JP2020079566A - Heat transition flow pump system - Google Patents

Abstract

To reduce an energy loss caused by the sensible heat of a gas in a heat transition flow pump system.SOLUTION: A heat transition flow pump system is formed by combining a heat transition flow pump 102 having a porous body 10 for partitioning a first space and a second space, and having an air hole whose fine hole diameter is ten times of an average free stroke of an inside gas or smaller, and transiting the gas into the first space from the second space via the air hole by heating a first face of the porous body 10 which contacts with the first space, and a thermal energy collection device for collecting the sensible heat of the gas which is heated by the heat transition flow pump 102.SELECTED DRAWING: Figure 4

Description

  The present invention relates to thermal transient flow pump systems.

  There is known a Knudsen pump that transfers the gas in the first space partitioned by the porous body to the space in the second space by heating one main surface of the porous body (Patent Document 1). Further, there is disclosed a configuration in which carbon is applied as a light absorber on the surface of a porous body used in a Knudsen pump and the porous body is heated by light (Non-Patent Document 1).

  On the other hand, a technique of using a selective absorption film excellent in both sunlight absorption performance and infrared radiation suppression performance on the surface portion of a copper plate or the like as a member for collecting solar heat is disclosed (Patent Document 2).

JP, 2014-145305, A JP, 2011-64395, A

M. Young, et. al., "Characterization and Optimization of a Radiantly Driven Multi-Stage Knudsen Compressor", RGD24 (2005).

  By the way, as a factor leading to energy loss in a thermal transition flow pump such as a Knudsen pump, there are radiant energy loss from materials, heat transfer energy loss to a structure, and sensible heat energy loss of gas. Among these, the radiant energy loss can be reduced by adopting a radiation suppressing material as a material forming the thermal transition flow pump. Further, the heat transfer energy loss can be reduced by adopting a low thermal conductivity material in a portion where the loss due to heat transfer is large.

  On the other hand, since the thermal transition flow pump uses the principle of transporting gas from the low temperature side to the high temperature side, it is impossible to reduce the sensible heat energy loss of gas in the thermal transition flow pump itself. On the other hand, as the countermeasures against the radiant energy loss and the heat transfer energy loss are advanced, the temperature and flow rate of the gas increase and the ratio of the sensible heat energy loss increases.

  One aspect of the present invention includes a porous body that partitions the first space and the second space, and has a pore having a pore diameter that is 10 times or less the mean free path of the gas inside, and is in contact with the first space. A thermal transition flow pump that transfers gas from the second space to the first space through the pores by heating the first surface of the porous body, and sensible heat of the gas heated in the thermal transition flow pump. It is a thermal transition flow pump system that combines a heat energy recovery device for recovery.

  Here, a plurality of the thermal transition flow pumps are provided, the plurality of the thermal transition flow pumps are connected in series and in multiple stages, and the sensible heat of the gas heated in one of the thermal transition flow pumps is recovered as the thermal energy. Afterwards, it is preferred to input the gas into another said thermal transition flow pump.

  Further, it is preferable that the heat energy recovery device includes at least one of a heat exchanger and a heat pump.

  Further, it is preferable that a heat exchanger for cooling the surface of the porous body opposite to the first surface is provided, and the heat exchanger and the thermal energy recovery device are connected in series.

  Further, it is preferable that a gas flow path connecting the thermal transition flow pump and the thermal energy recovery device is thermally insulated.

  According to the present invention, energy loss due to sensible heat of gas in a thermal transition flow pump system such as a Knudsen pump can be reduced.

It is a figure which shows the structural example of a thermal transition flow pump. It is a figure which shows the structural example of a heat transfer plate. It is a figure which shows the structural example of a cooler. It is a figure which shows another structural example of a thermal transition flow pump. It is a figure which shows the structure of the thermal transition flow pump system in embodiment of this invention. It is a figure which shows the structure of the thermal transition flow pump system in the modification 1. It is a figure which shows the structure of the thermal transition flow pump system in the modification 2. It is a figure which shows the structure of the thermal transition flow pump system in the modification 3. It is a figure which shows the structural example of the thermal transition flow pump in the modification 3.

