JP6800380B1 - Liquid flow generator and heat exchanger - Google Patents

Abstract

The liquid flow generator (100) is for holding the liquid inside and locally heating the substrate (10) having the first surface (11) in contact with the liquid to form microbubbles. (3a, 3b, 4a, 4b) is provided. The heating unit forms a plurality of heated regions (6d, 6e) arranged side by side in the X direction, and within each of the plurality of heated regions, a first region (3d, 3e) having a relatively high temperature is formed. And a plurality of second regions (4d, 4e) adjacent to the first region and having a relatively low temperature, and in the Y direction along the first surface and intersecting the X direction. Each first region of the heated region is provided so as to be arranged on the same side with respect to the second region.

Description

The present disclosure relates to a liquid flow generator and a heat exchanger.

In Japanese Patent Application Laid-Open No. 2007-263491, the number of refrigerant flow paths in the microtubes located below is located above in order to smoothly discharge the oil accumulated in the heat exchanger provided with the plurality of microtubes. There are more heat exchangers disclosed than the number of refrigerant channels in the microtube.

JP-A-2007-263491

In general, the flow velocity of a liquid flowing through a particular flow path decreases as it approaches the inner peripheral surface of the flow path due to the viscosity of the liquid. This effect increases as the inner diameter of the flow path becomes smaller.

Therefore, the flow velocity of the refrigerant flowing near the inner peripheral surface of each refrigerant flow path of the microtube of the heat exchanger is significantly lower than the flow velocity of the refrigerant flowing in the center of each refrigerant flow path of the microtube. As a result, in the heat exchanger, heat exchange is performed between the refrigerant flowing inside the microtube and the air flowing outside the microtube, so that the flow velocity of the refrigerant flowing near the inner peripheral surface of the refrigerant flow path decreases. The heat exchange performance of the heat exchanger is deteriorated.

A main object of the present disclosure is to provide a liquid flow generator that causes a liquid flow in the vicinity of the inner peripheral surface of the flow path in order to suppress a decrease in the flow velocity in the vicinity of the inner peripheral surface of the flow path, and a heat exchanger provided with the liquid flow generator. To do.

The liquid flow generator according to the present disclosure includes a substrate having a first surface that holds the liquid inside and is in contact with the liquid, and a heating unit for locally heating the first surface to form microbubbles. Be prepared. The heating unit forms a plurality of heated regions arranged side by side in the first direction along the first surface, and within each of the plurality of heated regions, a first region having a relatively high temperature and a first region having a relatively high temperature are formed. Each of the plurality of heated regions in the second direction, which forms a second region adjacent to the one region and has a relatively low temperature, and is along the first surface and intersects the first direction. The first region is provided so as to be arranged on the same side with respect to the second region.

According to the present disclosure, it is possible to provide a liquid flow generator that generates a liquid flow in the vicinity of the inner peripheral surface of the flow path, and a heat exchanger including the liquid flow generator.

It is a partial sectional view of the liquid flow generator which concerns on Embodiment 1. FIG. FIG. 5 is a partial plan view of the first surface of the liquid flow generator shown in FIG. 1 as a plan view. It is a graph which shows the temperature distribution on the 1st virtual straight line C1 of the 1st heated region shown in FIG. It is a partial plan view which shows the microbubbles and liquid flow generated by the liquid flow generator shown in FIG. It is a partial cross-sectional view of the modification of the liquid flow generator which concerns on Embodiment 1. FIG. It is a partial perspective sectional view of the heat exchanger according to the first embodiment. FIG. 5 is a partial plan view of the first surface of the liquid flow generator according to the second embodiment. FIG. 7 is a partial plan view showing microbubbles and liquid flow generated by the liquid flow generator shown in FIG. 7. It is a partial perspective sectional view of the heat exchanger according to the second embodiment. FIG. 5 is a partial plan view of a first surface of a modified example of the liquid flow generator according to the second embodiment. It is a partial sectional view of the liquid flow generator which concerns on Embodiment 3. FIG. It is a partial sectional view of the liquid flow generator which concerns on Embodiment 4. FIG. FIG. 2 is a partial plan view of the first surface of the liquid flow generator shown in FIG. 12 in a plan view. FIG. 5 is a partial plan view of the first surface of the liquid flow generator according to the fifth embodiment as a plan view. It is a partial perspective sectional view of the heat exchanger according to the fifth embodiment. FIG. 5 is a partial plan view of a first surface of a modified example of the liquid flow generator according to the fifth embodiment. FIG. 5 is a partial plan view of the first surface of another modification of the liquid flow generator according to the first to fifth embodiments.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings below, the same or corresponding parts are given the same reference numbers, and the explanations are not repeated.

Embodiment 1.
<Configuration of liquid flow generator>
As shown in FIGS. 1 to 3, the liquid flow generator 100 according to the first embodiment includes a substrate 10, a plurality of first laser light sources 3a to 3c as heating portions, and a plurality of second laser light sources 4a to. It includes 4c.

As shown in FIG. 1, the substrate 10 holds a liquid LQ inside. The liquid LQ may be any fluid having a liquid phase fluid, and is, for example, a refrigerant (liquid phase refrigerant or gas-liquid two-phase refrigerant).

The substrate 10 has a first surface 11 in contact with the liquid LQ and a second surface 12 located on the opposite side of the first surface 11 and not in contact with the liquid LQ. The first surface 11 is the inner surface of the substrate 10, and the second surface 12 is the outer surface of the substrate 10. The first surface 11 is, for example, a flat surface. The substrate 10 includes, for example, a substrate 1 having a second surface 12 and a thin film 2 having a first surface 11.

For the first laser beams L3a to L3c emitted from the first laser light sources 3a to 3c and the second laser beams L4a to L4c emitted from the second laser light sources 4a to 4c, the transmittance of the substrate 1 is that of the thin film 2. It is higher than the transmittance, and the absorption rate of the thin film 2 is higher than the absorption rate of the substrate 1.

The material constituting the substrate 1 is a material that transmits the first laser beam and the second laser beam. Preferably, the thermal conductivity of the material constituting the substrate 1 is lower than the thermal conductivity of the material constituting the thin film 2. The material constituting the substrate 1 is, for example, glass (SiO ₂ ).

The material constituting the thin film 2 may be any material that absorbs the first laser beam and the second laser beam and converts the energy of each laser beam into thermal energy (hereinafter referred to as photothermal conversion). Includes gold (Au). The thin film 2 is, for example, a film in which Au nanoparticles whose main constituent material is Au and whose particle size is on the order of nm are aggregated. The thin film 2 may be a film in which Au nanoparticles are bound via an arbitrary binder. The thin film of Au nanoparticles is useful for the thin film 2 because it absorbs near-infrared light well and exhibits a photoheat exchange effect even when the film thickness is thin due to localized surface plasmon resonance. The thickness of the thin film 2 in this case is, for example, 0.001 μm or more and 0.05 μm or less. The thin film 2 is formed by, for example, a sputtering method.

As shown in FIG. 1, the plurality of first laser light sources 3a to 3c and the plurality of second laser light sources 4a to 4c are arranged outside the substrate 10. The plurality of first laser light sources 3a to 3c and the plurality of second laser light sources 4a to 4c are arranged so as to face the second surface 12 of the substrate 10. The plurality of first laser light sources 3a to 3c and the plurality of second laser light sources 4a to 4c make the plurality of heated regions 6d to 6f (see FIG. 2) in the first surface 11 more local than their surrounding regions. It is provided so as to generate microbubbles 5a to 5c on each heated region at a high temperature.

The heated regions 6d to 6f may be provided by transmitting each of the first laser beams L3a to L3c through an optical filter having a transmittance distribution in the plane. The non-heated regions 6d to 6f may be provided by causing the first laser beams L3a to L3c to enter the spatial light modulator (SLM) to spatially modulate the laser light intensity.

Each of the first laser light sources 3a to 3c irradiates the first laser beam to the first region 3d to 3f (see FIG. 2) which is a minute region in the first surface 11, and also irradiates the first laser beam to the first region 3d. It is provided so as to collect light at ~ 3f. Each of the second laser light sources 4a to 4c irradiates the second region 4d to 4f (see FIG. 2), which is a minute region in the first surface 11, with the second laser light, and irradiates the second laser light with the second region 4d. It is provided so as to collect light at ~ 4f. The first laser light sources 3a to 3c and the second laser light sources 4a to 4c are, for example, semiconductor lasers. For example, a lens is used to collect each laser beam.

Each wavelength of the first laser beam and the second laser beam is a wavelength that is easily absorbed by the thin film 2. Preferably, the first laser beam and the second laser beam are near infrared rays. Preferably, the wavelength of the second laser beam is equal to the wavelength of the first laser beam. On the other hand, the intensity of the second laser beam is weaker than the intensity of the first laser beam.

