporator target temperature while detecting the temperature of the evaporator 20. The valve opening degree of the liquid refrigerant proportional valve 38 is controlled according to a command from the control means 40, and thereby the liquid level height H of the liquid refrigerant in the liquid refrigerant storage chamber 30 is controlled. The control means 40 calculates the valve opening degree in proportion to the evaporator temperature.

  Next, a specific configuration of the liquid refrigerant proportional valve 38 will be described with reference to FIG. As shown in FIG. 2, the liquid refrigerant proportional valve (proportional valve) 38 includes an annular coil 42, a hollow cylindrical rotor 44 that is accommodated in the coil 42 and can be moved up and down, and a lower end of the rotor 44. An annular female screw 46 fixed to the inner screw 46, a hollow cylindrical male screw 48 meshing with the female screw 46, a valve rod 50 fixed to the upper end of the rotor 44 and inserted through the male screw 48, and fixed to the lower end of the valve rod 50. A valve 52, a nozzle 54 opened and closed by the vertical movement of the valve 52, a fluid inlet 56 provided below the nozzle 54 and connected to the liquid refrigerant storage chamber, and a liquid refrigerant distributor provided above the nozzle 54 Formed by a fluid outlet 58 or the like connected to the.

  When a pulse current corresponding to a command from the control means 40 is applied to the coil 42, the rotor 44 rotates and is guided by the male screw 48 to move up and down, so that the valve 52 opens and closes the nozzle 54. For example, the valve 52 is formed such that the apex of the conical shape is positioned on the lower side, and the flow area between the valve 52 and the nozzle 54 is linearly proportional to the amount of vertical movement thereof. The liquid refrigerant flow rate is controlled in proportion to the liquid level, and the liquid level height H is controlled.

  Next, the control means that is a characteristic part of the absorption chiller / heater of this embodiment will be described. As shown in FIG. 3, the control means 40 includes an input I / F (input means) 60 for inputting the load fluid set temperature Ts and the evaporator temperature T, and a load fluid set temperature input from the input I / F 60. A central processing unit (calculating means) 64 for calculating the valve opening degree of the liquid refrigerant proportional valve 38 based on Ts and the evaporator temperature T, and an output I / F (output means) for outputting the calculated valve opening degree. 66 or the like. The central processing unit 64 calculates a valve opening degree corresponding to the load fluid set temperature Ts and the evaporator temperature T by executing an arithmetic expression by a software program stored in a storage means (not shown).

  The basic control of the valve opening degree of the control means 40 will be described with reference to FIG. In this figure, the horizontal axis represents the evaporator temperature, and the vertical axis represents the valve opening of the liquid refrigerant proportional valve. As shown in the figure, the valve opening is controlled in proportion to the evaporator temperature. That is, when the target temperature of the evaporator 20 is set and the detected temperature of the evaporator is lower than the target temperature, the solution concentration is increased by increasing the valve opening and increasing the liquid refrigerant flow rate. And lowering the absorption capacity of the absorber to increase the evaporator temperature.

  On the other hand, if the detected evaporator temperature is higher than the target temperature, the valve opening is decreased and the liquid refrigerant flow rate is decreased, thereby increasing the absorption capacity of the absorber and lowering the evaporator temperature. . In this way, the evaporator temperature is controlled so as to always reach the target temperature.

  Here, depending on the absorption chiller / heater, there is a set temperature of the load fluid that is not constant and can be changed within a predetermined range such as 5 ° C to 12 ° C. In such an absorption chiller / heater, conventionally, as shown in FIG. 5, the target temperature of the evaporator is set to 4 for example even though the set temperature of the load fluid is changed between 5 ° C. and 12 ° C., for example. The valve opening was controlled while maintaining a constant temperature.

  If the temperature of the evaporator is lower than the temperature of the load fluid by about 2 ° C., for example, the cooling capacity can be sufficiently satisfied. It is set. Then, the valve opening degree is suppressed to be lower than necessary, and the refrigerant is stored in the refrigerant storage chamber. As a result, the solution cycle concentration is kept high. As the solution cycle concentration is lower, the amount of heat input to the regenerator is less and the efficiency as a chiller / heater is increased. Therefore, the efficiency may be suppressed in an operation where the set temperature of the load fluid is high.

  Therefore, in this embodiment, as shown in FIG. 6, the evaporator target temperature is variably set according to the set temperature of the load fluid. That is, a value lower by t1 ° C. than the set temperature of the load fluid is set as the evaporator target temperature. For example, if t1 is 2 ° C., the target evaporator temperature is 3 ° C. if the set temperature of the load fluid is 5 ° C., and the target evaporator temperature is 10 ° C. if the set temperature of the load fluid is 12 ° C.

