JP2006329149A - Heat transportation device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat transportation device and its control method for detecting the condition of working fluid in a fluid circuit and controlling operation properly based on the results of detection. <P>SOLUTION: This heat transportation device having a liquid pump 111 for absorbing liquid phase fluid in the circuit 110 and feeding it under pressure to transport heat using the fluid as a medium is provided with excessive cooling degree grasping means S200 to S280 for grasping degree of excessive cooling of fluid flowing into the liquid pump 111 from operation characteristic values of the liquid pump 111 or other equipment 116 in the circuit 110 or operation characteristic values of the fluid and operation condition changing means S400 to S450 for changing an operation condition of the liquid pump 111 or the other equipment 116 to increase degree of excessive cooling when the degree of excessive cooling obtained by the excessive cooling degree grasping means S200 to S280 is lower than a predetermined degree of excessive cooling fixed in advance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat transport device suitable for use in, for example, a Rankine cycle for recovering power from waste heat from an external heat source, and a control method thereof.

  Conventionally, as shown in Patent Document 1, for example, a Rankine cycle equipped with a refrigerator that cools a fluid in a fluid circuit between a condenser and a liquid pump is known. In this Rankine cycle, the liquid pump is started after operating the refrigerator.

As a result, when the Rankine cycle is started, the liquid phase fluid with a high degree of supercooling can be reliably supplied to the suction side of the liquid pump, and the suction refrigerant evaporates (boils) on the suction side of the liquid pump. This prevents the liquid pump from being lowered, prevents the liquid pump efficiency (volumetric efficiency) from being lowered, and efficiently operates the Rankine cycle.
JP 2004-340081 A

  However, even during the normal operation of the Rankine cycle, the degree of subcooling of the fluid on the suction side of the liquid pump may change due to, for example, fluctuations in the condensing capacity of the condenser, leading to a reduction in the efficiency of the liquid pump.

  Further, the Rankine cycle disclosed in Patent Document 1 does not include a concept of actively grasping the state of fluid during operation and performing a treatment operation according to the state.

  In view of the above problems, an object of the present invention is to provide a heat transport device and a control method thereof capable of detecting the state of the working fluid in the fluid circuit and enabling appropriate operation control based on the detection result. There is.

  In order to achieve the above object, the present invention employs the following technical means.

  In the first aspect of the present invention, in the heat transport device that has the liquid pump (111) that sucks and pumps the liquid phase fluid in the circuit (110), and transports heat using the fluid as a medium, the liquid pump (111) ), Or a supercooling degree grasping means (S200) for grasping the supercooling degree of the fluid flowing into the liquid pump (111) from the operating characteristic value of the other device (116) in the circuit (110) or the operating characteristic value of the fluid. To S280) and the supercooling degree obtained by the supercooling degree grasping means (S200 to S280) when the supercooling degree is lower than a predetermined predetermined supercooling degree, the liquid pump (111), or others The operation state changing means (S400 to S450) for changing the operation state of the device (116) is provided.

  As a result, regardless of when the circuit (110) is started or during normal operation, the degree of supercooling of the fluid is grasped, and operation control is performed so that the degree of supercooling is increased when the degree of supercooling is lower than the predetermined supercooling degree. The liquid phase fluid is reliably supplied to the liquid pump (111), and the efficient operation of the liquid pump (111) becomes possible.

  In the invention according to claim 2, the circuit (110) includes a steam generator (112) that heats the liquid phase fluid pumped from the liquid pump (111) with heat from an external high heat source to form superheated steam, and a steam An expander (113) that recovers power by expansion of superheated steam that flows out from the generator (112), and superheated steam that flows out from the expander (113) is condensed and liquefied to form a liquid pump (111 The Rankine cycle (110) having a radiator (116) that flows out to the) side.

  The Rankine cycle (110) is suitable for use with the present invention because there may be insufficient condensation of the fluid in the radiator (116) and the generation of gas-phase fluid due to suction of the liquid pump (111).

  The invention according to claim 3 is characterized in that the supercooling degree grasping means (S200 to S280) indirectly grasps the supercooling degree from the shaft torque of the liquid pump (111).

  In the liquid pump (111), the gas phase fluid increases with a decrease in the degree of supercooling, and since the liquid pump (111) requires compressibility, the degree of supercooling is reduced. Since there is a correlation with the shaft torque, the degree of supercooling can be easily grasped by using the shaft torque of the liquid pump (111).

  In the invention according to claim 4, the supercooling degree grasping means (S200 to S280) grasps the supercooling degree from any two of the pressure, temperature and density of the liquid phase fluid on the suction side of the liquid pump (111). It is characterized by doing.

  Thereby, the supercooling degree of a fluid can be grasped | ascertained directly and the system of supercooling degree grasping | ascertainment can be improved.

  The invention according to claim 5 is characterized in that the supercooling degree grasping means (S200 to S280) indirectly grasps the supercooling degree from the shaft torque of the expander (113).

  In the expander (113), the expansion work is ensured according to the flow rate of the fluid pumped from the liquid pump (111), so the shaft torque of the expander (113) is correlated with the fluid flow rate of the liquid pump (111). To do. Further, since the fluid flow rate correlates with the degree of supercooling, the degree of supercooling can be easily grasped by using the shaft torque of the expander (113).

  In the invention of claim 6, the expander (113) is connected to a generator (114) that is driven by the recovered power and generates electric power, and the axial torque of the expander (113) It is characterized by being grasped from the current generated in (114).

  Since the shaft torque of the expander (113) correlates with the current of the generator (114), the shaft torque of the expander (113) can be grasped from the current and is normally used for controlling the generator (114). It is possible to grasp the degree of supercooling by using the current signal.

