JP6464918B2 - Fluid transport device - Google Patents

Description

  The present invention relates to a fluid transportation device.

  Patent Document 1 describes that a fluid (specifically, air) is pulsated to generate a turbulence in the flow of the fluid, and the turbulence increases the efficiency of heat transfer from the fluid to other objects.

JP 2008-292743 A

  However, Patent Document 1 does not describe any specific pulsation in order to increase the heat transfer rate by generating disturbance in the fluid flow.

  The present invention has been made in view of the above points, and an object of the present invention is to generate a pulsation suitable for increasing the heat transfer rate by generating a disturbance in the flow of the fluid.

In order to achieve the above object, the invention according to claim 1 includes a heat exchanger (76) having a flow path through which a fluid flows and exchanging heat between the fluid and another object, and the fluid in the flow path. Pulsation generating means (52, 53) for pulsating the fluid, and when the fluid flow is a steady flow that flows in the flow direction in the flow path, the fluid flow in at least a part of the flow path is When it becomes a laminar flow, and the result of subtracting the pressure of the fluid at the downstream end in the flow direction of the flow path from the pressure of the fluid at the upstream end in the flow direction of the flow path, the pulsation generating means By pulsating the fluid in the flow path, a reverse gradient period (T3) in which the flow velocity of the fluid decreases and the front-rear pressure difference becomes negative is generated, and in the reverse gradient period, Distance from center In the position it is close to the distance from the inner wall surface (51a) facing the flow path than the to the flow direction is a fluid transport device, characterized in that to generate a reverse flow traveling in the opposite direction to the fluid.

  Thus, the pulsation generating means pulsates the fluid in the flow path, thereby generating a backflow in the fluid in the vicinity of the inner wall surface in the reverse gradient period in which the front-rear pressure difference is negative. When the backflow occurs, the fluid flow in the flow path is disturbed, and as a result, the heat transfer coefficient between the fluid and other objects is improved. That is, by pulsating the fluid so as to generate a backflow in the fluid, it is possible to realize pulsation suitable for increasing the heat transfer rate by generating turbulence in the fluid flow.

In addition, the invention according to claim 7 includes a heat exchanger (76) having a flow path through which the fluid flows and exchanging heat between the fluid and another object, and generation of pulsation to pulsate the fluid in the flow path. Means (52, 53), and when the fluid flow is a steady flow in the flow direction in the flow path, the fluid flow in at least a part of the flow path is a laminar flow,
The pulsation generating means pulsates the fluid in the flow path from a state where the flow of the fluid in the flow path is a steady flow flowing in a flow direction based on a predetermined condition being satisfied. Thus, the fluid transport device is characterized in that the fluid flow is disturbed.

  The power energy required to generate pulsation is often higher than the power energy required to generate a steady flow. Therefore, by selecting a time when a predetermined condition is satisfied, that is, when a condition that requires an increase in the heat transfer performance of the heat exchanger is satisfied, a pulsating flow is generated. Power energy can be saved effectively.

  In addition, the code | symbol in the bracket | parenthesis in the said and the claim shows the correspondence of the term described in the claim, and the concrete thing etc. which illustrate the said term described in embodiment mentioned later. .

It is a block diagram of the experimental apparatus which concerns on 1st Embodiment. It is a figure which shows the voltage applied to the pump 52 in experiment. It is a figure which shows an example of the change of Reynolds number Re of 1st fluid, and pressure gradient -dp / dx. It is a figure which shows the change of Reynolds number Re and pressure gradient -dp / dx of the 1st fluid in one experiment. It is a graph showing the average Reynolds number _Reave of an experimental result, and heat-transfer coefficient ratio. It is a figure which shows the flow velocity vector of the 1st fluid in an acceleration period. It is a figure which shows the flow velocity vector of the 1st fluid in the deceleration period initial stage. It is an enlarged view of the VIII part of FIG. It is a figure which shows the flow velocity vector of the 1st fluid in the deceleration period middle period. It is an enlarged view of the X part of FIG. It is a figure which illustrates the change of the flow of the 1st fluid in a channel. It is a graph showing the dimensionless pressure gradient and heat transfer coefficient ratio of an experimental result. It is a flowchart of the process which a control apparatus performs in 2nd Embodiment. It is a flowchart of the process which a control apparatus performs in 3rd Embodiment. It is a figure which shows the shape of the inner wall surface 50a in 4th Embodiment. It is a figure which shows the shape of the inner wall surface 50a in 5th Embodiment. It is a figure which shows the flow path in 6th Embodiment, and the shape of the periphery. It is a figure which shows the flow path in 6th Embodiment, and the shape of the periphery.

(First embodiment)
The first embodiment will be described below. First, an experiment conducted by the inventor of the present application will be described. In the experimental apparatus shown in FIG. 1 (corresponding to an example of a fluid transport apparatus), a constant temperature water tank 51 for cooling the first fluid is provided in a part of the main pipe 50 through which the first fluid (specifically water) circulates. It is attached. In addition, an electric pump (more specifically, a DC pump and a positive displacement gear pump) that drives the first fluid is disposed downstream of the constant temperature water tank 51 in the main pipe 50. Then, a pump supply voltage is applied to the pump 52 by the control device 53, and the pump 52 operates with an output that increases as the pump supply voltage increases. The control device 53 is constituted by, for example, a DC power source and a function generator, and the supply voltage from the control device 53 to the pump 52 is variable.

  A flow meter 54 for measuring the flow rate of the first fluid is disposed downstream of the pump 52 in the main pipe 50. In addition, a first temperature sensor 55 that detects the temperature of the first fluid is disposed downstream of the flow meter 54 in the main pipe 50, and a first pressure sensor 56 that detects the pressure of the first fluid is further downstream of the first temperature sensor 55. Has been placed. A second pressure sensor 57 that detects the pressure of the first fluid is disposed downstream of the first pressure sensor 56.

  From the position where the first pressure sensor 56 of the main pipe 50 is disposed to the position where the second pressure sensor 57 is disposed is the pressure gradient measuring unit 61. The differential pressure gauge 58 detects a pressure gradient in the pressure gradient measuring unit 61, that is, a value obtained by subtracting the pressure detected by the second pressure sensor 57 from the pressure detected by the first pressure sensor 56.

