JP2008546984A - Heat transfer venturi - Google Patents

Abstract

  A heat pump consumes power to transfer heat from a heat source to a hotter sink. The present invention allows natural heat transfer from the heat source to a portion of the hotter working fluid, and the working fluid is locally cooled to a temperature below that of the heat source by the Bernoulli effect. The Bernoulli effect occurs in a venturi-shaped duct shaped to maintain laminar flow. Heat transfer efficiency is improved by restricting heat transfer to a small portion (10) of the venturi-type duct where flow temperature, flow rate, pressure gradient and Nusselt effect all promote heat transfer. Heat transfer within this region (10) is maximized by a thermally conductive grid extending across the venturi-shaped neck.

Description

  The present invention relates to a heat pump, i.e., a device that transfers heat from a heat source to a hotter heat sink. In particular, the present invention relates to a Bernoulli heat pump.

  A heat engine is a device that moves heat from a heat source to a sink. Heat engines are divided into two basic types that are distinguished by the direction in which heat travels. The heat naturally flows in the “downhill direction”, that is, toward the lower temperature. Similar to water flow, such “downhill” heat flow can be used to generate mechanical work as described, for example, by internal combustion engines. A device that moves heat in the “uphill” direction, that is, toward higher temperatures, is called a heat pump. A heat pump inevitably consumes power. A refrigerator and an air conditioner are examples of a heat pump. Many heat pumps operate by varying the temperature of the working fluid over a range that includes the temperature of the heat source and sink. In this way, heat naturally flows from the heat source to the portion of the working fluid that has a lower temperature than that temperature. Similarly, heat naturally flows from the portion of the working fluid having a temperature above the sink temperature to the sink. The required temperature change of the working fluid is generally performed by compression and expansion of the working fluid.

  In contrast, Bernoulli-type heat pumps transform the random molecular motion reflected in fluid temperature and pressure into directional motion reflected in macroscopic fluid flow, thereby reducing the required working fluid. Achieving temperature changes. The distinction between random and directional motion is particularly evident in the statistical distribution of molecular velocities. Random motion is the width of such statistical distribution, and directional flow is the average in the same statistical distribution. When the flow cross-sectional area decreases, for example, when the flow passes through a nozzle or venturi, the fluid naturally converts random molecular motion into directional motion. The change in temperature, density and pressure associated with the cross-sectional area is called Bernoulli's law. Compression consumes power, but the Bernoulli transformation does not consume power. The energy conservation characteristics of Bernoulli conversion are the basic efficiencies utilized by Bernoulli heat pumps.

  As shown in FIGS. 1a and 1b, the Bernoulli heat pump is in contrast to the conventional heat pump. As shown in FIG. 1a, the conventional heat pump is composed of four basic components: a compressor 4, an expansion valve 7, a low temperature side heat exchanger 6, and a high temperature side heat exchanger 5. FIG. 1 b shows that the Bernoulli heat pump combines the roles played by the expansion valve 7 and the low temperature side heat exchanger 6 into a single heat transferable venturi 8. Although the conventional system requires a large pressure change because the working fluid flow rate is relatively small, the Bernoulli heat pump requires a smaller pressure change because the working fluid flow rate is relatively high. Thus, in the Bernoulli heat pump (FIG. 1b), the compressor 4 which is a component of the conventional system (FIG. 1a) is replaced by a fan or blower 9. Conventional heat pumps, Bernoulli heat pumps, heat exchangers, compressors, blowers and venturis have all been widely described. The present invention provides a novel structure for efficiently transferring heat 3 to a fluid flowing through a venturi. An important aspect of the present invention is the improved efficiency that the present invention provides for Bernoulli heat pumps. The following description explains the problems of the prior art that have been studied and solved by the present invention.

