Method for Charging Refrigerant into Heat Transferring Apparatus and Refrigerant-Charging Control Apparatus for Heat Transferring Apparatus

The present invention relates to a method for charging a refrigerant into a heat transferring apparatus and a refrigerant-charging control apparatus for a heat transferring apparatus.

Apparatuses controlling closed loops working on a thermodynamic cycle are known in the art. Such an apparatus is disclosed in Japanese Patent Publication No. JP 6660095, for example.

The above Japanese Patent Publication No. JP 6660095 discloses an apparatus controlling a closed loop, which exchanges heat to/from an external heat source by using compression and expansion of a working fluid as a thermal medium, through a Rankine cycle as the thermodynamic cycle. A pump circulating and compressing the working fluid and a tank storing the working fluid in a liquid state, which flows into the pump, are arranged in the closed loop. A pressure source, which is a pressurized gas, is connected to the tank through a pressure control valve. The apparatus disclosed in the above Japanese Patent Publication No. JP 6660095 pressurizes the tank by flowing the gas from a pressure source separately from the working fluid by controlling operation of the pressure control valve during operation of the closed loop to prevent occurrence of cavitation in which the gas is produced in the pump.

Here, in the apparatus disclosed in the above Japanese Patent Publication No. JP 6660095, the refrigerant is pressurized by flowing the gas (inert gas) from the pressure source separately from the refrigerant into a flow path of the closed loop (refrigerant flow path) into which the working fluid (refrigerant) is charged. In such a case, in addition to dissolution of the inert gas into the refrigerant in the liquid phase state, variation of an amount of the inert gas dissolving into the refrigerant, depending on temperature and pressure of the refrigerant, makes it difficult to grasp an inflow amount (charging amount) of the inert gas in the refrigerant flow path. Since the temperature at which the refrigerant evaporates and condenses varies depending on the charging amount of the inert gas filled, it is desirable to easily grasp the charging amount of the inert gas charged separately from the refrigerant in a heat transferring apparatus using the thermodynamic cycle.

The present invention is intended to solve the above problem, and one object of the present invention is to provide a method for charging a refrigerant into a heat transferring apparatus and a refrigerant-charging control apparatus for a heat transferring apparatus capable of easily grasping a charging amount of an inert gas charged separately from a refrigerant in the heat transferring apparatus using a thermodynamic cycle.

A method for charging a refrigerant into a heat transferring apparatus according to a first aspect of the present invention includes a pre-charging step of charging an inert gas into a refrigerant flow path of the heat transferring apparatus to bring a pressure in the refrigerant flow path of the heat transferring apparatus to a predetermined pressure; and a main charging step of charging the refrigerant into the refrigerant flow path of the heat transferring apparatus to a predetermined amount required for the heat transferring apparatus to operate after the pre-charging step. Here, the “heat transferring apparatus” stated in this specification refers to a concept that includes a cooling apparatus cooling an object and a heating apparatus heating an object.

A refrigerant-charging control apparatus for a heat transferring apparatus according to a second aspect of the present invention includes a controller performing control to acquire a pressure in a refrigerant flow path of the heat transferring apparatus detected by a pressure detector, wherein if conducting pre-charging to charge an inert gas into the refrigerant flow path of the heat transferring apparatus to bring a pressure in the refrigerant flow path of the heat transferring apparatus to a predetermined pressure before conducting main charging to charge a refrigerant into the refrigerant flow path of the heat transferring apparatus to a predetermined amount required for the heat transferring apparatus to operate, the controller performs control to determine whether the charging of the inert gas is completed based on the pressure in the refrigerant flow path of the heat transferring apparatus detected by the pressure detector.

