JPS6138786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an absorption refrigerator that configures a refrigeration cycle using water or alcohol as a refrigerant and a salt solution such as a lithium bromide solution as an absorption solution.

A conventional refrigerator of this kind, for example, as shown in FIG. 1, has an absorber A, a generator G, a condenser C, an evaporator E,
Solution heat exchanger X, solution pump PS, refrigerant pump PM
is provided, and piping 1, 2, 3,
4, 5, a spray pipe 6, an overflow pipe 7, and pipes 8, 9 and a spray pipe 1 as a refrigerant path.
0, piping 11 connects the above-mentioned equipment to form a refrigeration cycle.

12 is a heating tube, and 13 is a heat source heat amount control valve.
The cooling water system includes a cooling water pump 14, piping 1
5, a cooling water pipe 16, a pipe 17, a cooling water pipe 18, and a pipe 19 are provided to cool the absorber A and the condenser C. 20 is a cold water pipe, pipe 2
1 and 22 lead cold water to the evaporator E.

In conventional systems with such a configuration, if the load during operation decreases or the cooling water temperature becomes too low, the refrigerating capacity increases relative to the load amount and becomes unbalanced. In this case, the absorption capacity becomes excessive, and absorption in the absorber A increases, resulting in a decrease in the concentration of the solution.

For example, as shown in FIG. 2, in a refrigeration system whose normal full-load cycle is cycle ABCD, when the load becomes a partial load, the refrigeration system begins to draw a cycle in which the concentration decreases, such as cycle ABCD. As a result, the refrigerant liquid level in the evaporator E decreases, and there is a risk that the refrigerant pump PM will cause cavitation due to insufficient pushing head. We are making adjustments to ensure that.

However, with this conventional method, the refrigerant pump
Because PM is controlled on and off, the flow rate fluctuates significantly, making operation unstable. Moreover, since the range of variation in concentration from full load to low load is large, there is a drawback that responsiveness is poor when the load changes.

In addition, when the cooling water temperature decreases, as shown in Figure 3, cycle ABCD, which is the full load cycle at normal cooling water temperature, shifts to the low concentration region and is operated like cycle ABCD. This caused problems similar to those caused when the load decreased as described above, and caused problems in driving.

In addition, in the conventional type, the refrigerant pump PM is always operated, and depending on the drop in the refrigerant level in the evaporator E, the valve of the outlet pipe of the refrigerant pump PM is throttled, or a bypass is provided on the outlet side. Although there are some systems in which a portion of the flow escapes as a bypass flow, all of them always consume a certain amount of power during operation, and some of them are accompanied by wasteful power consumption.

The present invention eliminates the above-mentioned drawbacks of the conventional method by detecting pushing head fluctuation factors and controlling the rotational speed of the refrigerant pump. It enables continuous operation, prevents cavitation, and ensures stable operation, and can quickly respond to changes in load and cooling temperature.Moreover, it reduces the pump power depending on the operating condition to maintain stable operation. The purpose of this invention is to provide an absorption refrigerator that can prevent wasteful consumption of.

The present invention provides absorbers, generators, condensers, evaporators,
In an absorption refrigerator that includes a solution heat exchanger, a solution pump, a refrigerant pump, and a solution path and a refrigerant path connecting these to form a refrigeration cycle, detecting fluctuations in the pushing head of the refrigerant pump. and a refrigerant pump control mechanism that controls the rotational speed of the refrigerant pump and adjusts the refrigerant flow rate in response to a signal from the push-in head detection mechanism. It is an absorption refrigerator.

The present invention will be explained with reference to the drawings according to an embodiment. FIG. 4 shows the vicinity of the absorber A and the evaporator E;
As a pushing head varying element, a float 41 for detecting the height of the refrigerant liquid level in the evaporator E is provided as a pushing head detection mechanism. float 4
A control mechanism 42 is provided that receives a signal from the movement of the refrigerant pump PM and controls the rotation speed of the refrigerant pump PM.
The rotation speed of the refrigerant pump PM is controlled by controlling the rotation speed of the drive motor, controlling the gear ratio by a speed change mechanism in the power transmission mechanism between the drive motor and the refrigerant pump PM, and the like. When the refrigerant liquid level becomes low, the rotation speed of the refrigerant pump PM is reduced.