  The main pipe 50 in the pressure gradient measuring unit 61 forms a straight circular pipe flow path, the inner diameter of the main pipe 50 is 9 mm, and the length in the longitudinal direction (fluid flow direction) is 2000 mm. Further, a second temperature sensor 59 for detecting the temperature of the first fluid is disposed downstream of the second pressure sensor 57 in the main pipe 50.

  Further, in the pressure gradient measuring unit 61, the part from the position of 1000 mm to the position of 1100 mm from the upstream end is a visualization unit 62 made of a transparent acrylic tube having a length of 100 mm. The portion other than the visualization unit 62 in the pressure gradient measurement unit 61 is configured by a stainless steel tube (that is, a SUS tube).

Further, the experimental apparatus is provided with a sub pipe 70 in which a second fluid (specifically, water) circulates, and a thermostat 71 for heating the second fluid is disposed in a part of the sub pipe 70, A pump 72 that drives the second fluid is disposed downstream of the thermostatic chamber 71. A flow meter 73 for measuring the flow rate of the second fluid is disposed downstream of the pump 72 in the sub pipe 70. Further, a third temperature sensor for detecting the temperature of the second fluid is provided downstream of the flow meter 73 in the sub pipe 70. The sub pipe 70 includes an outer pipe 70 a downstream of the third temperature sensor 74. The outer pipe 70a is disposed so as to surround the main pipe 50 by contacting a portion of the pressure gradient measuring unit 61 from a position 1100 mm to a position 1600 mm from the upstream end. Thereby, the said part of the main pipe 50 and the outer pipe 70a comprise the counterflow type double pipe type heat exchanger 76. FIG. The inner diameter of the outer tube 70a is 14 mm, and the length of the heat exchanger 76 in the longitudinal direction is 500 mm. This convection type double tube heat exchanger 76 corresponds to a heat transfer coefficient measuring unit used for measuring the heat transfer coefficient of the first fluid.

  Further, a fourth temperature sensor 75 for detecting the temperature of the second fluid at the position is disposed downstream of the outer tube 70a in the sub tube 70.

The flow rate of the second fluid flowing through the secondary pipe 70 is 1.5 × 10 ⁻⁵ m ³ / s, and the temperature of the second fluid flowing into the outer pipe 70a (the temperature detected by the third temperature sensor 74) is 333K. Thus, the temperature of the thermostatic chamber 71 is adjusted. Further, the temperature of the constant temperature water tank 51 is adjusted so that the temperature of the first fluid at the inlet of the pressure gradient measuring unit 61 (the temperature detected by the first temperature sensor 55) is 288K. When the flow of the first fluid is visualized, polystyrene particles having an average particle diameter of 55 μm and a specific gravity of 1.02 are mixed in the first fluid.

  The inventor conducted the following experiment using such an experimental apparatus. First, the control device 53 controls the operation of the pump 52 to generate a pulsating flow in the first fluid in the main pipe 50. The pulsating flow is a flow whose flow rate periodically changes, and is a flow that flows in one direction as a bulk.

  More specifically, by periodically applying a pump supply voltage as shown in FIG. 2 from the control device 53 to the pump 52, the output of the pump 52 is periodically changed. Specifically, in each one cycle T, first, in the first period a, the pump supply voltage is linearly increased from the minimum value Vmin to the maximum value Vmax. In the subsequent second period c, the pump supply voltage is maintained at the maximum value Vmax, and in the subsequent third period b, the pump supply voltage is linearly decreased from the maximum value Vmax to the minimum value Vmin. Thereafter, the pump supply voltage is maintained at the minimum value Vmin until the current cycle T ends.

  In the experiment, 0.27 seconds was adopted as the length of the first period a for increasing the output of the pump 52 and the length of the second period c for maintaining the output of the pump 52, respectively. Further, the length of the third period b for reducing the output of the pump 52 is 4 types of 0 seconds, 0.09 seconds, 0.18 seconds, and 0.27 seconds. Further, the length of one cycle T is 1.82 seconds, and the frequency is 0.55 Hz.

The inventor conducted a plurality of experiments under the above-described conditions. In each experiment, the heat transfer ratio, the change in the Reynolds number Re of the first fluid and the pressure gradient −dp / dx as illustrated in FIG. The change of was measured. The Reynolds number Re of the first fluid is calculated based on the previously known characteristics of the first fluid, the known inner diameter of the main pipe 50, and the flow rate measured by the flow meter 54. Specifically, it is obtained by the equation Re = u [m / s] × De [m] / ν [m ² / s]. Here, u is the flow velocity of the first fluid, De is the representative diameter (specifically, the inner diameter) of the pressure gradient measuring unit 61, and ν is the kinematic viscosity of the first fluid.

As shown in FIG. 3, when the pump supply voltage fluctuates periodically as shown in FIG. 2 and a pulsating flow is generated in the first fluid, the first fluid also periodically pulsates with the same period T, and the first fluid The Reynolds number Re and the pressure gradient -dp / dx also periodically vary with the same period T as the pump supply voltage. Here, the change of the Reynolds number Re of a fluid in each period T, the difference between the maximum Reynolds number Rmax and the minimum Reynolds number _{Re min} and Reynolds number amplitude DRE, and dividing the Reynolds number amplitude dR an average Reynolds number _{Re ave} The result is called the amplitude ratio.

As experimental results to be described later, only those having an average Reynolds number Re _ave of 500 to 2000 and an amplitude ratio of 1.5 are used. Such a region having an average Reynolds number Re _ave is realized in a flow channel inside a heat exchanger in which a large number of flow channels are arranged in parallel and the hydraulic diameter of each flow channel is small.

  Here, the pressure gradient −dp / dx and the heat transfer coefficient ratio measured in each experiment will be described. In each experiment, the Reynolds number change, pressure gradient change, and heat transfer coefficient of the first fluid are measured.

As the pressure gradient, a value (unit: N / m ³ ) obtained by dividing the measured value of the pump differential pressure gauge 58 by the total length (that is, 2000 mm) of the pressure gradient measuring unit 61 is adopted.

