JPH01263460A - Freezing device - Google Patents

Abstract

PURPOSE:To enable a smooth energization of a freezing device even under a hot or cold water condition while preventing an over-loaded state of a compressor motor by a method wherein a degree of opening of a controlling valve is controlled according to a pressure within an evaporator when the cold water in the cold water feeding pipe at an evaporator shows a hot temperature. CONSTITUTION:In case that a cold water temperature is high, for example, at about 40 deg.C, a pressure within an evaporator 1 is increased, a closing signal is produced from a pressure controller 7 to a controlling valve 5 and the controlling valve 5 is fully closed before energization. When a freezer is energized under this condition, the pressure within the evaporator 1 is decreased gradually. If the inner pressure of the evaporator is decreased to a set value of a pressure controller 7, an opening signal is produced to the controlling valve 5 and the coolant liquid is sent slightly to the evaporator 1. This coolant liquid is heated by cold water having a high temperature, so that a temperature of cold water is decreased and the pressure controlling unit 1 may detect the inner pressure and output a controlling signal so as to close the valve a little to the controlling valve 5. If the cold water shows a decreased temperature to the inlet port temperature of 30 deg.C, the controlling valve 5 is fully opened and then an amount of circulation of the coolant is controlled by an orifice 6 and a normal operation is carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a refrigeration system, and in particular, to smooth startup of a turbo chiller, for example, when cold water flowing through a group of cold water pipes of an evaporator is at a high temperature. The present invention relates to a refrigeration system suitable for

[Prior Art] In a conventional centrifugal chiller, the control valve on the compressor inlet side is fully closed at startup. This reduces the suction amount of high-density refrigerant gas when the cold water flowing through the cold water pipe group in the evaporator is at a high temperature, thereby preventing overload of the compressor motor. However, the temperature of the cold water is limited to about 35°C, and in regions such as the Middle East where the outside temperature rises to nearly 50°C, the temperature of the cold water can reach 40°C or higher. In such a case, by tightening the valve in the middle of the chilled water pipe, the chilled water outlet temperature is lowered, and the internal pressure of the evaporator is lowered.
A method has been used to reduce the density of refrigerant gas sucked into the compressor to prevent overflow of the compressor motor.

Regarding such conventional technology, for example, Japanese Patent Publication No. 55-4
It is described in Japanese Patent Laid-open No. 4864 or Japanese Patent Application Laid-open No. 150147/1983.

Here, the technology described in Japanese Patent Publication No. 55-4.4864 is a technology that exhibits good followability to fluctuations in hot water and cold water loads, not only in summer and winter, but also in the intermediate period. A technology has been disclosed in which a refrigerant and a cooling water condenser are arranged in series, and the refrigerant flow rate in a refrigerant path from the hot water condenser to the cooling water condenser is adjusted by fluctuations in the hot water outlet temperature or the hot water condenser pressure.

In addition, the technology described in Japanese Patent Application Laid-Open No. 51-150147 is
This technology detects the cold water outlet temperatures of the water-to-water evaporators connected in parallel in a single refrigeration circuit, selects the highest temperature among them, and uses this temperature as a control command to adjust the capacity of the compressor. This was also intended to ensure economical operation according to the load.

[Problems to be Solved by the Invention] In the conventional method described above, as the temperature of the chilled water increases, the valve of the chilled water piping must be fully opened, so that almost all of the chilled water in the evaporator tube (cold water pipe group) flows. As a result, there was a risk of a freezing accident occurring within the evaporator tube due to an operational error.

Also, if you try to automate the valve operation of chilled water piping,
Since the piping size is large, there is a problem in that the cost I~ increases significantly.

On the other hand, the prior art described in Japanese Patent Publication No. 55-44864 or Japanese Patent Application Laid-Open No. 51-15014.7 has
No consideration was given to starting turbo chillers, etc. used in high-temperature regions such as the Middle East, where outside air temperatures can reach nearly 50°C, when cold water temperatures are high.

The present invention has been made in order to solve the above-mentioned problems in the conventional technology. The purpose of the invention is to provide a refrigeration system that can be started smoothly even at low temperatures.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the refrigeration system according to the present invention includes a compressor, a condenser, an evaporator having a group of cold water pipes, and a refrigerant connecting each of these devices. In a refrigeration system consisting of piping, a control valve is provided in the refrigerant piping leading from the condenser to the evaporator, and a means for detecting the internal pressure of the evaporator is provided to control the cold water in the cold water pipe group in the evaporator. A control circuit is configured to control the opening degree of the control valve according to the internal pressure of the evaporator when the temperature is high.

In addition, the above object is achieved by providing a control valve in the middle of the refrigerant pipe flowing into the evaporator, and controlling the valve to close when the pressure inside the evaporator is high and open when the pressure inside the evaporator is low.

[Action Co. The operation of the above technical means will be described below.

