Patent Application
20150176436
1. Statement of the Technical Field
The invention concerns a mixer assembly and method for mixing various vaporized fluid. More particularly, the invention concerns a mixer assembly and method for providing a saturated combined working fluid.
2. Description of the Related Art
Heat engines and the like use energy provided in the form of heat to perform mechanical work. In some such applications, it is desirable to combine two or more working fluids prior to extraction of work from the combined fluid, for example via an expander. The pressure, temperature and construct of the working fluid mixture entering the expander is key for establishing the performance capability. It is understood that the expander performance is highly dependent on the energy content and expansion profile of the working fluid mixture flow. It would be understood by those skilled in the art that the volumetric flow rate, density, pressure, and temperature are important to establish the performance characteristics of the expander. These parameters can be established and controlled by controlling the characteristics of the working fluids, for example, by expanding, compressing or otherwise operating on the fluids before or after they are combined.
Embodiments of the invention concern a method for producing work from heat including mixing a first working fluid F1 vapor with a second working fluid F2 vapor to form a third working fluid F3; atomizing and/or vaporizing a liquid into the third working fluid F3 to define a saturated working fluid; and expanding the saturated working fluid to perform useful work. A high pressure F1(2) portion of the first working fluid F1 may be expanded prior to the mixing step while the F2 vapor is compressed prior to the mixing step. The steps of compressing the F2 vapor and expanding the high pressure F1(2) portion of the first working fluid F1 may be carried out by an integral compressor and expander assembly. The integral compressor and expander assembly may be positioned within a combined mixer assembly with an internal mixing chamber and outlets of both the compressor and expander are directed toward the mixing chamber.
The invention also includes a system for producing work from heat in a fluid flow including a mixing chamber configured to mix a first working fluid F1 vapor with a second working fluid F2 vapor to form a third working fluid F3 and to facilitate a transfer of thermal energy directly between the F1 vapor and the F2 vapor, exclusive of any intervening structure. A nozzle assembly is configured to vaporize and/or atomize a liquid into the third working fluid F3 to form a saturated working fluid. An expander is configured to expand the saturated working fluid to perform work. The system may further include an initial expander configured to expand a portion F1(2) of the first working fluid F1 before it is communicated to the mixing chamber and a compressor configured to compress the F2 working fluid before it is communicated to the mixing chamber. In at least one embodiment, the compressor and the initial expander are an integral unit and the integral compressor and expander assembly are positioned within an outer housing member of a combined mixer assembly and an inner housing member thereof defines the mixing chamber, and outlets of both the compressor and expander are directed toward the mixing chamber.
Embodiments will be described with reference to the following drawing figures, in which like numerals represent like items throughout the figures, and in which:
The invention is described with reference to the attached figures. The figures are not drawn to scale and they are provided merely to illustrate the instant invention. Several aspects of the invention are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One having ordinary skill in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operation are not shown in detail to avoid obscuring the invention. The invention is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the invention.
The invention concerns a combined mixer assembly 300 for use in a Hybrid Thermal Cycle (HTC), or other energy transfer operations utilizing fluids F1, F2, and F3 where F3 is comprised of a mixture of fluids F1 and F2. The F1 fluid is a fluid construct that is advantageously selected so that it is capable of transitioning from a liquid to a vapor in some parts of the cycle, and from a vapor to a liquid during other portions of the cycle. Fluid F2 is preferably selected so that it remains vaporous throughout the cycle. The F1 fluid is mixed with the F2 fluid in parts of the cycle to form the F3 fluid. Later in the cycle the F1 fluid is separated from the F3 fluid. Following a compression portion of the cycle during which F2 is compressed, there is an expansion part of the cycle during which F3, comprised of a mixture of F1 and F2, is expanded. During this expansion, the F1 fluid functions to support or maintain the temperature of the F2 fluid, preventing it from cooling more rapidly than without the latent heat that is available from the F1 fluid. If the F2 fluid were expanded without the portion of the F1 fluid it would cool more rapidly, having less capacity to perform work. This characteristic or effect in the cycle is desirable as it enables the fluid mixture F3 to perform work for a longer period of time during expansion. This ability of F1 to effectively delay the cooling of F2 essentially ends when the F1 fluid reaches a point where it transitions from a vapor back into a liquid. At the end of the expansion process, at least a portion of the F1 fluid condenses out of the F3, leaving a residual portion, which is F2.