  In this experiment, water that is an incompressible fluid and a liquid is used as the first fluid, and therefore the pressure gradient is the same in any part of the pressure gradient measurement unit 61. Therefore, the pressure gradient −dp / dx obtained in this experiment is consistent with the local pressure gradient of the first fluid in any part of the heat exchanger 76, and in the entire arbitrary section of the heat exchanger 76. It corresponds to the pressure gradient of the first fluid. For example, it matches the value obtained by dividing the pressure difference between the front and rear of the double-pipe heat exchanger 76 by the distance between the front and rear.

The heat transfer coefficient is specified based on the temperature of the second fluid measured by the third temperature sensor 74 and the temperature of the first fluid measured by the second temperature sensor 59. Further, from the Reynolds number change of the first fluid, the minimum Reynolds number Re _min , maximum Reynolds number Re _max , average Reynolds number Re _ave , and amplitude ratio per cycle T are specified.

  The heat transfer coefficient ratio in each experiment is the steady flow of the flow of the first fluid having the same Reynolds number as the average Reynolds number measured in the experiment. It is the value divided by the heat transfer coefficient when

  Here, the heat transfer coefficient when the flow of the first fluid is a steady flow is a state in which the first fluid is driven at a constant flow rate by applying a constant voltage to the pump 52 in the experimental apparatus in FIG. It is measured in the same manner as the above experiment. At that time, by adjusting the output of the pump 52, a steady flow having a desired Reynolds number by the first fluid can be realized. When the flow of the first fluid is a steady flow, the flow is a laminar flow in the entire pressure gradient measuring unit 61 of the main pipe 50. Here, the laminar flow refers to a flow that moves regularly on the streamline. On the other hand, the disturbance of the flow means that the flow moves irregularly in time and space.

  In the experimental results obtained in this way, the pressure gradient −dp / dx when the first fluid is pulsated fluctuates at the same period T as the pump supply voltage. Typically, it changes as shown in FIG. Specifically, in the first period “a”, the pressure gradient −dp / dx first increases with an increase in the pump supply voltage, but the pressure gradient −dp / dx reaches a peak at a certain point in time, and thereafter the pump supply is increased. The pressure gradient -dp / dx decreases as the voltage increases.

  Further, while the pump supply voltage is maintained in the second period c, the pressure gradient −dp / dx generally decreases while being generally positive. Thereafter, in the third period b, the pressure gradient −dp / dx decreases more rapidly than before and turns negative. Thereafter, the pressure gradient −dp / dx gradually increases until the third period b ends and the next first period starts.

  Here, according to the change of pressure gradient -dp / dx, it divides | segments into one period T, acceleration period T1, and deceleration period T2. The acceleration period T1 is a period from the start point of the first period a (that is, the increase start point of the pump supply voltage) to the point when the pressure gradient −dp / dx first changes from positive to negative in the second period b. . The deceleration time T2 is a period from the time point when the pressure gradient −dp / dx first changes from positive to negative in the second period b to the start point of the next first period (that is, the increase start point of the pump supply voltage). is there.

The experimental results thus obtained will be described below. First, as one of the experimental results, FIG. 4 shows waveforms of Reynolds number Re and pressure gradient −dp / dx when Re _ave is 2000 and the length of the third period b is 0.09 seconds.

  Immediately after the start of one cycle (t = 0), the pressure gradient −dp / dx greatly increased, and the Reynolds number Re also increased accordingly. Thereafter, the pressure gradient −dp / dx starts to decrease while the pump supply voltage increases, but the Reynolds number Re continues to increase because the pressure gradient −dp / dx is positive.

  Thereafter, immediately after the Reynolds number Re reaches the maximum Reynolds number, the pressure gradient −dp / dx becomes negative for a short period. This is a result of the pump supply voltage changing from an increased state to a constant state.

  Thereafter, at time t = 0.54 seconds, the pressure gradient −dp / dx begins to decrease more rapidly than before, as the pump supply voltage begins to decrease. Thereafter, the pressure gradient −dp / dx becomes negative and the Reynolds number Re decreases. This time point (t = 0.58 seconds) when the pressure gradient −dp / dx becomes negative is a time point when the acceleration period T1 shifts to the deceleration period T2.

  In the deceleration period T2, the pressure gradient −dp / dx rises after reaching the lower limit value once and turns from negative to positive, but from the start of the deceleration period T2, the time point when the pressure gradient first turns positive after that. This period is referred to as a reverse gradient period T3 (see FIG. 3).

Next, FIG. 5 shows a result of plotting a plurality of experimental results including the above one experimental result on a coordinate plane with the vertical axis representing the heat transfer coefficient ratio and the horizontal axis representing the average Reynolds number Re _ave . In addition, the rhombus in FIG. 5 shows the experimental result when the third period b is 0.0 seconds, the square shows the experimental result when the length of the third period b is 0.09 seconds, and the triangle shows the experimental result when the third period b is The experimental result of 0.18 seconds is shown, and the circle shows the experimental result of the third period b being 0.27 seconds. In all these experiments, the heat transfer coefficient ratio is greater than 1, which means that the heat transfer coefficient increased with respect to the steady flow due to the pulsating flow.

  FIG. 6 to FIG. 10 show velocity vectors obtained by visualization with respect to the experimental results shown in FIG. 6 to 10, the direction from the left to the right in the drawing corresponds to the flow direction of the pressure gradient measurement unit 61 (that is, the direction from the upstream to the downstream along the longitudinal direction of the flow path). Here, the flow direction is the same as the direction in which the pump 52 urges the first fluid in a state where the flow of the first fluid is a steady flow. 6, 7, and 9 correspond to the inner wall surface 50 a that faces the flow path in the main pipe 50. Moreover, in each figure, the direction and length of the arrow represent the direction and speed of the flow rate of the first fluid, respectively.

  In visualization, polystyrene particles (average particle size 55 μm, specific gravity 1.02) were mixed in the first fluid as described above, and the visualization unit 62 was photographed with a high-speed camera. And the flow velocity vector of the 1st fluid was obtained by carrying out the PIV process of the picked-up image. As a light source at the time of photographing, transmitted light from a metal halide lamp was used.

  The visualization unit 62 is outside the heat exchanger 76. However, the visualization unit 62 is located immediately upstream of the heat exchanger 76, and the flow channel shape of the main pipe 50 in the heat exchanger 76 and the flow channel shape of the visualization unit 62 are exactly the same. Therefore, the characteristic of the flow velocity vector of the first fluid in the visualization unit 62 is also the characteristic of the flow velocity vector of the first fluid in the heat exchanger 76.