When the load decreases or the cooling water temperature decreases during operation, the absorption capacity becomes relatively excessive due to the imbalance between the load amount and the refrigeration capacity, the concentration of the absorption solution decreases, and the refrigerant in the evaporator E The liquid level falls. When the refrigerant liquid level becomes lower than a predetermined height, the float 41 detects this, and the control mechanism 42 is operated to reduce the rotation speed of the refrigerant pump PM. As a result, when the spray flow rate is reduced, the amount of refrigerant sprinkled onto the cold water pipe 20 is reduced, and the amount of evaporation is suppressed, thereby preventing the concentration of the solution from decreasing excessively and ensuring the refrigerant liquid level in the evaporator E. By providing the necessary pushing head, it is possible to perform continuous operation and stable operation without causing cavitation of the refrigerant pump PM.

The rotation speed control of the refrigerant pump PM may be continuous or stepwise.

The cycle diagram in this case is cycle a′b′c′d′ in FIG. 2 or 3, and the concentration is higher than cycle abcd in the conventional method. Since the refrigerant liquid level in E is secured and the range of change in concentration with respect to the full load cycle is reduced, it exhibits good responsiveness to changes in load or cooling water temperature.

For example, when the load increases from a partial load state, the cold water temperature rises, and the heat source heat amount control valve 13 is operated by a control mechanism (not shown) to increase the heating amount in the generator G.

As a result, the amount of refrigerant vapor generated increases, the amount of refrigerant liquid returning to the evaporator E also increases, the refrigerant liquid level rises, and the spray flow rate increases due to the signal from the float 41.
The amount of evaporation of the refrigerant increases, the absorption capacity in the absorber A increases, the solution concentration decreases, and the refrigerating capacity can respond to changes in load conditions in a short time.

As the pushing head variation factor for estimating the pushing head variation, as in the example above, the most direct way is to measure the refrigerant liquid level in the evaporator E, but in addition, the cooling of the absorber A and the condenser C Fluid temperature around the water system (e.g., cooling water temperature in the cooling water system, solution temperature in absorber A, refrigerant temperature in condenser C, etc.), values indicating the refrigerating load in the chilled water system (e.g., chilled water It is also possible to capture factors related to the change in concentration of the solution, such as the outlet temperature difference, the amount of refrigeration load calculated by a calorimeter, etc.), the pressure and solution temperature in the generator G, and the solution concentration in the solution path.

Alternatively, two or more of these detected values may be combined to perform a calculation, and the calculated value may be captured to generate a signal.

For example, when controlling the rotation speed of a pump, the rotation speed of not only the refrigerant pump PM but also the solution pump PS is often controlled at the same time. In this case, the rotation speed of the solution pump PS is controlled using a chilled water load signal or the like, and the rotation speed of the refrigerant pump PM is also controlled using the same signal. When the control system is configured in this manner, when the refrigerant liquid level drops to a predetermined level, the rotational speed of the refrigerant pump PM is maintained at a predetermined low rotational speed regardless of the control signal. That is, in the above example, the signal for controlling the rotation speed of the refrigerant pump PM is a combination of the chilled water load equivalent signal and the refrigerant liquid level signal.

In FIG. 5, the temperature of the cooling water is detected by the temperature detector 43, and the refrigerant pump is controlled by the operation of the control mechanism 42.
An example of controlling the speed of PM will be shown. Absorber A using temperature sensor 44 instead of temperature sensor 43
The temperature of the solution inside the container may also be detected. When the cooling water temperature decreases, the solution temperature decreases, the absorption capacity increases, the solution concentration decreases, and the refrigerant liquid level in the generator E decreases.

Therefore, in this embodiment, when the cooling water temperature or solution temperature falls below a set value, the speed of the refrigerant pump PM is controlled to be reduced.

In the above embodiment, reducing the rotational speed of the refrigerant pump PM when the pushing head decreases reduces the required NPSH, which is also effective in preventing cavitation. Coupled with the recovery of the pushing head obtained by the reduction, effective cavitation prevention is achieved. Furthermore, since the flow rate is controlled by controlling the rotational speed of the refrigerant pump PM, unnecessary power consumption can be prevented.

