JPH01244258A - Absorption refrigerating machine - Google Patents

Abstract

PURPOSE:To allow a stable operation even if the coolant temperature fluctuates by an orifice disposed in a connecting pipe and a refrigerant bypass line having a U-tube, the joint of the refrigerant bypass line being situated higher than the joint of the connecting pipe. CONSTITUTION:During the 'HI' operation where the refrigerant flow rate to the evaporator 7 is high, the refrigerant flow from the liquid refrigerant well 2 to the liquid refrigerant reservoir 3 is regulated by an orifice 10, and so, the refrigerant that cannot enter the liquid refrigerant reservoir 3 flows through a refrigerant bypass line 9 to the evaporator 7. The refrigerant bypass line comprises a U-tube, and, as the pressure of refrigerant in the refrigerant bypass line is balanced across the ends of the U-tube while the pressure in the condenser 1 is higher than that of the evaporator 7, the level of the liquid surface 12 on the side of the condenser 1 is lower than the joint to the evaporator 7 and can change subject to the pressure change in the condenser. For example, when the coolant temperature is high, so is the condenser pressure. Therefore, the liquid level becomes lower to the B position. As the coolant temperature becomes lower, the pressure also becomes lower, and so, the liquid level 12 moves upward to the A position where it is balanced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an absorption refrigerator equipped with a refrigerant proportional valve.

In particular, the present invention relates to an absorption refrigerator that is equipped with a refrigerant bypass circuit and takes into account the control of absorption liquid concentration.

[Conventional technology]

Conventionally, as an absorption refrigerating machine equipped with a refrigerant proportional valve, there is an absorption refrigerating machine that performs three-stage capacity control (high-low switching) described in, for example, Japanese Patent Laid-Open No. 59-170665. In addition, as an example of an absorption refrigerator equipped with a refrigerant proportional valve, as shown in FIG. 2, a refrigerant proportional valve circuit 8 connecting the liquid refrigerant storage chamber 3 and the evaporator 7 via a refrigerant proportional valve 6, and a refrigerant proportional valve circuit 8 connected to the refrigerant proportional valve circuit 2; One is known that includes a refrigerant stop valve circuit that bypasses the upstream and downstream sides of the proportional valve via a refrigerant stop valve 5. In the absorption refrigerator mentioned above,
Further, the condenser 1 and the liquid refrigerant storage chamber 3 are communicated through a pressure equalizing pipe 4.

The refrigerating capacity of an absorption chiller depends on the amount of refrigerant evaporated in the evaporator, but in order to efficiently absorb the evaporated refrigerant vapor into a concentrated absorption solution, it is necessary to adjust the concentration of this concentrated solution to the amount of evaporation. need to be controlled.

Refrigerant R? The storage compartment 3 stores a part of the refrigerant circulating in the absorption refrigerator and controls the amount of refrigerant. a
It functions to control the concentration of the liquid.

In the absorption refrigerator shown in FIG. 3, the refrigerant condensed in the condenser 1 first collects in a liquid refrigerant reservoir 2.

The liquid refrigerant then flows into the evaporator 7 via the liquid refrigerant storage chamber 3 and the refrigerant proportional valve circuit 8. The amount of refrigerant required to flow into the evaporator 7 differs depending on the operating state of the absorption chiller: "high" operation, which produces a high refrigerating capacity, or "low and continuous operation," which produces a low refrigerating capacity.
In the "low" operation, only the refrigerant proportional valve 6 is opened, but in the "high" operation, the refrigerant stop valve 5 is also opened in addition to the refrigerant proportional valve 6, allowing a larger amount of refrigerant to be sent to the evaporator 7 than in the "low" operation. Furthermore, the refrigerant in the liquid refrigerant storage chamber 3 flows into the evaporator 7 via the refrigerant proportional valve circuit 8 due to the pressure difference between the condenser 1 and the evaporator 7. When the water temperature) fluctuates, the pressure in the condenser 1 and the refrigerant temperature in the evaporator 7 (hereinafter referred to as EVA temperature) fluctuate, and the pressure difference between the condenser 1 and the evaporator 7 fluctuates. If the opening degrees of the valve 6 and the refrigerant stop valve 5 are kept the same, the flow rate of refrigerant to the evaporator 7 will vary, and the amount of refrigerant stored in the liquid refrigerant storage chamber 3 will also change, causing operational problems. In addition to instability, there is a risk of freezing of the refrigerant in the evaporator and crystallization of the concentrated solution.