In the method for charging a refrigerant into a heat transferring apparatus according to the first aspect of the present invention, after the pre-charging is conducted to charge an inert gas into the refrigerant flow path of the heat transferring apparatus to bring a pressure in the refrigerant flow path of the heat transferring apparatus to a predetermined pressure, the main charging is conducted to charge a refrigerant into the refrigerant flow path of the heat transferring apparatus to a predetermined amount required for the heat transferring apparatus to operate. In the refrigerant-charging control apparatus for a heat transferring apparatus according to the second aspect of the present invention, before the main charging, an inert gas is charged into a refrigerant flow path of the heat transferring apparatus to bring a pressure in the refrigerant flow path of the heat transferring apparatus to a predetermined pressure. Accordingly, it is possible to prevent difficulty of grasping a charging amount of the inert gas caused by dissolution of the inert gas into the refrigerant dissimilar to a case in which the inert gas is charged into the refrigerant flow path after the refrigerant is charged. Consequently, it is possible to easily grasp the charging amount of the inert gas charged separately from the refrigerant in a heat transferring apparatus using a thermodynamic cycle. Also, in the present invention, since the inert gas is charged before the main charging in which the refrigerant is charged into the refrigerant flow path, a pressure of the inert gas required to charge the refrigerant into the refrigerant flow path can be smaller as compared with the case in which the inert gas is charged after the refrigerant is charged. Accordingly, since a relatively high-pressure inert gas source is not necessarily provided, it is possible to easily charge the inert gas into the refrigerant flow path.

The following description will describe embodiments embodying the present invention with reference to the drawings.

A method for charging a refrigerant (carbon dioxide refrigerant) into a cooling apparatus(heat transferring apparatus), which is to be operated by an operator, according to a first embodiment is first described with reference to.

The cooling apparatus(see) is a cooling apparatus that uses carbon dioxide as the refrigerant. The cooling apparatusis an apparatus that uses carbon dioxide in a gas-liquid two-phase state in which gas and liquid are mixed. The cooling apparatusincludes a condenser, a tank, a pump, an evaporator, and an apparatus controller. The cooling apparatusprevents occurrence of cavitation in the pumpby pressurizing the refrigerant, which is carbon dioxide, by using an inert gas. Cavitation refers to a phenomenon in which a gas is produced in the pumparranged on a refrigerant flow pathof the cooling apparatusduring operation of the cooling apparatus. Cavitation occurs due to the production of the gas if a pressure of the refrigerant in a liquid phase state flowing into the pumpbecomes smaller than a saturation vapor pressure in the pump. The inert gas is charged to a setting amount of the inert gas, which is previously set, to bring the pressure of the refrigerant flowing into the pumparranged on the refrigerant flow pathof the cooling apparatusto a pressure not smaller than the saturation vapor pressure of the refrigerant during operation of the cooling apparatus. Here, the cooling apparatusis an example of a “heat transferring apparatus” in the claims.

The refrigerant flow pathis formed of the condenser, the tank, pump, the evaporator, and pipes, which are connected to the condenser, the tank, the pumpand the evaporator, in the cooling apparatus.

The condensercondenses the refrigerant (carbon dioxide). The condenseris configured to cool and condense the refrigerant by using a chiller. The refrigerant flowing out of the condenseris transferred to the tank. The tankis a container storing the refrigerant. The refrigerant condensed by the condenserflows into the tank. The tankstores the refrigerant in a liquid phase or a gas-liquid two-phase. The refrigerant stored in the tankis transferred to the pump. Also, the inert gas is stored in the tanktogether with the refrigerant.

The pumptransfers the refrigerant (carbon dioxide) stored in the tankto the evaporator. The operation of the pumpis controlled by the apparatus controller. The evaporatorcools an object to be cooled (not shown) by evaporating the refrigerant discharged from the pump. Subsequently, the refrigerant flowing out of the evaporatoris returned to the condenserand is then condensed in the condenser.

The apparatus controlleris configured to entirely control the cooling apparatus. The apparatus controllerincludes a processor such as a CPU (Central Processing Unit), a memory, and the like. The apparatus controlleris configured to entirely control the cooling apparatusby using control software (program) recorded (stored) in the internal or external memory (storage device).

The cooling apparatusincludes temperature sensorsanddetecting temperatures of the refrigerant in the refrigerant flow path. Also, the cooling apparatusincludes pressure sensorsanddetecting pressures of the refrigerant in the refrigerant flow path. The pressure sensorsandare examples of a “pressure detector” in the claims.