  As shown in FIG. 6, the velocity vector of the first fluid is only parallel to the longitudinal direction of the main pipe 50 until t = 0.58 seconds when the acceleration period T1 changes to the deceleration period T2. That is, the flow of the first fluid is in a laminar flow state without disturbance.

  In the reverse gradient period T3 after t = 0.7 seconds immediately after the reverse pressure gradient starts to be applied, as shown in FIGS. 7 and 8, the vicinity of the inner wall surface of the main pipe 50 (rather than the distance from the center portion of the flow path). In the flow path at a position closer to the inner wall surface), a reverse flow (see the oval frame in FIG. 8) in which the first fluid travels in the direction opposite to the biasing direction of the pump 52 occurred. The energizing direction of the pump 52 is an energizing direction when realizing a steady flow.

  Thereafter, as shown in FIGS. 9 and 10, at t = 1.0 second, the flow in the direction perpendicular to the longitudinal direction of the main pipe is separated from the vicinity of the inner wall surface of the main pipe 50 (see the inside of the ellipse frame in FIG. 10). ) Occurred. That is, the first fluid flow was disturbed. Note that the reverse gradient period T3 has already passed at the time point of t = 1.0 seconds.

  At the time point of t = 1.0 seconds, as shown in FIG. 4, although the Reynolds number Re of the first fluid is lower than 2000 and further lower than 1500, the flow of the first fluid is disturbed. It has occurred.

  Conventionally, in a steady flow, a flow having a Reynolds number of 2000 or less is a laminar flow, and a flow having a Reynolds number of 3000 or more is a turbulent flow. However, in this embodiment, the disturbance occurs at a Reynolds number lower than 2000 and further lower than 1500. Therefore, by generating the backflow by the pulsating flow, the flow is disturbed even at a low Reynolds number as compared with the conventional case, thereby improving the heat transfer performance of the first fluid.

  In addition, this turbulence was observed to propagate downstream along the flow. Thereafter, before the acceleration period T1 of the next cycle, the velocity vector returned to only one parallel to the longitudinal direction of the main pipe 50. That is, the first fluid returned to the laminar flow state. The heat transfer coefficient ratio in this experimental result was 1.35.

  Hereinafter, the significance of the above experimental results will be described. The pulsating flow of the first fluid is reverse to the main flow (flow along the main pipe 50 in the same direction as the urging direction of the pump 52) in the vicinity of the inner wall surface of the main pipe 50 by applying a reverse pressure gradient in the deceleration period T2. Occurred. This is considered to be a phenomenon similar to the separation observed when a reverse pressure gradient is applied to a steady laminar flow.

  According to the above experimental results, the phenomenon shown in FIG. 11 occurs in the first fluid inside the heat exchanger 76. 11A to 11D, the flow velocity vectors 80 a to 80 d of the first fluid in the flow passage surrounded by the inner wall 50 a of the main pipe 50 in the heat exchanger 76, in a plane perpendicular to the longitudinal direction of the main pipe 50. The flow velocity distributions 81a to 81d of the first fluid and the shear force distributions 82a to 82d of the first fluid in the plane are shown.

  As shown in FIGS. 11 (a) and 11 (b), in the early and middle late periods of the acceleration period T1 (including the time when the Reynolds number Re is maximum), the flow velocity vectors 80a and 80b are directed in the mainstream direction. The first fluid is in a laminar flow state. Further, the flow velocity is highest at the central portion of the flow path and decreases as it approaches the inner wall surface 51a.

  Thereafter, in the initial stage of the deceleration period T2 (reverse gradient period T3), as shown in FIG. 11C, the flow rate of the first fluid decreases in the entire flow path, so that the reverse flow near the inner wall surface 50a of the main pipe 50 occurs. 80c is produced. Then, the direction of the shearing force 82c becomes the opposite direction to the main flow at the center of the flow path, and the difference between the maximum value and the minimum value of the shearing force 82c becomes the largest. Therefore, the first fluid is likely to generate a vortex in the vicinity of the inner wall surface 50a.

  As a result, as shown in FIG. 11D, in the middle and late stages of the deceleration period T2, the first fluid flow 80d is disturbed in the vicinity of the inner wall surface 50a. Further, the disturbance is propagated to the center of the flow path, and as a result, the Reynolds number Re is greatly reduced and minimized, so that the heat transfer coefficient ratio is increased.

  Next, FIG. 12 shows a result of plotting a plurality of experimental results including the above one experimental result on a coordinate plane in which the vertical axis represents the heat transfer coefficient ratio and the horizontal axis represents the dimensionless pressure gradient during deceleration. Here, the dimensionless pressure gradient is a value obtained by dividing the average value of the pressure gradient −dp / dx in the deceleration period T2 by the average value of the pressure gradient −dp / dx in one cycle T of pulsation. This value is the same as the result obtained by dividing the value obtained by averaging the pressure difference across the flow path of the heat exchanger 76 for the deceleration period T2 by the value obtained by averaging the pressure difference before and after the period T.

  Here, the pressure difference between the front and rear of the heat exchanger 76 is the pressure of the first fluid downstream in the flow direction of the flow path from the pressure of the first fluid at the upstream end of the flow path of the first fluid in the heat exchanger 76. Is the result of subtracting.

  The average value of the pressure gradient −dp / dx in the deceleration period T2 is represented by a symbol in FIG. 3 and FIG. 12 with a horizontal bar indicating the average above −dp / dx and a subscript T2. . Further, the average value of the pressure gradient -dp / dx in one cycle T of pulsation is a symbol in which a horizontal bar indicating the average is added above -dp / dx and a subscript T is added in FIG. 3 and FIG. It is represented.

In addition, diamonds in FIG. 12 indicate experimental results with an average Reynolds number Re _ave of 2000, asterisks (*) indicate experimental results with an average Reynolds number Re _ave of 1500, and circles indicate an experiment with an average Reynolds number Re _ave of 1000. Results are shown, triangles show experimental results with an average Reynolds number Re _ave of 750, and squares show experimental results with an average Reynolds number Re _ave of 500.