US Pat. No. 3,049,891 US Pat. No. 2,325,036 US Pat. No. 2,441,279 US Pat. No. 3,200,607

  2 and 3 provide a basis for comparing the present invention with the prior art including a Bernoulli heat pump. FIG. 2 shows the associated changes in temperature, density, pressure, flow rate and cross-sectional area of a so-called one-dimensional compressible gas. There are no new points or issues about this known and much studied phenomenon. The reason why the related changes in these properties of the flowing compressible fluid are reproduced here is that such related changes are compared between earlier technical efforts utilizing the Bernoulli transform and such initial technical efforts and the present invention. It provides a concise basis for comparison. In a one-dimensional flow, the designation for any one of the four quantities that change together implies the remaining three values, and pressure is the product of temperature and density. FIG. 2 shows the temperature, density, pressure and cross-sectional area implied by the flow velocity (squared). The flow velocity is displayed as a dimensionless Mach number. The linear decrease in temperature with the change in the square of the flow velocity is a direct result of energy conservation, ie, conversion from random kinetic energy to directional kinetic energy. It is not surprising that the velocity scale at which the Bernoulli effect occurs is the Mach number, which is the ratio of the two velocities. The quantities shown in FIG. 2 are normalized to the respective values in the stationary gas.

  FIG. 2 directly shows the relationship between the invention described in Patent Document 1, another invention, and the present invention. The invention described in Patent Document 1 requires that the flow is supersonic, that is, the value of Mach number is greater than one. FIG. 2 shows that the gas temperature is indeed low for supersonic flow. However, FIG. 2 also shows that the temperature reduction caused by subsonic flow is more than sufficient for many practical purposes. In this regard, it should be noted that the temperature scale in FIG. 2 is an absolute scale. That is, for example, at a flow rate of Mach 1, the gas temperature decreases by 25%. For example, if the temperature of the stationary gas is 70 ° F. (21.11 ° C.), the temperature near the venturi neck at Mach number 1 is −60 ° F. (−51.1 ° C.), which is lower than zero degrees. ). The numerical values shown in FIG. 2 assume an isentropic flow of an ideal gas (perfect gas), and the ideal gas is characterized by a specific heat ratio of monoatomic gas of 5/3. Thus, the challenge posed by Bernoulli-type heat pumps is not the generation of sufficiently low temperatures, but rather the efficient utilization of the low temperatures found near the neck of a venturi, particularly a subsonic venturi.

  The second direct implication of FIG. 2 is that the power required to maintain high velocity flow in the venturi neck is substantial. The pressure near the venturi neck is about half of the pressure at the venturi inlet. If this pressure drop is not recovered by the diffuser, i.e., the venturi divergent portion, the potential efficiency of the Bernoulli heat pump is reduced. In order to increase efficiency, in addition to requiring a diffuser, it is a requirement to maintain laminar or non-separated flow within the diffuser. This requirement is directly paraphrased as a diffuser with a very gradual slope at the divergent portion, ie, the venturi is very asymmetric and the converging and diverging sections are very different. Extensive literature relating to so-called “critical flow venturi” indicates, for example, that a conical diffuser should have a half angle of less than 10 ° (the angle between the cone wall and the axis of symmetry). Venturi asymmetry requirements for efficiency are not addressed. Although Patent Documents 2 to 4 describe Bernoulli-type heat pumps, these Patent Documents 2 to 4 do not deal with efficiency and the role of the diffuser. The first two of these patent documents 2-4 assume aircraft technology, where the power consumed by a short diffuser is a negligible part of the available power.

  The interest of the present invention is directed to the third aspect of FIG. 2 which is not addressed by any of the patent documents 1-4, ie between the flow velocity and the cross-sectional area of the flow, especially for flow velocities close to Mach number 1. Is directed to the relationship. FIG. 2 shows that when the flow rate is increased, the reciprocal of the area passes through the maximum value. This maximum value is the basis of the Laval nozzle. Another implied by this maximum is that when considered as a function of distance along the venturi axis, the temperature, density and pressure are all small transients near the venturi neck (the maximum of the reciprocal area). Have a negative reduction. That is, FIG. 2 shows that near Mach number 1, the temperature, density, and flow velocity all change significantly, while the cross-sectional area changes only slightly. Thus, when considered as a function of distance along the venturi axis, or in a similar sense as a function of cross-sectional area, temperature, density and pressure all have a significant temporary decrease at the venturi neck. Have. FIG. 3 shows the change in temperature with respect to the shape of the venturi 11 which has been subjected to specific and much research. Changes in temperature, density, pressure, and flow velocity along the Venturi axis are implicitly given from FIG. 2 by specifying the cross-sectional area as a function of distance along the Venturi axis. FIG. 3 is obtained by considering the cross-sectional area change as a change in the cross-sectional area of a so-called “doughnut” critical flow venturi. In these devices, the tapered portion of the venturi has a torus shape and the divergent portion has a conical shape. If the venturi wall is thermally conductive outside the temporarily reduced region shown in FIG. 3, the venturi wall is from somewhere else in the same flow up to the cold neck of the working fluid flow. It becomes a heat path to transfer heat. That is, the heat transferred to the neck portion of the working fluid flow comes from somewhere else in the same working fluid flow and has no net benefit. Not only is there no profit, it costs money. The heat transferred to the working fluid flow is the sum of the heat transferred from the heat source flow (desired effect) and the heat transferred from somewhere else in the working fluid flow, so the desired heat It can be seen that the amount transferred is directly reduced by the amount of heat transferred outside the temporarily decreasing region. Limiting the heat transfer between the working fluid and the venturi wall to the temporarily decreasing region shown in FIG. 3 is the core of the present invention. This limitation is not described in the above-mentioned patent document.