Therefore, when the EVA temperature changes due to fluctuations in the cooling water temperature, the opening degree of the refrigerant proportional valve 6 is changed in proportion to the change in the EVA temperature, thereby increasing the amount of refrigerant flowing into the evaporator 7 and liquid liquid. The liquid level position in the refrigerant storage chamber 3 is controlled to maintain the refrigerating capacity and to prevent freezing of the refrigerant and IA warm solution crystallization.

[Problem that the invention seeks to solve]

In this conventional technology, as shown in line C in Figure 4, when the cooling water temperature drops during "high" operation, the pressure in the condenser drops and the pressure between the condenser 1 and the evaporator 7 decreases. Since the pressure difference becomes smaller, the flow rate of refrigerant flowing through the refrigerant stop valve 5 decreases as shown by the line in FIG. On the other hand, the refrigerant proportional valve 6
When the cooling water temperature decreases and the EVA temperature decreases, E
The valve opening degree is increased as the VA temperature decreases to compensate for the drop in flow in the refrigerant stop valve and the drop in current in the refrigerant proportional valve itself due to the drop in pressure difference between the condenser and the evaporator.

Furthermore, since the liquid level in the liquid refrigerant storage chamber 3 is controlled to be maintained at a required position, the amount of refrigerant flowing through the refrigerant proportional valve 6 increases as the cooling water temperature decreases.

As a result, in the refrigerant circuit as a whole, as the cooling water temperature decreases, the refrigerant is caused to flow so as to reduce the amount of refrigerant in the liquid refrigerant storage chamber 3 in order to lower the concentration of the concentrated solution, and the flow rate shown by the line A in FIG. This characteristic corresponds to fluctuations in cooling water temperature during high-speed operation, and is designed to prevent freezing of the refrigerant and crystallization of concentrated solutions.

On the other hand, if the refrigerant stop valve 5 is closed and only the refrigerant proportional valve 6 is opened to perform "low" operation, if the cooling water temperature fluctuates, the opening degree of the refrigerant proportional valve 6 will be the same as in the case of "high" operation. So, pa low”
During operation, the opening degree is controlled including current correction of the refrigerant stop valve 5, which is not involved in the flow rate of the refrigerant, so the refrigerant flow rate has the characteristics shown in line B in Figure 4, which is ``compared to high-speed operation.'' The refrigerant flow rate fluctuates greatly in response to changes in cooling water temperature, and the liquid level in the liquid refrigerant storage chamber 3 cannot be controlled. 11 Liquid sensitivity cannot be controlled.

If the opening degree of the refrigerant proportional valve 6 is controlled based on the "low" operation, the same problem will occur because the amount of refrigerant flowing through the refrigerant stop valve 5 will be out of the control range during the "high" operation.

As mentioned above, when the cooling water temperature fluctuates, it is difficult to properly manage the refrigerant flow rate and the liquid refrigerant storage chamber liquid level in both "high" operation and "low" operation. When switching from "high" operation to "low" operation, the refrigerant in the liquid refrigerant storage chamber 3 may flow out to the evaporator 7 more than necessary, producing ineffective refrigerant, or from "low" operation. When switching to high-speed operation, the refrigerant is stored in the empty liquid refrigerant storage chamber, which has the disadvantage of compromising the equal partial load characteristic, which takes a long time for the refrigerant to produce its effect.

An object of the present invention is to provide an absorption refrigerator that can operate stably even when the cooling water temperature fluctuates.

[Means for solving problems]

The above-mentioned problem requires a liquid refrigerant reservoir provided at a lower part of a condenser, and a liquid refrigerant storage chamber having a pressure equalization pipe connected to the liquid refrigerant reservoir and communicating with the condenser.

In an absorption refrigerator comprising a refrigerant proportional valve circuit that communicates the liquid refrigerant storage chamber and the evaporator via a refrigerant proportional valve, an orifice provided in a communication pipe connecting the liquid refrigerant reservoir and the liquid refrigerant storage chamber. and a refrigerant bypass circuit including a U-shaped pipe that communicates the liquid refrigerant reservoir with the evaporator, and a connection portion between the refrigerant bypass circuit and the liquid refrigerant reservoir is connected to the communication pipe and the liquid refrigerant reservoir. This is achieved by an absorption refrigerator characterized in that it is provided above the connection part of the.

[Effect]

Fluctuations in the pressure difference between the condenser and evaporator change the liquid level of the refrigerant in the U-shaped tube, so all of the liquid refrigerant that flows into the refrigerant bypass circuit evaporates, regardless of fluctuations in the cooling water temperature. Flow into the vessel.