  As shown from this graph, there is a strong negative correlation between the dimensionless pressure gradient during deceleration and the heat transfer coefficient ratio. Specifically, the heat transfer coefficient ratio tends to increase as the dimensionless pressure gradient during deceleration decreases.

  The small dimensionless pressure gradient during deceleration indicates that the average pressure gradient −dp / dx in the deceleration period T2 is smaller than the average pressure gradient −dp / dx in the period T. That is, the greater the degree of deceleration of the first fluid in the deceleration period T2, the smaller the dimensionless pressure gradient during deceleration. As a result, the heat transfer coefficient ratio increases and the heat transfer performance improves.

  Further, in the example in which the dimensionless pressure gradient during deceleration was −0.4 or more, no backflow was observed in the vicinity of the inner wall surface 51a of the visualization unit 62 during the deceleration period T2. The generation of the backflow was not confirmed because the flow velocity was very small, and the backflow did not always occur. That is, in the example in which the non-dimensional pressure gradient is −0.4 or more, there is a possibility that a slight backflow is generated in the vicinity of the inner wall surface 51a during the deceleration period T2, or there is a possibility that no backflow is generated at all. In general, in a pulsation in which a weak deceleration is applied for a very short time, backflow does not occur and turbulence hardly occurs.

  Therefore, as the first fluid is decelerated more strongly, the back flow becomes more conspicuous, and the turbulence generated in the flow of the first fluid becomes larger. Further, when the turbulence generated in the flow of the first fluid increases, the portion of the first fluid that exchanges heat with another object (second fluid in this experiment) near the wall surface 50a moves away from the wall surface 50a. , Heat transfer is promoted and heat transfer efficiency is improved. This effect appears in the experimental results of FIG.

  Note that the positive displacement gear pump used in the above experiment has a higher degree of deceleration of the first fluid when the pump supply voltage is lowered than the centrifugal pump. It is relatively suitable for the purpose of improving heat transfer performance.

  As described above, in the present embodiment, the heat exchanger 76 that has a flow path through which the first fluid flows and exchanges heat between the first fluid and the second fluid (corresponding to an example of another object), and the flow A pump 52 and a control device 53 that pulsate the first fluid in the passage are provided. When the flow of the first fluid in the flow path is a steady flow that flows in the flow direction, the flow of the first fluid in the flow path becomes a laminar flow. The pump 52 pulsates the first fluid in the flow path to generate a reverse gradient period (T3) in which the pressure difference between the front and rear is negative, and in the reverse gradient period, a central portion of the flow path A fluid transporting device that causes the first fluid to generate a backflow that travels in a direction opposite to the flow direction at a position closer to the flow path from the inner wall surface that faces the flow path than the distance from the flow path.

  In this way, the pulsation generating means pulsates the first fluid in the flow path, thereby generating a back flow in the first fluid in the vicinity of the inner wall surface in the reverse gradient period in which the front-rear pressure difference is negative. When the backflow occurs, the flow of the first fluid in the flow path is disturbed, and as a result, the heat transfer coefficient between the first fluid and another object is improved. That is, the first fluid is pulsated by controlling the pressure difference before and after the heat exchanger 76 in the pulsation cycle T, the acceleration period T1, the deceleration time T2, and the deceleration period T2 so as to generate a backflow in the first fluid. Thus, it is possible to realize pulsation suitable for increasing the heat transfer coefficient by generating disturbance in the fluid flow.

  In addition, because at least a part of the flow path is laminar in the steady flow state, turbulence due to pulsation and backflow occurs in the flow where the flow was laminar during steady flow, resulting in a heat transfer coefficient. Will improve. In the present embodiment, the entire flow path is a laminar flow in a steady flow state.

  In addition, in this embodiment and each subsequent embodiment, the part which exists in the constant temperature water tank 51 in the main pipe 50 and the constant temperature water tank 51 discharge | release the heat | fever of the 1st fluid as a whole (it is also a heat exchanger). It corresponds to an example. The heat exchanger 76 corresponds to an example of a cooler that cools the second fluid. Moreover, the part except both the part which comprises the heat exchanger 76 in the main pipe 50, and the part which exists in the constant temperature water tank 51 corresponds to an example of an external piping part. The constant temperature bath, the sub pipe 70, and the second fluid correspond to an example of the heat generating portion as a whole. The pump 52 and the entire control device 53 correspond to an example of pulsation generating means.

(Second Embodiment)
Next, a second embodiment will be described. The fluid transportation device of this embodiment is a modification of a part of the fluid transportation device used as the experimental device in the first embodiment.

  Specifically, the control device 53 is changed so that a detection signal is input from the fourth temperature sensor 75 (corresponding to an example of a heat generating part temperature sensor) to the first embodiment. As the fourth temperature sensor 75, a sensor having a thermistor may be used, or a sensor having a thermocouple may be used. The control device 53 can acquire the temperature of the second fluid detected by the fourth temperature sensor 75 based on the detection signal.

  The control device 53 is a microcomputer provided with a CPU, RAM, ROM, etc. (not shown). The CPU executes data read from the ROM and uses the RAM as a work area during the execution. The process shown in FIG. 13 is executed.

  In the process of FIG. 13, first, in step 110, pump steady flow control is performed. In the pump steady flow control, the flow of the first fluid in the entire main pipe 50 is made constant by keeping the pump supply voltage to the pump 52 at a constant value. At this time, in the flow path in the heat exchanger 76, as shown in the first embodiment, the flow of the first fluid is a laminar flow.

  Subsequently, in step 120, the current temperature Tj of the second fluid specified based on the detection signal from the fourth temperature sensor 75 (the temperature downstream of the outer tube 70a) is 130 ° C. (corresponding to an example of the first temperature). It is determined whether it is less than. When the temperature is lower than 130 ° C., the process returns to step 110 to keep the pump supply voltage at a constant value, and the process proceeds to step 120 again.

  As described above, when the pump supply voltage is maintained at a constant value, the control device 53 continues to maintain the pump supply voltage at a constant value until the temperature Tj of the second fluid reaches 130 ° C. .