  Next, a control flowchart of the control means 40 will be described with reference to FIG. When the set temperature Ts of the load fluid is set (S1), the evaporator target temperature Te in the valve opening control of the liquid refrigerant proportional valve is calculated by Te = Ts−t1 (S2). Subsequently, the temperature of the evaporator 20 is detected (S3), and the valve opening is calculated by the valve opening proportional control shown in FIG. 4 based on this temperature and the evaporator target temperature calculated in S2. (S4). The valve opening command signal calculated in S4 is output to the liquid refrigerant proportional valve 38 (S5), and the liquid refrigerant proportional valve 38 controls the refrigerant flow rate based on this command signal.

  As described above, according to the present embodiment, the evaporator target temperature in the valve opening control of the liquid refrigerant proportional valve is varied in accordance with the set temperature of the load fluid, so when the set temperature is high, the refrigerant is The performance of the absorption chiller / heater can be improved by reducing the amount of refrigerant in the storage chamber and lowering the cycle concentration of the solution.

It is a figure which shows the whole structure of the absorption-type cold / hot water machine of this embodiment. It is a figure which shows the structure of a liquid refrigerant proportional valve. It is a figure which shows the structure of a control means. It is a figure explaining the control content of the basic valve opening degree of a control means. It is a figure which shows the conventional control aspect of a control means. It is a figure which shows the control aspect of the control means of this embodiment. It is a control flowchart of the valve opening degree of a control means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Absorption type cold / hot water machine 12 High temperature regenerator 14 Separator 16 Low temperature regenerator 18 Condenser 20 Evaporator 22 Absorber 24 Solution circulation pump 26 High temperature solution heat exchanger 28 Low temperature solution heat exchanger 30 Liquid refrigerant storage chamber 32 Liquid refrigerant Distributors 34, 36 Refrigerant flow path 38 Liquid refrigerant proportional valve 40 Control means

Claims (3)

A regenerator that heats a dilute solution to generate refrigerant vapor and a concentrated solution, a condenser that condenses the refrigerant vapor generated in the regenerator, and a refrigerant liquid and a load fluid condensed in the condenser are heated. The evaporator that exchanges and cools the load fluid, the absorber that absorbs the refrigerant evaporated in the evaporator into the concentrated solution generated in the regenerator and generates the dilute solution, and the absorber that is generated in the absorber A liquid refrigerant proportional valve that is connected to a solution circulation pump that sends a dilute solution to the regenerator to form an absorption refrigeration cycle and that is provided in a refrigerant flow path that connects the condenser and the evaporator to adjust the refrigerant flow rate And an absorption chiller / heater comprising control means for detecting the temperature of the evaporator and controlling the valve opening degree of the liquid refrigerant proportional valve so that the temperature becomes the evaporator target temperature,
The said control means variably sets the said evaporator target temperature according to the preset temperature of the said load fluid, The absorption-type cold / hot water machine characterized by the above-mentioned.   The absorption chiller / heater according to claim 1, wherein the control unit sets the evaporator target temperature to a value lower than a set temperature of the load fluid by a certain temperature. A high temperature regenerator for heating the dilute solution, a separator for separating the dilute solution into refrigerant vapor and an intermediate concentrated solution, a high temperature solution heat exchanger for lowering the temperature by heat exchange of the intermediate concentrated solution with the diluted solution, A low-temperature regenerator that reheats the cooled intermediate concentrated solution with the refrigerant vapor to generate a concentrated solution, a low-temperature solution heat exchanger that cools the concentrated solution with the dilute solution, and cools the refrigerant vapor. A condenser that condenses into a refrigerant and has a liquid refrigerant storage chamber for the liquid refrigerant, and a liquid refrigerant distributor that is connected to the liquid refrigerant storage chamber via a refrigerant flow path. An evaporator for dripping liquid refrigerant to exchange heat between the liquid refrigerant and the load fluid; and dropping the concentrated solution from the low-temperature solution heat exchanger to absorb the refrigerant evaporated by the evaporator to form a diluted solution Absorber to be generated and dilute solution generated by the absorber are sent to the high temperature regenerator A liquid circulation pump, and a liquid refrigerant proportional valve for adjusting a refrigerant flow rate is provided in the refrigerant flow path, and the temperature of the evaporator is detected so that the temperature becomes the evaporator target temperature. An absorption chiller / heater equipped with a control means for controlling the valve opening of the proportional valve,
The said control means variably sets the said evaporator target temperature according to the preset temperature of the said load fluid, The absorption-type cold / hot water machine characterized by the above-mentioned.

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