An exemplary heat engine 200 incorporating the combined mixer assembly 300 is illustrated in
The heat engine 200 makes use of a high temperature thermal source 225 and optionally a low temperature thermal source 227. The “high temperature” nomenclature which is used to describe thermal source 225 is intended to emphasize that such thermal source is at a higher temperature as compared to the temperature of low temperature thermal source 227. Although thermal source 225 will have a higher temperature compared to low temperature thermal source 227, it should be appreciated that high temperature thermal source 225 can actually have a relatively low temperature as compared to those temperatures which are normally used to provide efficient operation of a conventional heat engine. For example, in some embodiments, the high temperature thermal source 225 may actually only have a temperature of about 800° F. or less. In other embodiments, the high temperature thermal source 225 can have a temperature of about 400° F. or less. The ability to efficiently utilize such sources of heat is a significant advantage of the present invention.
Suitable choices for working fluids F1 and F2 will be described below in further detail. Still, given the anticipated temperatures for thermal source 225, 227, it can be advantageous to select the working fluid F1 to be a low vapor state formulation to facilitate vaporization of such working fluid at relatively low temperatures. Examples of such low vapor state formulations can include fluids such as methanol or pentane.
A high pressure boiler 203 can use as its primary heat source a supply of steam from the high temperature thermal source 225. For example, the high temperature thermal source can be a geothermal well or waste heat from some high temperature process or other power generation system. The low temperature thermal source can be a thermal source that is entirely independent of the high temperature thermal source 225. However, it can be advantageous to select the optional low temperature thermal source 227 to be a down-line flow from the high temperature thermal source 225, after such flow has provided a portion of its thermal energy to the high pressure boiler 203, as illustrated in
The exemplary heat engine 200 also includes a low pressure boiler 207. The high pressure boiler 203 will generally have a higher internal operating pressure as compared to the optional low pressure boiler 207. However, it should be appreciated that high pressure boiler 203 can actually have a relatively low pressure as compared to those operating pressures which are normally used to provide efficient operation of a conventional heat engine. For example, in conventional heat engines, high pressure boilers typically are understood as boilers that operate in the range of 1000 to 3000 psi. In contrast, the high pressure boiler 203 can operate at a pressure in the range of 300 psi or less. Still, the invention is not limited in this regard and the actual operating pressure in the high pressure boiler 203 and optional low pressure boiler 207 can vary in accordance with the available heat source and other design conditions.
Referring again to
A second flow F1(2) of a first liquid working fluid F1 is pressurized using a pump 201b. It is understood that the pumps 201a and 201b may combined in a single pump. The pressurized fluid is communicated to the high pressure boiler 203 which is maintained at a relatively high temperature as determined by high temperature thermal source 225. The high pressure boiler 203 will add a predetermined amount of thermal energy to the F1(2) working fluid. As a result of these operations, the F1(2) working fluid is converted to a vapor (sometimes referred to herein as F1(2) vapor). The F1(2) vapor formed in high pressure boiler 203 is communicated to an expander 209 of the combined mixer assembly 300 where the thermal energy contained in the F1(2) vapor is used to perform work and thereafter the F1(2) flow of F1 working fluid vapor is communicated to the mixing chamber 206 within the mixer assembly 300.
Additionally, the F2 fluid mentioned above is also delivered to the mixer assembly 300 in a low pressure vapor form. The F2 fluid passes through a compressor 204 within the mixer assembly 300 and then passes into the mixing chamber 206. The three separate vaporous fluid flows comprised of F1(1), F1(2) and F2 are combined or mixed to form a vaporous mixture which is referred to herein as third working fluid F3 (or F3 vapor).