The temperature sensoris arranged between the tankand the pump, and detects the temperature of the refrigerant flowing out of the tank. The temperature sensoris arranged between the evaporatorand the condenser, and detects the temperature of the refrigerant flowing out of the evaporator.

The pressure sensoris arranged between the tankand the pump, and detects the pressure of the refrigerant flowing between the tankand the pump. The pressure sensoris arranged between the evaporatorand the condenser, and detects the pressure of the refrigerant flowing between the evaporatorand the condenser.

Also, the apparatus controlleris connected to the pumpfor communication. Also, the apparatus controlleris connected to the temperature sensorsandfor communication. Also, the apparatus controlleris connected to the pressure sensorsandfor communication.

The apparatus controlleris configured to control the cooling apparatusby acquiring detection signals from the temperature sensor, the temperature sensor, the pressure sensor, and the pressure sensor.

Also, a cylinder, a cylinder, and a vacuum pumpare connected to the refrigerant flow pathof the cooling apparatusthrough a manifold.

The cylinderis filled with carbon dioxide (refrigerant). A flow control valveis provided between the cylinderand the manifold. The flow control valveadjusts a flow rate of carbon dioxide flowing out of the cylinderby adjusting its opening degree.

The cylinderis filled with the inert gas. The cylinderis filled with nitrogen, for example. A flow control valveis provided between the cylinderand the manifold. The flow control valveadjusts a flow rate of inert gas (nitrogen) flowing out of the cylinderby adjusting its opening degree.

The vacuum pumpis a pump that generates a vacuum in the refrigerant flow paths of the cooling apparatus. Note that, in this specification, the “vacuum” does not refer to an absolute vacuum but rather to a state in which a particular space is filled with a gas at a pressure lower than atmospheric pressure.

The manifoldis connected to the refrigerant flow pathof the cooling apparatus. Specifically, an internal flow path of the manifoldis connected to the pipe upstream of the tank(between the tankand the condenser). Also, the manifoldis connected to the pipes that connect the cylinder, the cylinderand the vacuum pumpto the manifold. The manifoldcan switch the pipes to which the refrigerant flow pathis connect by adjusting the opening degrees of the valvesandto close and open flow paths formed inside the manifold. Accordingly, the manifoldcan switch between introduction of carbon dioxide (refrigerant) into the refrigerant flow path, introduction of the inert gas into the refrigerant flow path, and generation of a vacuum in (exhaust from) the refrigerant flow path.

The following description describes a process flow (stepsto) of the method for charging a refrigerant into the cooling apparatusaccording to the first embodiment with reference to.

In step, an operator first generates a vacuum in the refrigerant flow path. The operator manipulates the manifold(valvesand) and the vacuum pumpto generate a vacuum in the pipes between refrigerant flow pathto the cylinderand the cylinder. After generation of a vacuum in the refrigerant flow pathis completed, the operator conducts an operation in step.

In step, the operator conducts pre-charging. In step, after previously charging the inert gas into the refrigerant flow pathof the cooling apparatus, the operator charges carbon dioxide into the refrigerant flow pathof the cooling apparatusat a charging rate preventing that dry ice (solid) is produced to bring a pressure in the refrigerant flow pathof the cooling apparatusto not smaller than the triple point pressure of carbon dioxide. In other words, the inert gas is charged into the refrigerant flow pathbefore carbon dioxide is charged into the refrigerant flow path. The inert gas is charged into the refrigerant flow pathto prevent occurrence of cavitation in the pump, as described above. Here, a charging amount (setting amount) of the inert gas required to prevent cavitation depends on the performance of the pump. In other words, the pressure in the refrigerant flow pathafter charging the inert gas into the refrigerant flow pathrequired to prevent cavitation depends on the performance of the pump. The inert gas is charged to the charging amount (setting amount), which is previously set, to bring the pressure in the refrigerant flow pathof the cooling apparatusto a predetermined pressure at which no cavitation occurs. In the first embodiment, the pressure in the refrigerant flow pathafter charging the inert gas is smaller than the triple point pressure of carbon dioxide.