  Thereafter, when the temperature Tj exceeds 130 ° C., the control device 53 determines in step 120 that the temperature is 130 ° C. or higher (a predetermined condition is satisfied), proceeds to step 130, and performs pump pulsation control. Specifically, a pump supply voltage similar to that in the experimental example in which the dimensionless pressure gradient is less than −0.04 in FIG. 12 of the first embodiment is applied to the pump 52. At this time, in the flow path in the heat exchanger 76, as shown in the first embodiment, fluctuations in the pressure gradient −dp / dx and the Reynolds number Re that are equivalent to the experimental result of the first embodiment occur, and the reverse Backflow occurs in the gradient period T2. As the reverse flow occurs, the flow of the first fluid is disturbed in the deceleration period T2. Therefore, compared with the case of steady flow control, the heat transfer coefficient between the first fluid and the second fluid is improved, and the temperature of the second fluid downstream of the outer tube 70a is lowered.

  Following step 130, in step 140, it is determined whether or not the current temperature Tj is less than 120 ° C. (corresponding to an example of a second temperature lower than the first temperature). Returning to 130, the pump pulsation control is continued, and the routine proceeds to step 140 again.

  In this way, during the pump pulsation control, the control device 53 continues the pump pulsation control until the temperature Tj of the second fluid drops below 120 ° C., so that the second downstream of the outer pipe 70a during that time. The fluid temperature continues to drop.

  Thereafter, when the temperature Tj decreases to less than 120 ° C., the controller 53 determines in step 140 that the temperature is less than 120 ° C., returns to step 110 to execute the pump steady flow control, and proceeds to step 120. By this pump steady flow control, the flow of the first fluid returns to the steady flow and returns to the laminar flow in the flow path in the heat exchanger 76.

  As described above, in the present embodiment, the control device 53 causes the flow of the first fluid in the flow path based on the fact that the predetermined condition is satisfied (the temperature of the heat generating part has become equal to or higher than the first temperature). By pulsating the first fluid from the steady flow state, the flow of the first fluid is disturbed.

  The power energy required to generate pulsation is often higher than the power energy required to generate a steady flow. Therefore, by selecting when the predetermined condition is satisfied, that is, selecting when the condition for increasing the heat transfer performance of the heat exchanger is satisfied and generating the pulsating flow, Energy can be saved effectively.

(Third embodiment)
Next, a second embodiment will be described. The fluid transportation device of this embodiment is a modification of a part of the fluid transportation device used as the experimental device in the first embodiment.

  Specifically, the control device 53 is changed so that a detection signal is input from the second temperature sensor 59 (corresponding to an example of a fluid temperature sensor) with respect to the first embodiment. The control device 53 can acquire the temperature of the first fluid detected by the second temperature sensor 59 based on the detection signal.

  The control device 53 is a microcomputer provided with a CPU, RAM, ROM, etc. (not shown). The CPU executes data read from the ROM and uses the RAM as a work area during the execution. 14 is executed.

  In the process of FIG. 14, first, in step 210, pump steady flow control is performed. The details of the pump steady flow control are the same as those in the second embodiment, and a description thereof will be omitted. At this time, in the flow path in the heat exchanger 76, as shown in the first embodiment, the flow of the first fluid is a laminar flow.

  Subsequently, at step 220, the current temperature Tf of the first fluid specified based on the detection signal from the second temperature sensor 59 (temperature downstream of the heat exchanger 76) corresponds to 65 ° C. (an example of the first temperature). ) Is determined whether or not. When the temperature is lower than 65 ° C., the process returns to step 210 to keep the pump supply voltage at a constant value, and then proceeds to step 220 again.

  As described above, when the pump supply voltage is maintained at a constant value, the control device 53 continues to maintain the pump supply voltage at a constant value until the temperature Tf of the first fluid reaches 65 ° C. .

  Thereafter, when the temperature Tf exceeds 65 ° C., the controller 53 determines in step 220 that the temperature is 65 ° C. or higher (a predetermined condition is satisfied), and proceeds to step 230 to perform pump pulsation control. Since the contents of the pump pulsation control are the same as those in the second embodiment, description thereof is omitted. At this time, in the flow path in the heat exchanger 76, as shown in the first embodiment, fluctuations in the pressure gradient −dp / dx and the Reynolds number Re that are equivalent to the experimental result of the first embodiment occur, and the reverse A backflow occurs in the gradient period T3. As the reverse flow occurs, the flow of the first fluid is disturbed in the deceleration period T2. Therefore, compared with the case of steady flow control, the heat transfer coefficient between the first fluid and the second fluid is improved, and the temperature of the second fluid downstream of the outer tube 70a is lowered.

  Subsequent to step 230, in step 240, it is determined whether or not the current temperature Tf is less than 60 ° C. (corresponding to an example of a second temperature lower than the first temperature). Returning to 230, the pump pulsation control continues, and the process proceeds to step 240 again.

  In this way, during the pump pulsation control, the control device 53 continues the pump pulsation control until the temperature Tf of the first fluid drops below 60 ° C. During this time, the control device 53 continues the pump pulsation control downstream of the heat exchanger 76. The temperature of one fluid continues to decrease.

  Thereafter, when the temperature Tf decreases to less than 60 ° C., the control device 53 determines that the temperature is less than 60 ° C. in step 240, returns to step 210, executes pump steady flow control, and proceeds to step 220. By this pump steady flow control, the flow of the first fluid returns to the steady flow and returns to the laminar flow in the flow path in the heat exchanger 76.

  As described above, in the present embodiment, the control device 53 causes the flow of the first fluid in the flow path based on the fact that the predetermined condition is satisfied (the temperature of the first fluid has become equal to or higher than the first temperature). From the state in which the flow is a steady flow, the first fluid is pulsated so that the flow of the first fluid is disturbed.

  Thereby, the effect equivalent to 2nd Embodiment can be acquired. Further, when it is difficult to detect the temperature of the heating element (for example, when the heating element is a vehicle engine unlike the present embodiment), it is not necessary to directly detect the temperature of the heating element, and the power energy Can be effectively saved.

(Fourth embodiment)
Next, a fourth embodiment will be described. The fluid transport device of the present embodiment changes the shape of the inner wall surface 50a facing the flow path of the first fluid in the heat exchanger 76 with respect to the fluid transport devices of the first to third embodiments.