An exemplary embodiment of a combined mixer assembly 300 will be described with reference to
Referring to
The inner housing member 308 tapers from a wider open end 312 to a narrow throat area 314 before expanding to the outlet 303 such that the inner housing member 308 defines a nozzle section 320, the function of which will be described below. A vapor mixing chamber 206 is defined within the inner housing member 308, extending from the open end 312 to the throat area 314. Mixing of the F1(1)(vapor), the F1(2) and the F2 fluids will be described in more detail below. The lower portion 306 of the outer housing member 302 is illustrated with a corresponding taper such that the housing members 302 and 308 meet at the junction 305, however, the outer housing member 302 may be otherwise configured provided it seals with the inner housing member to define the fluid chamber 307. With reference to
Referring to
The exemplary compressor 204 is an axial flow compressor with a housing 370 having an inlet 371 and an outlet 375 in axial alignment. The compressor housing 370 is supported by the outer housing member 302 at an opening 309 there-through such that the inlet 371 receives the F2 working fluid from the condenser 210. The housing 370 supports one or more internal stators 372. A shaft (not shown) drives a central drum 374 which has one or more annular blades 376. As is common in an axial flow compressor, the rotating blades accelerate the fluid while the stators convert the increased rotational kinetic energy into static pressure through diffusion and redirect the flow direction of the fluid, preparing it for the rotor blades of the next stage or to passage through the outlet 375. The housing 370 tapers inward moving from the inlet 371 to the outlet 375 to maintain optimum fluid properties as the fluid is compressed. The F2 working fluid leaves the compressor outlet 375 at a higher temperature and pressure.
In the exemplary embodiment, the expander 209 includes a housing 350 which is connected to the compressor housing 370 such that a passage 351 through the expander housing 350 is aligned with the compressor outlet 375 such that the F2 working fluid passes the expander 209 and enters the mixing chamber 206 as illustrated in
The expander wheel 358 preferably shares a common shaft (not shown) with the compressor drum 374 such that rotation of the expander wheel 358 by the high pressure F1(2) working fluid facilitates rotation of the compressor blades 376. In this configuration, the integral compressor 204 and expander 209 act similar to a turbocharger, with the exception that both exit flows mix together in this apparatus. While the exemplary compressor 204 and expander 209 are assembled as an integrated structure, such is not necessary and the components may be separately positioned and operated.
The arrangement of the co-located compressor and expander can form low pressure zones at the exit flow thereof. The means of creating an exit flow environment of one flow relative to the other exit flow inherently improves the system performance of the flow relationship as the fluids F1 and F2 are mixed. More specifically, the arrangement uses the compressor flow to create a low pressure zone adjacent to the exit of the expander flow, thereby effectively lowers the expander exit pressure and increases the performance of the expander relative to the compressor. Similarly, the arrangement uses the expander flow to create a low pressure zone adjacent to the exit of the compressor flow, thereby effectively lowering the compressor exit pressure and increasing the performance of the compressor relative to the first expander.
Referring to
Not all of the F1(1)(liquid) is vaporized, however, it has the resulting appearance of a vapor as the F3(S) working fluid actually contains micro droplets of the F1(1)(liquid). More specifically, the surface tension of the F1(1)(liquid) is lowered by the flow of the F3 working fluid. As the F1(1)(liquid) atomizes it also has the potential to vaporize as it can draw energy from the F3 working fluid flow. Additionally, the liquid that is residual in the F3(S) working fluid realizes a lower pressure in that flow, a phenomena known as partial pressures. As such, the molecular portion of the liquid that becomes vaporous is capable of sharing the same space with the molecules that comprise the F3(S) working fluid flow.
The characteristics of the F3 flow at the nozzle area 314 facilitate atomization and or vaporization of the introduced liquid portion. Such is facilitated by the relative low pressure state and high velocity of the F3 flow at the nozzle area 314. As such, a flow shear environment or effectively a mechanical separation of the surface tension for the liquid entering the F3 flow results where the F3 flow effectively lowers the surface tension of the liquid mechanically enabling the process of atomization and/or vaporization and energy is transferred from the F3 flow to the liquid having been atomized and/vaporized within the F3 flow. More specifically, at least a portion of the liquid introduced becomes vaporous first by mechanical means and remains vaporous in the F3 flow by acquisition of adjacent heat that is contained within the F3 flow. This is an inversion process that enables the F3 flow to give up heat without collapsing to vapor.
As a result, the denser working fluid F3(S) is a fluid combination that for all intended purposes appears vaporous and comprises a much higher density relative to the initial vapor flow. The F3(S) working fluid flow is then provided to the low pressure expander 208 where it is useful in performing work on the turbine blade with an increased power. Such increased power results from the fact that the energy must be transferred from the F3(S) working fluid to the turbine blade. The equations (mathematics) that govern this transfer of energy are dominated by velocity of the flow and the density of the flow. It has been shown by experiment that the density of the flow can be increased while maintaining a suitable flow velocity, i.e., some velocity will be lost, however, the beneficial gain in density overshadows the velocity reduction in this application.
It is not necessary for all thermal energy transfer between the F1(1), F1(2) and F2 vapor to occur within the mixing chamber 206. In some embodiments of the invention, a portion of such transfer can occur after the F3 vapor exits the mixing chamber. For example, in an embodiment of the invention, at least a portion of such transfer can continue occurring as the F3 vapor continues through an expansion cycle discussed below. Also, it is possible for the F1(1), F1(2) vapor, and the F2 vapor fluids to enter the mixer at approximately the same temperatures and pressures. However, as a result of the different chemical compositions of such fluids, transfer or exchange of thermal energy as between them, can still potentially take place in a subsequent expansion cycle. Details of the expansion cycle are discussed below with regard to expander 208.
The vaporous third working fluid F3(S) is communicated under pressure from the mixer assembly 300 to expander 208 for performing useful work. Well known conventional expander technology can be used for purposes of implementing expander 208, provided that it is capable of using a pressurized vapor to perform useful work. For example, the expander 208 can be an axial flow turbine, custom turbo-expander, vane expander or reciprocating expander. Advantageously the expander 208 will be selected by those skilled in the art to provide high conversion efficiency based on the specific thermodynamic and fluid properties of F3(S) delivered to the expander for a particular embodiment of the cycle. Still, the invention is not limited in this regard.
After such work is performed by the expander 208, the F3 working fluid is communicated from the expander to a condenser assembly 210 including a condenser 212. The condenser 212 can be any device capable of condensing at least a portion of the F1 working fluid from its vapor state to its liquid state.
As is well known in the art, condensing is commonly performed by cooling the working fluid under designated states of pressure. This cooling process will generally involve a release of heat contained in the third working fluid F3. The condenser cools the F3 fluid and thereby facilitates the condensing of the F1 fluid contained within the F3 fluid mixture. The F1 portion therefore drops out as a liquid in the form of condensate and is collected in the condenser as F1 fluid (liquid), and is available for reuse. This process leaves a residual portion of the F3 working fluid. The residual portion of F3 is a remaining portion of the one or more fluids previously comprising F3 that exist after the F1 condensate has been extracted from F3. With the F1 (liquid) condensate and the residual portion of F3 available separate, the process has essentially returned to its starting point. The residual portion of F3 working fluid can be communicated directly to the compressor 204, where it comprises the exclusive constituent of F2 working fluid. Thereafter, the entire process described above can be repeated in a continuous cycle.
The pressure, temperature and construct of the heated working fluid mixture F3(S) entering the expander is key for establishing the performance capability of the cycle. These factors include the constituent mass flow rates and therefore establish the parameters for the expansion rate and the design requirements of the expander 208. It is further understood that the expander performance is highly dependent on the energy content and expansion profile of the F3(S) flow. It would be understood by those skilled in the art that the volumetric flow rate, density, pressure, and temperature can be used to establish the performance characteristics and therefore provide the basis for the best expander design. These parameters can be established and controlled within the cycle construct for a broad range of applications where the cycle is designed around the available thermal source temperature and heat rate.
The first and second working fluids, and ratios thereof, should also be selected such that they work in concert with one another. In particular, the more rapid cooling of the second fluid (as compared to the first fluid) during the expansion process can facilitate the exchange of energy from the first fluid to the second fluid. This leaves the first fluid very close to the vapor to liquid transition point as it approaches the end of the expansion cycle. As the first working fluid condenses, it is therefore separated from the second working fluid and can be collected in the condenser. This unique fluid capability provides the means to tune the thermal take-up rates (heat addition/vaporization) and additionally the drop-out rates (condensate rates) of the fluids in operation.
Various examples of the operation of exemplary heat engine are provided in applicant's co-pending U.S. application Ser. No. 13/098,603, filed May 2, 2011; Ser. No. 13/239,674, filed Sep. 22, 2011; Ser. No. 13/477,394, filed May 22, 2012; Ser. No. 13/533,497, filed Jun. 26, 2012; and Ser. No. 13/556,387, filed on Jul. 24, 2012, each of which is incorporated herein by reference.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
All of the apparatus, methods and algorithms disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the invention has been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus, methods and sequence of steps of the method without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain components may be added to, combined with, or substituted for the components described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined.