  According to the seventh aspect of the present invention, the expander (113) is connected to the generator (114) that is driven by the recovered power and generates power, and the shaft torque of the expander (113) It is characterized by being grasped from the electric power generated in (114) and the rotation speed.

  Since the axial torque of the expander (113) is related to the generated power of the generator (114) and the rotational speed, the axial torque of the expander (113) can be grasped from the electric power and the rotational speed. It is possible to grasp the degree of supercooling by diverting the electric power and the rotational speed signal used for controlling the generator (114).

  The invention according to claim 8 is characterized in that the supercooling degree grasping means (S200 to S280) indirectly grasps the supercooling degree from the rotational speed of the expander (113).

  In the expander (113), expansion work is ensured according to the flow rate of fluid pumped from the liquid pump (111), and therefore the rotation speed of the expander (113) is correlated with the fluid flow rate of the liquid pump (111). To do. Further, since the fluid flow rate correlates with the degree of supercooling, the degree of supercooling can be easily grasped by detecting the rotational speed of the expander (113).

  The invention according to claim 9 is characterized in that the operating state changing means (S400 to S450) decreases the rotational speed of the liquid pump (111) and then gradually returns to the original rotational speed.

  As a result, the flow rate of the fluid pumped from the liquid pump (111) is reduced due to the decrease in the rotation speed of the liquid pump (111), the pressure loss due to the device (116) in the circuit (110) is reduced, and the liquid pump (111) is sucked. Since the fluid pressure on the side increases, the degree of supercooling can be increased. Then, after the degree of supercooling can be secured, the rotational speed of the liquid pump (111) may be returned to the original level.

  In the invention described in claim 10, when the supercooling degree cannot be increased to a predetermined supercooling degree or more by the operating state changing means (S400 to S450), the stopping means (S500 to S500) that stops the operation of the liquid pump (111). S520).

  As a result, if the degree of supercooling cannot be increased by the operating state changing means (S500 to S520), it is considered that the fluid filling amount in the circuit (110) is insufficient due to leakage or the like. 111) is stopped, it is possible to prevent the liquid pump (111) or other devices (112, 113, 116) from being damaged.

  In the invention described in claim 11, the radiator (116) is provided with a blower for supplying cooling air for cooling the superheated steam, and the operating state changing means varies the rotational speed of the blower. It is said.

  As a result, when the temperature difference between the saturation temperature (Tc) of the fluid in the radiator (116) and the cooling air temperature (Tb) is sufficiently larger than the predetermined supercooling degree, the rotational speed of the blower is increased and cooling is performed. The degree of supercooling can be increased by increasing the air volume.

  Further, when the temperature difference between the saturation temperature (Tc) of the fluid in the radiator (116) and the cooling air temperature (Tb) is smaller than the predetermined supercooling degree, the rotational speed of the blower is reduced or the blower is stopped. And the pressure of the fluid in a radiator (116) can be raised by reducing the amount of cooling air, and a supercooling degree can be raised in connection with this.

  Invention of Claim 12-Claim 22 is related with the control method for grasping | ascertaining the degree of supercooling in a heat transport apparatus (100), and the operation state change based on a degree of supercooling, The technical significance is Each is essentially the same as the heat transport device (100) according to claims 1-11.

  In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
In the first embodiment, the heat transport device of the present invention is applied to a Rankine cycle device 100 mounted on a vehicle including a traveling internal combustion engine (water-cooled engine). In the Rankine cycle apparatus 100, the operation of the Rankine cycle 110 is controlled by the control device 120 and the inverter 121. Hereinafter, the basic configuration of the Rankine cycle apparatus 100 will be described with reference to FIGS. 1 is a schematic diagram showing the Rankine cycle device 100, FIG. 2 is a schematic diagram showing the liquid pump 111, the control device 120, and the inverter 121, and FIG. 3A is a graph showing the axial torque of the liquid pump 111 with respect to the current of the inverter 121. FIG. 3B is a first control characteristic showing the relationship, and FIG. 3B is a second control characteristic showing the relationship of the axial torque of the liquid pump 111 with respect to the degree of supercooling.

  As illustrated in FIG. 1, the Rankine cycle 110 includes a liquid pump 111, a steam generator 112, an expander 113, and a radiator 116 that are connected in a ring shape. The liquid pump 111 is driven by a motor 111a described later, and circulates a refrigerant (corresponding to the fluid of the present invention) in the Rankine cycle 110.

  The steam generator 112 is a heat exchanger that heats the refrigerant pumped from the liquid pump 111 with waste heat of a water-cooled engine (not shown) as an external high heat source to produce superheated steam refrigerant. Specifically, inside the steam generator 112, a refrigerant flow path through which a refrigerant flows and a cooling water flow path through which engine cooling water (hot water) flows are formed close to each other so as to be opposed flow paths. Thus, heat exchange is performed between the cooling water and the refrigerant so that the refrigerant is heated. The engine coolant flows through the coolant flow path by the operation of a water pump connected to the engine and driven. A water temperature sensor (not shown) for detecting the temperature of the engine cooling water is provided on each of the inlet side and the outlet side of the cooling water flow path of the steam generator 112, and the detected temperature signal is a control device to be described later. 120 is input.

  The expander 113 is a fluid machine that generates a driving force (recovers thermal energy as mechanical energy) by the expansion of the superheated steam refrigerant flowing out from the steam generator 112, and the expander 113 includes the expander 113. A generator 114 that is driven by the driving force to perform the power generation function is connected. The expander 113 and the generator 114 form an energy recovery machine 113A. The electric power generated by the generator 114 is stored in the battery 115.

  The radiator 116 is a heat exchanger that condenses and liquefies the heat of the superheated vapor refrigerant (gas phase or gas-liquid two-phase) flowing out from the expander 113 with external air (external low heat source).