As shown in FIG. 1, the angle at which the first laser beams L3a to L3c emitted from the first laser light sources 3a to 3c are incident on the first surface 11 is more than 0 degrees and 90 degrees or less, for example, at 90 degrees. is there. The angle at which the second laser beams L4a to L4c emitted from the second laser light sources 4a to 4c are incident on the first surface 11 is, for example, more than 0 degrees, and the first laser beams L3a to L3c are on the first surface 11. It is less than the angle of incidence. The distance between the second laser light sources 4a to 4c and the first surface 11 is shorter than, for example, the distance between the first laser light sources 3a to 3c and the first surface 11.

As shown in FIGS. 1 and 2, the first region 3d irradiated with the first laser light by the first laser light source 3a is the second region 4d irradiated with the second laser light by the second laser light source 4a. , Adjacent in the Y direction. As used herein, the term "adjacent" refers to a state in which the outer edges of the first and second regions are in contact, a state in which parts of the first and second regions overlap, and a first. A state in which the region 3d and the second region 4d are separated from each other in the Y direction is included. The distance between the first region 3d and the second region 4d in the Y direction is preferably not more than twice the diameter of the second region 4d, and more preferably not more than the diameter of the second region 4d. The positional relationship between the first region 3d and the second region 4d is set according to the direction of the microscale flow 7 (see FIG. 4) to be generated in the liquid LQ.

The first region 3d and the second region 4d are locally heated to a higher temperature than the regions surrounding the first region 3d and the second region 4d. That is, the first region 3d and the second region 4d constitute one heated region. Hereinafter, the heated region composed of the first region 3d and the second region 4d is referred to as the first heated region 6d. The first heated region 6d is heated to a temperature higher than the temperature at which microbubbles are generated. The region around the first heated region 6d is not heated above the temperature at which microbubbles are generated.

As shown in FIGS. 1 and 2, the first region 3e irradiated with the first laser light by the first laser light source 3b is the second region 4e irradiated with the second laser light by the second laser light source 4b. , Adjacent in the Y direction. The positional relationship between the first region 3e and the second region 4e is set according to the direction of the microscale flow 7 (see FIG. 4) to be generated in the liquid LQ. The first region 3e and the second region 4e are locally heated to a higher temperature than the regions surrounding the first region 3e and the second region 4e. That is, the first region 3e and the second region 4e constitute one heated region. Hereinafter, the heated region composed of the first region 3e and the second region 4e is referred to as the second heated region 6e. The second heated region 6e is heated to a temperature higher than the temperature at which microbubbles are generated. The region around the second heated region 6e is not heated above the temperature at which microbubbles are generated.

As shown in FIGS. 1 and 2, the first region 3f irradiated with the first laser light by the first laser light source 3c is the second region 4f irradiated with the second laser light by the second laser light source 4c. , Adjacent in the Y direction. The positional relationship between the first region 3f and the second region 4f is set according to the direction of the microscale flow 7 (see FIG. 4) to be generated in the liquid LQ. The first region 3f and the second region 4f are locally heated to a higher temperature than the regions surrounding the first region 3f and the second region 4f. That is, the first region 3f and the second region 4f constitute one heated region. Hereinafter, the heated region composed of the first region 3f and the second region 4f is referred to as a third heated region 6f. The third heated region 6f is heated to a temperature higher than the temperature at which microbubbles are generated. The region around the third heated region 6f is not heated above the temperature at which microbubbles are generated.

As shown in FIG. 2, each planar shape of the first region 3d to 3f and the second region 4d to 4f is, for example, a circular shape. Each area of the first region 3d to 3f is larger than, for example, each area of the second region 4d to 4f. The second region 4d may be circumscribed with, for example, the first region 3d, may partially overlap each other, or may be separated from each other. The distance separated from each other is preferably not more than twice the diameter of the second region 4d, and more preferably not more than the diameter of the second region 4d.

The first virtual straight line C1 shown by the dotted line in FIG. 2 is the first of the first heated region 6d when the first surface 11 heated by the first laser light source 3a and the second laser light source 4a is viewed in a plan view. It is a virtual straight line passing through the hottest part 61d. The first virtual straight line C1 is the average temperature of the first portion 65d located on one side of the first maximum temperature portion 61d on the first virtual straight line C1 and the second located on the other side of the first maximum temperature portion 61d. The difference in average temperature of the portion 66d is set to be maximum. The "one side" with respect to the first maximum temperature portion 61d is set as the downstream side in the direction in which the liquid LQ should flow. The "other side" with respect to the first maximum temperature portion 61d is set as the upstream side in the direction in which the liquid LQ should flow. The reached temperature of the first maximum temperature portion 61d is a temperature at which microbubbles are generated on the first maximum temperature portion 61d.

The one-sided end of the first heated region 6d on the first virtual straight line C1 is defined as the first end 63d, and the other end of the first heated region 6d on the first virtual straight line C1. Is the second end portion 64d. The first end portion 63d is a boundary portion with the surrounding region of the first region 3d, and is the outermost peripheral portion in which the temperature rise with respect to the surrounding region can be measured in the first region 3d. The second end portion 64d is a boundary portion with the surrounding region of the second region 4d, and is the outermost peripheral portion in which the temperature rise with respect to the surrounding region can be measured in the second region 4d. The first portion 65d is a portion located between the first maximum temperature portion 61d and the first end portion 63d. The second portion 66d is a portion located between the first maximum temperature portion 61d and the second end portion 64d.

The first hottest portion 61d includes, for example, the center of the first heated region 6d in the X and Y directions. In this case, the first virtual straight line C1 is a virtual straight line passing through the center of the first heated region 6d. The first portion 65d is a portion located on the first virtual straight line C1 on one side of the center of the first heated region 6d. The second portion 66d is a portion located on the first virtual straight line C1 on the other side of the center of the first heated region 6d.

As shown in FIG. 3, the temperature distribution on the first virtual straight line C1 is asymmetric with respect to the first maximum temperature portion 61d. The temperature distribution on the first virtual straight line C1 is asymmetric with respect to the center of the first heated region 6d. The average temperature of the first portion 65d is higher than the average temperature of the second portion 66d.

The second virtual straight line C2 shown by the dotted line in FIG. 2 is the second of the second heated region 6e when the first surface 11 heated by the first laser light source 3b and the second laser light source 4b is viewed in a plan view. It is a virtual straight line passing through the hottest part 61e. The second virtual straight line C2 is the average temperature of the third portion 65e located on one side of the second maximum temperature portion 61e and the average temperature of the fourth portion 66e located on the other side on the second virtual straight line C2. The difference is set to the maximum.

The end on one side with respect to the second heated region 6e on the second virtual straight line C2 is defined as the first end 63e, and the end on the other side of the second heated region 6e on the second virtual straight line C2. Is the second end portion 64e. The first end portion 63e is a boundary portion with the surrounding region of the first region 3e, and is the outermost peripheral portion in which the temperature rise with respect to the surrounding region can be measured in the first region 3e. The second end portion 64e is a boundary portion with the surrounding region of the second region 4e, and is the outermost peripheral portion in which the temperature rise with respect to the surrounding region can be measured in the second region 4e. The third portion 65e is a portion located between the second maximum temperature portion 61e and the first end portion 63e. The fourth portion 66e is a portion located between the second maximum temperature portion 61e and the second end portion 64e.

The second hottest portion 61e includes, for example, the center of the second heated region 6e in the X and Y directions. In this case, the second virtual straight line C2 is a virtual straight line passing through the center of the second heated region 6e. The third portion 65e is a portion located on the second virtual straight line C2 on one side of the center of the second heated region 6e. The fourth portion 66e is a portion located on the second virtual straight line C2 on the other side of the center of the second heated region 6e.

The temperature distribution on the second virtual straight line C2 is asymmetric with respect to the second maximum temperature portion 61e. The temperature distribution on the second virtual straight line C2 is asymmetric with respect to the center of the second heated region 6e. The average temperature of the third portion 65e is higher than the average temperature of the fourth portion 66e.

The third virtual straight line C3 shown by the dotted line in FIG. 2 is the third of the third heated region 6f when the first surface 11 heated by the first laser light source 3c and the second laser light source 4c is viewed in a plan view. It is a virtual straight line passing through the hottest part 61f. The third virtual straight line C3 is the average temperature of the fifth portion 65f located on one side of the third maximum temperature portion 61f and the average temperature of the sixth portion 66f located on the other side on the third virtual straight line C3. The difference is set to the maximum.

The one-sided end of the third heated region 6f on the third virtual straight line C3 is defined as the first end 63f, and the other end of the third heated region 6f on the third virtual straight line C3. Is the second end portion 64f. The first end portion 63f is a boundary portion with the peripheral region of the first region 3f, and is the outermost peripheral portion in which the temperature rise with respect to the surrounding region can be measured in the first region 3f. The second end portion 64f is a boundary portion with the surrounding region of the second region 4f, and is the outermost peripheral portion in which the temperature rise with respect to the surrounding region can be measured in the second region 4f. The fifth portion 65f is a portion located between the third maximum temperature portion 61f and the first end portion 63f. The sixth portion 66f is a portion located between the third maximum temperature portion 61f and the second end portion 64f.