When the temperature of the chilled water is high, the saturated pressure of the refrigerant in the evaporator corresponds to the temperature of the chilled water. If you start the refrigeration equipment,
Since the compressor sucks refrigerant gas from the evaporator, the pressure inside the evaporator decreases. However, as long as the refrigerant liquid continues to be supplied to the evaporator, the pressure will not drop below a certain level. If the supply of refrigerant liquid is stopped at this point, the compressor continues to suck refrigerant gas, so the evaporator pressure gradually decreases. As a result, the density of the refrigerant gas sucked becomes lower,
Overload of the compressor motor in the refrigeration system can be prevented. In other words, by adjusting the amount of refrigerant liquid supplied to the evaporator, the pressure inside the evaporator can be kept below the pressure at which the motor is not overloaded.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The drawing is a configuration diagram of a centrifugal chiller according to an embodiment of the present invention.

In the drawing, 1 is an evaporator having a group of freezing tubes 1a in the container, 2 is a turbo compressor (hereinafter referred to as a compressor on the east), 2
a is a compressor motor; 3 is a condenser having a cooling water pipe group 3a inside; 4 is a refrigerant pipe connecting the condenser 3 and the evaporator 1; and 5 is a control valve provided in the refrigerant pipe 4. , 6 is an orifice provided near where the refrigerant pipe 4 connects to the evaporator 1;
7 is a pressure controller that detects the internal pressure of the evaporator 1 and outputs a control signal to the control valve 5; 8 is a compressor inlet control valve.

In the drawings, thick white arrows indicate the flow of refrigerant, and solid arrows indicate the flow of cold water or cooling water.

In the drawing, the temperature of the cold water in the cooling pipe connected to the evaporator is detected, and when the cold water is high temperature, the compressor inlet control valve 8 is activated.
This diagram schematically shows a control system that controls the amount of suction to reduce the amount of suction. Also,
The drive control system of the suction vane of the turbine compressor, etc. is also schematically shown.

However, since these control systems are not particularly different from those of the prior art, explanations of the configuration 2 functions thereof will be omitted with reference numerals.

Next, the operation of the centrifugal chiller of this embodiment will be explained.

The high temperature and high pressure refrigerant gas compressed by the compressor 2 is transferred to the condenser 3.
Heat exchange (heat radiation) of the cooling water flowing through the cooling water pipe group 3a
to condense and liquefy. The liquid refrigerant enters the evaporator through a refrigerant pipe 4, a control valve 5, and an orifice 6. Here, the refrigerant exchanges heat (endotherm) with the cold water flowing through the cold water pipe group 1a and evaporates, becoming a low-temperature, low-pressure refrigerant gas that is sucked into the compressor 2 via the compressor inlet control valve 8, and is Repeat the freezing cycle.

Now, when the chilled water temperature is high, for example about 40°C, the internal pressure of the evaporator 1 becomes high, and the pressure controller 7 sends a close signal to the control valve 5, and the control valve closes before starting. 5 is fully open.

When the refrigerator is started in this state, the internal pressure of the evaporator 1 (hereinafter referred to as internal pressure) gradually decreases because refrigerant liquid is not supplied. When the internal pressure falls to the set value of the pressure controller 7, an open signal is issued to the control valve 5, and a small amount of refrigerant liquid is sent into the evaporator 1.

This refrigerant liquid is heated by the high-temperature cold water, so it evaporates, and the temperature of the cold water decreases. Therefore, the internal pressure of the evaporator 1 increases by that amount, and the pressure controller 1 detects the internal pressure and outputs a control signal to the control valve 5 to slightly close the valve.

On the other hand, since the evaporated refrigerant gas is sucked into the compressor 2, the internal pressure of the evaporator 1 decreases again. Through this repetition,
The cold water temperature gradually decreases, and the control valve 5 gradually becomes fully open. When the cold water inlet temperature drops to about 30° C., the control valve 5 is fully opened, and the orifice 6 enters a normal operating state in which the amount of refrigerant circulation is controlled.

According to this embodiment, by providing a control valve 5 provided in the middle of the refrigerant pipe 4 from the condenser 3 to the evaporator 1 and a pressure controller 7 that detects the internal pressure of the evaporator 1, even when the water temperature is high, , the compressor motor 2a can be started smoothly without overlowing the compressor motor 2a and without throttling the flow rate of cold water.

In the above embodiment, an example of a centrifugal chiller using a turbo compressor was explained, but the present invention is not limited to the centrifugal chiller as shown in the drawings, and can be applied to other turbo chillers as long as similar effects are expected. This does not prevent application to other types of refrigeration equipment.

[Effects of the Invention] As described above, according to the present invention, it is possible to prevent overloading of the compressor motor at high cold water temperatures without incurring any cost, without risking cold water freezing, and without incurring the risk of cold water freezing. However, it is possible to provide a refrigeration system that can be started up smoothly.

[Brief explanation of the drawing]

The drawing is a configuration diagram of a centrifugal chiller according to an embodiment of the present invention. 1... Evaporator, 1a... Cold water pipe group, 2... Compressor,
3... Condenser, 4... Refrigerant piping, 5... Control valve, 7
...Pressure controller.

Claims (1)

[Claims] 1. In a refrigeration system consisting of a compressor, a condenser, an evaporator having a group of cold water pipes, and refrigerant pipes connecting these devices, a control valve is provided in the refrigerant pipe leading from the condenser to the evaporator, A means for detecting the internal pressure of the evaporator is provided, and when the cold water in the cold water pipe group in the evaporator is at a high temperature, the opening degree of the control valve is controlled according to the internal pressure of the evaporator. A refrigeration device characterized by comprising a circuit.