  As shown in FIG. 2, the liquid pump 111 is an electric pump driven by a motor 111a. A controller (ECU) 120 and an inverter 121 are connected to the motor 111a as control means for controlling the operation of the motor 111a (liquid pump 111). The control device 120 includes a supercooling degree grasping means, a supercooling degree determining means, an operating state changing means, and a stopping means for efficiently operating the Rankine cycle 110 (details will be described later).

  A signal for instructing the number of revolutions for the motor 111a is sent from the control device 120 to the inverter 121, and the inverter 121 supplies a current corresponding to the signal from the battery 115 to the motor 111a. The control device 120 includes a current value signal between the battery 115 and the inverter 121, an actual rotation number signal of the motor 111a from the inverter 121, and a vehicle speed signal obtained from a vehicle speed sensor (not shown) provided in the vehicle. , And a water temperature signal (inlet water temperature, outlet water temperature) obtained from a water temperature sensor provided in the cooling water flow path of the steam generator 112 is input, and the current value signal, actual rotation speed signal, vehicle speed signal are input. The water temperature signal is monitored by the control device 120.

  Further, the control device 120 stores in advance a first control characteristic shown in FIG. 3A and a second control characteristic shown in FIG. The first control characteristic is to calculate the shaft torque of the motor 111a (= the shaft torque of the liquid pump 111, corresponding to the operation characteristic value of the present invention) from the current value supplied to the motor 111a. The second control characteristic relates the axial torque of the liquid pump 111 and the degree of supercooling of the refrigerant flowing into the liquid pump 111, and the degree of supercooling to be the target of the refrigerant and the actual degree of supercooling. Used to keep track of which level is. The second control characteristic is that, as the degree of supercooling in the liquid pump 111 decreases, the gas-phase refrigerant increases, and the liquid pump 111 needs to be compressible. It shows the relationship.

  Next, the operation of the Rankine cycle apparatus 100 based on the above configuration will be described using the flowcharts shown in FIGS.

  As shown in FIG. 4, first, the control device 120 reads (inputs) a vehicle speed signal in step S100, and calculates an engine speed corresponding to the vehicle speed in step S110. In step S120, an engine cooling water flow rate (engine cooling water flow rate flowing through the steam generator 112) by a water pump that operates according to the engine speed is calculated.

  In step S130, the engine water temperature signal is read, and in step S140, the amount of waste heat obtained from the engine cooling water is calculated. This is calculated as a value proportional to the product of the engine coolant flow rate and the engine coolant temperature difference at the inlet / outlet of the steam generator 112. In step S150, the flow rate of refrigerant to be sent by the liquid pump 111 is determined from the amount of waste heat, and the target rotational speed of the liquid pump 111 for obtaining this flow rate of refrigerant is calculated. Note that the reading of the engine water temperature signal in step S130 may precede the step S100.

  And as shown in FIG. 5, the said liquid pump target rotation speed is output to the inverter 121 by step S200. Then, electric power (current) corresponding to the liquid pump target rotational speed is supplied from the inverter 121 to the motor 111a, the motor 111a is driven (step S210), and the liquid pump 111 is operated by this driving force. When the liquid pump 111 is operated, the refrigerant in the Rankine cycle 110 circulates in the order of the liquid pump 111 → the steam generator 112 → the expander 113 → the radiator 116 → the liquid pump 111.

  The refrigerant pumped from the liquid pump 111 is heated by the steam generator 112 to become superheated vapor refrigerant, flows into the expander 113, and the expander 113 is activated by the expansion of the heated vapor refrigerant to generate driving force. The The generator 114 is operated by the driving force of the expander 113 to generate power, and the generated electric power is stored in the battery 115. The refrigerant flowing out of the expander 113 is condensed and liquefied by the radiator 116 and flows out to the liquid pump 111 side.

  In step S220, the current value supplied to the inverter 121 (motor 111a) is read, and in step S230, the shaft torque corresponding to this current value (actual actual value of the liquid pump 111) is determined from the first control characteristic (FIG. 3A). (Corresponding to the shaft torque) is calculated.

  On the other hand, the target rotational speed of the expander 113 for maximizing the amount of power generated by the energy recovery machine 113A and the inlet side (suction side) pressure of the liquid pump 111 are input to the control device 120 (step S240, In step S260, the target high-pressure side pressure of the liquid pump 111 is calculated in step S260, and in step S270, the target high and low of the liquid pump 111 is calculated from the target high-pressure side pressure and the inlet side pressure. Calculate the pressure difference. In step S280, the target shaft torque of the liquid pump 111 for obtaining the target high / low pressure difference is calculated.

  In the second control characteristic (FIG. 3B), the degree of supercooling corresponding to the actual shaft torque of the liquid pump 111 obtained in step S230 corresponds to the actual degree of supercooling, and is obtained in step S280. The degree of supercooling corresponding to the target shaft torque thus obtained corresponds to the target degree of supercooling, and the degree of supercooling can be indirectly grasped with the shaft torque of the liquid pump 111. Steps S200 to S280 in FIG. 5 correspond to the supercooling degree grasping means in the first embodiment. Moreover, the order of execution of step S220 to step S230 and execution of step S240 to step S280 may be reversed.

  Next, as shown in FIG. 6, it is determined in step S300 whether or not the actual shaft torque (calculated value in step S230) of the liquid pump 111 is smaller than the target shaft torque (calculated value in step S280). No, that is, when the actual shaft torque is obtained to be equal to or greater than the target shaft torque, it is determined that the degree of subcooling of the refrigerant on the inlet side of the liquid pump 111 is sufficiently obtained, and the step In S310, the current control state (running state of Rankine cycle 110) is continued.