  In FIG. 15, the cross-sectional shape of the said inner wall surface 50a of this embodiment is shown. As shown in this figure, the inner wall surface 50a is formed to be uneven. Because the inner wall surface 50a has such a shape, the flow path in the heat exchanger 76 has a shape in which the diameter gradually decreases from the upstream toward the downstream and then increases relatively rapidly. Repeated.

  In the present embodiment, when the pump supply voltage applied to the pump 52 from the control device 53 is made constant and the output of the pump 52 is made constant, that is, the flow rate in the flow path in the heat exchanger 76 is constant (that is, temporally). In this case, a flow as indicated by an arrow in FIG. 15 is generated in the flow path.

  Specifically, in the vicinity of the inner wall surface at the location where the diameter has been expanded as described above, the first fluid wraps around the inner wall surface to form a vortex. Note that the flow of the first fluid in the portion where the vortex is not generated in the flow path (the central portion and a portion near the inner wall surface) is a steady flow and a laminar flow.

  Thus, in this embodiment, when the flow rate of the 1st fluid in the flow path in the heat exchanger 76 is constant because the inner wall surface 53a is formed in unevenness, The first fluid forms a vortex in a part (near the inner wall surface).

  Therefore, even when the pulsation is generated and the backflow is generated in the reverse gradient period T3 as in the first to third embodiments, the turbulence generated due to the backflow is further expanded by the original vortex. As a result, the phenomenon in which the flow of the first fluid is disturbed becomes more prominent, and as a result, the heat transfer performance is further improved.

  In the present embodiment, the shape of the inner wall surface 50a facing the flow path of the first fluid in the heat exchanger 76 is different from those in the first to third embodiments, and therefore, backflow occurs in the reverse gradient period T3 due to pulsation. The conditions for doing this are not the same as those in the first to third embodiments. However, basically, the pulsation parameters (period T, amplitude (ie, (Vmax−Vmin) are set so that the dimensionless pressure gradient during deceleration described in the first embodiment is sufficiently small to be less than −0.4. ) / Vmax) and the lengths of periods a, b, and c) are easy to adjust. Basically, the greater the amplitude, the smaller the decelerationless dimensionless pressure gradient, and the shorter the length of the third period b, the smaller the decelerationless dimensionless pressure gradient. It is in. This is the same in the fifth and sixth embodiments and modifications described later.

(Fifth embodiment)
Next, a fifth embodiment will be described. The fluid transport device of the present embodiment changes the shape of the inner wall surface 50a facing the flow path of the first fluid in the heat exchanger 76 with respect to the fluid transport devices of the first to third embodiments.

  In FIG. 16, the cross-sectional shape of the said inner wall surface 50a of this embodiment is shown. As shown in this figure, the inner wall surface 50a is formed to be uneven. Since the inner wall surface 50a has such a shape, the flow path in the heat exchanger 76 has a shape in which the diameter gradually increases from the upstream toward the downstream and then decreases relatively rapidly. Repeated.

  In the present embodiment, when the pump supply voltage applied to the pump 52 from the control device 53 is made constant and the output of the pump 52 is made constant, that is, the flow rate in the flow path in the heat exchanger 76 is constant (that is, temporally). 16), a flow as shown by an arrow in FIG. 16 is generated in the flow path.

  Specifically, as described above, after the first fluid spreads along the inner wall surface of the enlarged diameter portion, the first fluid collides with the inner wall surface of the reduced diameter portion, so that the first fluid forms a vortex. . Note that the flow of the first fluid in the portion where the vortex is not generated in the flow path (the central portion and a portion near the inner wall surface) is a steady flow and a laminar flow.

  Thus, in this embodiment, when the flow rate of the 1st fluid in the flow path in the heat exchanger 76 is constant because the inner wall surface 53a is formed in unevenness, The first fluid forms a vortex in a part (near the inner wall surface).

  Therefore, even when the pulsation is generated and the backflow is generated in the reverse gradient period T3 as in the first to third embodiments, the turbulence generated due to the backflow is further expanded by the original vortex. As a result, the phenomenon in which the flow of the first fluid is disturbed becomes more prominent, and as a result, the heat transfer performance is further improved.

(Sixth embodiment)
Next, a sixth embodiment will be described. The fluid transport device of the present embodiment is obtained by adding members to the inner wall surface 50a facing the flow path of the first fluid in the heat exchanger 76 with respect to the fluid transport devices of the first to third embodiments.

  In FIG. 17, the cross-sectional shape of the flow path of this embodiment and its periphery is shown. As shown in this figure, a plurality of variable resistance portions are arranged on the inner wall surface 50a of the present embodiment. Each of the variable resistance portions includes a movable plate 50b, a rotating shaft 50c, a bearing member 50d, and a rotation preventing member 50e.

  The movable plate 50b is a flat plate-like member, and is fixed to the rotating shaft 50c at one end in the longitudinal direction. The rotating shaft 50c is a rod-shaped member extending in parallel with the side of the movable plate 50b, and both ends thereof are instructed to be rotatable by the bearing member 50d. The bearing member 50d is a member that is fixed to the inner wall surface 50a and rotatably supports the rotary shaft 50c. The rotation preventing member 50e is a plate-shaped member formed integrally with the bearing member 50d. The direction perpendicular to both the normal direction of the movable plate 50b and the normal direction of the rotation preventing member 50e is perpendicular to the longitudinal direction of the flow path.

  Since each variable resistance portion has such a structure, the movable plate 50b is rotatable about the rotation shaft 50c, and a position where one surface of the plate surface abuts against the inner wall surface 50a. Thus, the rotation is restricted by the inner wall surface 50a, and the rotation is restricted by the anti-rotation member 50e at the position where the other side of the plate surface is in contact with the anti-rotation member 50e.

  In this embodiment, when the output of the pump 52 is made constant, that is, when the flow rate in the flow path in the heat exchanger 76 is made constant (that is, unchanged in time), the flow shown by the arrow in FIG. Is generated in the flow path. The same applies to the acceleration period T1 when the first fluid is pulsated.

  In this case, since no reverse flow is generated in the flow of the first fluid in the flow path, the movable plate 50b is urged in the flow direction in the case of a steady flow. Accordingly, as shown in FIG. 17, the movable member 50b is stopped at a position where one surface side of the plate surface is in contact with the inner wall surface 50a. As a result, since the plate surface of the movable member 50b is substantially parallel to the flow direction of the first fluid, the movable member 50b hardly obstructs the flow of the first fluid.

