WO2024186820A1

WO2024186820A1 - Use of compositions comprising pentafluoropropene, tetrafluoropropene, and tetrafluoroethane in power cycles; and power cycle apparatus

Info

Publication number: WO2024186820A1
Application number: PCT/US2024/018528
Authority: WO
Inventors: Joshua Hughes; Luke David SIMONI
Original assignee: The Chemours Company Fc, Llc
Priority date: 2023-03-07
Filing date: 2024-03-05
Publication date: 2024-09-12

Abstract

Disclosed herein are methods of producing mechanical energy from heat by use of working fluids comprising HFO-1225yeE, HFO-1234zeE, and optionally, HFC-134. Also disclosed are power cycle apparatus containing working fluids comprising HFO-1225yeE, HFO-1234zeE, and optionally HFC-134.

Description

TITLE

USE OF COMPOSITIONS COMPRISING PENTAFLUOROPROPENE, TETRAFLUOROPROPENE, AND TETRAFLUOROETHANE IN POWER CYCLES;

AND POWER CYCLE APPARATUS

FIELD

[0001] This invention relates to methods and systems having utility in numerous applications, and in particular, in power cycles such as organic Rankine cycles.

BACKGROUND

[0002] Low global warming potential working fluids are needed for power cycles such as organic Rankine cycles. Such materials must have low environmental impact, as measured by low global warming potential and low or zero ozone depletion potential. Ideally, the compositions will also be non-flammable.

SUMMARY

[0003] The present invention involves a composition comprising E-1 ,1 , 1 ,2,3- pentafluoropropene (HFO-1225yeE), E-1 ,3,3,3-tetrafluoropropene (HFO-1234zeE), and, optionally, 1 ,1 ,2,2-tetrafluoroethane (HFC-134) as described in detail herein.

[0004] According to the foregoing embodiments, a method for converting heat from a heat source to mechanical energy is provided, said method comprising heating a working fluid comprising HFO-1225yeE, HFO-1234zeE, and optionally HFC-134 using heat supplied from the heat source; and expanding the heated working fluid to lower the pressure of the working fluid and generate mechanical energy as the pressure of the working fluid is lowered.

[0005] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid is compressed prior to heating; and the expanded working fluid is cooled and compressed for repeated cycles.

[0006] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid is a non-flammable composition consisting essentially of HFO-1225yeE, HFO-1234zeE, and optionally HFC-134. [0007] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid consists essentially of from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134.

[0008] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid consists essentially of from about 10 to 78 weight percent HFO-1225yeE, about 11 to 64 weight percent HFO-1234zeE, and about 11 to 27 weight percent HFC-134.

[0009] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid comprises about 40 weight percent HFO-1225yeE and about 60 weight percent HFO-1234zeE.

[0010] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid comprises about 26 weight percent HFO-1225yeE, about 62 weight percent HFO-1234zeE, and about 12 weight percent HFC-134.

[0011] According to any of the foregoing embodiments, also disclosed herein is a method wherein the working fluid further comprises a lubricant.

[0012] According to any of the foregoing embodiments, also disclosed herein is a method wherein said lubricant is selected from the group consisting of polyalkylene glycols, polyol esters, polyvinyl ethers, perfluoropolyethers, polycarbonates, mineral oils, alkylbenzenes, synthetic paraffins, synthetic naphthenes, poly(alpha)olefins and combinations thereof.

[0013] According to any of the foregoing embodiments, also disclosed herein is a method wherein heat from a heat source is converted to mechanical energy using a sub-critical cycle comprising (a) compressing a liquid working fluid to a pressure below its critical pressure; (b) heating compressed liquid working fluid from (a) using heat supplied by the heat source to form vapor working fluid; (c) expanding heated working fluid from (b) to lower the pressure of the working fluid and generate mechanical energy; (d) cooling expanded working fluid from (c) to form a cooled liquid working fluid; and (e) cycling cooled liquid working fluid from (d) to (a) for compression. [0014] According to any of the foregoing embodiments, also disclosed herein is a method wherein heat from a heat source is converted to mechanical energy using a trans-critical cycle comprising (a) compressing a liquid working fluid above said working fluid’s critical pressure; (b) heating compressed working fluid from (a) using heat supplied by the heat source; (c) expanding heated working fluid from (b) to lower the pressure of the working fluid below its critical pressure and generate mechanical energy; (d) cooling expanded working fluid from (c) to form a cooled liquid working fluid; and (e) cycling cooled liquid working fluid from (d) to (a) for compression.