  The importance of this effect is altered and enhanced by four additional effects, the four additional effects being the so-called Nusselt effect and the three effects associated with the boundary layer. The Nusselt effect is an improvement in heat transfer at the fluid-solid interface by convection obtained by fluid flow. Since the flow velocity becomes zero at the interface, the heat transfer from the solid to the working fluid depends on the thermal conductivity. However, the flow of working fluid across the boundary layer dissipates (by convection) the heat transferred by conduction into the boundary layer. Convection is generally much more effective than conduction. At flow velocities near Mach number 1, the Nusselt effect is significant. For example, if the heat source is a fluid that flows slowly, the area where heat is transferred into the working fluid is much smaller than the area where heat is transferred outside the flow of the heat source.

  Two additional effects are associated with changes in the thickness of the boundary layer along the Venturi tube. Heat transferred to the working fluid at the venturi wall must pass through the boundary layer of the working fluid flow. The boundary layer is a region of fluid that flows adjacent to the solid-fluid interface. Since the flow velocity is zero at the interface, the flow velocity of the working fluid must increase or change rapidly near the interface. The narrow area where this increase or change occurs is called the boundary layer. Temperature transfer, and hence heat transfer by conduction, is significantly enhanced where the boundary layer is thin. The boundary layer thickness is greatly affected by the pressure gradient along the direction of working fluid flow.

  The first of the two boundary layer effects relates to the sign of the pressure gradient. It is known that so-called “reverse” or positive pressure gradients thicken the boundary layer. The pressure gradient becomes “reverse” in the end-spread portion (diffuser portion) of the venturi.

  In the venturi where the axial pressure gradient has a favorable sign, the thickness of the boundary layer is, according to general discussion, derived directly from the Naviestokes equation. , Inversely proportional to the square root of the axial pressure gradient. The axial pressure gradient increases rapidly in the region of temporary decrease in temperature. The further thinning of the boundary layer within the region of temporary decrease in temperature is the fourth motivation for limiting heat transfer to this region.

  A fifth or final consideration affecting the efficiency of the Bernoulli heat pump is addressed by the present invention. The portion of the venturi labeled “heat transfer” in FIG. 3 indicates the portion in the venturi axial direction where the conditions for heat transfer are preferred. These are all properties of the bulk of the working fluid flow. That is, temperature and axial pressure gradient are characteristics of the entire cross section of the working fluid flow, excluding the thin boundary layer around the cross section. The decrease in viscosity that occurs outside the temporary temperature decrease region is inconvenient and costly. The focus of the present invention is the thinness in the Venturi axial direction labeled “Heat Transfer” in FIG. 3 without causing the viscosity drop associated with the portion of the Venturi located outside the temporarily reduced region of FIG. It is to use the characteristics of the section 10 (narrow).

Thus, there are five problems associated with the temporary reduction region of FIG. 3 and not addressed in the prior art. These problems are as follows.
1. 1. Improving the Nusselt effect of heat transfer through the neck of the venturi wall. 2. Undesirable heat transfer from somewhere else in the flow of working fluid to the temporary reduction zone 3. Undesirable sign of axial pressure gradient in the diffuser 4. The preferred pressure gradient magnitude in the portion of the temporarily decreasing region located within the tapered portion of the venturi. Reduced efficiency due to reduced viscosity in the boundary layer located outside the temporary temperature decrease region of FIG.

