JPS63129263A - Cooling water controller for absorption refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an improvement in a control device for a cooling tower in an absorption refrigerator having a cooling tower in a cooling water pipe system.

(b) Conventional technology In general, as a cooling water control device in a conventional absorption refrigerator, that is, a cooling tower control device,
There was one as described in the -26136 publication.

What is described in this publication is an absorption refrigerator in which a refrigeration cycle is composed of a generator, a condenser, an evaporator, an absorber, etc., and a cooling tower is provided in the cooling water pipe system of the condenser and absorber. When the temperature of the cooling water dropped below a predetermined value, the operation of the blower in the cooling tower was stopped to prevent an abnormal drop in the temperature of the cooling water.

In other words, it is generally known that when the cooling water temperature drops excessively due to a drop in outside temperature, etc., the temperature of the dilute liquid, which absorbs refrigerant vapor from the evaporator and reduces its concentration while flowing down the absorber, also decreases. In the above device, when this diluted liquid exchanges heat with the concentrated liquid in the heat exchanger, it is necessary to prevent the concentrated liquid from being cooled and precipitating crystals, which would seriously impede the operation of the absorption refrigerator. It was.

(c) Problems to be Solved by the Invention In the conventional control device as described above, when the temperature of the cooling water at which the operation of the blower in the cooling tower stops is t-α℃, the temperature at which the operation of the blower is resumed is was set in toC. (Also, α is the differential width to prevent chattering between the operation and stop of the blower.) With such a control device, when the absorption chiller is operating under a normal cooling load, the temperature of the cooling water will be the same as that of the blower. By operating or stopping the cooling water, the temperature is approximately controlled within t-α°C≦cooling water temperature≦t°C.

However, when the cooling load decreases due to a drop in the outside temperature, etc., the rate of change in temperature of the cooling water becomes faster due to operation or stoppage of the blower, causing a delay in the response of the control device and increasing overshoot.

If the range of temperature change due to this overshoot is 4°C, the temperature of the cooling water is t-α-β°C≦Temperature of the cooling water≦t
+β°C. If this overshoot is large, the minimum temperature of the cooling water decreases, and at this minimum temperature, the refrigerant may freeze or the absorption liquid may crystallize, so failures of the absorption refrigerator cannot be sufficiently prevented.

In view of such problems, the present invention provides a control device that can reliably prevent an excessive drop in cooling water temperature.

(d) Means for solving the problem The present invention has a cooling tower in the cooling water pipe system of the generator, water-cooled condenser, evaporator, absorber, and condenser, and when the temperature of the cooling water in the condenser is high. In an absorption refrigerator equipped with a control device that controls the cooling tower blower motor to operate the cooling tower blower motor when the outside air temperature is low, and also to stop the blower operation when the cooling water temperature is low, In some cases, a mechanism is provided to reduce the temperature range between the operation of the blower motor and the time when the blower stops.

(E) Function In the cooling water control device for an absorption chiller of the present invention configured as described above, the differential width between the operation of the cooling tower blower motor and the stop of air blowing, which can be controlled by the temperature of the cooling water, is determined based on the outside air temperature. It is something that can be changed.

(F) Embodiment FIG. 1 is a schematic structural diagram showing an embodiment of this type of absorption refrigerator according to the present invention. In the figure, 1 is a high temperature generator, 2 is a generation condenser consisting of a low temperature generator 3 and a water-cooled condenser 4, 5 is an evaporative absorber consisting of an evaporator 6 and an absorber 7, and 8 and 9 are low and high temperatures, respectively. Solution heat exchanger, P
, PLA is a pump for dilute solution, 10 is a gas-liquid separator, and these devices include a liquid lift pipe 11, pipes 12 and 13 through which an intermediate concentration solution (hereinafter referred to as intermediate solution) flows,
Concentrated solution flows through tubes 15, 16, diluted solution flows through tube 17.
1B, 19, 20. A refrigerant flow pipe 21, a refrigerant liquid flow pipe 22, and a refrigerant liquid return pipe 23 and 24 are connected to form a circulation path for the refrigerant [water] and the solution [lithium bromide aqueous solution].

B is the burner of the high temperature generator 1, 25 is the heater of the low temperature generator 3, 26 is the cooler of the condenser 4, 27 is the heat exchanger of the evaporator 6, 28 is the cooler of the absorber 7, 29 .30 is a pipe line for cold water (hot water) that connects to the heat exchanger 27 and takes out cold and hot water.

In addition, the cooler 2 is connected to the cooling water pipes 31, 32, 33, and 34.
B, 26, the cooling tower 35, and the cooling water circulation pump Pc are connected in series to form a cooling water pipe system.