The third hottest portion 61f includes, for example, the center of the third heated region 6f in the X and Y directions. In this case, the third virtual straight line C3 is a virtual straight line passing through the center of the third heated region 6f. The fifth portion 65f is a portion located on the third virtual straight line C3 on one side of the center of the third heated region 6f. The sixth portion 66f is a portion located on the third virtual straight line C3 on the other side of the center of the third heated region 6f.

The temperature distribution on the third virtual straight line C3 is asymmetric with respect to the third maximum temperature portion 61f. The temperature distribution on the third virtual straight line C3 is asymmetric with respect to the center of the third heated region 6f. The average temperature of the fifth portion 65f is higher than the average temperature of the sixth portion 66f.

As shown in FIG. 2, in the first heated region 6d, the first portion 65d having a relatively high average temperature is arranged on one side of the second portion 66d having a relatively low average temperature. ing. In the second heated region 6e, the third portion 65e having a relatively high average temperature is arranged on one side of the fourth portion 66e having a relatively low average temperature. In the third heated region 6f, the fifth portion 65f having a relatively high average temperature is arranged on one side of the sixth portion 66f having a relatively low average temperature. That is, the portion where the average temperature is relatively high in each heated region is arranged on the downstream side in the direction in which the liquid LQ should flow with respect to the portion where the average temperature is relatively low.

The direction from the second portion 66d to the first portion 65d on the first virtual straight line C1 and the direction from the fourth portion 66e to the third portion 65e on the second virtual straight line C2 are not reversed. The direction from the second region 4d to the first region 3d and the direction from the second region 4e to the first region 3e are not reversed. The direction from the fourth portion 66e to the third portion 65e on the second virtual straight line C2 and the direction from the sixth portion 66f to the fifth portion 65f on the third virtual straight line C3 are not reversed. The direction from the second region 4e to the first region 3e and the direction from the second region 4f to the first region 3f are not reversed.

As shown in FIG. 2, each of the first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 is parallel to each other. That is, the angle formed by the first virtual straight line C1 with respect to the second virtual straight line C2 is 0 degrees. The angle formed by the second virtual straight line C2 with respect to the third virtual straight line C3 is 0 degrees.

In the present specification, the second direction in which the liquid LQ should flow is the Y direction, the first direction orthogonal to the Y direction and along the first surface 11 is the X direction, and the second direction is orthogonal to the Y direction and the X direction. The three directions, that is, the directions orthogonal to the first surface 11, are defined as the Z direction.

As shown in FIG. 2, the first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 are arranged side by side at intervals in the X direction. In other words, the first heated region 6d, the second heated region 6e, and the third heated region 6f are arranged side by side at intervals in the X direction. The first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 are parallel to each other. Preferably, the distance δ between the first hottest portion 61d and the second hottest portion 61e is less than 500 μm. The distance δ between the second hottest portion 61e and the third hottest portion 61f is less than 500 μm.

<Effect>
The operation of the liquid flow generator 100 will be described in comparison with the operation of the liquid flow generator (hereinafter referred to as the liquid flow generator of the comparative example) provided with only a plurality of first laser light sources 3a to 3c as the heating unit.

First, in the liquid flow generator of the comparative example, only the first regions 3d to 3f are formed on the first surface 11. In this case, in any virtual straight line passing through each of the highest temperature portions in the first region 3d to 3f, the average temperature of the portion on one side and the average of the portion on the other side with respect to the highest temperature portion on the virtual straight line. Equal to temperature. Therefore, the first virtual straight line C1 is not set in the liquid flow generator according to the comparative example. That is, in any direction along the first surface 11, the temperature distribution of the first region 3d to 3f is formed symmetrically around the highest temperature portion. As a result, the surface of each microbubble formed by the liquid in contact with each of the first regions 3d to 3f being heated and evaporated by the first regions 3d to 3f in any direction along the first surface 11. The temperature distribution of is formed symmetrically around the highest temperature part. In this case, since the surface tension distribution of each microbubble is uniformly formed with respect to the maximum temperature portion in any direction along the first surface 11, the liquid in the direction along the first surface 11 No flow (microscale flow) occurs.

On the other hand, in the liquid flow generator 100, the second regions 4d to 4f are formed on the first surface 11 in addition to the first regions 3d to 3f, and each of the first regions 3d to 3f is a second region. It is arranged on the same side in the Y direction with respect to each of 4d to 4f. As a result, the first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 are set as described above. That is, the temperature distribution of the first heated region 6d on the first virtual straight line C1 is formed asymmetrically with respect to the first maximum temperature portion 61d. The temperature distribution of the second heated region 6e on the second virtual straight line C2 is formed asymmetrically with respect to the second maximum temperature portion 61e. The temperature distribution of the third heated region 6f on the third virtual straight line C3 is formed asymmetrically with respect to the third maximum temperature portion 61f.

As a result, the temperature distribution on the surface of the liquid LQ in contact with the microbubbles 5a formed on the first maximum temperature portion 61d due to the liquid in contact with the first heated region 6d being heated by the first heated region 6d and evaporating. Is formed asymmetrically with respect to the first maximum temperature portion 61d on the first virtual straight line C1. Due to the temperature distribution, the surface tension distribution of the liquid LQ in contact with the microbubbles 5a is also formed asymmetrically with respect to the first maximum temperature portion 61d. Specifically, since the temperature of the first region 3d is higher than the temperature of the second region 4d, the surface tension of the liquid LQ in contact with the microbubbles 5a is the first from the first region 3d in the direction along the first virtual straight line C1. It increases toward 2 regions 4d.

In particular, the difference between the average temperature of the first portion 65d and the average temperature of the second portion 66d on the first virtual straight line C1 is the largest among any virtual straight lines passing through the highest temperature portions of the first region 3d to 3f. Therefore, the asymmetry of the temperature distribution of the first heated region 6d on the first virtual straight line C1 is within the asymmetry on any virtual straight line passing through each of the highest temperature portions of the first region 3d to 3f. Is the maximum. Therefore, the gradient of the surface tension of the liquid LQ in contact with the microbubbles 5a becomes maximum in the direction along the first virtual straight line C1. Due to this gradient of surface tension, so-called Marangoni convection 7a (see FIG. 4) is generated around the microbubbles 5a. The direction of the Marangoni convection 7a is from the second region 4d to the first region 3d in the Y direction along the first virtual straight line C1.

By the same mechanism, Marangoni convection 7b (see FIG. 4) is generated around the microbubbles 5b, and Marangoni convection 7c (see FIG. 4) is generated around the microbubbles 5c. That is, the temperature distribution on the surface of the liquid LQ in contact with the microbubbles 5b formed on the second heated region 6e is formed asymmetrically with respect to the second maximum temperature portion 61e on the second virtual straight line C2. The temperature distribution on the surface of the liquid LQ in contact with the microbubbles 5c formed on the third heated region 6f is asymmetrically formed on the third virtual straight line C3 with respect to the third maximum temperature portion 61f. As a result, the surface tension of the liquid LQ in contact with the microbubbles 5b increases from the first region 3e to the second region 4e in the direction along the second virtual straight line C2, and the surface tension of the liquid LQ in contact with the microbubbles 5c increases. It increases from the first region 3f toward the second region 4f in the direction along the third virtual straight line C3. As a result, Marangoni convection 7b and Marangoni convection 7c occur.

Further, in each heated region, the portion having a relatively high average temperature is arranged on the downstream side in the direction in which the liquid LQ should flow with respect to the portion having a relatively low average temperature.

Therefore, each of the Marangoni convection 7a, the Marangoni convection 7b, and the Marangoni convection 7c flows from the upstream side to the downstream side in the direction in which the liquid LQ should flow, and a microscale flow 7 is formed in the vicinity of the first surface 11.

Further, the first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 are parallel to each other. In this way, the directions of the Marangoni convection 7a, the Marangoni convection 7b, and the Marangoni convection 7c are the same.

In the liquid flow generator 100, the distance δ between the first maximum temperature portion 61d and the second maximum temperature portion 61e is less than 500 μm. The distance δ between the second hottest portion 61e and the third hottest portion 61f is less than 500 μm. In this way, the Marangoni convection 7a and the Marangoni convection 7b are densely formed as compared with the case where the distance δ is longer than 500 μm, so that the microscale flow 7 becomes faster.

In the liquid flow generator 100, the thermal conductivity of the material constituting the substrate 1 is lower than the thermal conductivity of the material constituting the thin film 2. Therefore, the heat generated by photothermal conversion in the heated region of the thin film 2 is difficult to diffuse to the substrate 1, and the temperature of the heated region irradiated with the laser beam is kept high. As a result, in the liquid flow generator 100, microbubbles are generated as compared with the case where the thermal conductivity of the material constituting the substrate 1 is equal to or higher than the thermal conductivity of the material constituting the thin film 2. The energy required is reduced.