  However, if it is determined in step S300 that the actual shaft torque is smaller than the target shaft torque, it is determined that the degree of supercooling of the refrigerant on the inlet side of the liquid pump 111 has not been sufficiently obtained, and the degree of supercooling recovery is recovered. Therefore, the process proceeds to step S400 and subsequent steps in the flowchart shown in FIG. Note that step S300 in the first embodiment corresponds to a supercooling degree determination unit that determines the quality of the supercooling degree of the refrigerant using the shaft torque of the liquid pump 111.

  In step S400 shown in FIG. 7, the number of rotations of the liquid pump 111 (motor 111a) is temporarily reduced by a predetermined number of rotations (for example, 50 rpm). In the present embodiment, the degree of supercooling is recovered by utilizing the fact that the pressure on the inlet side of the liquid pump 111 is increased by the pressure loss of the Rankine cycle 110 by lowering the rotational speed of the liquid pump 111. That is, by reducing the number of revolutions of the liquid pump 111 to reduce the refrigerant pumping amount, the pressure loss associated with the refrigerant pumping amount in the equipment (particularly the radiator 116) in the Rankine cycle 110 is reduced, and the liquid pump 111 has a high pressure. The pressure drop from the side pressure is reduced and the inlet side pressure in the liquid pump 111 is increased to increase the degree of supercooling.

  In step S410 and step S420, the actual shaft torque and the target shaft torque that accompany the decrease in the rotation speed of the liquid pump 111 are calculated. In step S430, the newly obtained actual shaft torque is compared with the target shaft torque (calculated results in steps S410 and S420). If the actual shaft torque is greater than the target torque, the degree of supercooling is It determines with having recovered, it progresses to step S440, and raises the rotation speed of the liquid pump 111 to the original target rotation speed (calculation result in step S150). Here, if the rotational speed is suddenly increased, the pressure drop on the inlet side due to the suction of the liquid pump 111 becomes large, and the vaporization (boiling) of the refrigerant may occur and the degree of supercooling may decrease. Increase the rotational speed gradually, such as in% increments. In step S450, the current control state (running state of Rankine cycle 110) is continued. Steps S400 to S450 correspond to the operating condition changing means in the first embodiment.

  However, if it is determined in step S430 that the actual shaft torque is equal to or less than the target shaft torque (determined that the degree of supercooling does not recover), the rotation speed of the liquid pump 111 and a predetermined determination rotation speed (for example, 1000 rpm) are determined in step S500. ). If it determines with the rotation speed of the liquid pump 111 being higher than the determination rotation speed (determination of YES), it will return to step S400 and will repeat step S400-step S430.

  In step S400, the number of rotations of the liquid pump 111 is decreased by 50 rpm each time the process is repeated from step S500. Despite the execution of this repetitive control, if the degree of supercooling is not recovered (NO determination in step S430) and the rotation speed of the liquid pump 111 becomes equal to or less than the determination rotation speed in step S500 (NO determination), the basic In step S510, the liquid pump 111 (motor 111a) is stopped to stop the operation of the Rankine cycle 110 in step S520. Note that steps S500 to S520 correspond to the stopping means in the first embodiment.

  As described above, in the first embodiment, the supercooling degree grasping means (steps S200 to S280) grasps the supercooling degree of the refrigerant regardless of whether the Rankine cycle 110 is started or during normal operation. When the supercooling degree is smaller than the target supercooling degree in the determination of the supercooling degree by the supercooling degree determining means (step S300), the supercooling degree is set to the target supercooling degree by the operation state changing means (step S400 to step S450). Since the operation is controlled so as to be increased, the liquid phase refrigerant is surely supplied to the liquid pump 111, and the operation of the liquid pump 111 and thus the Rankine cycle 110 can be performed efficiently.

  As shown in FIG. 8 (a), the operation state changing means (lowering and increasing the rotational speed of the liquid pump 111) avoids a state of insufficient supercooling of the refrigerant, and increases the pressure on the high pressure side of the liquid pump 111. The boosting time can be increased in a short time, and the startup time of the Rankine cycle 110 can be shortened as compared with the conventional technique (without the operating state changing means) shown in FIG.

  In addition, since the liquid pump 111 has a correlation (second control characteristic) between the degree of supercooling and the shaft torque, the degree of supercooling can be easily achieved by using the shaft torque of the liquid pump 111. I can grasp it. For example, a sensor or the like for detecting the operation characteristics (pressure, temperature, etc.) of the refrigerant for grasping the degree of supercooling can be handled as unnecessary.

  If the degree of supercooling cannot be increased by the operating state changing means (steps S400 to S450), it is basically determined that the refrigerant charging amount in the Rankine cycle 110 is insufficient, and the stopping means (step S500). In step S520), the liquid pump 111 is stopped, so that it is possible to prevent the liquid pump 111 or other devices (112, 113, 116) from being damaged.

(Second Embodiment)
A second embodiment of the present invention is shown in FIGS. In the second embodiment, the degree of supercooling of the refrigerant is grasped from the pressure and temperature on the inlet side of the liquid pump 111 as the operation characteristic value of the refrigerant, compared to the first embodiment.

  Here, as shown in FIG. 9, a pressure sensor 131 that detects the pressure of the refrigerant and a thermometer 132 that detects the temperature of the refrigerant are provided on the inlet side of the liquid pump 111, and the refrigerant pressure obtained by the pressure sensor 131 is provided. The signal and the refrigerant temperature signal obtained by the thermometer 132 are input to the control device 120.

  In the second embodiment, the supercooling degree is grasped and the operation state is changed based on the flowchart shown in FIG. That is, after calculating the target rotational speed of the liquid pump 111 described in FIG. 4 (step S150), the control device 120 instructs the liquid pump target rotational speed to the inverter 121 (step S200), and the motor 111a (liquid pump 111). ) Is activated (step S210).