<Structure of Knudsen pump>
Before describing the configuration of the thermal transition flow pump system in the present embodiment, an example of the thermal transition flow pump will be described. In the present embodiment, a Knudsen pump will be described as an example of the thermal transition flow pump.

  As shown in FIG. 1, the Knudsen pump 100 includes a porous body 10, a heat transfer plate 12, a base material 14, a selective absorption film 16, a cooler 18, an airtight seal 20 and a housing 22.

  The Knudsen pump 100 partitions the first space and the second space by the porous body 10 and heats the surface (first surface) of the porous body 10 on the side of the first space to thereby surface the porous body 10 on the side of the second space. A gas is transferred from the second space to the first space by generating a temperature gradient with the (second surface). For example, the Knudsen pump 100 is used to connect a gas generator for generating a desired gas to the second space and transfer the gas supplied from the gas generator from the second space to the first space. ..

  The porous body 10 is a flat plate-shaped member having a large number of pores. The pore size of the pores of the porous body 10 is preferably 10 times or less than the mean free path of the gas in the first space and the second space. For example, since the mean free path of gas under atmospheric pressure is about 60 nm, it is preferable that the pore diameter of the porous body 10 be about 10 nm.

The porous body 10 is preferably made of a material having a low thermal conductivity, in other words, a material in which heat is hard to be transferred from the first surface on the first space side to the second surface on the second space side opposite to the first surface. The porous body 10 can be configured by, for example, a silica airgel in which a large number of pores are formed inside a silicon dioxide (silica, SiO ₂ ) material, a glass fiber filter in which glass fibers are bundled, or the like.

  The heat transfer plate 12 is a member for transferring heat from the selective absorption film 16 described later to the porous body 10. The heat transfer plate 12 is preferably made of a material having a high thermal conductivity, for example, a material containing a metal material such as copper, silver or gold.

  In order to efficiently transfer heat from the selective absorption film 16 to the first surface of the porous body 10, the heat transfer plate 12 is preferably in contact with the surfaces of the porous body 10 and the selective absorption film 16 in the largest possible area. On the other hand, it is necessary to release the gas transferred from the second space to the first space from the first surface of the porous body 10 with the highest possible efficiency. Therefore, as shown in the plan view and the cross-sectional view (cross-sectional view taken along the line AA) of FIG. 2, it is preferable to form a gas flow path 12a that is a groove through which gas flows in the heat transfer plate 12. In the present embodiment, the disk-shaped member is provided with a plurality of gas flow paths 12a extending parallel to each other to the edge of the heat transfer plate 12. However, the shape of the heat transfer plate 12 is not limited to this.

  The selective absorption film 16 is a member for receiving the irradiation of light such as sunlight and converting the absorbed light energy into heat energy to heat the porous body 10. The selective absorption film 16 includes a material having a different reflectance for light depending on the wavelength. That is, when light is incident on the selective absorption film 16, the reflectance is low for light of a certain wavelength and the absorption is high, and the reflectance is high for light of another wavelength and the radiation is large. In the present embodiment, it is preferable that the selective absorption film 16 contains a material whose reflectance at the peak wavelength of the emitted light at 100° C. is 5 times or more the reflectance at the peak wavelength of the absorbed light. Further, it is more preferable that the selective absorption film 16 contains a material whose reflectance at the peak wavelength of the emitted light at 200° C. and 300° C. is 5 times or more the reflectance at the peak wavelength of the absorbed light. As a material of such a selective absorption film 16, for example, Tinox manufactured by Armeco Co., Ltd. may be mentioned.

  Although a general absorption plate made of carbon or the like has a high absorption rate of solar energy, it cannot hold heat, and at 100° C., about half of the energy is released as radiation. On the other hand, the selective absorption film 16 does not release the heat once absorbed, and can convert about 90% of the energy absorbed from sunlight into heat at 100°C. Therefore, by using the selective absorption film 16, the first surface of the porous body 10 can be efficiently heated by irradiating with light.

  The selective absorption film 16 has a high absorptivity in the wavelength band of the spectrum of incident light and a low emissivity in the wavelength band of the spectrum of thermal radiation. For example, when TINOX manufactured by ALMECCO is used as the selective absorption film 16, sunlight can be absorbed by 90% or more, and thermal radiation can be reduced by 90% or more at 100°C.