(Modification example)
The first surface 11 shown in FIG. 1 is a flat surface, but is not limited thereto. As shown in FIG. 5, the first surface 11 may be a curved surface. In the cross section intersecting the first virtual straight line C1 and the second virtual straight line C2, the center of curvature of the first surface 11 is arranged on the side opposite to the substrate 10 with respect to the first surface 11, for example. From a different point of view, the substrate 10 is provided in a tubular shape, and the first surface 11 may be configured as an inner peripheral surface thereof. Preferably, the first virtual straight line C1 and the second virtual straight line C2 are arranged so as to be spaced apart from each other in the circumferential direction of the base 10, and extend along the axial direction of the base 10.

The second region 4d shown in FIG. 2 is circumscribed with the first region 3d, but is not limited thereto. A part of the second region 4d may be formed so as to overlap a part of the first region 3d.

Although the three first laser light sources 3a to 3c and the three second laser light sources 4a to 4c are shown in FIGS. 1 and 2, the number of the first laser light source and the second laser light source is not particularly limited. .. The liquid flow generator 100 may include four or more first laser light sources 3a to 3c and four or more second laser light sources 4a to 4c. Further, the liquid flow generator 100 may include only two first laser light sources 3a and 3b and two second laser light sources 4a and 4b.

Further, each of the plurality of heated regions 6d to 6f shown in FIG. 2 is composed of the first region 3d to 3f and the second region 4d to 4f, but the first region 3d to 3f and the second region In addition to 4d to 4f, other regions may be included. The other region is, for example, a region irradiated with a third laser beam having a lower intensity than the second laser beam, and is arranged on the side opposite to the first region with respect to the second region.

<Structure of heat exchanger>
The heat exchanger 200 shown in FIG. 6 includes a liquid flow generator 100, and the substrate 10 is configured as a microtube 20. Inside the microtube 20, a plurality of flow paths 20a, 20b, 20c through which the refrigerant flows are formed. The extending direction of each of the flow paths 20a, 20b, 20c is the direction in which the refrigerant should flow. The first surface 11 of the substrate 10 is configured as the inner peripheral surface 21 of the flow paths 20a, 20b, 20c. The second surface 12 of the substrate 10 is configured as the outer peripheral surface 22 of the microtube 20. The inner diameters of the flow paths 20a, 20b, and 20c are on the order of μm.

Preferably, the liquid flow generator 100 includes, as a heating unit, first optical fibers 8a to 8c that guide the first laser beams emitted from the plurality of first laser light sources 3a to 3c to the first regions 3d to 3f. It further includes second optical fibers 9a to 9c that guide the second laser beams emitted from the plurality of second laser light sources 4a to 4c to the second regions 4d to 4f. Around the microtube 20, the space required for one optical fiber to be placed can be smaller than the space required for one laser light source to be placed. Therefore, according to the above configuration, the heated regions can be arranged more densely than in the case where the laser light is directly applied to each heated region from the laser light source.

An air passage through which a gas such as air flows is formed outside the microtube 20. In the heat exchanger 200, the refrigerant flowing through the flow paths 20a, 20b, 20c of the microtube 20 and the gas flowing outside the microtube 20 exchange heat.

In the heat exchanger 200 shown in FIG. 6, the first heated region in which the first virtual straight line C1 is set and the second heated region in which the second virtual straight line C2 is set are formed on different flow paths. Has been done. The first virtual straight line C1 is arranged in the first flow path 20a. The second virtual straight line C2 is arranged in the second flow path 20b. The third virtual straight line C3 is arranged in the third flow path 20c. The first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 are set so as to follow the extending directions of the flow paths 20a, 20b, and 20c.

In this way, the liquid flow generator 100 can form a microscale flow in the vicinity of the inner peripheral surfaces 21 of the flow paths 20a, 20b, and 20c of the microtube 20. Therefore, the flow velocity of the microscale flow formed in the vicinity of the inner peripheral surfaces 21 of the respective flow paths 20a, 20b, 20c is the inner peripheral surface of each flow path in the conventional heat exchanger not provided with the liquid flow generator 100. It will be faster than the flow velocity of the nearby refrigerant. As a result, the heat exchange performance of the heat exchanger 200 is higher than the heat exchange performance of the conventional heat exchanger not provided with the liquid flow generator 100.

The first virtual straight line C1 is arranged, for example, on the region of the inner peripheral surface 21 of the first flow path 20a that has the shortest distance from the outer peripheral surface 22. The second virtual straight line C2 is arranged, for example, on the region of the inner peripheral surface 21 of the second flow path 20b that has the shortest distance from the outer peripheral surface 22. The third virtual straight line C3 is arranged, for example, on the region of the inner peripheral surface 21 of the third flow path 20c that has the shortest distance from the outer peripheral surface 22. In this way, the heat exchange performance of the heat exchanger 200 is effectively enhanced.

In the heat exchanger 200, the first heated region and the second heated region may be formed on the inner peripheral surface 21 of one flow path 20a of the microtube 20. In other words, the first virtual straight line C1 and the second virtual straight line C2 may be set on the inner peripheral surface 21 of one flow path 20a. In this case, the first heated region and the second heated region are arranged side by side in the circumferential direction of the inner peripheral surface 21. In this way, since a plurality of microscale flows 7 are formed in one flow path 20a, the flow path is compared with the case where one microscale flow 7 is formed in one flow path 20a. The flow velocity of the refrigerant flowing through 20a becomes high, and the heat exchange performance becomes high.

(Modification example)
In the heat exchanger 200, the first heated region and the second heated region may be formed on one flow path. The first heated region and the second heated region may be arranged at intervals in the circumferential direction of one flow path.

Embodiment 2.
<Configuration of liquid flow generator>
The liquid flow generator according to the second embodiment has basically the same configuration as the liquid flow generator 100 according to the first embodiment, but as shown in FIG. 7, the fourth heated region 6d2 is Y. It differs from the liquid flow generator 100 in that it is formed at a distance from the first heated region 6d in the direction.

In addition to the first laser light sources 3a to 3c, the liquid flow generator according to the second embodiment includes a first laser light source (not shown) that irradiates the first region 3d2 with the first laser light, and a second region 4d2. It further includes a second laser light source (not shown) that irradiates the second laser beam. The first laser light source that irradiates the first region 3d2 with the first laser beam is arranged at a distance in the Y direction from the first laser light source 3a (see FIG. 1) that irradiates the first region 3d with the first laser beam. Has been done. The first laser light source has the same configuration as the first laser light sources 3a to 3c. The second laser light source that irradiates the second region 4d2 with the second laser beam is arranged at a distance in the Y direction from the second laser light source 4a (see FIG. 1) that irradiates the second region 4d with the second laser beam. Has been done. The second laser light source has the same configuration as the second laser light sources 4a to 4c.

As shown in FIG. 7, the fourth heated region 6d2 is composed of a first region 3d2 and a second region 4d2. The first region 3d2 and the second region 4d2 are locally heated to a higher temperature than the surrounding regions of the first region 3d2 and the second region 4d2. The first region 3d2 has the same configuration as the first region 3d. The second region 4d2 has the same configuration as the second region 4d.

The distance in the Y direction between the first heated region 6d and the fourth heated region 6d2 is, for example, 10 μm or more so that the diameter of the stably generated microbubbles is about 10 μm and interference between the microbubbles is avoided. is there.

The first virtual straight line C1 shown by the dotted line in FIG. 7 has the same configuration as the first virtual straight line C1 shown in FIG.

The fourth maximum temperature portion 61d2 of the fourth heated region 6d2 is arranged on the first virtual straight line C1. As a result, when the first surface 11 heated by the first laser light source and the second laser light source is viewed in a plan view, the microbubbles 5d2 generated by the fourth heated region 6d2 and the micro bubbles generated by the first heated region 6d The bubble 5d is arranged on the first virtual straight line C1. The average temperature of the seventh portion 65d2 located on one side of the fourth maximum temperature portion 61d2 on the first virtual straight line C1 is the eighth located on the other side of the fourth maximum temperature portion 61d2. It is higher than the average temperature of the portion 66d2. The seventh portion 65d2 is located on the side opposite to the first heated region 6d with respect to the fourth maximum temperature portion 61d2. The eighth portion 66d2 is located on the first heated region 6d side with respect to the fourth maximum temperature portion 61d2.

Preferably, the difference between the average temperatures of the seventh portion 65d2 and the eighth portion 66d2 located on the first virtual straight line C1 is the fourth maximum temperature portion 61d2 on any virtual straight line passing through the fourth maximum temperature portion 61d2. This is the largest difference between the average temperature of the portion located on one side and the average temperature of the portion located on the other side.

The fourth maximum temperature portion 61d2 of the fourth heated region 6d2 includes, for example, the center of the fourth heated region 6d2. In this case, the center of the fourth heated region 6d2 is arranged on the first virtual straight line C1. The seventh portion 65d2 is a portion located on one side of the center of the fourth heated region 6d2 on the first virtual straight line C1. The eighth portion 66d2 is a portion located on the first virtual straight line C1 on the other side of the center of the fourth heated region 6d2.

