JPH11211265A - Absorption type refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a higher efficiency than ever despite a freezing load in a double effect oriented absorption type refrigerating machine in which a refrigerant steam generated in a high temperature regenerator is supplied to a low temperature regenerator to condense and the refrigerant liquefied by condensation is supplied to a condenser. SOLUTION: An orifice 71 and a control valve 81 are mounted as pressure regulating means on a piping 7 for supplying a refrigerant liquefied by a low temperature regenerator 12 to a condenser 11. A control circuit 9 is connected to the control valve 81 and the control valve 81 is fully opened during the period to the stabilization of a load from the rising and after the load is stabilized, the travel of the control valve 81 is gradually reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double effect absorption refrigerator in which refrigerant vapor generated in a high-temperature regenerator is supplied to a low-temperature regenerator to be condensed, and refrigerant liquefied by the condensation is supplied to a condenser. It is about.

[0002]

2. Description of the Related Art As shown in FIG. 5, a double effect absorption refrigerator has an upper body comprising a condenser (11) and a low temperature regenerator (12).
(1) Lower trunk (2) consisting of evaporator (21) and absorber (22), high temperature regenerator (3) with built-in burner (31), high temperature heat exchanger
(4) The low-temperature heat exchanger (5) and the like are connected to each other by pipes, and the absorbent is pumped by the absorbent pump (6) into the high-temperature regenerator (3), the low-temperature regenerator (12) and the absorber (22). The refrigeration cycle is realized by circulating between the refrigeration cycles.

In a double effect absorption refrigerator, as shown in FIG. 6, an orifice (7) is provided in a pipe (7) for supplying a refrigerant liquefied in a low temperature regenerator (12) to a condenser (11). 70) is attached, and the refrigerant liquefied by the low-temperature regenerator (12) is decompressed and supplied to the condenser (11). This keeps the inside of the low-temperature regenerator (12) at a low pressure,
The refrigerant vapor generated in (12) is condensed and liquefied in the condenser (11). On the other hand, the refrigerant vapor generated in the high-temperature regenerator (3) is condensed in a heat transfer tube in the low-temperature regenerator (12), liquefied while giving heat of condensation to the absorbing liquid, and becomes a refrigerant liquid to form the above-described orifice After being supplied to the condenser (11) via (70), the refrigerant returns to the evaporator (21) together with the refrigerant liquid liquefied in the condenser (11).

As shown in FIG. 5, a pipe for supplying fuel gas to a burner (31) in a high-temperature regenerator (3) has a gas valve (3).
2) is attached, the temperature of the cold water flowing out of the evaporator (21)
(Cold water outlet temperature Tc_out) to maintain the target value, gas valve (3
The opening of 2) is controlled, and the supply amount of fuel gas is adjusted.

[0005]

By the way, in the double effect type absorption refrigerator, the heat input to the high temperature regenerator (3) generates steam in the high temperature regenerator (3) in accordance with the heat input. Ideally, the low-temperature regenerator (12) generates the same amount of steam by the steam, and the maximum efficiency is obtained at this time. In order to make this ideal state as close as possible, the hole diameter of the orifice (70) is optimized,
It is necessary to apply an appropriate amount of reduced pressure. Here, the optimal value of the pressure reduction amount changes according to the magnitude of the refrigeration load. However, in the conventional double-effect absorption refrigerator, a fixed orifice having a fixed hole diameter is used as the orifice (70), so that the magnitude of the depressurization amount deviates from the optimum value with a change in the refrigeration load. Was supposed to be.

In addition, in the absorption refrigerator, the flow rate of the refrigerant liquid flowing out of the low-temperature regenerator (12) at the time of start-up becomes larger than the flow rate in a stable load state. As the orifice (70), one having a larger hole diameter than the optimum hole diameter has been employed. Therefore,
In the conventional double-effect absorption refrigerator, after startup, the pressure reduction in an operation state in which the refrigeration load is stable becomes insufficient, and there has been a problem that the efficiency is reduced due to this.

[0007] It is an object of the present invention to provide a double effect absorption chiller that can obtain higher efficiency than conventional irrespective of the refrigeration load.

[0008]

An absorption refrigerator according to the present invention comprises a pipe (7) for supplying a refrigerant liquefied by a low-temperature regenerator (12) to a condenser (11). It is characterized in that a pressure adjusting means capable of adjusting the pressure reduction amount while reducing the flowing refrigerant is provided, and the pressure reduction amount is adjusted according to the magnitude of the refrigeration load. As a result, the optimum pressure reduction amount is set regardless of the refrigeration load. As a result, the high temperature regenerator (3) and the low temperature regenerator
In each of (12), a sufficient amount of steam generation corresponding to the amount of heat input to the high-temperature regenerator (3) is obtained, so that higher efficiency than before can be obtained.