  In step S221 and step S222, the refrigerant temperature and refrigerant pressure on the inlet side of the liquid pump 111 are read (input), respectively, and in step S223, the saturation temperature of the refrigerant on the inlet side of the liquid pump 111 is calculated. The saturation temperature is the intersection of the constant pressure line at the refrigerant pressure value input in step S222 and the saturated liquid line of the refrigerant in the refrigerant phase state diagram (Mollier diagram) when the pressure and enthalpy are variables. Calculated. In step S231, the degree of supercooling is calculated as the difference between the saturation temperature and the refrigerant temperature. In the second embodiment, steps S200 to S231 in FIG. 10 correspond to the degree of supercooling degree grasping means.

  Next, in step S301, it is determined whether or not the degree of supercooling is smaller than 0. If it is determined as NO (NO), that is, if the degree of supercooling is determined to be 0 or more, the inlet of the liquid pump 111 is determined. It is determined that the degree of supercooling of the side refrigerant is sufficiently obtained, and the current control state (running state of Rankine cycle 110) is continued in step S310.

  However, if it is determined in step S301 that the degree of supercooling is smaller than 0, the process proceeds to step S400 and subsequent steps to recover the degree of supercooling. Note that step S301 corresponds to the degree of supercooling determination means for determining whether the degree of supercooling of the liquid pump 111 in the second embodiment is good or bad.

  In step S400, similarly to the first embodiment, the rotational speed of the liquid pump 111 (motor 111a) is once decreased by a predetermined rotational speed (for example, 50 rpm). Then, the degree of supercooling after the rotation speed of the liquid pump 111 is reduced in step S411 is calculated in the same manner as in step S231. In step S431, the newly obtained actual supercooling degree is compared with a predetermined target supercooling degree. If the actual supercooling degree is larger than the target supercooling degree, the supercooling degree is recovered. In step S440, the rotational speed of the liquid pump 111 is increased to the original target rotational speed (calculation result in step S150) in the same manner as in the first embodiment. In step S450, the current control state (running state of Rankine cycle 110) is continued. The steps S400, S411, S431, S440, and S450 correspond to the operating condition changing unit in the second embodiment.

  However, if the actual supercooling degree is less than or equal to the target supercooling degree in step S431 (the supercooling degree does not recover), steps S400 to S431 are repeated. In addition, between the step S431 and step S400, you may make it perform by providing the stop means (step S500-step S520) demonstrated in the said 1st Embodiment.

  Thereby, the supercooling degree of a refrigerant | coolant can be grasped | ascertained directly from a refrigerant | coolant pressure and a refrigerant temperature, and the system of supercooling degree grasping | ascertainment can be improved.

  As shown in FIGS. 11 and 12, the refrigerant density may be used instead of the refrigerant temperature as the operation characteristic value of the refrigerant, and a thermometer 132 is provided on the inlet side of the liquid pump 111 as shown in FIG. A density meter 133 can be provided instead of (FIG. 9).

  In grasping the degree of supercooling, as shown in FIG. 12, step S221 is abolished, the refrigerant density is read from the density meter 133 in step 224, and the refrigerant temperature is calculated from the refrigerant pressure and refrigerant density in step S225. In step S231, the degree of supercooling may be calculated.

(Third embodiment)
A third embodiment of the present invention is shown in FIGS. In the third embodiment, the degree of supercooling of the refrigerant is grasped from the axial torque of the expander 113 as the operation characteristic value of other equipment in the Rankine cycle 110, compared with the first embodiment. The shaft torque is calculated from the current value of the generator 114.

  As shown in FIG. 13, the generator 114 of the energy recovery machine 113 </ b> A is provided with a generator inverter 122, and the electric power generated by the generator 114 is stored in the battery 115 via the generator inverter 122. . Here, the current signal output from the generator 114 is input to the control device 120.

  The control device 120 stores in advance the third control characteristic shown in FIG. The third control characteristic relates the shaft torque of the expander 113 and the current value output from the generator 114, and the shaft torque of the expander 113 is calculated from the current value input to the control device 120. It has come to be.

  In the expander 113, expansion work is ensured according to the flow rate of the refrigerant pumped from the liquid pump 111, so that the axial torque of the expander 113 correlates with the refrigerant flow rate of the liquid pump 111. Further, since the refrigerant flow rate correlates with the degree of supercooling, the shaft torque of the expander 113 indirectly indicates the degree of supercooling.

  Hereinafter, the control for grasping the degree of supercooling using the shaft torque of the expander 113 will be described with reference to the flowchart shown in FIG.

  The flowchart shown in FIG. 15 is obtained by changing Step S220, Step S230, Step S270, and Step S280 to Step S226, Step S232, Step S271, and Step S281, respectively, with respect to that described in FIG. 5 of the first embodiment. It is.

  That is, when the Rankine cycle 110 is operated by driving the motor 111a of the liquid pump 111 in step S210, the expander 113 is operated, and the generator 114 generates power. Then, the control device 120 reads (inputs) the current value during power generation in step S226, and in step S232, the shaft torque corresponding to this current value from the third control characteristic (FIG. 14) (the actual shaft of the expander 113). (Corresponding to torque) is calculated.

  Further, after calculating the target high-pressure side pressure of the liquid pump 111 in step S260, the target high-low pressure difference of the expander 113 is calculated from the target high-pressure side pressure and the inlet side pressure in step S271. In step S281, the target shaft torque of the expander 113 for obtaining the target high / low pressure difference is calculated.

  Note that the actual shaft torque of the expander 113 obtained in step S232 corresponds to the actual degree of supercooling, and the target shaft torque obtained in step S281 corresponds to the target degree of supercooling. Steps S200 to S281 in FIG. 15 correspond to the supercooling degree grasping means in the third embodiment. Further, the order of execution of steps S226 to S232 and the execution of steps S240 to S281 may be reversed.