[0015] According to any of the foregoing embodiments, also disclosed herein is a method wherein heat from a heat source is converted to mechanical energy using a super-critical cycle comprising (a) compressing a working fluid from a pressure above its critical pressure to a higher pressure; (b) heating compressed working fluid from (a) using heat supplied by the heat source; (c) expanding heated working fluid from (b) to lower the pressure of the working fluid to a pressure above its critical pressure and generate mechanical energy; (d) cooling expanded working fluid from (c) to form a cooled working fluid above its critical pressure; and (e) cycling cooled liquid working fluid from (d) to (a) for compression.

[0016] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus containing a working fluid comprising HFO-1225yeE, HFO- 1234zeE, and optionally HFC-134.

[0017] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus comprising (a) a heat exchange unit; (b) an expander in fluid communication with the heat exchange unit; (c) a working fluid cooling unit in fluid communication with the expander; and (d) a compressor or pump in fluid communication with the working fluid cooler; wherein the compressor or pump is further being in fluid communication with the heat exchange unit such that the working fluid then repeats flow through components (a), (b), (c) and (d) in a repeating cycle.

[0018] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus, wherein the working fluid is a non-flammable composition consisting essentially of HFO-1225yeE, HFO-1234zeE, and optionally HFC-134. [0019] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus wherein the working fluid consists essentially of from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134.

[0020] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus wherein the working fluid consists essentially of from about 10 to 78 weight percent HFO-1225yeE, about 11 to 64 weight percent HFO- 1234zeE, and about 11 to 27 weight percent HFC-134.

[0021] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus wherein the working fluid comprises about 40 weight percent HFO-1225yeE and about 60 weight percent HFO-1234zeE.

[0022] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus wherein the working fluid comprises about 26 weight percent HFO-1225yeE, about 62 weight percent HFO-1234zeE, and about 12 weight percent HFC-134.

[0023] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus wherein the working fluid further comprises a lubricant.

[0024] According to any of the foregoing embodiments, also disclosed herein is a power cycle apparatus wherein said lubricant is selected from the group consisting of polyalkylene glycols, polyol esters, polyvinyl ethers, perfluoropolyethers, polycarbonates, mineral oils, alkylbenzenes, synthetic paraffins, synthetic naphthenes, poly(alpha)olefins and combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a block diagram of a heat source and an organic Rankine cycle system in direct heat exchange according to the present invention.

[0026] FIG. 2 is a block diagram of a heat source and an organic Rankine cycle system which uses a secondary loop configuration to provide heat from a heat source to a heat exchanger for conversion to mechanical energy according to the present invention. DETAILED DESCRIPTION

DEFINITIONS

[0027] Before addressing details of embodiments described below, some terms are defined or clarified.

[0028] Global warming potential (GWP) is an index for estimating relative global warming contribution due to atmospheric emission of a kilogram of a particular greenhouse gas compared to emission of a kilogram of carbon dioxide. GWP can be calculated for different time horizons showing the effect of atmospheric lifetime for a given gas. The GWP for the 100-year time horizon is commonly the value referenced. For mixtures, a weighted average can be calculated based on the individual GWPs for each component. The United Nations Intergovernmental Panel on Climate Change (IPCC) provides vetted values for refrigerant GWPs in official assessment reports (ARs.) The fourth assessment report is denoted as AR4 and the fifth assessment report is denoted as AR5. The GWP values reported for refrigerant mixtures or working fluids of the present invention herein refer to the AR5 values, for those compounds listed therein.