In the first embodiment, in step(pre-charging), the inert gas is previously charged into the refrigerant flow pathin which a vacuum is generated before carbon dioxide is charged into the refrigerant flow path. In a case in which the inert gas is previously charged into the refrigerant flow pathin which a vacuum is generated, no dry ice is naturally generated. Accordingly, the pressure in the refrigerant flow pathcan be easily increased to approach the triple point pressure of carbon dioxide by previously charging the inert gas as compared with a case in which the pressure in the refrigerant flow pathis gradually increased by gradually charging carbon dioxide into the refrigerant flow pathin which a vacuum is generated. Accordingly, the pressure in the refrigerant flow pathcan be increased to not smaller than the triple point pressure of carbon dioxide without producing dry ice in the refrigerant flow pathas compared with a case in which the inert gas is charged after carbon dioxide is charged into the refrigerant flow pathin which a vacuum is generated by charging carbon dioxide into the refrigerant flow pathafter previously charging the inert gas into the refrigerant flow pathin which a vacuum is generated.

In step, the operator charges carbon dioxide into the refrigerant flow pathof the cooling apparatusat a charging rate preventing that dry ice is produced to bring the pressure in the refrigerant flow pathof the cooling apparatusto not smaller than the triple point pressure of carbon dioxide (0.52 MPa-a). In other words, the operator charges carbon dioxide into the refrigerant flow pathof the cooling apparatuswhose internal pressure is smaller than the triple point pressure of carbon dioxide (0.52 MPa-a) and which has been charged with the inert gas to bring the internal pressure to not smaller than the triple point pressure of carbon dioxide (0.52 MPa-a). For example, carbon dioxide is charged to bring the pressure in the refrigerant flow pathof the cooling apparatusfrom a state of smaller than the triple point pressure of carbon dioxide (0.52 MPa-a) to a state of 0.7 MPa-a or greater. Here, stepis an example of a “pre-charging step” in the claims.

Here, the charging rate of carbon dioxide in step(pre-charging) is smaller than the charging rate of carbon dioxide in step(main charging), which will be described later. The ratio of the charging rate of carbon dioxide in the pre-charging to the charging rate of carbon dioxide in the main charging depends on an internal volume of the cooling apparatus(refrigerant flow path). The operator adjusts the opening degrees of the valveand the flow control valveof the manifoldto gradually charge carbon dioxide into the refrigerant flow pathto prevent that dry ice is produced in the refrigerant flow path.

In step, the operator confirms whether temperatures in the refrigerant flow pathof the cooling apparatusfall within a predetermined temperature range. The operator confirms the temperatures in the refrigerant flow pathdetected by the temperature sensorsand. The operator then confirms that no dry ice is produced in the refrigerant flow pathbased on the temperatures in the refrigerant flow pathdetected by the temperature sensorsand. The operator may confirm the temperatures in the refrigerant flow paththrough a display and a gaging instrument (meter) included in the cooling apparatus(not shown) or confirm the temperatures in the refrigerant flow pathby using an apparatus for charging operation, which will be described in a second embodiment later.

If the temperatures in the refrigerant flow pathof the cooling apparatusfall outside the predetermined temperature range, the operator waits until the temperatures in the refrigerant flow pathof the cooling apparatusfall within the predetermined temperature range. Subsequently, if the temperatures in the refrigerant flow pathof the cooling apparatusfall within the predetermined temperature range, the operator starts the main charging of carbon dioxide (step).

In other words, stepis activated based on the temperatures in the refrigerant flow pathof the cooling apparatusfalling within the predetermined temperature range. Here, stepis an example of a “main charging step” in the claims.