From a different point of view, the fourth virtual straight line C4 is set in the liquid flow generator according to the second embodiment. The fourth virtual straight line C4 is a virtual straight line that passes through the fourth hottest portion 61d2 of the fourth heated region 6d2 when the first surface 11 heated by the first laser light source and the second laser light source is viewed in a plan view. is there. On the fourth virtual straight line C4, the average temperature of the portion located on one side of the fourth maximum temperature portion 61d2 is higher than the average temperature of the portion located on the other side with respect to the fourth maximum temperature portion 61d2, and both portions. It is subtracted so that the difference in average temperature of is maximized. The fourth virtual straight line C4 is set so as to be continuous with the first virtual straight line C1. The fourth virtual straight line C4 is set so as to overlap with, for example, the first virtual straight line C1.

<Effect>
Since the liquid flow generator according to the second embodiment has basically the same configuration as the liquid flow generator 100 according to the first embodiment, the same effect as that of the liquid flow generator 100 can be obtained.

Further, in the liquid flow generator according to the second embodiment, the temperature distribution of the fourth heated region 6d2 on the first virtual straight line C1 is formed asymmetrically with respect to the fourth maximum temperature portion 61d2. Therefore, as shown in FIG. 8, the temperature distribution on the surface of the liquid LQ in contact with the microbubbles 5d2 formed by the liquid in contact with the fourth heated region 6d2 being heated and evaporated by the fourth heated region 6d2 is , Is formed asymmetrically with respect to the fourth maximum temperature portion 61d2 on the first virtual straight line C1. The distribution of the surface tension of the liquid LQ in contact with the microbubbles 5d2 is also formed asymmetrically with respect to the fourth maximum temperature portion 61d2.

As a result, as shown in FIG. 8, the Marangoni convection 7a2 is formed downstream of the Marangoni convection 7a, and the Marangoni convection 7a2 does not oppose the Marangoni convection 7a. As a result, the microscale flow 7 generated by the liquid flow generator according to the second embodiment becomes longer in the Y direction than the microscale flow 7 generated by the liquid flow generator 100 according to the first embodiment.

The flow velocity of the microscale flow 7 decreases as the distance from the microbubbles 5a increases due to friction on the first surface 11. If the distance between the first heated region 6d and the fourth heated region 6d2 in the Y direction is 10 μm or less, the microscale flow 7 can be extended in the Y direction in which the liquid LQ should flow.

Further, if the fourth virtual straight line C4 is set to overlap with the first virtual straight line C1, the Marangoni convection 7a2 faces the same direction as the Marangoni convection 7a, so that the liquid LQ flows efficiently in that direction.

As shown in FIG. 7, in the liquid flow generator according to the second embodiment, a plurality of heated regions 6d3, 6e2, 6e3, 6f2, 6f3 arranged at intervals in the X direction and the Y direction are further provided. It may be formed.

Each of the plurality of heated regions 6d3, 6e2, 6e3, 6f2, 6f3 has the same configuration as the first heated region 6d, the second heated region 6e, the third heated region 6f, and the fourth heated region 6d2. It has.

The hottest portion of the heated region 6d3 is arranged on the first virtual straight line C1. The first maximum temperature portion 61d of the first heated region 6d, the fourth maximum temperature portion 61d2 of the fourth heated region 6d2, and the maximum temperature portion of the heated region 6d3 are arranged side by side on the first virtual straight line C1. To.

Each of the hottest portions of the heated regions 6e2 and 6e3 is arranged on the second virtual straight line C2. The second maximum temperature portion 61e of the second heated region 6e and the maximum temperature portions of the heated regions 6e2 and 6e3 are arranged side by side on the second virtual straight line C2.

Each of the hottest portions of the heated regions 6f2 and 6f3 is arranged on the third virtual straight line C3. The third maximum temperature portion 61f of the third heated region 6f and the maximum temperature portions of the heated regions 6f2 and 6f3 are arranged side by side on the third virtual straight line C3.

For each first region of the first heated region 6d, the second heated region 6e, the third heated region 6f, the fourth heated region 6d2, and the plurality of heated regions 6d3, 6e2, 6e3, 6f2, 6f3. The relative positional relationship of the second region is equivalent.

In this way, the microscale flow 7 is formed over a wider area in the X direction and in a longer area in the Y direction.

<Structure of heat exchanger>
The heat exchanger 201 shown in FIG. 9 includes the liquid flow generator 101 according to the second embodiment, and the substrate 10 is configured as a microtube 30. At least one flow path through which the refrigerant flows is formed inside the microtube 30. The extending direction of the one flow path of the microtube 30 is the direction in which the refrigerant should flow. The first surface 11 of the substrate 10 is configured as the inner peripheral surface 31 of the one flow path. The second surface 12 of the substrate 10 is configured as the outer peripheral surface 32 of the microtube 30. The inner diameter of the flow path is on the order of μm.

As shown in FIG. 9, in the heat exchanger 201, a plurality of heated regions are formed on the inner peripheral surface 31, and the heated regions are arranged side by side in the circumferential direction R of the microtube 30. , The microtubes 30 are arranged side by side in the extending direction.

The first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 are arranged side by side in the circumferential direction R. Each of the first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 is set to pass through the hottest part of the plurality of heated regions.

In this way, the liquid flow generator 101 can form a plurality of microscale flows arranged in the circumferential direction in the vicinity of the inner peripheral surface 31 of the microtube 30. Therefore, each flow velocity of the plurality of microscale flows formed in the vicinity of the inner peripheral surface 31 is faster than the flow velocity of the refrigerant in the vicinity of the inner peripheral surface in the conventional heat exchanger not provided with the liquid flow generator 101. As a result, the heat exchange performance of the heat exchanger 201 is higher than that of the conventional heat exchanger not provided with the liquid flow generator 101.

As shown in FIG. 10, in the heat exchanger 201, the microtube 30 may have a curved shape. The microtube 30 includes a first tube portion 33, a second tube portion 34, and a third tube portion 35, which are sequentially connected in series. The curvature of the central axis of the second pipe portion 34 is larger than the curvature of the central axis of the first pipe portion 33 and the curvature of the central axis of the third pipe portion 35.

In the liquid flow generator according to the second embodiment, a plurality of first heating portions that locally heat the inner peripheral surface 31 of the first pipe portion 33 and the inner peripheral surface 31 of the second pipe portion 34 are locally heated. A plurality of second heating portions for heating and a plurality of third heating portions for locally heating the inner peripheral surface 31 of the third pipe portion 35 are provided. Each of the plurality of first heating portions, the plurality of second heating portions, and the plurality of third heating portions includes a first laser light source and a second laser light source.

Each of the plurality of first heating portions is arranged side by side in a direction along the central axis of the first pipe portion 33. Each of the plurality of second heating portions is arranged side by side in the direction along the central axis of the second pipe portion 34. Each of the plurality of third heating portions is arranged side by side in the direction along the central axis of the third pipe portion 35.

The plurality of second heating portions are arranged more densely in the direction in which the refrigerant should flow than the plurality of first heating portions. In other words, the shortest distance between the plurality of second heating portions in the direction along the central axis of the second pipe portion 34 is the shortest distance between the plurality of first heating portions in the direction along the central axis of the first pipe portion 33. Shorter than the distance. Similarly, the plurality of second heating portions are arranged more densely in the direction in which the refrigerant should flow than the plurality of third heating portions. In other words, the shortest distance between the plurality of second heating portions in the direction along the central axis of the second pipe portion 34 is the shortest distance between the plurality of third heating portions in the direction along the central axis of the third pipe portion 35. Shorter than the distance.

The first heated region 6d, the fourth heated region 6d2, and the heated region 6d3, 6d4, 6d5, 6d6, 6d7, 6d8, 6d9, 6d10 (hereinafter referred to as the first group heated region) shown in FIG. Each of the above is arranged side by side in the extending direction of the microtube 30. Each of the second heated region 6e and the heated region 6e2, 6e3, 6e4, 6e5, 6e6, 6e7, 6e8, 6e9, 6e10 (hereinafter referred to as the heated region of the second group) extends in the extending direction of the microtube 30. They are arranged side by side in.

The first tube portion 33 is arranged with a first heated region 6d, a fourth heated region 6d2, a heated region 6d3, and a second heated region 6e and a heated region 6e2, 6e3. Areas to be heated 6d4, 6d5, 6d6, 6d7, 6e4, 6e5, 6e6, 6e7 are arranged in the second pipe portion 34. Areas to be heated 6d8, 6d9, 6d10, 6e8, 6e9, 6e10 are arranged in the third pipe portion 35.