Specifically, the pressure adjusting means includes
Orifice (71) attached to (7), and the orifice
A bypass pipe (8) that bypasses (71), a control valve (81) interposed in the middle of the bypass pipe (8), and a control circuit (9) that controls the opening of the control valve (81). Is done. In this specific configuration, the pressure reduction amount of the refrigerant passing through the orifice (71) and the control valve (81) is adjusted by adjusting the opening of the control valve (81).

In a more specific configuration, a high-temperature regenerator (3)
Is controlled so that the chilled water outlet temperature approaches the target value, and the control circuit (9) fully opens the control valve (81) from the time of startup until the load is stabilized, and the load is stabilized. Thereafter, as long as the amount of heat input to the high-temperature regenerator (3) decreases, control for gradually reducing the opening of the control valve (81) is executed.
In the specific configuration, by fully opening the control valve (81) at startup, regardless of the increase in the flow rate of the refrigerant liquid flowing out of the low-temperature regenerator (12), without causing the refrigerant liquid to stay, It can be sent to the condenser (11). Then, by gradually narrowing the opening of the control valve (81) while the load is stable, the pressure reduction amount gradually increases, and the refrigerant saturation temperature in the pipe in the low-temperature regenerator (12) and the solution outside the pipe. Since the difference between the saturation temperatures increases, the amount of steam generated from the low-temperature regenerator (12) increases accordingly. Here, when the amount of heat input to the high-temperature regenerator (3) is controlled so that the chilled water outlet temperature approaches the target value, the amount of heat input decreases. But the control valve
When the opening degree of (81) falls below a certain value, the flow rate of the refrigerant decreases, and conversely, the heat input increases. Therefore, when the heat input changes from a decrease to an increase, the adjustment of the opening of the control valve (81) is stopped. As a result, the optimal opening degree in the load stable state is set, and higher efficiency than before can be obtained.

[0011]

According to the absorption refrigerator of the present invention, higher efficiency can be obtained than before, regardless of the refrigeration load.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. The double-effect absorption refrigerator according to the present invention comprises an upper body (1) comprising a condenser (11) and a low-temperature regenerator (12), as in the conventional absorption refrigerator shown in FIG. Lower body (2) consisting of vessel (21) and absorber (22),
High temperature regenerator (3) with built-in burner (31), high temperature heat exchanger
(4) The low-temperature heat exchanger (5) and the like are connected to each other by pipes, and the absorbent is pumped by the absorbent pump (6) into the high-temperature regenerator (3), the low-temperature regenerator (12) and the absorber (22). The refrigeration cycle is realized by circulating between the refrigeration cycles. Burner (3) in high temperature regenerator (3)
A gas valve (32) is attached to a pipe for supplying a fuel gas to (1), and a gas valve (32) is provided to keep the temperature of the cold water flowing out of the evaporator (21) (the cold water outlet temperature Tc_out) at a target value. 32)
Is controlled, and the supply amount of the fuel gas is adjusted.

FIG. 1 shows a characteristic configuration of an absorption refrigerator according to the present invention, and a pipe (7) for supplying a refrigerant liquefied by a low-temperature regenerator (12) to a condenser (11). Further, an orifice (71) having a smaller hole diameter than the conventional orifice is attached thereto. A bypass pipe (8) bypassing the orifice (71) is connected to the pipe (7), and a control valve (81) is interposed in the middle of the bypass pipe (8). The control circuit (9) is connected to the control valve (81). The control circuit (9) creates an opening degree command A that changes according to the flow rate Q of the fuel gas to be supplied to the high temperature regenerator and supplies it to the control valve (81). Thus, the opening of the control valve (81) is optimally controlled as described later.

FIG. 2 shows the configuration of a control system for the absorption refrigerator main body (10). The outlet temperature Tc_out of the chilled water obtained from the absorption chiller body (10) and its target value (for example, 7 ° C.) are supplied to the PID controller (90), and PID control for bringing the outlet temperature Tc_out of the chilled water closer to the target value is performed. Is executed. Thereby, the PID controller (90)
Outputs a command about the flow rate Q of the fuel gas to be supplied to the high-temperature regenerator. The gas flow rate Q commanded by the PID controller (90) is supplied to the gas valve of the absorption refrigerator main body (10), and the valve opening is controlled. The gas flow rate Q instructed by the PID controller (90) is controlled by a control circuit.
(9), the valve opening A for the control valve (81) is created as described above, and is supplied to the absorption refrigerator main body (10).

FIG. 3 shows a control procedure when the above-mentioned control system is constituted by a microcomputer. First, in step S1, the valve opening A is set to the maximum opening Amax, and in step S2, the PID controller (9
0), PID control of the gas flow rate Q is executed. Then, in step S3, the cooling water outlet temperature Tco_out is
It is determined whether or not the cooling water outlet temperature follows the target value, depending on whether the temperature is within a predetermined temperature range (Tx to Ty) including the target value. If the answer is no,
The PID control of step S2 is continued.