  None of these five issues are addressed in the prior art.

  What Applicants have noted at the end of the description of the prior art is that the Bernoulli conversion is an energy conservation phenomenon, ie it is true that it does not consume power, but the Bernoulli heat pump is not a permanent engine. That is also true. Bernoulli heat pumps consume power in two ways. First, as a requirement of the second law of thermodynamics, when the temperature at which heat 3 is added to the working fluid stream is different from the temperature at which heat 2 is removed from the working fluid stream, a net increase in entropy occurs, It must be compensated by reversible work. The effect of the second law of thermodynamics is the reason why the “heat output” indicated by the arrows in FIGS. 1a and 1b is larger than the “heat input”. The power required to compensate for this entropy generation is proportional to the difference between the temperature at which heat is applied and the temperature at which heat is removed. Second, and more importantly, the change in flow velocity across the boundary layer implies viscous dissipation that must be compensated by reversible work. If the first effect is a major issue, Carnot efficiency can be achieved. The bigger problem is the problem due to viscous dissipation in the boundary layer.

  The present invention is a structure utilizing the “heat transfer” section shown in FIG. 3 and a system utilizing this structure. This structure is a venturi specifically designed to provide effective heat transfer to the fluid, particularly through the venturi. The present invention consists of two uses of the “heat transfer” section. First, heat transfer is limited to the heat transfer section. Second, heat transfer within the heat transfer section is maximized by using dedicated fins within the heat transfer section.

  According to another aspect of the invention, the heat source of heat transferred to the working fluid may be a flowing fluid, gas or liquid, or may be a non-fluid such as an exothermic electrical component. For both fluid and non-fluid heat sources, an important requirement is a heat conductor that couples the heat source to a narrow portion of the venturi axis shown in FIG. 3 as a “heat transfer” section.

  According to another aspect of the invention, the power consumed is reduced by making the spread of the diffuser very slow to maintain laminar or attached flow.

  According to another aspect of the present invention, multiple venturis are configured in multiple stages to obtain either a larger capacity or a larger temperature difference.

  According to another aspect of the present invention, the venturi wall corrugation creates multiple “heat transfer slices” within a single venturi.

  According to another aspect of the present invention, the rate of heat transfer to the working fluid can be continuously varied by changing the flow rate through the venturi.

  According to another aspect of the invention, the heat transfer venturi based system may be open or closed. That is, the system may exhaust the heated working fluid or circulate a working fluid that is optimized for heat transfer or other characteristics.

  In accordance with another aspect of the invention, a heat transfer venturi based system may be used to pump heat in the “downhill” direction. That is, a heat source having a temperature higher than that of the stationary working fluid is cooled by heat conduction. As the working fluid flows, the Nusselt effect and convection are utilized. The working fluid flows through the venturi to further promote cooling. Cooling is further promoted by the working fluid flowing through the heat transfer venturi.

  As with other heat pump technologies, Bernoulli heat pumps can be used for heating or cooling purposes.

  The present invention provides an improved heat transfer structure for use in a Bernoulli heat pump. Embodiments of the heat transfer structure are shown in FIGS. All of these embodiments utilize the “heat transfer” section of the venturi shown in FIG. The heat transfer section is utilized in two basic ways. First, heat transfer to the working fluid through the venturi is limited to the “heat transfer” section 10. Second, heat transfer in the “heat transfer” section 10 is maximized by the introduction of thermally conductive fins that help increase the surface area available for heat transfer in the “heat transfer” section of the venturi.

