JPH01107057A - Method and device for controlling screw type air conditioner - Google Patents

Abstract

PURPOSE: To lower power consumption by controlling the opening or closing a solenoid valve inserted into an economizer cycle based on a difference of changing rate in the water temperature of a water side heat exchanger in teams of time to prevent uselessly excessive cooling or heating. CONSTITUTION: In the cooling operation, when the temperature gradient of cold water in terms of time is small, a solenoid valve 6 inserted into an economizer cycle is turned OFF. As a result, the economizer cycle is released to reduce the capacity corresponding to the effect attributed to the economizer 5, which reverses the balance with a load and the temperature of the cold water gradually rises. In this manner, the operation with the economizer cycle released is continued until the temperature of the cold water reaches an ON point of a temperature adjuster. Then, as the temperature adjuster is turned ON, the solenoid valve 6 is turned ON to form the economizer cycle again. In the starting of the cooling operation when the temperature gradient of the cold water in terms of time is small, this cycle is activated by turning ON the solenoid valve 6 thereby accomplishing an operation with a shortened pulldown time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for controlling a screw air conditioner equipped with an economizer cycle.

[Conventional technology]

The opening or closing control of the economizer cycle in conventional screw type air conditioners is independent of the water temperature change rate, and the economizer cycle is utilized during full load operation of the refrigeration cycle.

[Problem that the invention seeks to solve]

In the above conventional technology, the water temperature is 0N101i'F of the temperature controller.
If the water temperature is within the temperature range, the economizer cycle will continue to operate until the OFF point.For example, if it is an air conditioner, continuing to operate until the water temperature is low will result in inefficiency and wasteful operation due to excessive cooling, and the screw Since gas is injected into the compressor during the compression process, it has the disadvantage of increasing power consumption.

Furthermore, in the above-mentioned conventional technology, no consideration is given to shortening the pull-down time by increasing the capacity when pulling down the water temperature at the start of operation, and the pull-down time is long, and the water does not cool down quickly (during cooling) and does not warm up quickly. There was also a problem (during heating).

The purpose of the present invention is to prevent unnecessary overcooling or overheating in a screw type air conditioner, reduce power consumption, perform efficient operation, and shorten the pull-down time at the start of operation. The object of the present invention is to provide a control method and a control device that enable efficient operation.

[Means for solving problems]

The above purpose is to control ON/OFF of the economizer cycle based on the temperature gradient of water temperature over time when the water temperature is within the ON/OFF temperature range of the temperature controller, and also to control the ON/OFF of the economizer cycle based on the temperature gradient of water temperature over time, and This is achieved by controlling ON/OFF of the economizer cycle by the gradient.

In other words, in the case of cooling operation, when the tendency of chilled water temperature to decrease is slower than the tendency of temperature change to be controlled, the economizer cycle is turned off even if the OFF point has not been reached. When the downward trend is slower than the controlled temperature change trend, turn on the economizer cycle.
Rather than turning on/off the economizer cycle
The above objective is achieved by introducing "temporal change rate of water temperature" into the determination element of F control.

As a specific configuration for practically applying the above-mentioned process, the method for controlling a screw type air conditioner according to the present invention includes:
A screw compressor, an air side heat exchanger, a pressure reducing device,
In a refrigeration cycle that includes a water side heat exchanger and piping that connects these devices, and has an economizer cycle that injects gas into the compression process section between the rotors of the screw compressor, an electromagnetic The valve is characterized in that opening and closing of the valve is controlled based on the magnitude of the rate of change of the water temperature of the water side heat exchanger with respect to the time axis.

Further, the control device of the present invention created to carry out the above-mentioned method of the invention includes: (a) a means for detecting the water temperature of the water side heat exchanger, and Φ) a solenoid valve in the middle of the economizer cycle. (c) providing an automatic calculator for calculating the temporal rate of change in the output signal value of the water temperature detection means; and (d) determining the magnitude of the rate of change in water temperature calculated by the automatic calculator. The present invention is characterized in that an automatic control means for controlling opening and closing of the electromagnetic valve based on the following is provided.

[Effect]

In carrying out the invention using the above device, the economizer cycle is turned on and off by turning on and off a solenoid valve inserted into the cycle. for example,
When the temperature gradient of cold water over time is small during cooling operation, the economizer cycle is canceled by turning off the solenoid valve, and the capacity is reduced by the economizer effect.
The balance with the load is reversed, the chilled water temperature gradually rises,
The economizer cycle release operation continues until the temperature controller reaches the 08 point. When the temperature controller reaches point 08, the solenoid valve is turned on and the economizer cycle is again formed. Thereafter, the above operation is repeated depending on the temperature gradient. Here, when the temperature gradient is large, the above-mentioned control is not performed because the ON/OFF frequency of the solenoid valve etc. is not increased.

In addition, when the temperature gradient of cold water over time is small when starting cooling operation, by turning on the solenoid valve, the economizer cycle is utilized, and the capacity increases only by the economizer effect, then rapidly decreases, and the pull-down time This results in a shorter driving time. Here again, when the temperature gradient is large, the above-mentioned control is not performed because the ON/OFF frequency of solenoid valves etc. is not increased.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Note that although the explanation will be given using a cooling operation as an example, the same applies to a heating operation. FIG. 1 is a diagram of a refrigeration cycle having an economizer cycle, in which high-pressure gas refrigerant discharged from a screw compressor 1 passes through a four-way valve 2, is condensed and liquefied in an air-side heat exchanger 3, passes through a blocking valve 4, After passing the command to the economizer 5', the cycle is branched into a main refrigeration cycle and an economizer cycle. In the main refrigeration cycle, the supercooled refrigerant passes through the pressure reducing device 8 to become a low-pressure refrigerant, is led to the water-side heat exchanger 9, and exhibits the required cooling effect in the process of gasifying the saturated liquid refrigerant. The low-pressure gas refrigerant leaving the water-side heat exchanger 9 passes through the four-way valve 2 and the accumulator 10, is sucked into the screw compressor 1, and repeats the same cycle again.

