US20120260676A1

US20120260676A1 - Cooling system utilizing a conical body

Info

Publication number: US20120260676A1
Application number: US13/088,593
Authority: US
Inventors: Serguei Charamko
Original assignee: Caitin Inc
Current assignee: Caitin Inc
Priority date: 2011-04-18
Filing date: 2011-04-18
Publication date: 2012-10-18

Abstract

Cooling via acceleration of a compressible fluid is disclosed. The fluid is accelerated by a rotatable body to a velocity that may be equal to or greater than the speed of sound in the fluid. No conventional mechanical pump is required to accelerate the fluid. A phase change of the fluid may be utilized to transfer heat from an element to be cooled.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to cooling via a fluid flow cycle. More specifically, the present invention is related to cooling systems that establish a cooling cycle using a rotatable body.
2. Description of the Related Art
Vapor compression systems are used in many cooling applications such as air conditioning and industrial refrigeration. A vapor compression system generally includes a compressor, a condenser, an expansion device, and an evaporator. In a prior art vapor compression system, a gas in a saturated vapor state is compressed to raise the temperature of that gas, the gas then being in a superheated vapor state. The compressed gas is then run through a condenser and turned into a liquid, and heat is rejected from the system. The condensed and liquefied gas is then taken through an expansion device, which drops the pressure and the corresponding temperature. The resulting refrigerant is then boiled in an evaporator, with the refrigerant absorbing heat. The saturated vapor is then returned to the compressor.
FIG. 1 illustrates a vapor compression system 100 as might be found in the prior art. In the prior art vapor compression system 100 of FIG. 1, compressor 110 compresses the gas to (approximately) 238 pounds per square inch (PSI) and a temperature of 190° F. Condenser 120 then liquefies the heated and compressed gas to (approximately) 220 PSI and 117° F. The gas that was liquefied by the condenser 120 is then passed through the expansion valve 130 of FIG. 1. By passing the liquefied gas through expansion valve 130, the pressure is dropped to (approximately) 20 PSI.
A corresponding drop in temperature accompanies the drop in pressure, which is reflected as a temperature drop to (approximately) 34° F. in FIG. 1. The refrigerant that results from dropping the pressure and temperature at the expansion value 130 is boiled at evaporator 140. Through boiling of the refrigerant by evaporator 140, a low temperature vapor results. The vapor is illustrated in FIG. 1 as having a temperature of (approximately) 39° F. and a corresponding pressure of 20 PSI.
The cycle carried out by the system 100 of FIG. 1 is an example of a vapor compression cycle. Such a cycle generally results in a coefficient of performance (COP) between 2.4 and 3.5. The COP, as illustrated in FIG. 1, is the evaporator cooling power or capacity divided by compressor power. It should be noted that the temperature and PSI references that are shown in FIG. 1 are exemplary and are for the purpose of illustration only.
FIG. 2 illustrates the performance that might be expected of a vapor compression system similar to that illustrated in FIG. 1. The COP illustrated in FIG. 2 corresponds to a typical home or automotive vapor compression system operating at an ambient temperature of (approximately) 90° F. The COP shown in FIG. 2 corresponds to a vapor compression system utilizing a fixed orifice tube system.
A system like that illustrated in FIG. 1 and FIG. 2 typically operates at an efficiency rate or COP that is far below that of system potential. To compress gas in a conventional vapor compression system like that illustrated in FIG. 1 (system 100) typically takes 1.75-2.50 kilowatts for every 5 kilowatts of cooling power. This exchange rate is less than optimal and directly correlates to the rise in pressure times the volumetric flow rate. Degraded performance is similarly and ultimately related to performance (or lack thereof) by the compressor 110.
Haloalkane refrigerants such as tetrafluoroethane (CH₂FCF₃) are inert gases that are commonly used as refrigerants in refrigerators and automobile air conditioners. Tetrafluoroethane has also been used to cool over-clocked computers. These gases are referred to as R-134 gases. The volume of an R-134 gas can be 600-1000 times greater than its corresponding liquid form. This multiplier shows that the theoretical efficiency of a system utilizing an R-134 gas is much higher than is currently being realized, and evidences the need for an improved cooling system that more fully recognizes system potential and overcomes technical barriers related to compressor performance.
In light of the theoretical efficiencies of systems using haloalkanes or other fluids, there is a need in the art for an improved cooling system that more fully recognizes system potential and overcomes technical barriers related to compressor performance. There is a further need for a cooling system that operates without the use of a conventional mechanical pump.

SUMMARY OF THE CLAIMED INVENTION

A first claimed embodiment is for a cooling system that includes a rotatable body positioned in a fluid flow path. The system further includes a stationary housing for the rotatable body and a driving mechanism that provides a motive force to induce rotation of the rotatable body. The rotation of the rotatable body accelerates a fluid in the fluid flow path and imparts a rotational velocity to the fluid to change the pressure of the fluid. Concurrent with the pressure change, the temperature of the fluid is reduced and heat is exchanged with an element to be cooled.
A cooling method is also claimed. The claimed method includes rotating a body to accelerate the flow of a fluid in a fluid flow path and to impart a rotational velocity to the fluid to establish a low pressure region in the fluid flow path. The method further includes forming a compression wave in the fluid as the fluid passes from a high pressure region to the low pressure region. Heat is exchanged during a phase change of the fluid that occurs as the fluid flows from the high pressure region to the low pressure region.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a vapor compression cooling system as may be found in the prior art.

FIG. 2 is a pressure-enthalpy graph for a vapor compression cooling system like that illustrated in FIG. 1.

FIG. 3 is an exemplary pressure-enthalpy graph for a cooling system as described herein.

FIG. 4 is a sectional view of an exemplary cooling unit.

FIG. 5 illustrates an exemplary evaporator utilizing a rotatable conical body.

FIG. 6 illustrates an exemplary conical body.

FIG. 7 shows a stationary housing of the evaporator.

FIG. 8 illustrates the underside of the stationary housing.

FIG. 9 illustrates a method of cooling.

DETAILED DESCRIPTION

Embodiments of the present invention implement a cooling cycle that may utilize rotating flow and that increases efficiency as compared to prior art cooling systems. While the system will be described herein generally in terms of a cooling system, those skilled in the art will recognize that the system may be implemented as a heat pump, and thereby serve to heat a given element.
A system utilizing the present invention may operate at a COP of 2 or greater, 3 or greater, 4 or greater, 5 or greater, 6 or greater, 7 or greater, 8 or greater, 9 or greater, 10 or greater, or 20 or greater due to the elimination of certain hardware elements. Nor do embodiments of the present invention require a compressor or a conventional mechanical pump to operate. Only an electric motor or some other driving mechanism to impart a rotating force is required.
Part of the increase in COP for systems utilizing the cooling cycle that may utilize rotating flow and that utilizes a rotatable body is due to the fact that such systems do not need to compress a gas as otherwise occurs at compressor 110 in a prior art vapor compression system 100 like the one shown in FIG. 1. A pressure-enthalpy chart of an exemplary cooling system is illustrated in FIG. 3. The performance curve illustrated is one that might be expected for a cooling system as described herein.
An exemplary cooling system 400, as illustrated in FIG. 4, operates by accelerating a working fluid, which may be water, in an evaporator 500 (see FIG. 5). Due to the operating cycle of the cooling system 400, the system does not require the use of a condenser 120 or a conventional mechanical pump as does the prior art compression system 100 of FIG. 1. The cooling system 400 instead utilizes the evaporator 500 that employs a rotatable body. The rotatable body accelerates the working fluid in the cooling system 400 and may generates a compression wave. While various configurations of the rotatable body may be acceptable within the principles of the present invention, the description herein will describe the operation of the system with reference to a rotatable conical body 410.
The cooling system 400 may operate in the critical flow regime of the working fluid. In this regime, in which the fluid is accelerated to supersonic velocity, the pressure of the fluid in the system 400 will remain almost constant and then ‘jump’ or ‘shock up’ to the ambient pressure.
Because the cooling system 400 accelerates and creates a pressure differential in the working fluid through rotational movement of the conical body 410, the cooling system 400 does not require the use of a conventional mechanical pump. The reduced amount of hardware required to operate a cooling system 400—there is no need for a compressor or a conventional mechanical pump—gives rise to a greatly improved coefficient of performance (COP) for the system.
The conical body 410 may be mounted in an interior stationary housing 420. The motive force required to spin the conical body 410 may be supplied by any number of driving mechanisms known to those skilled in the art. An example of a suitable driving mechanism is an electric motor with a drive axis coupled to the conical body 410.
A lower section of the stationary housing 420 may include one or more flow apertures 430. The flow apertures 430 (visible in FIGS. 5 and 6) allow the working fluid to enter the interior of the housing 420, and may be considered to be the starting point of a fluid flow path.
The rotation of the conical body 410 creates suction that draws the working fluid upward through an inlet 440. The inlet 440 is also shown in FIG. 7. The inlet 440 is coupled to a plurality of acceleration grooves 450. The acceleration grooves 450 are formed in a surface of the stationary housing 420 that forms a conical depression to receive the conical body 410.
As the working fluid is accelerated through the acceleration grooves 450, a cavitation effect may be generated at least in part due to shear forces created between the rotatable conical body 410 and the acceleration grooves 450 formed in the stationary housing 420. The cavitation effect helps to turn the liquid working fluid into a two phase fluid, which aids the formation of a compression wave in the working fluid.
As the fluid is accelerated in the acceleration grooves 450, the fluid is induced to spin within the grooves 450. The rotation imparted to the fluid within the acceleration grooves 450 adds a rotational velocity to the linear velocity, thereby creating a centrifugal effect. The centrifugal effect creates a low pressure area in the acceleration grooves 450. In the acceleration grooves 450, the rotational acceleration is equal to velocity squared divided by the radius of rotation. Therefore small radii of rotation yield large acceleration forces with minimal velocities. This is another factor that provides improved efficiencies for the cooling system 400.
The centrifugal forces created by the rotational velocity within the acceleration grooves 450 create a lowered pressure area near the center of rotation. The lowered pressure promotes evaporation within the acceleration grooves 450, which assists the cooling effect of the system 400. The lowered pressure area may induce cooling prior to the fluid reaching supersonic velocity.
As the working fluid is accelerated in the acceleration grooves 450, the fluid is accelerated to a speed equal to or greater than the speed of sound in the fluid. The resultant phase change contributes to the desired cooling effect of the system 400.
The working fluid shocks up as it exits the acceleration grooves 450 and returns to ambient pressure. The fluid flows through a pathway 460 formed between the surface of the stationary housing 420 and a system enclosure 470. The liquid working fluid then pools at the lower end of the stationary housing portion 420 where it returns to the flow apertures 430.
The fluid flow path of the working fluid may be seen as beginning at the flow apertures 430 in the lower section of the stationary housing 420. The liquid working fluid is sucked into the inlet 440 in the stationary housing 420 by suction (vacuum) created by the acceleration of the fluid due to the rotation of the conical body 410. The working fluid flows upward through the acceleration grooves 450 formed in the stationary housing 420. Post shock, the fluid exits the acceleration grooves 450 and flows downward through the pathway 460 formed between the stationary housing 420 and the system enclosure 470.
As is explained in further detail below, a phase change occurs in the working fluid as the fluid is accelerated in the acceleration grooves 450. As the working fluid travels through the fluid flow path, the system 400 generates a cooling effect via the method delineated in FIG. 9. In a step 910, the motive force for the fluid is provided by spinning the rotatable conical body 410 mounted in the stationary housing 420. The desired rotational speed of the rotatable conical body 410 is determined by the parameters of the system and the selected working fluid. In one embodiment of the system 400, the rotatable conical body 410 may be spun at from approximately 5,000 rpm to approximately 10,000 rpm or faster. In various other embodiments, system conditions may be such that the rotatable conical body 410 may rotate at far slower speeds, such as less than 10 RPM. The rotational speed of the rotatable conical body 410 may vary with the requirements of a given application, and will vary inversely with the size of the body 410.
In a step 920, the working fluid is drawn through inlet 440 in the stationary housing 420 by suction created by the phase change due at least in part to acceleration of the fluid as the conical body 410 rotates.
In a further step 930, as the fluid is accelerated through the acceleration grooves 450, a rotational velocity is imparted to the working fluid in the grooves 450 in addition to the linear velocity. The evaporator 500 may be constructed such that a cavitation effect is created by shear forces generated between the surface of the rotatable conical body 410 and the stationary housing 420, and by a lowered pressure area generated by the centrifugal force created by spinning the rotatable body 410 to accelerate the working fluid through the acceleration grooves 450. The cavitation lowers the speed of sound in the fluid, and thereby assists in the phase change and resultant lowered temperature of the fluid to create a cooling effect in the evaporator 500 in step 940.
Critical flow rate, which is the maximum flow rate that can be attained by a compressible fluid as that fluid passes from a high pressure region to a low pressure region (i.e., the critical flow regime), allows for a compression wave to be established and utilized in the critical flow regime established in the evaporator 500. Critical flow occurs when the velocity of the fluid is greater than or equal to the speed of sound in the fluid. In critical flow, the pressure in the evaporator 500 will not be influenced by the exit pressure. In step 950, the working fluid may ‘shock up’ to the ambient conditions as the fluid exits the acceleration grooves 450.
The pressure change of the fluid in the system 400 may include a range of approximately 20 PSI in the low pressure region to 100 PSI in the high pressure region. In some instances, the pressure may be increased to more than 100 PSI, and in some instance, the pressure may be decreased to less than 20 PSI. Depending upon the characteristics of a given system, the pressure change range may vary from that described immediately above.
The cooling effect of the system 400 may be realized in an object to be cooled by putting the object in direct contact with the system enclosure 470. Another method of transferring heat from the object to be cooled into the system 400 may be accomplished in an optional step 960. In optional step 960, the cooled working fluid is coupled to a heat exchanger. The heat exchanger may transport a heated circulating fluid from the object to be cooled to the cooling system 400.
While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. The descriptions are not intended to limit the scope of the invention to the particular forms set forth herein. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments. It should be understood that the above description is illustrative and not restrictive. To the contrary, the present descriptions are intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims and otherwise appreciated by one of ordinary skill in the art. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.

Claims

1. A cooling system, the system comprising:

a rotatable body positioned in a fluid flow path;

a stationary housing for the rotatable body; and

a driving mechanism that provides a motive force to induce rotation of the rotatable body, the rotation of the rotatable body accelerating a fluid in the fluid flow path and imparting a rotational velocity to the fluid to change the pressure of the fluid so that the temperature of the fluid is reduced to allow heat to be exchanged with an element to be cooled.

2. The system of claim 1, wherein, the rotatable body is generally conical in shape.

3. The system of claim 1, wherein rotation of the rotatable body accelerates fluid and imparts a rotational velocity as the fluid flows through acceleration grooves in the stationary housing.

4. The system of claim 1, wherein rotation of the rotatable body generates cavitation via shear forces and a lowered pressure area in the fluid in the fluid flow path.

5. The system of claim 1, further including an enclosure surrounding the fluid flow path, the enclosure being thermally coupled to the element to be cooled.

6. The system of claim 1, wherein the acceleration of the fluid by the rotation of the rotatable body creates a region in the fluid flow path in which the fluid undergoes a phase change as the pressure of the fluid changes.

7. The system of claim 1, wherein the fluid pressure changes between a high pressure region and a low pressure region, the pressure change created by the acceleration of the fluid and a rotational velocity imparted to the fluid.

8. The system of claim 7, wherein the high pressure region of the fluid is at a pressure greater than 100 PSI.

9. The system of claim 7, wherein the low pressure region of the fluid is at a pressure less than 20 PSI.

10. A method for cooling, the method comprising:

rotating a body to accelerate the flow of a fluid in a fluid flow path and to impart a rotational velocity to the fluid to establish a low pressure region in the fluid flow path;

forming a compression wave in the fluid as the fluid passes from a high pressure region to the low pressure region; and

exchanging heat introduced into the fluid flow path during a phase change of the fluid that occurs as the fluid flows from the high pressure region to the low pressure region.

11. The method of claim 10, wherein exchanging heat occurs at least in part as a result of at least one heat conductive surface being thermally coupled to the fluid flow path.

12. The method of claim 10, wherein acceleration of the flow of the fluid is initiated by rotating a conical body located in a conical depression in a stationary housing of an evaporator.

13. The method of claim 10, further comprising creating a cavitation effect by rotating the conical body to generate shear forces and to impart a rotational velocity to the fluid.

14. The method of claim 10, wherein the rotation of the body creates suction that draws the fluid through an inlet in the fluid flow path.

15. The method of claim 10, further comprising effectuating a phase change in the fluid as a result of a pressure change generated by the rotation of the body.

16. The method of claim 15, wherein the pressure change of the fluid occurs within a range of approximately 20 PSI to 100 PSI.

17. The method of claim 15, wherein the pressure change of the fluid involves a change to a pressure greater than or equal to 100 PSI.

18. The method of claim 15, wherein the pressure change of the fluid involves a change to a pressure less than or equal to 20 PSI.

19. The method of claim 10, wherein the fluid shocks up to an elevated pressure as the fluid exits the low pressure region.

20. The method of claim 19, wherein the elevated pressure is an ambient pressure.