  Hereinafter, after step S281, the shaft torque and the target shaft torque in FIGS. 6 and 7 described in the first embodiment are handled and controlled as the shaft torque value of the expander 113.

  Thereby, by using the axial torque of the expander 113, the degree of supercooling can be easily grasped similarly to the first embodiment, and the operation of the liquid pump 111 can be performed efficiently. Here, since the generated current value of the generator 114 is detected and calculated in order to grasp the shaft torque of the expander 113, the current signal used for controlling the generator 114 is usually diverted. This makes it possible to grasp the degree of supercooling.

(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIG. In the fourth embodiment, the shaft torque of the expander 113 is calculated from the output (electric power) of the generator 114 and the rotational speed, as compared with the third embodiment.

  An output signal (product of a current signal and a voltage signal) of the generator 114 and a rotation speed signal e are input to the control device 120 from the generator inverter 122.

  Here, the control device 120 calculates the shaft torque Tr of the expander 113 from the output W obtained from the generator inverter 122 and the rotational speed Ne using the following formula 1.

(Equation 1)
Tr = W / (Ne × ηi × ηmg)
Where ηi is the efficiency of the generator inverter 122
ηmg is the efficiency of the generator 114 and is stored in the control device 120 in advance.

  The control device 120 controls the supercooling degree grasp using the shaft torque of the expander 113 using the flowchart shown in FIG. The flowchart shown in FIG. 16 is obtained by changing step S226 to step S227 and step S228 with respect to that described in FIG. 15 of the third embodiment.

  That is, when the Rankine cycle 110 is operated by driving the motor 111a of the liquid pump 111 in step S210, the expander 113 is operated, and the generator 114 generates power. The control device 120 reads (inputs) the rotational speed Ne of the expander 113 (generator 114) and the output W of the expander 113 (generator 114) in steps S227 and S228, respectively, and formula 1 in step S232. Is used to calculate the shaft torque of the expander 113 (corresponding to the actual shaft torque of the expander 113). The following steps are the same as those in the third embodiment.

  Note that the actual shaft torque of the expander 113 obtained in step S232 corresponds to the actual degree of supercooling, and the target shaft torque obtained in step S281 corresponds to the target degree of supercooling. Steps S200 to S281 in FIG. 16 correspond to the supercooling degree grasping means in the fourth embodiment. In addition, the execution of steps S227 to S232 and the execution of steps S240 to S281 may be reversed.

  Thereby, by using the shaft torque of the expander 113 calculated from the output W of the generator 114 and the rotational speed Ne, the degree of supercooling can be easily grasped similarly to the first embodiment, and the efficient liquid pump 111 can be obtained. Can be operated. Here, in order to grasp the shaft torque of the expander 113, the output W and the rotational speed Ne of the generator 114 are detected and calculated. Therefore, normally, an output signal used for controlling the generator 114 and It is possible to grasp the degree of supercooling by using the rotational speed signal.

(Fifth embodiment)
A fifth embodiment of the present invention is shown in FIG. In the fifth embodiment, the degree of supercooling of the refrigerant is grasped from the rotational speed of the expander 113 as the operating characteristic value of other equipment in the Rankine cycle 110, compared to the third and fourth embodiments. It is.

  Here, the rotational speed signal output from the generator 114 is input from the generator inverter 121 to the control device 120. In the expander 113, the expansion work is ensured according to the flow rate of the refrigerant pumped from the liquid pump 111. Therefore, the rotation speed of the expander 113 (the generator 114) correlates with the refrigerant flow rate of the liquid pump 111. . Further, since the refrigerant flow rate correlates with the degree of supercooling, the rotational speed of the expander 113 indirectly indicates the degree of supercooling.

  Hereinafter, the control for grasping the degree of supercooling using the rotation speed of the expander 113 will be described with reference to the flowchart shown in FIG.

  The controller 120 instructs the liquid pump 111 to rotate (step S200), drives the motor 111a of the liquid pump 111, and activates the Rankine cycle 110 (step S210). When Rankine cycle 110 is operated, expander 113 is operated, and the actual rotational speed of expander 114 is read (input) in step S229.

  Further, in step S241 and step S250, the target torque of the expander 113 for maximizing the power generation amount in the energy recovery machine 113A and the inlet side pressure of the liquid pump 111 are input, and in steps S260 and S271, respectively. The target high pressure and the target high / low pressure difference of the expander 113 are calculated, and the target rotational speed of the expander 113 is calculated from the result in step S282.

  Note that the actual rotational speed of the expander 113 obtained in step S229 corresponds to the actual supercooling degree, and the target shaft rotational speed of the expander 113 obtained in step S282 corresponds to the target supercooling degree. Become. Steps S200 to S282 in FIG. 17 correspond to the supercooling degree grasping means in the fifth embodiment.

  Next, in step S302, it is determined whether or not the actual rotational speed is smaller than the target rotational speed. If it is determined that the actual rotational speed is greater than or equal to the target rotational speed, It is determined that the degree of supercooling of the refrigerant on the inlet side of the liquid pump 111 is sufficiently obtained, and the current control state (the operation state of the Rankine cycle 110) is continued in step S310.

  However, if it is determined in step S302 that the actual rotational speed is smaller than the target rotational speed, the process proceeds to step S400 and subsequent steps in order to recover the degree of supercooling. Note that step S302 corresponds to a supercooling degree determination unit that determines whether the supercooling degree of the liquid pump 111 in the fifth embodiment is good or bad.