  The selective absorption film 16 can be formed on the surface of the base material 14. The base material 14 is preferably made of a material that can efficiently transfer heat from the selective absorption film 16 to the heat transfer plate 12. In addition, the base material 14 is preferably made of a material on which the selective absorption film 16 can be easily formed. The base material 14 can be made of a material including a metal material such as copper, silver, or gold. In order to efficiently transfer heat from the selective absorption film 16 to the heat transfer plate 12, the base material 14 is preferably in contact with the heat transfer plate 12 in the largest possible area. Therefore, the base material 14 preferably has the same shape and size as the heat transfer plate 12.

  The base material 14 is bonded to the heat transfer plate 12 on the side surface opposite to the surface on which the selective absorption film 16 is formed. For the adhesion, for example, a silver paste or the like can be used.

  The cooler 18 is a member for cooling the second surface of the porous body 10. The cooler 18 can be a heat sink or a heat exchanger. The cooler 18 is preferably made of a material having a high heat transfer coefficient. The cooler 18 is preferably made of a material containing a metal material such as copper, silver or gold.

  The cooler 18 is preferably in contact with the surface of the porous body 10 in the largest possible area in order to efficiently remove heat from the second surface of the porous body 10. On the other hand, it is necessary to supply the gas transferred from the second space to the first space to the second surface of the porous body 10 as efficiently as possible. Therefore, as shown in the plan view and the cross-sectional view (cross-sectional view taken along the line BB) of FIG. 3, it is preferable to form a gas flow path 18a that is a groove through which gas flows in the cooler 18. In the present embodiment, the disk-shaped member is provided with a plurality of gas flow paths 18a that are through holes arranged in parallel with each other. However, the shape of the cooler 18 is not limited to this.

  The airtight seal 20 forms a gap between the porous body 10 and the cooler 18 or a gap between the cooler 18 and the housing 22 when the first space and the second space are partitioned by the porous body 10 and the cooler 18. It is a member for filling. The hermetic seal 20 can be, for example, a thermosetting resin, an adhesive, an O-ring, or the like. By using the airtight seal 20, the first space and the second space are connected via only the pores of the porous body 10.

  The housing 22 is a member that houses the porous body 10, the heat transfer plate 12, the base material 14, the selective absorption film 16, the cooler 18, and the airtight seal 20, and constitutes a gas flow path together with these members. The housing 22 is made of a member having mechanical strength. In the present embodiment, the housing 22 is a tubular member.

Hereinafter, the operation principle of the Knudsen pump 100 will be described. The Knudsen pump 100 functions as a pump that uses a thermal transition flow. The thermal transition flow is a flow unique to a lean gas, and when a wall with a temperature gradient exists in the lean gas, a unidirectional gas flow formed from a low temperature portion to a high temperature portion of the wall. Point to. The dilute gas is a gas in which, when a certain region is considered, the number of collisions between gas molecules is so small that an equilibrium state cannot be maintained therein. In a dilute gas, the influence of collision between gas molecules and the wall extends far from the wall (distance to some extent). For example, when the pressure in the region of about 1 cm ³ is as low as about 1 Pa, a thermal transition flow occurs. A thermal transition flow also occurs when the pressure in the narrow region of the space of about 10 nm×10 nm×10 nm is about atmospheric pressure.

  In the Knudsen pump 100, the pores of the porous body 10 have a role of a wall. Specifically, the pore diameter of the porous body 10 is set to 10 times or less of the mean free path of gas in the first space and the second space.

  In the Knudsen pump 100, the light energy absorbed by the selective absorption film 16 is converted into thermal energy by making light incident on the selective absorption film 16, and the thermal energy is passed through the base material 14 and the heat transfer plate 12 to form a porous body. The first surface of the porous body 10 is heated by being transmitted to the porous body 10. On the other hand, the cooler 18 cools the second surface of the porous body 10. Thereby, a temperature gradient is generated between the first surface and the second surface of the porous body 10. A thermal transition flow is generated with the temperature gradient, and the gas in the second space is transferred to the first space. That is, the first space of the Knudsen pump 100 is pressurized and the second space is depressurized. The gas generated from the gas generator or the like is drawn into the depressurized second space. The gas flows into the porous body 10 from the second space via the gas flow path 18a of the cooler 18, passes through the pores of the porous body 10, and passes through the gas flow path 12a of the heat transfer plate 12 into the first space. Transferred to. The gas transferred to the first space is sent to the outside of the Knudsen pump 100.