If the answer is affirmative in step S3, the process proceeds to step S4 to determine whether the load has stabilized based on whether the difference between the chilled water outlet temperature Tc_out and the chilled water inlet temperature Tc_in has become constant. If the determination is no, the process returns to step S2 to continue the PID control.

If the answer is affirmative in step S4, the process proceeds to step S5, in which the valve opening A is increased by a predetermined amount Δ
After decreasing by A, it is determined in step S6 whether the gas flow rate Q has decreased. Immediately after the load is stabilized, the opening of the valve is excessively large.Thus, reducing the opening increases the amount of condensation and reduces the gas flow rate.However, if the valve opening falls below the optimal value in the stable load state, the refrigerant flow rate will decrease. As a result, the amount of condensed matter decreases, and the gas flow rate increases.

Therefore, if the answer is YES in step S6, the process returns to step S5, and the valve opening A
Squeeze. Thereafter, when it is determined NO in step S6, the process proceeds to step S7, and the adjustment of the valve opening is stopped. Finally, in step S8, whether or not the load has increased is detected by, for example, a difference in the temperature of the chilled water inlet / outlet. When the load is constant or decreases, the process returns to step S7 to maintain the valve opening at that time. On the other hand, when the load increases, the process returns to step S1, and the above procedure is repeated with the valve opening being maximized.

According to the control procedure shown in FIG. 3, during the period from the start-up to the time when the load is stabilized, the control valve (81) is fully opened and the refrigerant liquid flowing out of the low-temperature regenerator (12) After passing through the control valve (81) and the orifice (71), it is sent to the condenser (11) without stagnation. Then, after that, in a state where the load is stable, the control valve (81) is throttled until the gas flow rate changes from decreasing to increasing, and the optimal pressure reduction amount is set. As a result, higher efficiency than before can be obtained regardless of the load.

FIG. 4 shows the relationship between the refrigeration load at a cooling water temperature of 30 ° C. and the coefficient of performance COP in the absorption chiller according to the present invention (with control) and the conventional absorption chiller (without control). , Which were examined and graphed by experiment. As is clear from this graph, in the absorption refrigerator according to the present invention, a large coefficient of performance COP is obtained regardless of the magnitude of the load.

The configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims. For example, the adjustment of the opening of the control valve (81)
Not limited to the procedure shown in FIG. 3, various controls for optimally adjusting the reduced pressure amount according to the magnitude of the refrigeration load can be employed. Alternatively, both the orifice (71) and the control valve (81) may be attached to the pipe (7), and the bypass pipe (8) may be omitted. Further, if a control valve (81) having a pressure reducing function is adopted, the control valve (81) is attached to the pipe (7), and the bypass pipe is connected.
It is also possible to omit (8) and the orifice (71).

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of a main part of an absorption refrigerator according to the present invention.

FIG. 2 is a block diagram showing a control system of the absorption refrigerator according to the present invention.

FIG. 3 is a flowchart showing a control procedure in the absorption refrigerator according to the present invention.

FIG. 4 is a graph showing a relationship between a refrigeration load and a coefficient of performance.

FIG. 5 is a system diagram showing the entire configuration of a double-effect absorption refrigerator.

FIG. 6 is a system diagram corresponding to FIG. 1 of a conventional absorption refrigerator.

[Explanation of symbols]

 (1) Upper body (11) Condenser (12) Low temperature regenerator (2) Lower body (21) Evaporator (22) Absorber (3) High temperature regenerator (7) Piping (71) Orifice (8) Bypass pipe (81) Control valve (9) Control circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Fujiwara 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Toshihiro Yamada 2-5-2 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd.

Claims (3)

[Claims] The refrigerant vapor generated in the high-temperature regenerator (3) is supplied to the low-temperature regenerator (12) to be condensed, and the refrigerant liquefied by the condensation is supplied to the condenser (11) in a double effect type absorption. In the refrigerator, the refrigerant liquefied by the low-temperature regenerator (12)
The pipe (7) for supplying to the pipe (11) is provided with a pressure adjusting means capable of reducing the pressure of the refrigerant flowing through the pipe and adjusting the reduced pressure, and adjusting the reduced pressure according to the magnitude of the refrigeration load. An absorption refrigerator. 2. The pressure adjusting means includes an orifice (71) attached to the pipe (7), a bypass pipe (8) bypassing the orifice (71), and a pressure adjusting means interposed in the middle of the bypass pipe (8). Control valve (81) and a control circuit for controlling the opening of the control valve (81)
The absorption refrigerator according to claim 1, comprising (9). The amount of heat input to the high-temperature regenerator (3) is controlled so that the chilled water outlet temperature approaches a target value.
(9) is the period from start-up until the load stabilizes,
After the control valve (81) is fully opened and the load is stabilized, control is performed to gradually narrow the opening of the control valve (81) as long as the amount of heat input to the high-temperature regenerator (3) decreases. The absorption refrigerator as described in the above.