  FIG. 4 shows a first embodiment of the asymmetric venturi 16, that is, a heat transfer structure having a venturi shape in which the shape of the converging section and the shape of the diverging section are different from each other. The working fluid experiences a Bernoulli transformation. The length of the arrow indicates the flow rate, and the long arrow indicates that the speed is high. As the working fluid 12 enters the venturi, the gas moves slowly and is relatively hot and relatively dense. As the cross-sectional area decreases, the flow velocity must increase in order to maintain a constant mass flow rate. The energy required for this increase in flow rate is derived from random kinetic energy reflected in temperature, as shown in FIG. The decrease in temperature is proportional to the square of the flow velocity, i.e. a Bernoulli effect occurs. Thus, as the gas travels through the venturi, the flow rate increases and reaches a maximum velocity 13 at the minimum cross-sectional area. The change in the axial direction of the flow velocity is a mirror image of the change in temperature shown in FIG. As the cross-sectional area begins to increase in the venturi diffuser portion, the flow velocity decreases 14 as the gas proceeds to the venturi outlet, and the gas 15 at the venturi outlet heats from the heat source stream 17 through the thermally conductive material 18. The temperature is raised to the extent that it is transferred. It is an important aspect of the present invention that the exposure of the thermal conductor 18 to the working fluid is limited to the “heat transfer” section 10 shown in FIG. The venturi wall 16 is thermally insulating anywhere outside the “heat transfer” section 10. In particular, this structure eliminates undesirable heat transfer of the working fluid from other regions of the working fluid to the “heat transfer” section 10.

  The heat source shown in FIG. 4 selected as an example is a flowing fluid. The nature of the heat source 17 and its thermal coupling to the heat conductor 18 are very arbitrary. Limiting heat transfer to the working fluid to the “heat transfer” section 10 is inherent to the present invention.

  The second basic component of the present invention is the additional structure shown in FIG. 5 in an enlarged cross-sectional view of the “heat transfer” section of the venturi. In FIG. 5, it should be noted that, in contrast to FIG. 4, the “heat transfer” section of the venturi is located in the plane of the drawing. In this case, the amount of heat transfer to the working fluid is increased by thermally conductive fins 19 extending from the venturi wall 20 into the working fluid flow. Using fins to increase the amount of heat exchange is a common technique. The novel technique here over this content is that the spread of the thermally conductive fins 19 in the direction of flow, ie in a direction parallel to the axis of the venturi, is limited. Here, the thermally conductive fins 19 are limited to the scope of the “heat transfer” section 10. The pattern of heat conductive fins used is very arbitrary. FIGS. 5 a and 5 b show fins extending across the venturi that intersect each other to form a grid 19 in the “heat transfer” section 10. Useful visualization of such a grid structure is provided by tennis rackets, apple corers and tea strainers (flat tea strainers). Figures 5a and 5b also help to emphasize that the cross-sectional shape of the venturi is arbitrary. Many venturis have cylindrical symmetry, but this is not a requirement.

  Another aspect of the present invention is the cross-sectional shape of the thermally conductive fin. The cross-sectional shape of the thermally conductive fin is an airfoil shape and is designed to minimize the aerodynamic drag acting on the working fluid flow by the fin. The vertical component of the drag, the so-called “pressure” component, is negligibly small due to the aerodynamic cross-sectional shape of the fin. Unlike the more common airfoils, the inventor's thermally conductive fins do not need to provide lift and do not need to change their angle of attack. Thus, the fins should be thin and oriented in a direction along the streamline of the working fluid flow to further reduce drag. In this regard, fixed airfoil arrays are often used to suppress turbulence in the flow in the duct.

  Another degree of design freedom with respect to the grid element is the change in the cross-section of the grid element as a function of distance from the venturi wall. This degree of freedom has a trade-off between heat transfer and structural strength. With respect to structural strength, there is a need to increase the area as the distance from the venturi wall increases. There is an opposite requirement for heat conduction. The appropriate balance depends on the material selected for the grid elements.

  As with Bernoulli type heat pumps that do not utilize the “heat transfer” section, the multiple heat transfer venturis of the present invention may be configured in parallel to achieve greater capacity, and may have higher or lower temperatures. It may be configured in series to achieve. Such a configuration is shown in FIGS. 6a and 6b.

  The fin grid cross section can be optimized to minimize turbulence and drag on the scale of the heat transfer section, so that the overall shape of the venturi, especially the diffuser, can be independently It can be optimized to reduce drag and thus reduce the power required by the blower / fan mechanism 9 required to maintain working fluid flow. A common requirement in this regard is that the cross-sectional area of the venturi diffuser section must be very gentle in order to maintain laminar or attached flow. Laminar or attached flow helps to minimize the component with the highest aerodynamic drag, the so-called pressure drag, leaving only the small component associated with viscosity loss. A 95% recovery of the pressure drop required to achieve a Mach number 1 flow was reported.