  In addition, as shown in FIG. 4, as the Knudsen pump 102, the porous body 10, the heat transfer plate 12, the base material 14, the selective absorption film 16, the cooler 18, the airtight seal 20, the housing 22, the window 24, and the transparent heat insulating material. It may be configured to include 26. In the Knudsen pump 102, the transparent heat insulating material 26 is configured to fill the gap between the window 24 and the selective absorption film 16.

  With the configuration of the Knudsen pump 102, heat loss due to convection of gas in the first space can be reduced. Therefore, the effect of heating by the selective absorption film 16 can be further enhanced, and the performance of the Knudsen pump 102 can be improved.

  Further, when the pressure in the first space is lower than that in the third space outside the housing 22, the window 24 can be thinned by providing the transparent heat insulating material 26. Therefore, the cost can be reduced and the weight can be reduced. Further, when the light transmittance of the transparent heat insulating material 26 is higher than that of the window 24, the irradiation of light to the selective absorption film 16 is increased by making the window 24 thin, and the heating effect by the selective absorption film 16 can be enhanced. ..

  Further, by pressing the selective absorption film 16, the base material 14, and the heat transfer plate 12 against the cooler 18 by the transparent heat insulating material 26, it is possible to reduce the contact thermal resistance of each part. Thereby, the effect of heating by the selective absorption film 16 can be enhanced. Further, the airtight seal between the porous body 10 and the cooler 18 becomes easy. For example, the airtightness between the porous body 10 and the cooler 18 can be enhanced without using the airtight seal 20. Further, it is not necessary to use a fixing material such as an adhesive for fixing the selective absorption film 16 and the transparent heat insulating material 26. In particular, when a fixing material such as an adhesive is used between the selective absorption film 16 and the porous body 10, the flow passage is likely to be blocked and the characteristics of the Knudsen pump 102 may be deteriorated, which can be prevented. ..

  The fluid pump applied to the thermal transition flow pump system in the present embodiment is not limited to the above example, and may be a thermal transition flow pump.

<Configuration of thermal transition flow pump system>
The thermal transition flow pump system in the present embodiment is configured by combining a Knudsen pump 100 and a heat exchanger 200, as shown in FIG. The heat exchanger 200 is used as a heat energy recovery device that recovers the sensible heat energy of the gas delivered from the Knudsen pump 100.

  As described above, the low temperature gas is introduced into the Knudsen pump 100, and the gas is heated inside and is transferred and sent to the outside. At this time, the gas is sent to the outside in a state where sensible heat energy is applied to the gas by the Knudsen pump 100.

  The Knudsen pump 100 and the heat exchanger 200 are connected via a pipe 30. That is, the gas delivered from the Knudsen pump 100 is delivered to the heat exchanger 200 connected to the Knudsen pump 100 via the pipe 30.

  In the heat exchanger 200, heat energy is exchanged between the gas sent from the Knudsen pump 100 and the heat medium. Here, the gas sent from the Knudsen pump 100 is used as the heat medium on the primary side, and heat energy is exchanged with the heat medium on the secondary side input to the heat exchanger 200. As a result, the sensible heat energy of the gas delivered from the Knudsen pump 100 is recovered.

  The high-temperature heat medium output from the heat exchanger 200 can be used, for example, as hot water or for heating the room.

  In addition, as shown in FIG. 5, it is preferable to provide a heat insulating material 32 in the pipe 30 that connects the Knudsen pump 100 and the heat exchanger 200. For example, it is preferable to cover the outer peripheral surface and the inner peripheral surface of the pipe 30 with the heat insulating material 32. The heat insulating material 32 preferably has a thermal conductivity of 0.3 W/m·K or less, and more preferably 0.05 W/m·K or less.

  As a result, the sensible heat energy released from the gas in the pipe 30 connecting the Knudsen pump 100 and the heat exchanger 200 can be reduced, and the sensible heat energy in the heat exchanger 200 can be recovered more efficiently. Will be possible.