In step, the operator conducts the main charging of carbon dioxide. Specifically, the operator charges carbon dioxide into the refrigerant flow pathof the cooling apparatusto a predetermined amount required for the cooling apparatusto operate with the pressure in the refrigerant flow pathof the cooling apparatushaving been brought to the triple point pressure of carbon dioxide. Specifically, the operator adjusts the opening degrees of the valveand the flow control valveof the manifoldto charge the predetermined amount of carbon dioxide required for the cooling apparatusto operate into the refrigerant flow path.

In the first embodiment, the following advantages are obtained.

In the first embodiment, after the pre-charging is conducted to charge an inert gas into the refrigerant flow pathof the cooling apparatus(heat transferring apparatus) to bring pressures in the refrigerant flow pathof the cooling apparatusto a predetermined pressure, the main charging is conducted to charge a refrigerant into the refrigerant flow pathof the cooling apparatusto a predetermined amount required for the cooling apparatusto operate. Accordingly, it is possible to prevent difficulty of grasping a charging amount of the inert gas caused by dissolution of the inert gas into the refrigerant dissimilar to a case in which the inert gas is charged into the refrigerant flow path after the refrigerant is charged. Consequently, it is possible to easily grasp the charging amount of the inert gas charged separately from the refrigerant in a cooling apparatususing a thermodynamic cycle. Also, in the first embodiment, since the inert gas is charged before the main charging in which the refrigerant is charged into the refrigerant flow path, a pressure of the inert gas required to charge the refrigerant can be smaller as compared with the case in which the inert gas is charged after the refrigerant is charged. Accordingly, since a relatively high-pressure inert gas source is not necessarily provided, it is possible to easily charge the inert gas into the refrigerant flow path.

Also, since the charging charging amount of the inert gas into the refrigerant flow pathcan be grasped by charging the inert gas to a predetermined pressure, it is possible to easily grasp the charging amount of the inert gas as compared with a case in which the charging amount is measured based on a weight of the inert gas. In particular, in a case in which the amount of the inert gas required is small, since it is difficult to measure the charging amount based on its weight in some cases, the charging amount of the inert gas can be more effectively grasped by charging the inert gas to the predetermined pressure.

Also, in the first embodiment, the inert gas is charged to the predetermined pressure at which no cavitation occurs and no gas is produced in a pumparranged on the refrigerant flow pathof the cooling apparatusduring operation of the cooling apparatus(heat transferring apparatus) in the pre-charging step (step). According to this configuration, since the charging amount of the inert gas can be easily grasped by charging the inert gas in the pre-charging step (step) before stepas main charging of the refrigerant (carbon dioxide), the charging amount of inert gas, which is charged to prevent occurrence of cavitation, can be effectively and easily grasped by charging the inert gas to the predetermined pressure at which no cavitation occurs in the pre-charging step.

In the first embodiment, the inert gas is charged to bring the pressure in the refrigerant flow pathof the cooling apparatusto the predetermined pressure so as to bring the pressure of the refrigerant, which flows into the pumparranged on the refrigerant flow pathof the cooling apparatus, to not smaller than a saturation vapor pressure of the refrigerant during operation of the cooling apparatus(heat transferring apparatus) in the pre-charging step (step). According to this configuration, since the inert gas is charged in the pre-charging step (step), it is possible to more effectively and easily grasp that the inert gas is charged to the charging amount (setting amount), which is set to bring the pressure of the refrigerant flowing into the pumpduring operation of the cooling apparatusto not smaller than the saturation vapor pressure of the refrigerant.

Also, in the first embodiment, nitrogen as the inert gas is charged to bring the pressure in the refrigerant flow pathof the cooling apparatus(heat transferring apparatus) to the predetermined pressure in the pre-charging step (step). According to this configuration, occurrence of cavitation caused by the inert gas can be stably prevented by charging nitrogen, which is a relatively stable substance, as the inert gas. Accordingly, the cooling apparatuscan be more stably operated by charging nitrogen as the inert gas in the pre-charging step (step), and the charging amount of inert gas required for the cooling apparatusto more stably operate can be more effectively and easily grasped.