  Another design option relates to the flow rate at which the present invention operates. In contrast to traditional heat pumps based on changes in the phase of the working fluid, the operating conditions of a Bernoulli heat pump may be easily and continuously changed. In particular, by changing the power delivered to the blower that maintains the heat sink flow, the flow rate of the heat sink flow, and hence its temperature, can be changed. One important implication of this degree of freedom is the inefficiency of conventional systems at start-up. In the Bernoulli type heat pump including the present invention, the heat pumping rate is continuously variable, thereby effectively eliminating the transient state and its inefficiency at the start. For example, a blower that maintains the flow of working fluid can be thermostat controlled. A second advantage of continuous change and control is to increase the thermodynamically acceptable efficiency with smaller temperature differences. Carnot efficiency is inversely proportional to the temperature difference when pumping heat. Thus, the present invention obtains an efficiency gain associated with longer operation over smaller temperature differences.

  Finally, FIG. 7 shows a corrugated form of a venturi wall designed to form multiple “heat transfer” sections within a single venturi. That is, as described above, the venturi wall is thermally insulating outside the “heat transfer” section, but here there are multiple “heat transfer” sections as shown in FIG.

[Definition]
Venturi: A fluid flow duct or channel structure whose cross-sectional area varies along the axial direction. The change in cross-sectional area along the duct axis has at least one local minimum. Although most venturi cross-sectional areas have diffuser sections that increase along the axis, the inventor's definition of venturi includes nozzles that are short or absent. Thus, this extension of the definition extends the applicability of the present invention to applications where power consumption is not critical.

  Working fluid: a fluid that allows natural heat inflow and natural heat outflow when the temperature is locally varied, for example when the temperature of the heat source is lower than the temperature of the sink.

  Working fluid flow: The working fluid flow through the venturi structure.

  Cross section: An area inside a closed curve formed by the intersection of a plane perpendicular to the venturi axis and the venturi surface.

  Heat transfer section: The portion of the venturi (see FIG. 3) that is located between two planes perpendicular to the venturi axis near the venturi neck and is characterized by low temperature, high flow rate.

  Fin: Made of a high thermal conductivity material, extending from a thermally conductive surface into a fluid flow adjacent to the thermally conductive surface, and heat between the thermally conductive surface and the fluid flow while minimizing resistance to flow It is a structure intended to increase the surface area available for transfer.

  Diffuser: The part of the venturi characterized by a monotonically increasing cross-sectional area along the axial direction, ie the flow direction.

It is a figure which shows the component of a conventional heat pump. It is a figure which shows the component of a Bernoulli type heat pump. FIG. 5 is a graph showing changes in associated flow velocity, temperature, density, pressure and cross-sectional area in a laminar flow of compressible gas. FIG. 5 illustrates an axial change in temperature and venturi shape (dashed line) within the venturi, while revealing the “heat transfer” section of the venturi. 1 is a cross-sectional view of a heat transfer venturi according to an embodiment of the present invention. 2 is a cross-sectional view in a “heat transfer” section of a rectangular venturi according to an embodiment of the present invention including a grid of thermally conductive fins across the heat transfer section. FIG. FIG. 4 is a cross-sectional view in a “heat transfer” section of a non-rectangular venturi according to an embodiment of the present invention including a grid of thermally conductive fins across the heat transfer section. FIG. 6 is a cross-sectional view of a number of heat transfer venturis according to embodiments of the invention arranged in parallel stages to obtain increased capacity. FIG. 3 is a cross-sectional view of a number of heat transfer venturis according to embodiments of the present invention arranged in series to obtain increased capacity. FIG. 2 is a cross-sectional view of a venturi according to an embodiment of the present invention having a corrugated wall and multiple “heat transfer” sections.