  In step S400, the inlet side pressure in the liquid pump 111 is increased by reducing the rotational speed of the liquid pump 111 (motor 111a) by a predetermined rotational speed (for example, 50 rpm) (same as in the first embodiment). Then, the actual rotation speed and the target rotation speed of the expander 113 associated with the decrease in the rotation speed of the liquid pump 111 are calculated in steps S412 and S421. In step S432, the newly obtained actual rotational speed is compared with the target rotational speed (calculated results in step S412 and step S421), and if the actual rotational speed is greater than the target rotational speed, the degree of supercooling In step S440, the rotational speed of the liquid pump 111 is increased to the original target rotational speed (calculation result in step S150). At this time, the rotational speed of the liquid pump 111 is gradually increased by 1%, for example. In step S450, the current control state (running state of Rankine cycle 110) is continued. Steps S400 to S450 correspond to the operating condition changing means in the fifth embodiment.

  However, if it is determined in step S432 that the actual rotational speed is equal to or lower than the target rotational speed (determined that the degree of supercooling does not recover), steps S400 to S432 are repeated. In addition, you may make it perform by providing the stop means (step S500-step S520) demonstrated in the said 1st Embodiment between step S432 and step S400.

  Thereby, by using the rotation speed of the expander 113, the degree of supercooling can be easily grasped similarly to the first embodiment, and the operation of the liquid pump 111 can be performed efficiently.

(Sixth embodiment)
A sixth embodiment of the present invention is shown in FIG. In the sixth embodiment, when the degree of supercooling of the refrigerant is equal to or lower than the target supercooling degree, the heat dissipating capacity of the radiator 116 is varied as the operating state changing means, compared to the first to fifth embodiments. The degree of supercooling is recovered. The variable heat dissipation capability of the radiator 116 corresponds to the variable rotation speed of a radiator fan (not shown).

Specifically, when the target supercooling degree is ΔTa, the temperature of the external air (cooling air) supplied to the radiator 116 by the radiator fan is Tb, and the saturation temperature of the refrigerant in the radiator 116 is Tc,
When ΔTa <(Tc−Tb), that is, when the temperature difference between the saturation temperature Tc and the external air temperature Tb is sufficiently large with respect to the target supercooling degree ΔTa, the heat dissipation capability of the radiator 116 is sufficient. Since it is obtained, control is performed to gradually increase the rotational speed of the radiator fan. By increasing the number of rotations of the radiator fan, the amount of heat dissipated in the radiator 116 increases, so that the degree of supercooling can be increased (X → Y in FIG. 18).

  Further, if ΔTa> (Tc−Tb), that is, if the temperature difference between the saturation temperature Tc and the external air temperature Tb is small with respect to the target supercooling degree ΔTa, sufficient heat dissipation capability by the radiator 116 is obtained. Since it is not possible, control is performed to stop the radiator fan until ΔTa = (Tc−Tb). By temporarily stopping the blower for the radiator, the refrigerant pressure (inlet side pressure of the liquid pump 111) in the radiator 116 can be increased to obtain the degree of supercooling (X → Z in FIG. 18).

(Other embodiments)
In the said 1st-6th embodiment, although demonstrated about what was made into the Rankine cycle 110 as a heat transport apparatus, you may apply not only to this but to a brine system, a thermal storage air-conditioning system, etc. As shown in FIG. 19, the brine system cools the secondary cycle refrigerant (for example, CO ₂ ) circulated by the liquid pump with the primary cycle refrigerant (NH ₃ ). In addition, the heat storage air conditioning system stores some or all of the air conditioning load in the heat storage tank as cold or hot heat using time other than the air conditioning time, and operates the liquid pump as needed during air conditioning. It is pumped up and supplied to the load side.

It is a mimetic diagram showing a Rankine cycle device in a 1st embodiment. It is a schematic diagram which shows the liquid pump, control apparatus, and inverter in 1st Embodiment. (A) is the 1st control characteristic which shows the relationship of the axial torque of the liquid pump with respect to an inverter electric current, (b) is the 2nd control characteristic which shows the relationship of the axial torque of the liquid pump with respect to a supercooling degree. It is a control flow for liquid pump target rotation speed calculation in a 1st embodiment. It is a control flow (supercooling degree grasping means) for grasping the degree of supercooling in the first embodiment. It is a control flow (supercooling degree determination means) for supercooling degree determination in 1st Embodiment. It is a control flow (an operation state change means and a stop means) for supercooling degree recovery | restoration in 1st Embodiment, and Rankine cycle protection. (A) is a graph which shows the rise time of the high pressure side pressure of the liquid pump in 1st Embodiment, (b) is a graph which shows the rise time of the high pressure side pressure of the liquid pump in a prior art. It is a schematic diagram which shows the Rankine-cycle apparatus in 2nd Embodiment. It is a control flow (supercooling degree grasping means, supercooling degree judging means, operation state changing means) for supercooling degree grasping, supercooling degree judgment, and supercooling degree recovery in the second embodiment. It is a schematic diagram which shows the Rankine cycle apparatus in the modification of 2nd Embodiment. It is a control flow (supercooling degree grasping means, supercooling degree judging means, operation state changing means) for supercooling degree grasping, supercooling degree judgment, and supercooling degree recovery in a modification of the second embodiment. It is a schematic diagram which shows the energy recovery machine in 3rd Embodiment, a control apparatus, and the inverter for generators. It is a 3rd control characteristic which shows the relationship of the shaft torque of the expander with respect to an inverter electric current. It is a control flow (supercooling degree grasping means) for supercooling degree grasping in a 3rd embodiment. It is a control flow (supercooling degree grasping means) for grasping the degree of supercooling in the fourth embodiment. It is a control flow (supercooling degree grasping means, supercooling degree judging means, operation state changing means) for supercooling degree grasping, supercooling degree judgment, and supercooling degree recovery in the fifth embodiment. It is a pressure-enthalpy diagram which shows the supercooling degree recovery state in 6th Embodiment. It is a schematic diagram which shows the brine system in other embodiment.