[0029] Ozone-depletion potential (ODP) is a number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of R-11 or trichlorofluoromethane. R-1 1 is a type of chlorofluorocarbon (CFC) and as such has chlorine in it which contributes to ozone depletion. Furthermore, the ODP of CFC-11 is defined to be 1.0. Other CFCs and hydrofluorochlorocarbons (HCFCs) have ODPs that range from 0.01 to 1.0. Hydrofluorocarbons (HFCs) and the hydrofluoroolefins (HFO’s) described herein have zero ODP because they do not contain chlorine, bromine or iodine, species known to contribute to ozone breakdown and depletion.

[0030] Net cycle power output (or simply “power”) is the rate of mechanical work generation at the expander (e.g., a turbine) less the rate of mechanical work consumed by the compressor or pump.

[0031] Volumetric capacity for power generation is the net cycle power output per unit volume of working fluid as measured at the conditions at the expander outlet. [0032] Cycle efficiency (also referred to as thermal efficiency or simply “efficiency”) is the net cycle power output divided by the rate at which heat is received by the working fluid during the heating stage of a power cycle (e.g., organic Rankine cycle).

[0033] Subcooling is the reduction of the temperature of a liquid below that liquid's bubble point for a given pressure. The bubble point is the temperature at which a vapor composition is completely condensed to a liquid. But subcooling continues to cool the liquid to a lower temperature liquid at the given pressure. Subcooling amount is the amount of cooling below the bubble point temperature (in degrees).

[0034] Superheat is a term that defines how far above its dew point temperature of a vapor composition is heated. Dew point temperature is the temperature at which, if the composition is cooled, the first drop of liquid is formed.

[0035] Temperature glide (sometimes referred to simply as “glide”) is the absolute value of the difference between the starting and ending temperatures of a phasechange process by a refrigerant within a component of a refrigerant system, exclusive of any subcooling or superheating. This term may be used to describe condensation or evaporation of a near azeotrope or non-azeotropic composition. Average glide refers to the average of the glide in the evaporator and the glide in the condenser of a specific ORC system operating under a given set of conditions.

[0036] As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present), and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0037] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. If in the claim such would close the claim to the inclusion of materials other than those recited except for impurities ordinarily associated therewith. When the phrase "consists of" appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.

[0038] The transitional phrase "consisting essentially of" is used to define a composition, method or apparatus that includes materials, steps, features, components, or elements, in addition to those literally disclosed provided that these additional included materials, steps, features, components, or elements do not materially affect the basic and novel characteristic(s) of the claimed invention. The term 'consisting essentially of occupies a middle ground between “comprising” and 'consisting of'.

[0039] Where applicants have defined an invention or a portion thereof with an open-ended term such as “comprising,” it should be readily understood that (unless otherwise stated) the description should be interpreted to also describe such an invention using the terms “consisting essentially of” or “consisting of.”

[0040] Also, use of “a” or “an” are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0041] Unless otherwise defined, all 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. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, unless a particular passage is cited. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

[0042] E-1 ,2,3,3,3-pentafluoropropene (HFO-1225yeE) may be made by methods known in the art. In particular, this compound can be made by reaction of CFC- 215bb (CF3CFCICFCI2) with hydrogen and HF over palladium on fluorided alumina catalyst, as described in U.S. Patent Publication No. 2009/0264690 A1 , incorporated herein by reference.

[0043] E-1 ,3,3,3-tetrafluoropropene (HFO-1234zeE, E-CHF=CHCF3) is available commercially from fluorocarbon manufacturers or may be made by methods known in the art. In particular, this compound may be prepared by dehydrofluorination of a group of pentafluoropropanes, including 1 ,1 ,1 ,2,3-pentafluoropropane (HFC-245eb, CF3CHFCH2F), and 1 ,1 ,1 ,3,3-pentafluoropropane (HFC-245fa, CF3CH2CHF2). The dehydrofluorination reaction may take place in the vapor phase in the presence or absence of catalyst, and also in the liquid phase by reaction with caustic, such as NaOH or KOH. These reactions are described in more detail in U.S. Patent Publication No. 2006/0106263 A1 , incorporated herein by reference.

[0044] 1 ,1 ,2,2-tetrafluoroethane (HFC-134, CHF2CHF2) is available commercially from fluorocarbon manufacturers, such as Chemours™ (Wilmington, DE) or may be made by the hydrogenation of 1 ,2-dichloro-1 ,1 ,2,2-tetrafluoroethane (i.e., CCIF2CCIF2 or CFC-114) to 1 , 1 ,2,2-tetrafluoroethane.