Also, in the first embodiment, the pre-charging is conducted by previously charging the inert gas into the refrigerant flow pathof the cooling apparatus(heat transferring apparatus) and then charging carbon dioxide (refrigerant) into the refrigerant flow pathof the cooling apparatus, in which a vacuum is generated, at a charging rate preventing that dry ice (solid) is produced to bring a pressure in the refrigerant flow pathof the cooling apparatusto not smaller than the triple point pressure of carbon dioxide. Accordingly, the main charging can be conducted to charge carbon dioxide into the refrigerant flow pathof the cooling apparatusto a predetermined amount of carbon dioxide required for the cooling apparatusto operate with the pressure in the refrigerant flow pathhaving been brought to the triple point pressure of carbon dioxide. Consequently, since carbon dioxide can be charged into the refrigerant flow pathin a pressure state in which no dry ice is generated during the main charging of carbon dioxide, it is possible to prevent occurrence of clogging of the refrigerant flow pathcaused by generation of dry ice without heating or cooling carbon dioxide. For these reasons, since an additional device heating or cooling carbon dioxide is not required dissimilar to a case in which carbon dioxide is heated or cooled when charging carbon dioxide, it is possible to prevent a complicated apparatus configuration of the apparatus charging carbon dioxide refrigerant into the refrigerant flow pathof the cooling apparatuswhile preventing occurrence of clogging of the refrigerant flow pathcaused by generation of dry ice without heating or cooling carbon dioxide.

In addition, following additional advantages can be acquired by conducting steps discussed below in the method for charging a refrigerant into the cooling apparatus(heat transferring apparatus) according to the first embodiment.

In the first embodiment, the main charging step (step) is activated based on the temperatures in the refrigerant flow pathof the cooling apparatus(heat transferring apparatus) falling within the predetermined temperature range. Accordingly, it is possible to activate the main charging of carbon dioxide after confirming that no temperature drop due to generation of dry ice has occurred in the refrigerant flow path. Consequently, it is possible to prevent clogging of the refrigerant flow pathcaused by generation of dry ice during the main charging of carbon dioxide.

Also, in the first embodiment, the charging rate of carbon dioxide in the pre-charging step (step) is smaller than the charging rate of carbon dioxide in the main charging step (step). Accordingly, it is possible to prevent a sharp drop in temperature of carbon dioxide caused by adiabatic expansion as compared with a case in which the charging rate of carbon dioxide in the pre-charging step is substantially equal to the charging rate of carbon dioxide in the main charging step. Consequently, it is possible to prevent carbon dioxide from becoming dry ice in the refrigerant flow pathdue to the sharp drop in temperature caused by adiabatic expansion. In addition, since the charging rate of carbon dioxide in the main charging step is greater than the charging rate of carbon dioxide in the pre-charging step, it is possible to reduce the time required for the main charging of carbon dioxide. Consequently, it is possible to reduce the time required to charge carbon dioxide to a predetermined amount required for the cooling apparatus(heat transferring apparatus) to operate.

The following description describes a method for charging a refrigerant into a cooling apparatusaccording to a second embodiment in which the refrigerant-charging control apparatusprovides indication to urge an operator to conduct an operation in the method for charging the refrigerant into the cooling apparatuswith reference to.

The refrigerant-charging control apparatusincludes a controllerand a display. The refrigerant-charging control apparatusis an example of a “refrigerant-charging control apparatus for a heat transferring apparatus” in the claims. The displayis an example of a “notifier” in the claims.

The controlleris configured to entirely control the refrigerant-charging control apparatus. The controllerincludes a processor such as a CPU, a memory, and the like. The controlleris configured to control charging of carbon dioxide refrigerant into the cooling apparatusby using control software (program) recorded (stored) in the internal or external memory (storage device).

The controllerperforms control to acquire temperatures of the refrigerant flowing through the refrigerant flow pathof the cooling apparatusdetected by temperature sensorsand. The controllerperforms control to acquire pressures of the refrigerant flowing through the refrigerant flow pathof the cooling apparatusdetected by pressure sensorsand. In other words, the controllercontrols the acquisition of the pressures in the refrigerant flow pathof the cooling apparatusdetected by the pressure sensorsand.