The heated regions 6d4, 6d5, 6d6, 6d7, 6e4, 6e5, 6e6, 6e7 of the second pipe portion 34 are the first heated region 6d, the fourth heated region 6d2, and the heated region 6d3 of the first pipe portion 33. , And the second heated region 6e and the heated regions 6e2 and 6e3 are arranged more densely in the direction in which the refrigerant should flow. In other words, the shortest distance D2 between two adjacent heated regions among the plurality of heated regions arranged in the second pipe portion 34 is adjacent to the plurality of heated regions arranged in the first pipe portion 33. It is shorter than the shortest distance D1 between the two mating regions to be heated.

The heated regions 6d4, 6d5, 6d6, 6d7, 6e4, 6e5, 6e6, 6e7 of the second pipe portion 34 are compared with the heated regions 6d8, 6d9, 6d10, 6e8, 6e9, 6e10 of the third pipe portion 35. It is densely arranged in the direction in which the refrigerant should flow. In other words, the shortest distance D2 between two adjacent heated regions among the plurality of heated regions arranged in the second pipe portion 34 is adjacent to the plurality of heated regions arranged in the third pipe portion 35. It is shorter than the shortest distance D3 between the two mating regions to be heated.

The distance between two adjacent regions in the heated region of the first group becomes shorter as the curvature between the two regions increases. Similarly, the distance between two adjacent regions of the heated region of the second group becomes shorter as the curvature between the two regions increases.

The distance between two adjacent regions among the plurality of heated regions arranged in the first pipe portion 33 becomes gradually shorter as it approaches, for example, the second pipe portion 34. Similarly, the distance between two adjacent regions among the plurality of heated regions arranged in the third pipe portion 35 gradually increases as the distance from the second pipe portion 34 increases, for example.

The heated region of the first group is arranged closer to the center of curvature of the second pipe portion 34 than, for example, the heated region of the second group. In this case, the distance between two adjacent regions in the second pipe portion 34 of the heated region of the first group is, for example, two adjacent regions in the second pipe portion 34 of the heated region of the second group. Shorter than the spacing between regions.

The pressure loss of the refrigerant flowing through the second pipe portion 34 having a relatively large curvature is larger than the pressure loss of the refrigerant flowing through the first pipe portion 33 and the third pipe portion 35 having a relatively small curvature. Therefore, the shortest distance between two adjacent heated regions among the plurality of heated regions arranged in the second pipe portion 34 and two adjacent heated regions among the plurality of heated regions arranged in the first pipe portion 33. When the shortest distance between the heated regions is equal, the flow velocity of the microscale flow 7 in the second pipe portion 34 is smaller than the flow velocity of the microscale flow 7 in the first pipe portion 33.

On the other hand, in the heat exchanger 201 provided with the microtube 30 shown in FIG. 10, the plurality of heated regions of the second pipe portion 34 are the plurality of heated regions of the first pipe portion 33 in the direction in which the refrigerant should flow. It is arranged more densely than. Therefore, in the microtube 30, the decrease in the flow velocity of the refrigerant in the second pipe portion 34 due to the pressure loss is suppressed.

In the liquid flow generator 101 and the heat exchanger 201 according to the second embodiment, the number of arrangements in the Y direction of the plurality of heated regions may be 2 or more, and the arrangements of the plurality of heated regions in the X direction may be used. The number is not particularly limited.

Embodiment 3.
As shown in FIG. 11, the liquid flow generator 102 according to the third embodiment has basically the same configuration as the liquid flow generator 100 according to the first embodiment, but the material constituting the thin film 2 is used. It differs from the liquid flow generator 100 in that it contains a compound semiconductor.

The material constituting the thin film 2 contains at least one selected from the group consisting of gallium antimonide (GaSb), indium antimonide (InSb), indium nitride (InN), and indium arsenide (InAs). Each energy bandgap of the above group of compound semiconductors is 1 eV or less. Therefore, in the liquid flow generator 102, the energy of the laser beam required to cause photothermal conversion in the thin film 2 can also be set to 1 eV or less. As a result, the energy required to generate the microbubbles in the liquid flow generator 102 is lower than that in the liquid flow generator 100.

Further, each thermal conductivity of the compound semiconductors of the above group 1 is 50 W / m · K or less. Therefore, in the liquid flow generator 102, the heat generated by photothermal conversion in the heated region of the thin film 2 is difficult to diffuse to the region around the heated region of the thin film 2, and the temperature of the heated region is kept high. As a result, the energy required to generate the microbubbles in the liquid flow generator 102 is further lower than that in the liquid flow generator 100.

Further, the strength of the above-mentioned group of compound semiconductors is higher than the strength of a thin film formed by a plurality of Au nanoparticles bonded via agglomerates or binders. This is because the atoms of the above group of compound semiconductors are covalently bonded. Therefore, the impact resistance of the thin film 2 in the liquid flow generator 102 is higher than that of the liquid flow generator 100.

For this reason, the liquid flow generator 102 is suitable for a liquid flow generator that causes a flow in a liquid LQ having a relatively small amount of dissolved gas.

It is known that the process of generating microbubbles affects the amount of dissolved gas in a liquid. When a liquid with a relatively large amount of dissolved gas is heated, microbubbles containing air as a main component (hereinafter referred to as air microbubbles) are generated, and when a liquid with a relatively small amount of dissolved gas is heated. Generates microbubbles containing water vapor as the main component (hereinafter referred to as water vapor microbubbles).

Since the diameter of the water vapor microbubbles is smaller than the diameter of the air microbubbles, the gradient of the surface tension of the liquid in contact with the water vapor microbubbles is larger than that of the air microbubbles. As a result, the flow velocity of the Marangoni convection caused by the water vapor microbubbles is faster than the flow velocity of the Marangoni convection caused by the air microbubbles, and the flow velocity of the microscale flow caused by the water vapor microbubbles is also higher than the flow velocity of the microscale flow caused by the air microbubbles. It will be faster.

On the other hand, it has been confirmed that the impact applied to the thin film 2 when the water vapor microbubbles are generated is larger than the impact applied to the thin film 2 when the air microbubbles are generated. Therefore, when the liquid flow generator 100 in which the thin film 2 is a thin film of Au nanoparticles is continuously used for the purpose of generating a flow in the liquid LQ having a relatively small amount of dissolved gas, the thin film 2 generates water vapor microbubbles. There is a risk of continuous damage due to the impact. On the other hand, in the liquid flow generator 102, even when the liquid LQ having a relatively small amount of dissolved gas continues to be used for the purpose of generating a flow, the thin film 2 is subjected to an impact when water vapor microbubbles are generated. Can withstand.

The liquid flow generator 102 is also suitable for a liquid flow generator that causes a flow in a liquid LQ having a relatively large amount of dissolved gas.

The liquid flow generator 102 according to the third embodiment has basically the same configuration as the liquid flow generator according to the second embodiment, and only in that the material constituting the thin film 2 contains a compound semiconductor. It may be different from the liquid flow generator according to 2.

Since the liquid flow generator according to the third embodiment has basically the same configuration as the liquid flow generator 100 according to the first embodiment, the same effect as that of the liquid flow generator 100 can be obtained. ..

Embodiment 4.
<Configuration of liquid flow generator>
As shown in FIG. 12, the liquid flow generator 103 according to the fourth embodiment has basically the same configuration as the liquid flow generator 100 according to the first embodiment, but has a first laser light source and a second laser light source. It differs from the liquid flow generator 100 in that it includes a heating element 13 instead of the laser light source.

The heating element 13 is arranged so as to be in contact with the second surface 12 of the substrate 10 and is provided so as to heat the first surface 11 of the thin film 2 via the substrate 1. For example, the entire surface of the heating element 13 in contact with the second surface 12 generates heat.

The thin film 2 includes a first surface portion 15d to 15f, a first surface portion 15d to 15f, and a third surface portion 17. The second surface portions 16d to 16f are arranged adjacent to the first surface portions 15d to 15f. The third surface portion 17 is arranged in a region other than the first surface portions 15d to 15f and the second surface portions 16d to 16f in the first surface 11.

The thermal conductivity of the materials constituting the first surface portions 15d to 15f is higher than the thermal conductivity of the materials constituting the second surface portions 16d to 16f. The thermal conductivity of the materials constituting the second surface portions 16d to 16f is higher than the thermal conductivity of the materials constituting the third surface portion 17. The thermal conductivity of the material constituting the third surface portion 17 is set so as to suppress heat transfer from the surface of the third surface portion 17 in contact with the substrate 1 to the first surface 11. The material constituting the first surface portions 15d to 15f contains, for example, copper (Cu). The material constituting the second surface portions 16d to 16f contains, for example, aluminum (Al). The material constituting the third surface portion 17 includes, for example, carbon steel, chrome steel, or stainless steel. Each of the first surface portions 15d to 15f has the same configuration as each other. Each of the second surface portions 16d to 16f has the same configuration as each other.