Explanation of symbols

100 Rankine cycle equipment (heat transport equipment)
110 Rankine cycle (circuit)
111 Liquid pump 112 Steam generator 113 Expander 114 Generator 116 Radiator (other equipment)
120 Control device 121 Inverter

Claims (22)

In a heat transport device having a liquid pump (111) for sucking and pumping a liquid phase fluid in a circuit (110), and transporting heat using the fluid as a medium,
The degree of supercooling of the fluid flowing into the liquid pump (111) from the operating characteristic value of the liquid pump (111) or another device (116) in the circuit (110) or the operating characteristic value of the fluid is determined. Supercooling degree grasping means (S200 to S280) to grasp,
When the supercooling degree obtained by the supercooling degree grasping means (S200 to S280) is lower than a predetermined supercooling degree, the liquid pump (111) or the other An operation state changing means (S400 to S450) for changing the operation state of the device (116). The circuit (110) includes a steam generator (112) that heats the liquid phase fluid pumped from the liquid pump (111) with heat from an external high heat source to form superheated steam;
An expander (113) for recovering power by expansion of the superheated steam flowing out from the steam generator (112);
It is a Rankine cycle (110) having a radiator (116) that condenses and liquefies the superheated steam flowing out from the expander (113) and flows out to the liquid pump (111) side as the liquid phase fluid. The heat transport device according to claim 1.   The heat transport according to claim 1 or 2, wherein the supercooling degree grasping means (S200 to S280) indirectly grasps the supercooling degree from an axial torque of the liquid pump (111). apparatus.   The supercooling degree grasping means (S200 to S280) grasps the supercooling degree from any two of the pressure, temperature and density of the liquid phase fluid on the suction side of the liquid pump (111). The heat transport device according to claim 1 or 2.   The heat transport device according to claim 2, wherein the supercooling degree grasping means (S200 to S280) grasps the supercooling degree indirectly from the axial torque of the expander (113). The expander (113) is connected to a generator (114) that is driven by the recovered power to generate power,
The heat transport device according to claim 5, wherein the shaft torque of the expander (113) is grasped from a current generated by the generator (114). The expander (113) is connected to a generator (114) that is driven by the recovered power to generate power,
The heat transport device according to claim 5, wherein the shaft torque of the expander (113) is grasped from electric power generated by the generator (114) and a rotational speed.   The heat transport device according to claim 2, wherein the supercooling degree grasping means (S200 to S280) grasps the supercooling degree indirectly from the rotational speed of the expander (113).   The operating state changing means (S400 to S450) reduces the rotational speed of the liquid pump (111) and then gradually returns it to the original rotational speed. The heat transport device according to claim 1.   Stop means (S500 to S520) for stopping the operation of the liquid pump (111) when the degree of supercooling cannot be raised to the predetermined degree or lower by the operating state changing means (S400 to S450). The heat transport device according to any one of claims 1 to 9, wherein The radiator (116) includes a blower for supplying cooling air for cooling the superheated steam,
The heat transport device according to any one of claims 1 to 8, wherein the operating state changing unit varies a rotational speed of the blower. A control method of a heat transport device having a liquid pump (111) for sucking and pumping a liquid phase fluid in a circuit (110), and transporting heat using the fluid as a medium,
The degree of supercooling of the fluid flowing into the liquid pump (111) from the operating characteristic value of the liquid pump (111) or another device (116) in the circuit (110) or the operating characteristic value of the fluid is determined. Grasp,
Changing the operating state of the liquid pump (111) or the other device (116) to increase the supercooling degree when the grasped supercooling degree is lower than a predetermined supercooling degree. A control method for a heat transport device. The circuit (110) includes a steam generator (112) that heats the liquid phase fluid pumped from the liquid pump (111) with heat from an external high heat source to form superheated steam;
An expander (113) for recovering power by expansion of the superheated steam flowing out from the steam generator (112);
It is a Rankine cycle (110) having a radiator (116) that condenses and liquefies the superheated steam flowing out from the expander (113) and flows out to the liquid pump (111) side as the liquid phase fluid. The method for controlling a heat transport device according to claim 12.   The method for controlling a heat transport device according to claim 12 or 13, wherein the degree of supercooling is indirectly grasped from an axial torque of the liquid pump (111).   The heat transport according to claim 12 or 13, wherein the degree of supercooling is determined from any two of pressure, temperature, and density of the liquid phase fluid on the suction side of the liquid pump (111). Control method of the device.   The method for controlling a heat transport device according to claim 13, wherein the degree of supercooling is indirectly grasped from a shaft torque of the expander (113). The expander (113) is connected to a generator (114) that is driven by the recovered power to generate power,
The method of controlling a heat transport device according to claim 16, wherein the shaft torque of the expander (113) is grasped from a current generated by the generator (114). The expander (113) is connected to a generator (114) that is driven by the recovered power to generate power,
The method for controlling a heat transport device according to claim 16, wherein the shaft torque of the expander (113) is obtained from the electric power and the rotational speed generated by the generator (114).   The method for controlling a heat transport device according to claim 13, wherein the degree of supercooling is grasped indirectly from the rotational speed of the expander (113).   20. The supercooling degree is increased by lowering the rotational speed of the liquid pump (111) and then gradually returning to the original rotational speed. The control method of the heat transport apparatus as described.   The operation of the liquid pump (111) is performed when the degree of supercooling cannot be increased beyond the predetermined degree of supercooling even if the operation state of the liquid pump (111) or the other device (116) is changed. The method for controlling a heat transport device according to any one of claims 12 to 20, wherein the control is stopped. The radiator (116) includes a blower for supplying cooling air for cooling the superheated steam,
The method for controlling a heat transport device according to any one of claims 12 to 19, wherein the degree of supercooling is increased by changing a rotation speed of the blower.

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