Explanation of symbols

1 Working fluid, fluid to which heat is applied by heat transfer venturi 2 Heat removed from working fluid at sink temperature (relatively high temperature) 3 Heat applied to working fluid at heat source temperature (relatively low temperature) 4 Temperature of working fluid And a compressor 5 for increasing pressure, a high temperature side heat exchanger 6 for transferring heat from the working fluid to the sink, a low temperature side heat exchanger 7 for transferring heat from the heat source to the working fluid, an expansion valve 8 for reducing the pressure of the working fluid, a venturi, That is, a duct 9 with a variable cross-sectional area 9 A fan or blower 10 that maintains the flow of working fluid A cross-sectional portion 11 of a venturi having a low pressure, temperature and density, a large flow velocity and pressure gradient, and a cross-sectional area 12 of a normal “critical flow venturi” Working fluid flow portion 13 moving at low speed and relatively hot 13 Working fluid flow portion 14 moving at high speed and relatively low temperature Pressure gradient "Undesirable" working fluid flow deceleration portion 15 Working fluid flow portion 16 when working fluid carrying heat applied in the "heat transfer" section of the venturi exits the venturi 16 Venturi wall 17 in the plane of the drawing A heat source fluid 18 that flows in and out of the heat conductor 19 that carries heat from the heat source stream to the working fluid stream 19 A heat conductive fin that transfers heat from the venturi to the working fluid stream

Claims (15)

A solid heat transfer venturi duct structure capable of guiding a fluid flow comprising:
The cross-sectional area of the heat transfer venturi duct varies along the axis of the heat transfer venturi duct,
Having at least one local minimum cross-sectional area due to a change in cross-sectional area;
The heat transfer venturi duct wall is adiabatic, except for at least one thin heat conducting cross-section located near the minimum cross-sectional area and a heat conductor that couples the heat conducting cross-section to a heat source, heat transfer Venturi duct structure.   The heat transfer venturi duct structure of claim 1 having at least one heat conductive fin extending from a heat conductive cross-sectional portion of a wall of the heat transfer venturi duct into the interior of the heat transfer venturi duct structure.   The heat transfer venturi duct structure of claim 2, wherein the heat conductive fins extend across the heat transfer venturi duct.   The heat transfer venturi duct structure of claim 2, wherein the plurality of heat conductive fins form a heat conductive grid within the heat transfer cross-sectional portion of the heat transfer venturi duct.   The heat transfer venturi duct structure of claim 2, wherein the heat conductive fins are shaped to minimize aerodynamic drag acting on the fluid flowing through the heat transfer venturi duct structure.   The heat transfer venturi duct structure of claim 2, wherein the thermally conductive fins align with fluid streamlines flowing through the heat transfer venturi duct structure to reduce drag acting on the fluid flow.   The heat transfer venturi duct structure of claim 2, wherein a cross-sectional area of the thermally conductive fin varies with distance from a venturi wall.   The heat transfer venturi duct structure of claim 1, wherein the heat transfer rate is controlled by varying the pressure drop across the heat transfer venturi duct structure.   The heat transfer venturi duct structure according to claim 1, comprising a diffuser.   The heat transfer venturi duct structure of claim 9, wherein the diffuser expands gently enough to maintain laminar flow.   The heat transfer venturi duct structure of claim 1, wherein the heat transfer venturi duct discharges a flow into its local ambient environment. Bernoulli type heat pump system,
A heat source,
A heat transfer venturi duct structure according to claim 1;
A thermal coupling between the heat source and a heat conducting section of the heat transfer venturi duct structure;
A working fluid flowing through the heat transfer venturi duct structure;
A blower mechanism that maintains the flow of the working fluid through the heat transfer venturi duct structure;
A Bernoulli type heat pump system comprising: a duct structure that couples the heat transfer venturi duct structure to the blower mechanism. Furthermore, with a heat sink,
A heat exchange mechanism for transferring heat from the working fluid flow to the heat sink;
A duct structure connecting the blower mechanism to the heat exchange mechanism;
The Bernoulli type heat pump system according to claim 12, further comprising a duct structure that connects the heat exchange mechanism to an inlet of the heat transfer venturi duct structure. A method of transferring heat to a flow,
Maintaining a pressure drop to maintain fluid flow through the heat transfer venturi duct structure of claim 1;
Maintaining a flow of heat into at least one thermally conductive cross-sectional portion of the heat transfer slice of the heat transfer venturi duct structure.   The method of claim 14, wherein a heat transfer rate is controlled by a change in the pressure drop.

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