<Modification 1>
As shown in FIG. 6, a plurality of Knudsen pumps 100 may be connected in series and in multiple stages. In this case, the sensible heat energy of the gas sent from the first-stage Knudsen pump 100a is recovered by the heat exchanger 200, and the gas is introduced into the second-stage Knudsen pump 100b. Similarly, a plurality of Knudsen pumps 100 are connected to the subsequent stages.

  The gas introduced into the Knudsen pump 100 is preferably sufficiently low in temperature. According to the configuration of the thermal transition flow pump system of this modification, the sensible heat energy is recovered in the heat exchanger 200 and the gas whose temperature has been lowered can be introduced into the Knudsen pump 100 in the next stage, so that the efficiency of the entire system is improved. Can be increased.

  In FIG. 6, one heat exchanger 200 is commonly connected to four Knudsen pumps 100, but the present invention is not limited to this. For example, the number of Knudsen pumps 100 may be changed, or the number of heat exchangers 200 may be changed.

<Modification 2>
As shown in FIG. 7, the thermal transition flow pump system in the present embodiment may be configured by combining Knudsen pump 100, heat exchanger 200, and heat pump 300. The heat pump 300 is used as a thermal energy recovery device that recovers the sensible heat energy of the gas delivered from the Knudsen pump 100.

  In this modification, the heat pump 300 is operated by utilizing the sensible heat energy of the gas discharged from the heat exchanger 200. The heat pump 300 can be used for cooling the gas introduced into the Knudsen pump 100. Further, the sensible heat energy transferred to the heat medium by the heat pump 300 can be used as hot water or used for heating the room.

<Modification 3>
As shown in FIG. 8, the thermal transient flow pump system in the present embodiment may be configured to introduce the refrigerant from the heat exchanger 202 for cooling the cooler 18 in the Knudsen pump 100 into the heat exchanger 200. .. That is, the heat medium from the heat exchanger 202 for recovering the heat transfer energy from the cooler 18 is introduced into the heat exchanger 200 for recovering the sensible heat energy of the gas sent from the Knudsen pump 100.

  For example, as shown in FIG. 9, the heat exchanger 202 is preferably configured to exchange heat with the cooler 18 by providing a pipe 34 for the cooler 18 and flowing a heat medium. However, the configuration of the heat exchanger 202 is not limited to this, and may be any one that can recover the heat transfer energy from the cooler 18.

  With such a configuration, it is possible to reduce the loss of thermal energy in the thermal transition flow pump system.

10 porous body, 12 heat transfer plate, 12a gas channel, 14 base material, 16 selective absorption film, 18 cooler, 18a gas channel, 20 airtight seal, 22 housing, 24 window, 26 transparent heat insulating material, 30 piping , 32 heat insulating material, 34 piping, 100 (100a, 100b), 102 Knudsen pump, 200, 202 heat exchanger, 300 heat pump.

Claims (5)

The first space and the second space are partitioned from each other, and a porous body having pores whose pore diameter is 10 times or less of the mean free path of the gas inside is provided, and the first surface of the porous body in contact with the first space is heated. A thermal transition pump that transfers gas from the second space to the first space through the pores;
A thermal energy recovery device for recovering sensible heat of gas heated in the thermal transition flow pump,
A combined heat transfer pump system. The thermal transient flow pump system of claim 1, wherein
A plurality of the thermal transition flow pumps are provided, and the plurality of thermal transition flow pumps are connected in series and in multiple stages,
A thermal transition flow pump system, wherein the sensible heat of a gas heated in one of the thermal transition flow pumps is recovered to the thermal energy, and then the gas is input to another thermal transition flow pump. A thermal transient flow pump system according to claim 1 or 2, wherein
The thermal energy recovery device includes at least one of a heat exchanger and a heat pump, and a thermal transition flow pump system. A thermal transient flow pump system according to any one of claims 1-3.
A heat transition flow pump comprising a heat exchanger for cooling the surface of the porous body opposite to the first surface, and the heat exchanger and the thermal energy recovery device are connected in series. system. A thermal transient flow pump system according to any one of claims 1 to 4,
A thermal transition flow pump system, wherein a gas flow path connecting the thermal transition flow pump and the thermal energy recovery device is insulated.

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