The heat generated in the heating element 13 passes through the substrate 1 and reaches the thin film 2. Due to the distribution of thermal conductivity of the first surface portions 15d to 15f, the second surface portions 16d to 16f, and the third surface portion 17, the first surface portions 15d to 15f and the second surface of the first surface 11 The region located on the portions 16d to 16f is locally heated to a higher temperature than the region located on the third surface portion 17 of the first surface 11. Further, the region of the first surface 11 located on the first surface portions 15d to 15f is locally heated to a higher temperature than the region of the first surface 11 located on the second surface portions 16d to 16f. ..

That is, in the liquid flow generator 103, the thin film 2 including the first surface portions 15d to 15f, the first surface portions 15d to 15f, and the third surface portion 17, and the heating element 13 locally cover the first surface 11. It constitutes a heating part that heats up.

In the liquid flow generator 103, the first regions 3d to 3f are configured as regions located on the first surface portions 15d to 15f of the first surface 11, and the second regions 4d to 4f are the first of the first surfaces 11. 2 It is configured as a region located on the surface portions 16d to 16f. The region of the first surface 11 located on the third surface portion 17 constitutes a region around the first heated region 6d, the second heated region 6e, and the third heated region 6f.

Each of the first heated region 6d, the second heated region 6e, and the third heated region 6f is heated to a temperature higher than the temperature at which microbubbles are generated. The first surface 11 on the third surface portion 17 is not heated above the temperature at which microbubbles are generated.

The first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 shown by the dotted lines in FIG. 13 can be set in the same manner as those in the liquid flow generator 100 according to the first embodiment.

The liquid flow generator 103 can be deformed in the same manner as the liquid flow generator 100. For example, the first surface 11 may be a curved surface.

<Effect>
Since the liquid flow generator according to the fourth embodiment has basically the same configuration as the liquid flow generator 100 according to the first embodiment, the same effect as that of the liquid flow generator 100 can be obtained.

<Structure of heat exchanger>
The heat exchanger according to the fourth embodiment includes the liquid flow generator 103 according to the fourth embodiment, and the substrate 10 is configured as a microtube. The microtube may have basically the same configuration as the microtube 20 in the heat exchanger 200 according to the first embodiment, but the heating element 13 is provided so as to cover the outer peripheral surface of the microtube. It differs from the microtube 20 in that it is.

Embodiment 5.
<Configuration of liquid flow generator>
The liquid flow generator according to the fifth embodiment has basically the same configuration as the liquid flow generator 103 according to the fourth embodiment, but as shown in FIG. 14, the fourth heated region 6d2 is Y. It differs from the liquid flow generator 103 in that it is formed at a distance from the first heated region 6d in the direction. From a different point of view, the liquid flow generator according to the fifth embodiment has basically the same configuration as the liquid flow generator according to the second embodiment, but instead of the first laser light source and the second laser light source. The heating element 13 is provided as a heating unit, which is different from the liquid flow generator according to the second embodiment.

As shown in FIG. 14, the thin film 2 has a first surface portion for forming a first region 3d2 in addition to the first surface portions 15d to 15f, the first surface portions 15d to 15f, and the third surface portion 17. It further includes 15d2 and a second surface portion 16d2 for forming the second region 4d2.

The first surface portion 15d2 for forming the first region 3d2 is arranged at a distance in the Y direction from the first surface portion 15d for forming the first region 3d. The first surface portion 15d2 has the same configuration as the first surface portions 15d to 15f. The second surface portion 16d2 for forming the second region 4d2 is arranged at a distance in the Y direction from the second surface portion 16d for forming the second region 4d. The second surface portion 16d2 has the same configuration as the second surface portions 16d to 16f.

As shown in FIG. 7, the fourth heated region 6d2 is composed of a first region 3d2 and a second region 4d2. The first region 3d2 and the second region 4d2 are locally heated to a higher temperature than the surrounding regions of the first region 3d2 and the second region 4d2. The first region 3d2 has the same configuration as the first region 3d. The second region 4d2 has the same configuration as the second region 4d.

The distance in the Y direction between the first heated region 6d and the fourth heated region 6d2 is, for example, 10 μm or more so that the diameter of the stably generated microbubbles is about 10 μm and interference between the microbubbles is avoided. is there.

The first virtual straight line C1, the second virtual straight line C2, and the third virtual straight line C3 shown by the dotted lines in FIG. 14 can be set in the same manner as those in the liquid flow generator according to the second embodiment. The plurality of heated regions shown in FIG. 14 have the same configuration as those in the liquid flow generator according to the second embodiment.

<Effect>
Since the liquid flow generator according to the fifth embodiment has basically the same configuration as the liquid flow generator 103 according to the fourth embodiment, the same effect as that of the liquid flow generator 103 can be obtained.

Further, since the liquid flow generator according to the fifth embodiment has basically the same configuration as the liquid flow generator according to the second embodiment, the same effect as that of the liquid flow generator according to the second embodiment can be obtained. Can play.

<Structure of heat exchanger>
The heat exchanger according to the fifth embodiment includes the liquid flow generator 101 according to the fifth embodiment, and the substrate 10 is configured as a microtube 40. The microtube 40 has basically the same configuration as the microtube 30, but the inner peripheral surface 41 of the microtube 40 is configured as the first surface 11 of the substrate 10 according to the fifth embodiment, and the microtube It differs from the microtube 30 in that the outer peripheral surface 42 of the 40 is covered with the heating element 13.

As shown in FIG. 15, in the microtube 40, a plurality of sets of a set of first surface portions and a set of second surface portions for forming one set of heated regions are provided. The first surface portion and the second surface portion of each set are arranged side by side in the circumferential direction R of the microtube 40, and are arranged side by side in the extending direction of the microtube 40. As a result, in the microtube 40, a plurality of heated regions are formed on the inner peripheral surface 41, and the heated regions are arranged side by side in the circumferential direction R of the microtube 40 and extend the microtube 40. They are arranged side by side in the current direction.

As shown in FIG. 16, the microtube 40 may have a curved shape similar to the microtube 30 shown in FIG. The microtube 40 includes a first tube portion 43, a second tube portion 44, and a third tube portion 45, which are sequentially connected in series. The curvature of the central axis of the second pipe portion 44 is larger than the curvature of the central axis of the first pipe portion 43 and the curvature of the central axis of the third pipe portion 45.

In this case, the heat exchanger according to the fifth embodiment includes a plurality of first heating portions that locally heat the inner peripheral surface 41 of the first pipe portion 43, similarly to the heat exchanger according to the second embodiment. , A plurality of second heating portions for locally heating the inner peripheral surface 41 of the second pipe portion 44, and a plurality of third heating portions for locally heating the inner peripheral surface 41 of the third pipe portion 45 are provided. .. In the heat exchanger according to the fifth embodiment, the plurality of first heating portions, the plurality of second heating portions, and the plurality of third heating portions are each a first surface portion, a second surface portion, and a third surface portion. It is different from the heat exchanger according to the second embodiment in that it is composed of a thin film containing the above and a heating element.

The plurality of first surface portions and the plurality of second surface portions contained in the plurality of second heating portions are more refrigerant than the plurality of first surface portions and the plurality of second surface portions contained in the plurality of first heating portions. Are densely arranged in the direction in which they should flow. In other words, the first surface portion 15d4 located on the upstream side of the two sets of the first surface portion and the second surface portion adjacent to each other in the direction along the central axis of the second pipe portion 44 in the direction in which the refrigerant should flow. The shortest distance between the second surface portion 16d5 located on the downstream side of this is one of the two sets of the first surface portion and the second surface portion adjacent to each other in the direction along the central axis of the first pipe portion 43. It is shorter than the shortest distance between the first surface portion 15d located on the upstream side in the direction in which the refrigerant should flow and the second surface portion 16d2 located on the downstream side of the first surface portion 15d.

The plurality of heated regions arranged in the microtube 40 shown in FIG. 16 has the same configuration as the plurality of heated regions arranged in the microtube 30 shown in FIG. As a result, the heat exchanger according to the fifth embodiment can exhibit the same effect as the heat exchanger according to the second embodiment.

In the liquid flow generator and heat exchanger according to the fifth embodiment, the number of arrangements in the Y direction of the plurality of heated regions may be 2 or more, and the number of arrangements in the X direction of the plurality of heated regions may be 2. There are no particular restrictions.

In the liquid flow generator or heat exchanger shown in FIGS. 1 to 16, the first virtual straight line C1 is set in parallel with the second virtual straight line C2, but the present invention is not limited to this. The angle formed by the first virtual straight line C1 with respect to the second virtual straight line C2 may be less than 90 degrees. Preferably, the angle formed by the first virtual straight line C1 with respect to the second virtual straight line C2 is 45 degrees or less. More preferably, as shown in FIG. 17, the angle formed by the first virtual straight line C1 with respect to the second virtual straight line C2 is 30 degrees or less. As shown in FIG. 17, the third virtual straight line C3 may be set so as to have a line-symmetrical relationship with the first virtual straight line C1 with respect to the second virtual straight line C2.

Although the embodiments of the present disclosure have been described above, the above-described embodiments can be variously modified. Moreover, the basic scope of the present disclosure is not limited to the above-described embodiment. The basic scope of the present disclosure is indicated by the scope of claims and is intended to include all modifications within the meaning and scope of the claims.