36 is an overflow pipe connecting the gas-liquid separator 10 and the low temperature generator 3, and a pole float type,
A trap T, such as a packet type, in which the valve part is opened by the inflow of intermediate solution and closed by the inflow of refrigerant vapor.
It is equipped with Further, 37 is a cold temperature switching valve V that connects the gas-liquid separator 10 and the evaporative absorber 5. It is a tube with an H.

SL is a liquid level detector provided in the liquid reservoir 38 of the evaporator 6, and a refrigerant liquid pump P is activated based on a signal from this detector.

The start and stop of the is now controlled.

S, , S are a cooling water temperature detector and an outside air temperature detector, which are respectively installed on the cooling water pipe 31 and the absorption side of the blower 39 of the cooling tower 35 (any position is sufficient as long as the outside air temperature can be detected). It is being

40 is a cooling water control device, which includes a cooling water temperature detector Sw,
Outside temperature sensor S. Based on the temperature detected by 1 wind loss 3
This controls the operation of the motor 41 for 9.

The main part of this control device 40 is constituted by an electric circuit shown in FIG. In FIG. 2, 43 is a resistor, which is connected to a constant voltage circuit 46 in series with a temperature detector Sw (for example, a thermistor). 42, 44.45 are resistors connected in series to the constant voltage circuit 46, 47 is a comparator whose non-inverting input terminal is connected to the connection point between the resistor 42 and the resistor 44, and the resistors 42, 44.45 are connected to this terminal. A reference voltage determined by 45 is applied. Further, the inverting input terminal is connected to the connection point between the resistor 43 and the temperature detector Sw.

Therefore, a reference voltage corresponding to the set temperature and a voltage corresponding to the temperature that can be detected by the temperature detector Sw are applied to the comparator 47. 49.50 is a positive feedback resistor connected in series.

48 is energized (L) when the output of the comparator 47 is an H level voltage.
This is a relay that can be cut off when the voltage is at level level, and has a normally open contact piece 51. 52 is an outside air temperature detector S. (The contact opens when the temperature is below 24°C, and closes again when the temperature rises above 25°C.) It is a relay whose energization is controlled through a normally open contact piece 53 and a normally open contact piece 54. have.

This normally open contact piece 53 is connected in parallel with the resistor 45, and the normally open contact piece 54 is connected in parallel with the positive feedback resistor 50.

Note that 55 is a relay whose energization is controlled by a normally open contact piece 51, and the operation of the motor for the blower 39 can be controlled by the normally open contact piece of this relay.

First, the outside air temperature is high, so the outside air temperature detector S is used. When the contacts are closed and the relay 52 is energized, i.e. when the normally open contact 53 is closed and the normally open contact 54 is closed, the reference applied to the non-inverting input terminal of the comparator 47 Voltage is resistance 4
It is determined by 2.44. The temperature corresponding to this reference voltage is to
Let it be oC. At this time, the temperature range corresponding to the feedback current determined based on the feedback resistor 49 is α. 'C (differential). Since a negative characteristic thermistor is used for the temperature detector Sw, the resistance value increases as the temperature of the cooling water decreases.

That is, the voltage applied to the inverting input terminal of comparator 47 is increased. Therefore, the temperature t of the cooling water is "t2=tO℃"
At this time, the voltage applied to the inverting input terminal is lower than the reference voltage applied to the non-inverting input terminal, so the output of the comparator 47 is an H level voltage. With this output, feedback is applied to the non-inverting input terminal via a resistor 49, and the voltage applied to the inverting input terminal must be equal to or higher than the voltage calculated by the reference voltage + feedback current applied to the non-inverting input terminal. This is a state in which the output of the comparator 47 is not inverted to an L level voltage. In other words, if the temperature t of the cooling water does not satisfy "t≦t0-α..C", the relay 48 voltage will not be fed back to the non-inverting input terminal, so the voltage applied to the non-inverting input terminal will be the reference voltage. Only. In other words, the cooling water temperature t is “t≧
t. The output of the comparator 47 is maintained at the L level voltage until the voltage rises to ``.''.

Therefore, the temperature t of the cooling water of the motor 41 is t≦t. −α. When temperature t reaches t0, operation is resumed.

Next, the outside temperature is low, so the outside temperature detector S. When the contact is open and the relay 52 is de-energized, that is, when the normally open contact piece 53 is open and the normally open contact piece 54 is open, a voltage is applied to the non-inverting input terminal of the comparator 47. The reference voltage that can be traced is the resistors 42 and 44.