  On the other hand, in the deceleration period T1 when the first fluid is pulsated, backflow or flow disturbance occurs in the vicinity of the inner wall surface. Accordingly, as shown in FIG. 18, the movable member 50b is stopped at the position where the other surface side of the plate surface abuts against the rotation preventing member 50e. At this time, since the movable member 50b is in such a posture as to block the backflow of the first fluid, the backflowing first fluid is likely to generate a vortex. That is, disturbance is likely to occur. As a result, the phenomenon in which the flow of the first fluid is disturbed becomes more prominent, and as a result, the heat transfer performance is further improved.

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, the elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case. In particular, when a plurality of values are exemplified for a certain amount, it is also possible to adopt a value between the plurality of values unless specifically stated otherwise and in principle impossible. . Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like. The present invention also allows the following modifications to the above embodiments. In addition, the following modifications can select application and non-application to the said embodiment each independently. In other words, any combination of the following modifications can be applied to the above-described embodiment.

(Modification 1)
In the said embodiment, the counterflow type | mold double tube type heat exchanger 76 is illustrated as a heat exchanger. However, the heat exchanger of the present invention is not limited to such an example, and may be any heat exchanger. For example, the present invention can be applied to a heat exchanger in which a plurality of (for example, 10 or more) flow paths are arranged in parallel and the hydraulic diameter of each flow path is as small as 1 mm.

(Modification 2)
Moreover, in the said embodiment, all the internal diameters of the main pipe 50 were the same. However, this is not necessarily the case. For example, the external pipe part excluding both the part constituting the heat exchanger 76 and the part existing in the constant temperature water tank 51 of the main pipe 50 may be thicker than the above embodiment.

(Modification 3)
The first temperature and the second temperature of the second and third embodiments are 130 ° C., 120 ° C., 65 ° C., and 60 ° C., respectively, but the first temperature and the second temperature are the first temperature. Any temperature may be used as long as it is equal to or higher than the second temperature.

(Modification 4)
In the present invention, the heat generating portion need not be as shown in the above embodiment, and may be an inverter or a vehicle engine, for example.

(Modification 5)
In the second and third embodiments, the contents of control of the pump 52 by the control device 53 (specifically, pump pulsation) based on the temperature of the second fluid (heating element) and the temperature of the first fluid, respectively. Control execution / non-execution). However, the control content of the pump 52 by the control device 53 may be changed based on other factors.

  For example, the amplitude in pulsation (that is, (Vmax−Vmin) / Vmax), the pulsation period T, and the like may be changed based on the detection result of the flow meter 54. More specifically, if the flow rate detected by the flow meter 54 is lower than the average flow rate required for heat transport, the amplitude may be increased so as to increase the average flow rate.

  Further, for example, based on the detection result of the first pressure sensor 56, the second pressure sensor 57, or the differential pressure gauge 58, the amplitude in the pulsation (that is, (Vmax) is set so that the pressure difference (negative value) before and after the reverse gradient period T3 decreases. -Vmin) / Vmax), the period T of pulsation, and the like may be changed.

51a Inner wall surface 52 Pump 53 Control device 59 Second temperature sensor 75 Fourth temperature sensor 76 Counterflow double-pipe heat exchanger T1 Acceleration period T2 Deceleration period T3 Reverse gradient period

Claims (6)

A heat exchanger (76) having a flow path through which the fluid flows and exchanging heat between the fluid and another object;
Pulsation generating means (52, 53) for pulsating the fluid in the flow path,
When the flow of the fluid in the flow path is a steady flow that flows in the flow direction, the flow of the fluid in at least a part of the flow path becomes a laminar flow,
When the result of subtracting the pressure of the fluid at the downstream end in the flow direction of the flow path from the pressure of the fluid at the upstream end in the flow direction of the flow path is a front-rear pressure difference, the pulsation generating means Pulsating the fluid, a reverse gradient period (T3) in which the flow velocity of the fluid decreases and the front-rear pressure difference becomes negative is generated, and in the reverse gradient period, from the center of the flow path A fluid transporting device, wherein the fluid generates a backflow that travels in a direction opposite to the flow direction at a position closer to the flow path than the inner wall surface (51a) facing the flow path. The pulsation generating means has a pump (52) for driving the fluid and a control device (53) for controlling the pump,
The controller periodically pulsates the fluid by periodically varying the output of the pump,
A length from the upstream end to the downstream end is obtained by subtracting the pressure of the fluid at the downstream end in the flow direction of the flow path from the pressure of the fluid at the upstream end in the flow direction of the flow path. Is a pressure gradient, and a period from the time when the pressure gradient first changes from positive to negative in the period (b) in which the pump output is reduced to the time when the pump output starts to increase is a deceleration period. Assuming that (T2), the result of dividing the value obtained by averaging the pressure gradient for the deceleration period by the value obtained by averaging the pressure gradient for one period (T) of the pulsation of the fluid is less than −0.4. The fluid transport device according to claim 1. The pulsation generating means has a pump (52) for driving the fluid,
The fluid transport device according to claim 1, wherein the pump is a positive displacement pump.   The pulsation generating means pulsates the fluid in the flow path, so that the distance from the inner wall surface facing the flow path is closer than the distance from the center of the flow path during the reverse gradient period. 4. The flow according to claim 1, wherein a reverse flow is generated in the fluid in a direction opposite to the flow direction at a position, thereby disturbing the flow of the fluid at a Reynolds number lower than 2000. 5. The fluid transport device according to claim 1.   Since the inner wall surface is formed to be uneven, the fluid forms a vortex in a part of the flow path when the flow rate of the fluid in the flow path is constant. The fluid transport device according to any one of claims 1 to 4.   The pulsation generating means pulsates the fluid in the flow path from a state in which the flow of the fluid in the flow path is a steady flow flowing in the flow direction based on a predetermined condition being satisfied. Thus, in the reverse gradient period, a reverse flow that travels in a direction opposite to the flow direction at a position closer to the distance from the inner wall surface facing the flow path than to a distance from the center of the flow path. The fluid transport device according to any one of claims 1 to 5, wherein the fluid flow is disturbed by being generated in the fluid.