In addition, since an orifice is provided in the communication pipe through which the refrigerant flows by connecting the liquid refrigerant storage chamber equipped with a pressure equalization pipe between the liquid refrigerant reservoir and the condenser, the size of the orifice and the liquid refrigerant in the refrigerant bypass circuit are determined. By adjusting the connection position to the reservoir, the ratio of the liquid refrigerant inlet plate during "high" operation and "low" operation is adjusted such that the liquid refrigerant flows from the liquid refrigerant storage chamber to the evaporator via the refrigerant proportional valve circuit. By making the ratio of the amount of refrigerant during the "high" operation and the amount of the refrigerant during the "low" operation, the same refrigerant proportional valve can control the refrigerant flow rate during the "high" operation and the "low" operation.

〔Example〕

The present invention will be described in detail with reference to FIG.

In this embodiment, a liquid refrigerant storage chamber 3 is connected to a liquid refrigerant reservoir 2 provided at the lower part of the condenser 1 via a communication pipe 11 provided with an orifice 10. 1 and a pressure equalizing pipe 4 communicating with the refrigerant proportional valve 6.
It communicates with the evaporator 7 via a refrigerant proportional valve circuit 8 having a refrigerant proportional valve circuit 8 . Further, the liquid refrigerant reservoir 2 is communicated with the evaporator 7 by a refrigerant bypass circuit 9 that is a U-shaped tube connected above the position where the communication pipe 11 is connected.

In the case of "high" operation where the refrigerant flow rate to the evaporator 7 is large, the amount of refrigerant flowing from the liquid refrigerant reservoir 2 to the liquid refrigerant storage chamber 3 is restricted by the orifice 10, so that it cannot flow to the liquid refrigerant storage chamber 3. The refrigerant flows to the evaporator 7 via the refrigerant bypass circuit 9. This refrigerant bypass circuit has a U-shaped tube, and the refrigerant in the refrigerant bypass circuit is balanced by the pressure on both sides of the U-shaped tube, and since the pressure in the condenser 1 is higher than the pressure in the evaporator 7, the condenser The liquid level 12 on the first side is located at a lower position than the connection to the evaporator 7, as shown in FIG. 2, and fluctuates according to pressure changes in the condenser. For example, when the cooling water temperature is high, the condenser pressure is also high, so the liquid level will be at a low level biB, and when the cooling water temperature is low, the condenser pressure will also be low, so the liquid level 12 will move to a higher position A and balance. . When the refrigerant enters the refrigerant bypass circuit and the liquid level 12 becomes higher than this balanced liquid level, the refrigerant flows into the evaporator 7 until the liquid level 12 reaches the balanced position. Therefore, the entire amount of refrigerant that overflows from the liquid refrigerant reservoir 2 and flows into the refrigerant bypass circuit flows to the evaporator 7.

On the other hand, the liquid level in the liquid refrigerant reservoir 2 is always at a constant position defined by the connection position of the refrigerant bypass circuit 9 in the "high" operating state where the refrigerant flow rate is large, and the pressure in the refrigerant storage chamber 3 is 4 is the same as condenser 1, so liquid refrigerant reservoir 2
The amount of refrigerant flowing from the liquid refrigerant storage chamber 3 to the liquid refrigerant storage chamber 3 is determined by the difference H□ between the connection position of the communication pipe 11 and the connection position of the refrigerant bypass circuit and the size of the orifice 10, and is constant regardless of changes in condenser pressure. Further, this constant flow rate value is set to a value larger than the refrigerant flow rate during the ``low'' operation.

Therefore, the refrigerant proportional valve 6 always supplies the refrigerant flowing in at a constant rate to the E
As the VA temperature and the pressure difference between the condenser and the evaporator change, the opening is controlled so that the liquid refrigerant flows into the evaporator while keeping the liquid level in the liquid refrigerant storage chamber 3 at a position that maintains the concentration of the concentrated solution appropriately. Ru.

Next, in the case of "low-temperature" operation, the refrigerant flow rate is small and is below the constant flow rate determined by the size of the above-mentioned H□ and the orifice 10.
It flows into the evaporator 7 through the.

As mentioned above, the refrigerant flow rate during "low" operation is lower than the refrigerant flow rate during "high" operation, but the condenser cooling water current is the same during "high" and "low" operation. As a result, even if the cooling water temperature is the same, the condenser pressure is lower during "low" operation than during "high" operation, and the differential pressure between the condenser and evaporator is also smaller. Therefore, when the refrigerant proportional valve 6 is at the same opening degree, the liquid refrigerant storage chamber 3 during "high" operation and "low" continuous operation.
The amount of refrigerant sent to the evaporator 7 due to the pressure difference between the condenser and the evaporation chamber is larger during "high speed" operation than during "low" operation.