In addition, the economizer cycle is branched into multiple branches from the main refrigeration cycle immediately before the pressure reducing device 8, and is led to the compression process of the screw compressor 1 via the solenoid valve 6, capillary tube 7, and economizer 5, and turns on/off the economizer cycle. OFF
is determined by ON/OFF of the solenoid valve 6. FIG. 2 is a Mollier diagram. The solid line shows the state when the economizer cycle is OFF'F, and the broken line shows the state when the economizer cycle is ON. As you can see, the power consumption Wi K when the economizer cycle is ON is
The power consumption is large compared to when the economizer cycle is in the OFF state.

Figure 3 shows the O of the economizer cycle in this example.
It shows an N/OFF state diagram.

In other words, when the chilled water temperature is within the ON/OFF temperature range of the chilled water temperature regulator, the solenoid valve 6 of the economizer cycle is turned OFF when the amount of decrease in water temperature after a certain period of time is small.
L. The economizer cycle is shut off to prevent unnecessary operation due to overcooling, and to achieve highly efficient operation and operation with low power consumption. On the other hand, when the amount of decrease in water temperature after a certain period of time is large, the ON/OFF frequency of solenoid valve 6 etc. is not increased, so the economizer cycle remains active (solenoid valve 6 is turned ON/OFF).
Leave it as N).

According to this embodiment, in the screw type air conditioner,
This prevents unnecessary overcooling and overheating, resulting in highly efficient and power-saving operation.

Next, with reference to FIG. 1, as well as FIGS. 4 and 5, the functions and effects at the start of cooling operation will be described.

FIG. 4 is a Mollier diagram.

The solid line shows the state when the economizer cycle is OFF, and the broken line shows the state when the economizer cycle is ON.

As you can see, the cooling capacity QeB when the economizer cycle is ON is 0F when the economizer cycle is ON.
The cooling capacity is larger than that in the II' state.

No. 58 shows an ON/OFF state diagram of the economizer cycle depending on the water temperature change rate at the start of operation in this embodiment. In other words, the solenoid valve 6 of the economizer cycle is turned ON when the amount of decrease in water temperature after a certain period of time from the start of chilled water temperature operation is small, and the economizer cycle is utilized to shorten the water temperature pull-down time at the start of operation and achieve highly efficient operation. conduct. On the other hand, when the water temperature decreases significantly after a certain period of time from the start of operation, the economizer cycle remains shut off (the solenoid valve 6 remains OFF'OFF) in order not to increase the ON10FF frequency of the solenoid valve 6, etc. In the embodiment, since the water temperature pull-down time at the start of operation can be shortened, there is an effect of highly efficient operation.

〔Effect of the invention〕

As detailed above, when the control method of the present invention is applied to a screw type air conditioner, it has the excellent practical effect of preventing unnecessary overcooling or overheating, and shortening the pull-down time at the start of operation. play.

[Brief explanation of the drawing]

Fig. 1 shows a refrigeration cycle diagram with an economizer cycle, Fig. 2 shows a Mollier diagram, and Fig. 3 shows a water temperature change state diagram (chilled water change) when the economizer cycle is turned on/off according to the water temperature change rate of the present invention. This is a diagram. Figure 4 is a Mollier diagram for explaining the effects and effects at the beginning of cooling operation, and Figure 5 is a chart showing a water temperature change state diagram (chilled water change) when the economizer cycle is turned on/off depending on the water temperature change rate. be. 1...Screw compressor 2...Four-way valve 3.
... Air side heat exchanger 4 ... Blocking valve 5 ... Economizer 6 ... Solenoid valve 7 ... Capillary tube 8 ... Pressure reducing device 9 ... Water side heat exchanger
1o...accumulator.

Claims (1)

[Claims] 1. A screw compressor, an air-side heat exchanger, a pressure reducing device, a water-side heat exchanger, and piping connecting these devices, and a rotor intermediate of the screw compressor. In a refrigeration cycle having an economizer cycle that injects gas into a compression process section, a solenoid valve inserted in the economizer cycle is controlled to open and close based on the magnitude of a rate of change in water temperature of the water side heat exchanger with respect to a time axis. A control method for a screw type air conditioner, characterized by: 2.Equipped with a screw compressor, an air side heat exchanger, a pressure reducing device, a water side heat exchanger, and piping connecting these devices, and a gas is supplied to the compression process section between the rotor of the screw compressor. In a refrigeration cycle having an economizer cycle for injection, (a) a means for detecting the water temperature of the water side heat exchanger is provided, (b) a solenoid valve is interposed and connected in the middle of the economizer cycle, and (c) an automatic calculator for calculating a temporal rate of change in the output signal value of the water temperature detection means, and (d) opening/closing control of the solenoid valve based on the magnitude of the rate of change in water temperature calculated by the automatic calculator. 1. A control device for a screw type air conditioner, characterized in that it is equipped with an automatic control means for controlling the air conditioner. 3. When the water temperature is within the ON/OFF temperature range of the temperature controller and the cooling operation is being performed, the automatic control means reaches the OFF point when the cooling water temperature does not tend to fall slowly. 3. The control device for a screw type air conditioner according to claim 2, wherein the control device is configured to control the solenoid valve so as to turn off the economizer cycle even when the economizer cycle is not activated. 4. The automatic control means is configured to control the solenoid valve so as to turn on the economizer cycle when the cooling water temperature does not tend to decrease immediately after the start of cooling operation. A control device for a screw air conditioner according to claim 2.