1 substrate, 2 thin films, 3a, 3b, 3c first laser light source, 3d, 3d2, 3e, 3f first region, 4a, 4b, 4c second laser light source, 4d, 4d2, 4e, 4f second region, 5a, 5b, 5c, 5d2, 5d microbubbles, 6d 1st heated region, 6e 2nd heated region, 6f 3rd heated region, 6d2 4th heated region, 7 microscale flow, 7a, 7b, 7c, 7a2 Marangoni convection, 8a, 8c 1st optical fiber, 9a, 9c 2nd optical fiber, 10 substrates, 11 1st surface, 12 2nd surface, 13 heating element, 15d, 15d2, 15d4, 15f 1st surface part, 16d, 16d2 16d5, 16f 2nd surface, 17 3rd surface, 20, 30, 40 microtubes, 20a, 20b, 20c flow path, 21, 31, 41 inner peripheral surface, 22, 32, 42 outer peripheral surface, 33, 43 1st pipe, 34,44 2nd pipe, 35,45 3rd pipe, 61d 1st hottest part, 61e 2nd hottest part, 61f 3rd hottest part, 61d2 4th hottest part, 63d , 63e, 63f 1st end, 64d, 64e, 64f 2nd end, 65d 1st part, 66d 2nd part, 65e 3rd part, 66e 4th part, 65f 5th part, 66f 6th part, 65d2 7th part, 66d2 8th part, 100, 101, 102, 103 liquid flow generator, 200, 201 heat exchanger.

Claims (10)

A substrate having a first surface in contact with the liquid is formed, and the substrate is provided so that the liquid flows in the second direction in the center of the flow path.
A heating unit for locally heating the first surface to form microbubbles is provided.
The heating part
A plurality of heated regions are formed on the first surface.
Within each of the plurality of heated regions, a first region having a relatively high temperature and a second region adjacent to the first region and having a relatively low temperature are formed, and the first region is formed. In the second direction along the surface, the first region of each of the plurality of heated regions is provided so as to be arranged on the same side with respect to the second region, and further.
When the first surface is being heated, the heating unit forms a flow of the liquid along the second direction in the center of the flow path, and the second direction is in the vicinity of the first surface. It is provided so as to form a flow of the liquid along the
The heating unit has a second laser light source that irradiates the first region with a first laser beam having a wavelength absorbed by the substrate, and a second laser source having at least one of a wavelength and an intensity different from that of the first laser beam. Including a second laser light source that irradiates the second region with a laser beam.
The material constituting the first surface comprises at least one selected from the group consisting of gallium antimonide (GaSb), indium antimonide (InSb), indium nitride (InN), and indium arsenide (InAs). Liquid flow generator. The heating unit further includes a first optical fiber that irradiates the first region with the first laser beam, and a second optical fiber that irradiates the second region with the second laser beam , according to claim 1. Liquid flow generator. A substrate having a first surface in contact with the liquid is formed, and the substrate is provided so that the liquid flows in the second direction in the center of the flow path.
A heating unit for locally heating the first surface to form microbubbles is provided.
The heating part
A plurality of heated regions are formed on the first surface.
Within each of the plurality of heated regions, a first region having a relatively high temperature and a second region adjacent to the first region and having a relatively low temperature are formed.
In the second direction along the first surface, the first region of each of the plurality of heated regions is provided so as to be arranged on the same side with respect to the second region, and further.
When the first surface is being heated, the heating unit forms a flow of the liquid along the second direction in the center of the flow path, and the second direction is in the vicinity of the first surface. It is provided so as to form a flow of the liquid along the
The heating portion includes a heating element arranged in a region not in contact with the liquid, and a first surface portion, a second surface portion, and a third surface portion exposed on the first surface.
The second surface portion is arranged adjacent to the first surface portion.
The third surface portion is arranged in a region other than the first surface portion and the second surface portion.
The thermal conductivity of the material constituting the first surface portion is higher than the thermal conductivity of the material constituting the second surface portion.
The thermal conductivity of the material constituting the second surface portion is higher than the thermal conductivity of the material constituting the third surface portion.
The heating unit forms the first region in a region of the first surface located on the first surface portion, and the first surface is located in a region of the first surface located on the second surface portion. A liquid flow generator that forms two regions . When the first surface heated by the heating portion is viewed in a plan view, the first virtual straight line passing through the first maximum temperature portion of the first heated region, which is one of the plurality of heated regions. , A second virtual straight line passing through the second maximum temperature portion of the second heated region, which is the other one of the plurality of heated regions, is set.
The heating part
The average temperature of the first portion located on one side of the first maximum temperature portion on the first virtual straight line is higher than the average temperature of the second portion located on the other side, and the first portion The difference between the average temperature of the above and the average temperature of the second part is the maximum, and
The average temperature of the third portion located on one side of the second maximum temperature portion on the second virtual straight line is the fourth portion located on the other side of the second maximum temperature portion. The difference between the average temperature of the third part and the average temperature of the fourth part is the largest and is higher than the average temperature of the above.
The liquid flow generator according to any one of claims 1 to 3 , which is provided so that the angle formed by the first virtual straight line with respect to the second virtual straight line is 0 degrees or more and less than 90 degrees. .. The heated portion covers a third heated region, which is still one of the plurality of heated regions.
It is provided to form further,
When the first surface heated by the heating portion is viewed in a plan view, a third virtual straight line passing through the third maximum temperature portion of the third heated region is further set.
The heating part
The average temperature of the fifth portion located on one side of the third maximum temperature portion on the third virtual straight line is the average temperature of the sixth portion located on the other side of the third maximum temperature portion. It is higher than the average temperature, and the difference between the average temperature of the fifth part and the average temperature of the sixth part is maximum, and
The liquid flow generator according to claim 4 , wherein the first virtual straight line, the second virtual straight line, and the third virtual straight line are provided so as to be parallel to each other . The liquid flow generator according to claim 4 or 5 , wherein the heating unit is provided so that the distance between the first maximum temperature unit and the second maximum temperature unit is 500 μm or less . The heated portion is provided so as to further form a fourth heated region, which is still one of the plurality of heated regions.
In the heating portion, the fourth maximum temperature portion of the fourth heated region is arranged on the first virtual straight line, and the heating portion is on one side of the fourth maximum temperature portion on the first virtual straight line. Any of claims 4 to 6 , which are provided so that the average temperature of the seventh portion located is higher than the average temperature of the eighth portion located on the other side of the fourth maximum temperature portion. The liquid flow generator according to item 1. The liquid flow generator according to any one of claims 1 to 7 , wherein the first surface is a curved surface . The liquid flow generator according to any one of claims 1 to 8 is provided.
The substrate is configured as a microtube through which the liquid flows.
The liquid flowing inside the microtube and the heat medium flowing outside the microtube exchange heat with each other.
The microtube includes a first tube portion and a second tube portion connected in series with the first tube portion.
The curvature of the central axis of the second pipe portion is larger than the curvature of the central axis of the first pipe portion.
The heating section includes a plurality of first heating sections that locally heat the first surface of the first tube section and are arranged side by side along the central axis of the first tube section, and the first heating section. It includes a plurality of second heating portions that locally heat the first surface of the two pipe portions and are arranged side by side in a direction along the central axis of the second pipe portion.
A heat exchanger in which the plurality of second heating portions are arranged closer than the plurality of first heating portions in the extending direction of the microtube. Equipped with a liquid flow generator
The liquid flow generator is
A substrate having a first surface in contact with the liquid is formed, and the substrate is provided so that the liquid flows in the second direction in the center of the flow path.
A heating unit for locally heating the first surface to form microbubbles is provided.
The heating part
A plurality of heated regions are formed on the first surface.
Within each of the plurality of heated regions, a first region having a relatively high temperature and a second region adjacent to the first region and having a relatively low temperature are formed.
In the second direction along the first surface, the first region of each of the plurality of heated regions is provided so as to be arranged on the same side with respect to the second region, and further.
When the first surface is being heated, the heating unit forms a flow of the liquid along the second direction in the center of the flow path, and the second direction is in the vicinity of the first surface. It is provided so as to form a flow of the liquid along the
The substrate is configured as a microtube through which the liquid flows.
The microtube includes a first tube portion and a second tube portion connected in series with the first tube portion.
The curvature of the central axis of the second pipe portion is larger than the curvature of the central axis of the first pipe portion.
The heating section includes a plurality of first heating sections that locally heat the first surface of the first tube section and are arranged side by side along the central axis of the first tube section, and the first heating section. It includes a plurality of second heating portions that locally heat the first surface of the two pipe portions and are arranged side by side in a direction along the central axis of the second pipe portion.
In the extending direction of the microtube, the plurality of second heating portions are arranged more densely than the plurality of first heating portions.
A heat exchanger in which the liquid flowing inside the microtube and the heat medium flowing outside the microtube exchange heat.