The size of the orifice 10 and the height Hl of the connection position of the refrigerant bypass circuit are determined by the pressure difference between the condenser 1 and the evaporator 7, which causes the liquid refrigerant to flow from the liquid refrigerant storage chamber 3 to the evaporator 7 at the same opening degree of the refrigerant proportional valve 6. The ratio of the amount of refrigerant that is sent during "high" and "low" operations and the ratio of the amount of refrigerant that flows from the liquid refrigerant reservoir 2 to the liquid refrigerant storage chamber 3 regardless of the condenser pressure during "high" and "low" operations. are determined to be the same, and the same - of the refrigerant proportional valve 6 is determined to be the same.
Depending on the degree of opening, the refrigerant can flow through the liquid refrigerant storage chamber 3 during high-temperature operation and low-temperature operation. Since the same refrigerant proportional valve is set, the ``high''
The opening degree of the refrigerant proportional valve can be controlled based on the EVA temperature both during operation and during low-temperature operation, making it possible to effectively control the concentration of the concentrated solution.

The height 1 from the bottom of the U-shaped pipe provided in the refrigerant bypass circuit 9 to the connection point to the evaporator 7 is a water column with a pressure at least equal to the maximum differential pressure between the condenser 1 and the evaporator 7. In this embodiment, after the refrigerant proportional valve circuit 8 and the refrigerant bypass circuit 9 are assembled into one,
Although they are connected to the evaporator 7, the effect remains the same even if each is connected to the evaporator 7 individually.

According to this embodiment, even if the cooling water temperature fluctuates, E V
Based on the A temperature, it is possible to control the amount of refrigerant passing through the liquid refrigerant storage chamber in both ``high'' and ``low'' operations, and the concentration of concentrated solution can be controlled by controlling the liquid level in the liquid refrigerant storage chamber. Therefore, even if the cooling water temperature fluctuated, the absorption chiller could be operated stably.

〔Effect of the invention〕

According to the present invention, the liquid refrigerant reservoir and the evaporator are communicated with each other through a refrigerant bypass circuit equipped with a U-shaped tube. It is now possible to supply the evaporator from the reservoir, and since an orifice has been installed in the communication pipe connecting the liquid refrigerant reservoir and the liquid refrigerant storage chamber, the liquid refrigerant can be supplied from the reservoir to the evaporator during high and low power operation. The ratio of the amount of refrigerant flowing into the liquid refrigerant storage chamber can be set to a desired value by the size of the orifice and the height of the refrigerant bypass circuit connected to the liquid refrigerant reservoir. With a single refrigerant proportional valve, it is possible to control the amount of refrigerant flowing from the liquid refrigerant storage chamber to the evaporator in both high and high operation and low operation, and the concentration of concentrated solution can be controlled even when the cooling water temperature fluctuates. This has the effect of preventing freezing of the refrigerant, preventing crystallization of concentrated solutions, reducing the amount of ineffective refrigerant at partial load, and shortening the rise time.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, FIG. 3 is a system diagram showing an example of the prior art, and FIG. It is a graph conceptually showing the relationship between water temperature and pressure difference between a refrigerant flow plate and a condenser-evaporator. DESCRIPTION OF SYMBOLS 1...Condenser, 2...Liquid refrigerant reservoir, 3...Liquid refrigerant storage chamber, 4...Pressure equalization pipe, 6...Refrigerant proportional valve, 7...
- Evaporator, 8... Refrigerant proportional valve circuit, 9... Refrigerant bypass circuit, 10... Orifice, 11... Communication pipe.

Claims (1)

[Claims] 1. A liquid refrigerant reservoir provided at the bottom of the condenser, a liquid refrigerant storage chamber connected to the liquid refrigerant reservoir and having a pressure equalization pipe communicating with the condenser, and the liquid refrigerant storage chamber and an evaporator. and a refrigerant proportional valve circuit that communicates between the liquid refrigerant reservoir and the liquid refrigerant storage chamber through a refrigerant proportional valve, an orifice provided in a communication pipe connecting the liquid refrigerant reservoir and the liquid refrigerant storage chamber; a refrigerant bypass circuit including a U-shaped pipe that communicates with the evaporator, and a connection portion between the refrigerant bypass circuit and the liquid refrigerant reservoir is provided above a connection portion between the communication pipe and the liquid refrigerant reservoir. An absorption refrigerator characterized by: