WO2017170649A1

WO2017170649A1 - Purging device, refrigerator equipped with same, and method for controlling purging device

Info

Publication number: WO2017170649A1
Application number: PCT/JP2017/012826
Authority: WO
Inventors: 良枝栂野; 和島　一喜; 直也三吉
Original assignee: 三菱重工サーマルシステムズ株式会社
Priority date: 2016-03-31
Filing date: 2017-03-29
Publication date: 2017-10-05
Also published as: CN108700355B; CN108700355A; JP2017180994A; JP6644620B2; US20190056159A1

Abstract

A purging device equipped with: a purging pipe (17) for purging a gas mixture containing a coolant and a non-condensable gas from a refrigerator; a purging tank (40) for storing the gas mixture purged from the purging pipe (17); a cooling device (42) which cools the interior of the purging tank (40) and condenses the coolant in the gas mixture; a drainage pipe (19) for discharging the liquid coolant inside the purging tank (40) to the refrigerator; an exhaust pipe (50) for discharging the non-condensable gas in the gas mixture inside the purging tank (40) to the exterior; and a control unit (16) which stops operation of the purging device (15) when the discharged non-condensable gas amount discharged from the exhaust pipe (50) exceeds the introduced non-condensable gas amount introduced into the refrigerator.

Description

Bleed device, refrigerator equipped with the same, and control method of bleed device

The present invention relates to an extraction device for extracting non-condensable gas such as air that has entered a refrigerator, a refrigerator equipped with the extraction device, and a control method for the extraction device.

In refrigeration equipment that uses refrigerant (so-called low-pressure refrigerant) whose operating pressure during operation is partially negative in the machine, after non-condensable gas such as air enters the machine from the negative pressure part and passes through the compressor, etc. In the condenser. If the non-condensable gas stays in the condenser, the refrigerant condensing performance in the condenser is hindered, and the performance as a cooling / heating device is lowered. For this reason, a certain performance is ensured by extracting air from the refrigerator and discharging non-condensable gas outside the apparatus. By extraction, the non-condensable gas is drawn into the extraction device together with the refrigerant gas, and the refrigerant is cooled and condensed, whereby the non-condensable gas is separated from the refrigerant and discharged to the outside by an exhaust pump or the like (Patent Document 1 below) And 2).

Japanese Patent Laid-Open No. 2001-50618 JP 2006-38346 A

However, if the operation of the bleeder is continued excessively without properly performing the operation stop timing, the refrigerant is excessively extracted from the chiller, which may reduce the capacity of the chiller.

The present invention has been made in view of such circumstances, and an extraction device capable of appropriately determining the timing of operation stop and preventing excessive operation continuation, a refrigerator equipped with the extraction device, and a control method for the extraction device The purpose is to provide.

In order to solve the above-mentioned problems, the bleeder of the present invention, the refrigerator equipped with the bleeder, and the control method of the bleeder employ the following means.
That is, an extraction device according to an aspect of the present invention includes an extraction pipe that extracts a mixed gas containing refrigerant and non-condensable gas from a refrigerator, an extraction tank that stores the mixed gas extracted from the extraction pipe, A cooler that cools the inside of the extraction tank to condense the refrigerant in the mixed gas, a drain pipe that discharges the liquid refrigerant in the extraction tank to the refrigerator, and a fault in the mixed gas in the extraction tank. Exhaust piping for discharging condensed gas to the outside, and control for stopping the operation of the extraction device when the amount of non-condensable gas discharged from the exhaust piping exceeds the amount of non-condensable gas entering the refrigerator Department.

When the inside of the bleed tank is cooled by the cooler, the pressure in the bleed tank is reduced, so that a differential pressure with the refrigerant system of the refrigerator (for example, a condenser) is formed, and the chiller is connected to the bleed tank through the bleed pipe. A mixed gas containing refrigerant and non-condensable gas is drawn. In the extraction tank, the refrigerant in the mixed gas is condensed by the cooler to become a liquid refrigerant and is accumulated below the extraction tank. On the other hand, the non-condensable gas in the mixed gas introduced into the extraction tank remains in the extraction tank as a gas without being condensed even when cooled by the cooler. Thereby, the refrigerant and the non-condensable gas are separated in the extraction tank. The separated non-condensable gas is discharged to the outside through the exhaust pipe. The liquid refrigerant accumulated in the extraction tank is discharged to a refrigerator (for example, an evaporator) through a drain pipe and reused in the refrigerator.
When the amount of non-condensable gas discharged from the exhaust pipe exceeds the amount of non-condensable gas that has entered the refrigerator, the bleeder is stopped. It is possible to prevent excessive continuation of operation.

Furthermore, in the bleeder according to one aspect of the present invention, the control unit includes a non-condensable gas density in the bleed tank obtained from a temperature and a pressure in the bleed tank, and an exhaust gas amount from the exhaust pipe. From the above, the amount of non-condensable exhaust gas is obtained.

When there is only refrigerant in the extraction tank, the pressure and temperature in the extraction tank have a saturation relationship. However, when non-condensable gas is contained in the extraction tank, the extraction tank pressure increases by the partial pressure of the non-condensable gas in accordance with the non-condensable gas density included. By utilizing this, the non-condensable gas density was obtained from the temperature and pressure in the extraction tank. That is, the partial pressure of the refrigerant in the extraction tank is obtained from the temperature in the extraction tank, and the partial pressure of the non-condensable gas is obtained by subtracting the partial pressure of the refrigerant from the pressure in the extraction tank. And the non-condensable gas density can be obtained from the partial pressure of the non-condensable gas using the equation of state of the ideal gas. If the non-condensable gas density is obtained, the exhaust non-condensable gas amount can be obtained using the exhaust gas amount from the exhaust pipe. The amount of exhaust gas can be obtained, for example, from the differential pressure of the exhaust pipe during exhaust and the exhaust time, or can be obtained from the internal volume of the extraction tank and the pressure difference before and after exhaust.

Furthermore, in the bleeder according to one aspect of the present invention, the control unit obtains the intrusion non-condensable gas amount based on a differential pressure between the pressure in the refrigerant system of the refrigerator and the pressure outside the refrigerator.

When the pressure in the refrigerant system of the refrigerator becomes lower than the pressure outside the refrigerator, non-condensable gas enters the refrigerant system of the refrigerator. Therefore, the amount of invasion non-condensable gas is obtained based on the pressure difference between the pressure in the refrigerant system of the refrigerator and the pressure outside the refrigerator.

Furthermore, in the bleeder according to an aspect of the present invention, the control unit is configured to perform the bleeder when the increase in the partial pressure of the non-condensable gas in the bleed tank within a predetermined time is equal to or less than a set value. Stop the operation.

If the increase in the partial pressure of the non-condensable gas in the extraction tank is equal to or less than the set value, it can be determined that the non-condensable gas in the extraction tank is substantially exhausted, so the extraction device is stopped.

Further, a refrigerator according to an aspect of the present invention includes the extraction device described in any of the above.

Since any one of the above extraction devices is provided, a refrigerator that can prevent excessive operation of the extraction device can be provided.

Moreover, the control method of the extraction apparatus which concerns on 1 aspect of this invention is the extraction piping which extracts the mixed gas containing a refrigerant | coolant and non-condensable gas from a refrigerator, and the extraction tank which stores the said mixed gas extracted from the said extraction piping A cooler that cools the inside of the extraction tank and condenses the refrigerant in the mixed gas, a drain pipe that discharges the liquid refrigerant in the extraction tank to the refrigerator, and the mixed gas in the extraction tank And an exhaust pipe for exhausting non-condensable gas to the outside, wherein the amount of exhausted non-condensable gas exhausted from the exhaust pipe is reduced to the amount of invading non-condensable gas that has entered the refrigerator. When it exceeds, the operation of the extraction device is stopped.

It is possible to prevent excessive operation of the bleeder from being continued by appropriately determining the timing of stopping the bleeder.

It is the schematic block diagram which showed the refrigerator using the extraction apparatus which concerns on one Embodiment of this invention. It is the schematic block diagram which showed the bleeder periphery of FIG. It is the flowchart which showed operation | movement of the extraction apparatus. It is the flowchart which showed operation | movement of the extraction apparatus. It is the flowchart which showed operation | movement of the extraction apparatus.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic configuration of a refrigerator using the extraction device of the present invention. As shown in the figure, the refrigerator 1 is a turbo refrigerator, and includes a turbo compressor 11 that compresses the refrigerant, and a condenser 12 that condenses the high-temperature and high-pressure gas refrigerant compressed by the compressor 11. An expansion valve 13 for expanding the liquid refrigerant from the condenser 12, an evaporator 14 for evaporating the liquid refrigerant expanded by the expansion valve 13, and air (non-condensable gas) entering the refrigerant system of the refrigerator 1 ) To the atmosphere, and a control device (control unit) 16 that controls each unit included in the refrigerator 1 as main components.
As the refrigerant, for example, a low-pressure refrigerant such as HFO-1233zd (E) is used, and a low-pressure part such as an evaporator becomes an atmospheric pressure or lower during operation.

The compressor 11 is a multistage centrifugal compressor driven by an inverter motor 20. The output of the inverter motor 20 is controlled by the control device 16.

The condenser 12 is, for example, a shell and tube heat exchanger. The condenser 12 is inserted with a cooling water heat transfer tube 12a through which cooling water for cooling the refrigerant flows. A cooling water return pipe 22a and a cooling water return pipe 22b are connected to the cooling water heat transfer pipe 12a. The cooling water led to the condenser 12 via the cooling water return pipe 22a is led to a cooling tower (not shown) via the cooling water return pipe 22b and exhausted to the outside, and then is discharged to the outside via the cooling water return pipe 22a. It is led to the condenser 12 again.
The cooling water delivery pipe 22a is provided with a cooling water pump (not shown) for supplying cooling water and a cooling water inlet temperature sensor 23a for measuring the cooling water inlet temperature Tcin. The cooling water return pipe 22b is provided with a cooling water outlet temperature sensor 23b for measuring the cooling water outlet temperature Tcout and a cooling water flow rate sensor 24 for measuring the cooling water flow rate F2.
The condenser 12 is provided with a condenser pressure sensor 25 that measures the condensation pressure Pc in the condenser 12.
The measured values of these

sensors

23 a, 23 b, 24, and 25 are transmitted to the control device 16.

The expansion valve 13 is electrically operated, and the opening degree is set by the control device 16.

The evaporator 14 is a heat exchanger of, for example, a shell and tube type. The evaporator 14 is inserted with a cold water heat transfer tube 14a through which cold water that exchanges heat with the refrigerant flows. A chilled water return pipe 32a and a chilled water return pipe 32b are connected to the chilled water heat transfer pipe 14a. The chilled water led to the evaporator 14 via the chilled water outgoing pipe 32a is cooled to a rated temperature (for example, 7 ° C.), and is led to an external load (not shown) via the chilled water return pipe 32b to supply cold heat. It is again led to the evaporator 14 via the forward piping 32a.
The chilled water delivery pipe 32a is provided with a chilled water pump (not shown) for feeding chilled water and a chilled water inlet temperature sensor 33a for measuring the chilled water inlet temperature Tin. The cold water return pipe 32b is provided with a cold water outlet temperature sensor 33b for measuring the cold water outlet temperature Tout and a cold water flow rate sensor 34 for measuring the cold water flow rate F1.
The evaporator 14 is provided with an evaporator pressure sensor 35 that measures the evaporation pressure Pe in the evaporator 14.
The measurement values of these

sensors

33a, 33b, 34, and 35 are transmitted to the control device 16.

A bleeder 15 is provided between the condenser 12 and the evaporator 14. The extraction device 15 is connected to an extraction pipe 17 that guides a mixed gas containing refrigerant and non-condensable gas (air) from the condenser 12. The extraction pipe 17 is provided with an extraction solenoid valve (extraction valve) 18 for controlling the flow and blocking of the mixed gas. The opening and closing of the extraction solenoid valve 18 is controlled by the control device 16.
A drainage pipe 19 that discharges the liquid refrigerant condensed in the extraction device 15 to the evaporator 14 is connected to the extraction device 15. The drainage pipe 19 is provided with a drainage solenoid valve (drainage valve) 21 for controlling the flow and blocking of the liquid refrigerant. Opening and closing of the drainage electromagnetic valve 21 is controlled by the control device 16.

FIG. 2 shows the configuration around the extraction device 15. The bleeder 15 is provided with a bleed tank 40 for storing a mixed gas containing a refrigerant led from the bleed pipe 17 and a non-condensable gas. The extraction tank 40 is provided with a cooler 42 that cools the inside of the extraction tank 40 and a heater 44 that heats the inside of the extraction tank 40.

The cooler 42 includes a Peltier element, and is provided so that the cooling heat transfer surface 42 a cooled by the Peltier element is exposed in the extraction tank 40. The cooling heat transfer surface 42 a is provided along the vertical direction of the extraction tank 40. A power supply unit (not shown) is connected to the Peltier element of the cooler 42. By controlling the current flowing through the power supply unit by the control device 16, the start and stop of the cooler 42 can be switched. Further, the Peltier element of the cooler 42 is provided with a heat radiating portion (not shown) for releasing the heat absorbed by the cooling heat transfer surface 42a to the outside. The heat radiating part is provided with a water cooling device for allowing cooling water to flow, and radiates heat at a constant temperature. In addition, a heat radiating part is good also as an air cooling type which is not provided with a water cooling device.

The heater 44 is, for example, an electric heater, and is attached to the bottom of the extraction tank 40. The start and stop of the heater 44 are controlled by the control device 16.

The extraction tank 40 is provided with an extraction tank pressure sensor 46 for detecting the pressure Pt in the extraction tank 40 and an extraction tank temperature sensor 48 for detecting the temperature Tt in the extraction tank 40. The measured values of these sensors 46 and 48 are transmitted to the control device 16.
An exhaust pipe 50 for discharging gas (mainly non-condensable gas) in the extraction tank 40 is connected to the upper portion of the extraction tank 40. The exhaust pipe 50 is provided with an exhaust solenoid valve (exhaust valve) 52 for controlling the flow and shutoff of gas. The opening and closing of the exhaust electromagnetic valve 52 is controlled by the control device 16.

The control device 16 has a function of controlling the number of revolutions of the compressor 11 based on a measured value received from each sensor, a load factor sent from the host system, and a control function of the bleeder 15. Yes.

The control device 16 includes, for example, a CPU (Central Processing Unit) (not shown), a memory such as a RAM (Random Access Memory), and a computer-readable recording medium. A series of processing steps for realizing various functions to be described later are recorded in a recording medium or the like in the form of a program, and the CPU reads the program into a RAM or the like to execute information processing / arithmetic processing. Thus, various functions described later are realized.

Since the refrigerator 1 described above uses a low-pressure refrigerant, air that is a non-condensable gas enters the refrigerator 1 from the negative pressure portion during operation. Examples of the negative pressure portion include a region where the pressure is relatively low during a refrigeration cycle such as an evaporator, but the condenser 12 can also have a negative pressure in winter. The air that has entered the refrigerator 1 is mainly accumulated in the condenser 12. The bleeder 15 operates the air accumulated in the condenser 12 at a predetermined interval and discharges the air in the refrigerator 1 to the outside.

Next, the operation of the bleeder 15 will be described with reference to FIGS.
Table 1 summarizes the operating states of the Peltier element, each solenoid valve, and the like in each step described below. In the table below, a circle indicates ON or open, and a circle indicates OFF or closed.

When the refrigerator 1 is in operation and the amount of air that is non-condensable gas entering the refrigerator 1 is less than a predetermined value, the extraction device 15 is stopped (step S1). At this time, the Peltier element of the cooler 42 is turned off, the extraction solenoid valve 18 and the exhaust solenoid valve 52 are closed, the drainage solenoid valve 21 is opened, and the heater 44 is turned off.

In step S2, calculation of the amount of air entering the refrigerant system of the refrigerator 1 is performed as follows. The control device 16 obtains the condensation pressure Pc from the condenser pressure sensor 25 and the evaporation pressure Pe from the evaporator pressure sensor 35, and calculates the differential pressure between the condenser 12 and the atmospheric pressure in the evaporator 14 by the following equation. Do as follows.
Differential pressure (condenser) = atmospheric pressure−condensation pressure Pc (1)
Differential pressure (evaporator) = Atmospheric pressure-Evaporation pressure Pe (2)
And based on Formula (1) and Formula (2), the air penetration | invasion amount (instantaneous value) is calculated like the following Formula.
Air intrusion amount (instantaneous value) = f (differential pressure) (3)
That is, the air intrusion amount (instantaneous value) is a function of the differential pressure (for example, a function of a ½ power of the differential pressure), and is the sum of the air intrusion amount in the condenser 12 and the air intrusion amount in the evaporator 14.
The air amount (integrated value) that has entered the refrigerant system of the refrigerator 1 is calculated as a value obtained by integrating the air intrusion amount (instantaneous value) with time.
Air intrusion amount (integrated value) = Σ air intrusion amount (instantaneous value) (4)

When the air intrusion amount (integrated value) calculated as described above exceeds a predetermined set value (step S3), preparation for starting the bleeder 15 is performed (step S4). Specifically, the Peltier element of the cooler 42 is turned on, and the drainage solenoid valve 21 is closed. Thereby, the inside of the extraction tank 40 becomes a closed space, and heat is absorbed from the cooling heat transfer surface 42a by cooling by the Peltier element. Due to the heat absorption from the cooling heat transfer surface 42a, the temperature in the extraction tank 40 decreases and the pressure in the extraction tank 40 also decreases.
When the value obtained by subtracting the extraction tank pressure Pt obtained by the extraction tank pressure sensor 46 from the condensation pressure Pc obtained by the condenser pressure sensor 25 exceeds the set value (step S5), the extraction electromagnetic valve 18 is opened. (Step S6).

By opening the extraction solenoid valve 18, the mixed gas containing the refrigerant and the air flows into the extraction tank 40 from the condenser 12 through the extraction pipe 17 according to the differential pressure between the condenser 12 and the extraction tank 40. Flows in. In the extraction tank 40, the refrigerant is cooled to the condensation temperature or lower and liquefied by cooling from the cooling heat transfer surface 42a. On the other hand, the air, which is a non-condensable gas, stays in the extraction tank 40 in a gas state without being condensed even by cooling from the cooling heat transfer surface 42a.
As will be described below, the level of the liquid refrigerant condensed in the extraction tank 40 and accumulated below the extraction tank 40 is detected by two methods.

[Liquid level detection by pressure change (step S7)]
As shown in step S7, when the value obtained by subtracting the extraction tank pressure Pt obtained by the extraction tank pressure sensor 46 from the condensation pressure Pc obtained by the condenser pressure sensor 25 exceeds the set value, the extraction tank 40 It is determined that the liquid level of the liquid refrigerant has increased. This set value is determined in advance by a test or the like.

Since the cooling heat transfer surface 42a is installed in the extraction tank 40 in the height direction (see FIG. 2), when the liquid level of the liquid refrigerant accumulated below the extraction tank 40 rises, the cooling heat transfer surface The surface 42a is submerged from below with the liquid refrigerant. When the cooling heat transfer surface 42a is submerged by the liquid refrigerant, the heat transfer area for cooling the gas is reduced, and the condensing capacity is reduced. When the condensing capacity decreases, the pressure Pt in the extraction tank 40 increases, and the differential pressure from the condensing pressure Pc of the condenser 12 decreases. As described above, when the inside of the extraction tank 40 is cooled, the pressure in the extraction tank 40 is reduced. However, when the refrigerant condenses in the extraction tank 40, liquid refrigerant is accumulated in the extraction tank 40 and the cooling heat transfer surface 42a. When the liquid refrigerant covers this, a decrease occurs in that the pressure Pt in the extraction tank 40 increases. Therefore, the pressure Pt in the bleed tank 40 is measured by the bleed tank pressure sensor 46, and after the measured value has fallen, it rises to become a predetermined value or more and captures that the differential pressure from the condensation pressure Pc exceeds the set value. The rise in the liquid level of the liquid refrigerant in the extraction tank 40 is detected.
When the rise in the liquid level of the liquid refrigerant in the extraction tank 40 is detected as described above, the process proceeds to step S10 and the liquid is discharged.

[Liquid level detection by calculation (steps S8 and S9)]
In the liquid level detection of the liquid refrigerant by calculation, the refrigerant condensation amount is calculated as shown in step S8.
First, in order to calculate the refrigerant condensation amount (instantaneous value), the temperature in the extraction tank 40 is obtained. Specifically, the extraction tank temperature Tt is obtained by the extraction tank temperature sensor 48. When the extraction tank temperature sensor 48 is not used, the extraction tank temperature may be calculated from the extraction tank pressure Pt obtained by the extraction tank pressure sensor 46. Specifically, the saturation temperature obtained from the extraction tank pressure Pt is set as the extraction tank temperature.

The refrigerant condensation amount (instantaneous value) is obtained from the cooling capacity of the cooler 42 and the latent heat of condensation of the refrigerant.
The cooling capacity of the Peltier element used in the cooler 42 is determined by the difference between the heat absorption side temperature and the heat radiation temperature and the current flowing through the Peltier element. If the heat radiation temperature (cooling water temperature or outside air temperature) and the current flowing through the Peltier element are constant, the cooling capacity Qp_W [W] is calculated as a function of the heat absorption side temperature (≈the extraction tank temperature Tt) as follows: .
Qp_W = f (Tt) (5)
Since the refrigerant latent heat of condensation Q_LH [kJ / kg] is the difference between the gas enthalpy and the liquid enthalpy at the saturation temperature (saturation pressure), it is defined as a function of the extraction tank internal temperature Tt for each refrigerant as shown in the following equation. .
Q_LH = f (Tt) (6)
The refrigerant condensing amount (instantaneous value) G_in_ref [kg / h] is calculated as follows using the cooling capacity Qp_W and the condensation latent heat Q_LH obtained as described above.
G_in_ref = Qp_W / Q_LH × 3600/10 ³ (7)
The refrigerant condensation amount (integrated value) is obtained by integrating the refrigerant condensation amount (instantaneous value) obtained by the above equation (7) with time.
Refrigerant condensation amount (integrated value) = Σrefrigerant condensation amount (instantaneous value) (8)

When the refrigerant condensation amount (integrated value) exceeds the set value (step S9), it is determined that the liquid level of the liquid refrigerant in the extraction tank 40 has risen, and the process proceeds to step S10 to drain the liquid.

In step S10, the drain solenoid valve 21 is opened, and the liquid refrigerant in the extraction tank 40 is discharged. The liquid refrigerant in the extraction tank 40 is guided to the evaporator 14 through the drain pipe 19.

After a certain period of time has elapsed since the drainage solenoid valve 21 was opened in step S10, the drainage solenoid valve 21 is closed and the drainage is terminated (step S11). This predetermined time is set in advance by a test before the refrigerator 1 is installed.

Next, by detecting whether air, which is non-condensable gas accumulated in the bleed tank 40, is discharged to the outside (atmosphere) via the exhaust pipe 50, it is detected by the following two methods. Do.
[Detection by pressure change (step S12)]
When the liquid refrigerant is discharged from the extraction tank 40 in step S10, the liquid immersion of the cooling heat transfer surface 42a of the cooler 42 is eliminated and the cooling capacity is restored, so that the pressure in the extraction tank 40 decreases. However, if air, which is a non-condensable gas, stays in the extraction tank 40 in a predetermined amount or more, the air covers the cooling heat transfer surface 42a and the heat transfer performance is hindered. Therefore, if the pressure in the extraction tank 40 does not drop to a predetermined value or less after the liquid refrigerant is discharged, it can be determined that air is staying in the extraction tank 40 by a predetermined amount or more. Therefore, when the difference value obtained by subtracting the extraction tank pressure Pt obtained by the extraction tank pressure sensor 46 from the condensation pressure Pc obtained by the condenser pressure sensor 25 in step S12 exceeds the set value, that is, When the extraction tank pressure Pt does not fall below the predetermined value, it is determined that the air stays in the extraction tank 40 at a predetermined amount or more.
When it is determined that the air stays in the extraction tank 40 at a predetermined amount or more, the process proceeds to step S15 and preparation for exhaust is performed.

[Detection by calculation (steps S13 and S14)]
In step S13, the amount of air in the extraction tank (integrated value), which is the amount of air remaining in the extraction tank 40, is obtained by calculation. Specifically, it is calculated based on the air intrusion amount (integrated value) calculated in step S2 described above. When the amount of air in the extraction tank (integrated value) exceeds the set value (step S14), it is determined that air is staying in the extraction tank 40 at a predetermined amount or more, and the process proceeds to step S15, where the exhaust gas is exhausted. Make preparations.

In step S15, the gas in the extraction tank 40 is prepared to be exhausted. Specifically, the Peltier element of the cooler 42 is turned off, the extraction solenoid valve 18 is closed, and the heater 44 is turned on. As a result, the internal temperature rises after the inside of the extraction tank 40 is sealed, so that the pressure in the extraction tank 40 increases. Then, when the bleed tank pressure Pt obtained from the bleed tank pressure sensor 46 increases and exceeds a set value (atmospheric pressure + α) that is higher than the atmospheric pressure by a predetermined value α (step S16), the process proceeds to step S17. Proceed and start exhausting.

In step S17, the exhaust solenoid valve 52 is opened and the heater 44 is turned off. Thereby, the gas which has the air in the extraction tank 40 as a main component through the exhaust pipe 50 is released to the outside (atmosphere). The reason why the heater 44 is turned off at this time is that the refrigerant remaining in the extraction tank 40 is not discharged to the outside more than necessary.

When the pressure in the extraction tank 40 falls below the set value (atmospheric pressure + β) that is higher by the predetermined value β than the atmospheric pressure (step S18), the process proceeds to step S19. The reason why this set value is set to a pressure higher than the atmospheric pressure by a predetermined value β is that if the exhaust electromagnetic valve 52 is opened until the atmospheric pressure falls below the atmospheric pressure, the atmosphere flows backward and is introduced into the extraction tank 40. This is to prevent it.
In step S19, the exhaust solenoid valve 52 is closed and the exhaust is terminated.

Next, it progresses to step S20 and after, and the stop of the extraction apparatus 15 is determined.
In step S20, an exhaust air amount (integrated value) that is the total amount of air exhausted to the outside (atmosphere) via the exhaust pipe 50 is calculated. Specifically, it is as follows.
First, in order to obtain the air density ρ_t_air [kg / m ³ ] in the extraction tank 40, the refrigerant saturation pressure Pt_ref [MPa (abs)] in the extraction tank 40 is calculated. The refrigerant saturation pressure Pt_ref in the extraction tank 40 is a saturation pressure corresponding to the temperature Tt in the extraction tank 40. The relational expression between the saturation pressure and the saturation temperature can be defined as the following expression as a function of the saturation temperature for each refrigerant.
Pt_ref = f (Tt) (9)
Then, the air partial pressure Pt_air [MPa (abs)] in the bleed tank 40 can be calculated as follows using the bleed tank pressure Pt (total pressure).
Pt_air = Pt−Pt_ref (10)
Therefore, the air mass w_t_air [kg] in the extraction tank 40 is expressed by the following equation from the ideal gas state equation.
w_t_air = Pt_air × Vt × M_air / (R × Tt) (11)
Here, Vt is the volume [m ³ ] of the extraction tank 40, M_air is the molecular weight [kg / mol] of air, R is a gas constant, and Tt is the temperature [K] in the extraction tank 40.
Therefore, the air density ρ_t_air in the extraction tank 40 is expressed by the following formula.
ρ_t_air = w_t_air / Vt (12)

When the air density ρ_t_air in the extraction tank 40 is obtained as described above, the exhaust air amount w_ex_air [kg] is calculated.
The exhaust gas volume V_ex [m ³ ] is estimated from the differential pressure between the pressure Pt in the extraction tank 40 and the atmospheric pressure Pa and the time Time_ex [sec] during which the exhaust electromagnetic valve 52 is open in step S17.
V_ex = f (Pt−Pa, Time_ex) (13)
The exhaust gas volume V_ex may be obtained from the volume Vt of the extraction tank 40 and the pressure difference before and after the exhaust, instead of the above equation (13).
Using the exhaust gas volume V_ex obtained by the above equation and the air density ρ_t_air in the extraction tank 40, the exhaust air amount w_ex_air is calculated by the following equation.
w_ex_air = V_ex × ρ_t_air (14)

Since the exhaust air amount w_ex_air obtained by the above equation (14) is a value per exhaust, when the exhaust is performed a plurality of times, the exhaust air amount w_ex_air is multiplied by the exhaust number n. The obtained value is the exhaust air amount (integrated value).
Exhaust air amount (integrated value) = w_ex_air × n (15)
When the exhaust air amount (integrated value) is obtained in this way, the process proceeds to step S21.

In step S21, it is determined whether or not the exhaust air amount (integrated value) exceeds the intrusion air amount (integrated value) obtained in step S2.
If the exhausted air amount (integrated value) exceeds the intruding air amount (integrated value), it is determined that exhaust has been sufficiently performed, and the process proceeds to step S23, where the extraction device 15 is stopped.

On the other hand, when the discharged air amount (integrated value) does not exceed the intruding air amount (integrated value), the process returns to step S4, and the above-described extraction, drainage, and exhaust are repeated.
Even if the exhausted air amount (integrated value) does not exceed the intruding air amount (integrated value), as shown in step S22, the partial pressure of air in the extraction tank 40 within a predetermined time period is set. If the increase in Pt_air (see equation (10)) is equal to or less than the set value, the process proceeds to step S23, and the bleeder 15 is stopped. This step S22 sets an increase in the partial pressure of air in the extraction tank 40 even when the calculation of the exhaust air amount (integrated value) or the intrusion air amount (integrated value) is inaccurate for some reason. This is because it can be determined that the air in the extraction tank 40 is substantially exhausted if the value is less than or equal to the value.

In step S23 for stopping the bleeder 15, the drain solenoid valve 21 is opened. Thereby, the inside of the extraction tank 40 is communicated with the evaporator 14. This is to prevent the pressure inside the extraction tank 40 from increasing due to the influence of the outside air temperature.

As described above, according to the present embodiment, the following operational effects are obtained.
As explained in steps S20 and S21, when the amount of exhaust air (integrated value) exhausted from the exhaust pipe 50 exceeds the amount of intruded air (integrated value) that has entered the refrigerator 1, the bleeder 15 is turned on. Since the operation is stopped, it is possible to appropriately determine the operation stop timing and to prevent the bleeder 15 from continuing to operate excessively.

When only the refrigerant exists in the extraction tank 40, the pressure Pt and the temperature Tt in the extraction tank 40 have a saturation relationship. However, when air is contained in the bleed tank 40, the bleed tank pressure Pt increases by the partial pressure of air according to the air density contained. By utilizing this, the air density is obtained from the temperature Tt and the pressure Pt in the extraction tank 40 (see formula (9) to formula (12)). As described above, the air density can be obtained by calculation only by obtaining the temperature Tt and the pressure Pt of the extraction tank 40, and thus the exhaust air amount can be obtained.

As described in step S22, in consideration of the case where the calculation of the exhaust air amount (integrated value) or the intrusion air amount (integrated value) is inaccurate for some reason, the exhaust air amount ( Even if the integrated value) does not exceed the intrusion air amount (integrated value), the air in the extraction tank 40 is substantially exhausted if the increase in the air partial pressure in the extraction tank 40 is equal to or less than the set value. It was decided that the bleeder was stopped. Thereby, excessive operation continuation of the bleeder 15 can be prevented.

In addition, the structure of the refrigerator 1 shown in FIG. 1 is an example, and is not limited to this structure. For example, it is good also as a structure which replaces with the water-cooled condenser 12 and arrange | positions an air heat exchanger and performs heat exchange between external air and a refrigerant | coolant. Moreover, the refrigerator 1 is not limited to the case having only a cooling function, for example, it may have only a heat pump function or both a cooling function and a heat pump function.

Further, although the Peltier element is used as a cooling device used for the cooler 42, the present invention is not limited to this, and any other device can be used as long as the inside of the extraction tank 40 can be cooled below the condensation temperature of the refrigerant. The cooling device may be used.

In addition, although an electric heater is used as the heater 44, the present invention is not limited to this, and a heat transfer tube through which a high-temperature refrigerant flows is used as long as the inside of the extraction tank 40 can be heated. Other types of heaters such as a heater may be used.

DESCRIPTION OF SYMBOLS 1 Refrigerator 11 Compressor 12 Condenser 13 Expansion valve 14 Evaporator 15 Extraction device 16 Control apparatus (control part)
17 Extraction piping 18 Extraction solenoid valve (extraction valve)
19 Drainage pipe 20 Inverter motor 21 Drainage solenoid valve (drainage valve)
22a Cooling water outlet pipe 22b Cooling water return pipe 23a Cooling water inlet temperature sensor 23b Cooling water outlet temperature sensor 24 Cooling water flow rate sensor 25 Condenser pressure sensor 32a Chilled water outgoing pipe 32b Chilled water return pipe 33a Chilled water inlet temperature sensor 33b Chilled water outlet temperature sensor 34 Chilled water flow sensor 35 Evaporator pressure sensor 40 Extraction tank 42 Cooler 44 Heater 46 Extraction tank pressure sensor 48 Extraction tank temperature sensor 50 Exhaust piping 52 Exhaust solenoid valve (exhaust valve)

Claims

An extraction pipe for extracting a mixed gas containing refrigerant and non-condensable gas from the refrigerator;
An extraction tank for storing the mixed gas extracted from the extraction pipe;
A cooler that cools the inside of the extraction tank and condenses the refrigerant in the mixed gas;
A drainage pipe for discharging the liquid refrigerant in the extraction tank to the refrigerator;
An exhaust pipe for discharging the non-condensable gas in the mixed gas in the extraction tank to the outside;
A control unit that stops the operation of the extraction device when the amount of non-condensable gas discharged from the exhaust pipe exceeds the amount of non-condensable gas that has entered the refrigerator;
A bleed device comprising:
The control unit obtains the exhaust non-condensable gas amount from the non-condensable gas density in the extraction tank obtained from the temperature and pressure in the extraction tank and the exhaust gas amount from the exhaust pipe. The bleeder described in 1.
The bleeder according to claim 1 or 2, wherein the control unit obtains the intrusion non-condensable gas amount based on a differential pressure between a pressure in the refrigerant system of the refrigerator and a pressure outside the refrigerator.
The control unit according to any one of claims 1 to 3, wherein the control unit stops the operation of the extraction device when the increase in the partial pressure of the non-condensable gas in the extraction tank within a predetermined time period is equal to or less than a set value. The bleeder described in 1.
A refrigerator having the extraction device according to any one of claims 1 to 4.
An extraction pipe for extracting a mixed gas containing refrigerant and non-condensable gas from the refrigerator;
An extraction tank for storing the mixed gas extracted from the extraction pipe;
A cooler that cools the inside of the extraction tank and condenses the refrigerant in the mixed gas;
A drainage pipe for discharging the liquid refrigerant in the extraction tank to the refrigerator;
An exhaust pipe for discharging the non-condensable gas in the mixed gas in the extraction tank to the outside;
A method for controlling a bleeder comprising:
A control method of a bleeder that stops the operation of the bleeder when the amount of discharged non-condensable gas discharged from the exhaust pipe exceeds the amount of invaded non-condensed gas that has entered the refrigerator.