The present invention provides absorbers, generators, condensers, evaporators,
In an absorption refrigerator that includes a solution heat exchanger, a solution pump, a refrigerant pump, and a solution path and a refrigerant path connecting these to form a refrigeration cycle, detecting fluctuations in the pushing head of the refrigerant pump. A push-in head detection mechanism detects the push-in head by the push-in head detection mechanism, and a refrigerant pump control mechanism receives the signal from the push-in head detection mechanism to control the rotation speed of the refrigerant pump to adjust the refrigerant flow rate. Even if there are fluctuations in the cooling water temperature, the refrigerant level in the evaporator is maintained,
In addition, the required NPSH decreases in response to a decrease in rotational speed, preventing cavitation and ensuring stable continuous operation of the refrigerant pump.It also has excellent responsiveness to fluctuations, and even when the cooling load is reduced. It is possible to provide an absorption refrigerator that prevents wasteful power consumption when driving a refrigerant pump,
This has an extremely large effect in terms of practical use and energy saving.

[Brief explanation of the drawing]

Figure 1 is a flow diagram of the conventional example, Figures 2 and 3 are comparison diagrams of solution cycles between the conventional example and the embodiment of the present invention, and Figures 4 and 5 are different embodiments of the present invention. FIG. 2 is a flow diagram of the vicinity of the absorber and evaporator. A...absorber, G...generator, C...condenser,
E...Evaporator, X...Solution heat exchanger, PS...Solution pump, PM...Refrigerant pump. 1...Piping, 2
...Piping, 3...Piping, 4...Piping, 5...Piping, 6...Spray pipe, 7...Overflow pipe, 8...Piping, 9...Piping, 10...Spray pipe, 11... Piping, 12...Heating pipe, 13...Heat source heat amount control valve, 14...Cooling water pump, 15...
Piping, 16... Cooling water pipe, 17... Piping, 18...
...Cooling water pipe, 19...Piping, 20...Cold water pipe, 2
1...Piping, 22...Piping, 41...Float,
42...Control mechanism, 43, 44...Temperature detector.

Claims (1)

[Claims] 1. An absorption refrigerating machine comprising an absorber, a generator, a condenser, an evaporator, a solution heat exchanger, a solution pump, a refrigerant pump, and a solution path and a refrigerant path connecting these to form a refrigeration cycle. a push-in head detection mechanism that detects fluctuations in the push-in head of the refrigerant pump by detecting push-fluctuation elements; and a push-in head detection mechanism that controls the rotational speed of the refrigerant pump in response to a signal from the push-in head detection mechanism. An absorption refrigerator characterized by being equipped with a refrigerant pump control mechanism that adjusts the flow rate of refrigerant. 2. The absorption refrigerating machine according to claim 1, wherein the detection of the pushing head variation element is the detection of a refrigerant liquid level in the evaporator. 3. The absorption refrigerating machine according to claim 1, wherein the detection of the pushing head variation element is the detection of fluid temperature around a cooling water system path of the absorber and condenser. 4. The absorption refrigerator according to claim 3, wherein the fluid around the cooling water system path is cooling water in the cooling water system path. 5. The absorption refrigerator according to claim 3, wherein the fluid around the cooling water system path is a solution in the absorber. 6. The absorption refrigerator according to claim 3, wherein the fluid around the cooling water system path is a refrigerant in the condenser. 7. The absorption refrigerating machine according to claim 1, wherein the detection of the pushing head variation element is the detection of a refrigerating load amount of a chilled water system line combined with the evaporator. 8. The absorption refrigerating machine according to claim 7, wherein the detection of the refrigeration load amount is performed by detecting the cold water outlet temperature of the cold water system path. 9. Detection of the pushing head variation element includes detection of a refrigerant liquid level in the evaporator, detection of fluid temperature around a cooling water system path of the absorber and condenser, or detection of a cooling water system path combined with the evaporator. At least two of the detections of the refrigeration load amount are performed,
2. The absorption refrigerator according to claim 1, wherein the detection is performed using a calculated value obtained by calculating these detected values using a predetermined method.