It is determined by 45. The temperature corresponding to this reference voltage is t. -t
It becomes l'c. (The reference voltage is higher than when the normally closed contact piece 53 is closed. The operating temperature is lowered accordingly.) At this time, the temperature range corresponding to the feedback current determined based on the feedback resistor 49.50 is α. -α8°C (As the feedback resistance value increases, the feedback current decreases, and the temperature range also becomes smaller.) Therefore, just as the outside temperature is Fife and JR, the motor 41 has a cooling water temperature t of “t≦to t+”. (α0
-α, )゛, it becomes stopped and the temperature t becomes “t
When the temperature reaches ≧t o t I”C”, operation is restarted.

In addition, in the above example, t0ki 29°C, tot s
Ru.

When an absorption refrigerator is operated using the cold/hot water control device configured as described above, the temperature change of the cooling water is as shown in FIG. 4. When the outside air temperature is high, the cooling load is generally large and the rate of change in temperature of the cooling water due to switching between operation and stop of the motor 41 for the blower 39 is small, so the delay in response of the cooling water temperature due to control of the blower 41 is also small. This also reduces the overshoot of the cooling water temperature. Therefore, the cooling water temperature t is controlled within the range of approximately 25.6<t<29.4.

On the other hand, when the outside air temperature is low, the cooling load is generally small and the rate of change in the temperature of the cooling water due to the initial operation and stopping of the motor 41 for the blower 39 becomes large, so the response of the cooling water temperature due to the control of the blower 41 may vary. Temperature changes due to this increase will also increase. Therefore, the overshoot of the cooling water temperature increases, but the temperature of the cooling water at which the motor 41 for the wind blowing loss 39 stops is increased accordingly, and the temperature of the cooling water at which the operation of the motor 41 resumes is lowered. This overshoot prevents the cooling water temperature from fluctuating greatly, and in this way, as shown in FIG.
It can be controlled within the range of 29.4.

In this way, when the outside air temperature is low, the overshoot of the cooling water temperature to the positive side is prevented by lowering the temperature at which the motor 41 resumes operation, and the overshoot of the cooling water temperature to the negative side is prevented by lowering the temperature at which the motor 41 restarts. This is prevented by increasing the temperature at which the operation of 41 stops.

Therefore, the minimum temperature of the cooling water does not drop excessively during low loads, and failures of the absorption refrigerator due to freezing of the refrigerant, crystallization of the absorption liquid, etc. can be prevented.

(g) Effects of the invention As described above, the present invention has a cooling tower in the cooling water pipe system of the generator, water-cooled condenser, evaporator, absorber, and condenser, and when the cooling water temperature of the condenser is high. In an absorption chiller equipped with a cooling water control device that controls the cooling tower blower motor to operate the cooling tower blower motor when the cooling water temperature is low and to stop the blower operation when the cooling water temperature is low, this control device has a control device that controls the outside air temperature. The system is equipped with a mechanism that reduces the temperature range between operating the blower motor and stopping the blower when the temperature is low. Even when overshoot occurs, the temperature range between when the blower motor operates and when the blower stops is made small to compensate for this overshoot, making the range of fluctuation in the cooling water temperature almost the same as the range of fluctuation when the outside air temperature is high. be able to.

That is, when the outside air temperature is low, it is possible to prevent the temperature of the cooling water from dropping excessively, and to prevent malfunctions of the absorption refrigerator due to freezing of the refrigerant, crystallization of the absorption liquid, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an absorption refrigerator using an embodiment of the cooling water control device of the present invention, FIG. 2 is an electrical circuit diagram of the main part of the cooling water control device shown in FIG. 1, and FIG. 2 is an explanatory diagram showing the operation of the circuit shown in FIG. 2, and FIG. 4 is an explanatory diagram showing the temperature change of cooling water when the control device shown in FIG. 2 is used. 1... Generator, 4... Water-cooled condenser, 6.
... Evaporator, 7. Absorber, 35. Cooling tower, 39. Blower, 40. Cooling water control device, 41. Motor.

Claims (1)

[Claims] (1) A cooling tower is provided in the cooling water pipe system of the generator, water-cooled condenser, evaporator, absorber, and condenser, and when the cooling water temperature of the condenser is high, the blower of the cooling tower is operated, and the cooling water In an absorption chiller equipped with a cooling water control device that controls the blower motor of the cooling tower to stop blowing operation when the outside temperature is low, this control device has a control device that controls the temperature at which the blower motor starts operating when the outside temperature is low. A cooling water control device for an absorption chiller, characterized in that a mechanism is provided to reduce the temperature range between the temperature and the blowing stop temperature.