Power cycle methods

[0045] Heat at temperatures up to about 150°C is abundantly available from various sources. It can be captured as a byproduct from various industrial processes, it can be collected from solar irradiation through solar panels or it can be extracted from geological hot water reservoirs through shallow or deep wells. Additionally, waste heat from sources such as diesel engine exhaust may also serve as a heat source. Such heat can be converted to mechanical or electrical power for various uses through Rankine cycles using working fluids comprising HFO-1225yeE, HFO-1234zeE, and, optionally, HFC-134.

[0046] A sub-critical organic Rankine cycle (ORC) is defined as a Rankine cycle in which the organic working fluid used in the cycle receives heat at a pressure lower than the critical pressure of the organic working fluid and the working fluid remains below its critical pressure throughout the entire cycle.

[0047] A trans-critical ORC is defined as a Rankine cycle in which the organic working fluid used in the cycle receives heat at a pressure higher than the critical pressure of the organic working fluid. In a trans-critical cycle, the working fluid is not at a pressure higher than its critical pressure throughout the entire cycle.

[0048] A super-critical power cycle is defined as a power cycle which operates at pressures higher than the critical pressure of the organic working fluid used in the cycle and involves the following steps: compression; heating; expansion; cooling.

[0049] In accordance with this invention, a method is provided for converting heat from a heat source to mechanical energy. The method comprises heating a working fluid using heat supplied from the heat source; and expanding the heated working fluid to lower the pressure of the working fluid and generate mechanical energy as the pressure of the working fluid is lowered. The method is characterized by using a working fluid comprising HFO-1225yeE and HFO-1234zeE, and optionally, HFC-134. In another embodiment, the method is characterized by using a working fluid comprising HFO-1225yeE and HFO-1234zeE, or a working fluid comprising HFO- 1225yeE, HFO-1234zeE, and HFC-134.

[0050] The method of this invention is typically used in an organic Rankine power cycle. Heat available at relatively low temperatures compared to steam (inorganic) power cycles can be used to generate mechanical power through Rankine cycles using working fluids comprising HFO-1225yeE, E-HFO-1234ze and optionally HFC- 134. In the method of this invention, working fluid comprising HFO-1225yeE, E-HFO- 1234ze, and optionally, HFC-134 is compressed prior to being heated. Compression may be provided by a pump which pumps working fluid to a heat transfer unit (e.g., a heat exchanger or an evaporator) where heat from the heat source is used to heat the working fluid. The heated working fluid is then expanded, lowering its pressure. Mechanical energy is generated during the working fluid expansion using an expander. Examples of expanders include turbo or dynamic expanders, such as turbines, and positive displacement expanders, such as screw expanders, scroll expanders, and piston expanders. Examples of expanders also include rotary vane expanders (Tahir, et al, International Journal of Civil and Environmental Engineering 2: 1 , 2010).

[0051] Mechanical power can be used directly (e.g., to drive a compressor) or be converted to electrical power through the use of electrical power generators. In a power cycle, the expanded working fluid is cooled. Cooling may be accomplished in a working fluid cooling unit (e.g., a heat exchanger or a condenser). The cooled working fluid can then be used for repeated cycles (i.e. , compression, heating, expansion, etc.). The same pump used for compression may be used for transferring the working fluid from the cooling stage.

[0052] In one embodiment, the method for converting heat to mechanical energy uses a working fluid comprising HFO-1225yeE and E-HFO-1234ze or using a working fluid comprising HFO-1225yeE, HFO-1234zeE, and HFC-134. Of note in the method for converting heat to mechanical energy are working fluids that consist essentially of HFO-1225yeE and E-HFO-1234ze or working fluids that consist essentially of HFO-1225yeE, HFO-1234zeE, and HFC-134. Also, of note in the method for converting heat to mechanical energy are working fluids consisting of HFO-1225yeE and HFO-1234zeE, or working fluids consisting of HFO-1225yeE, HFO-1234zeE, and HFC-134.

[0053] In one embodiment, for use in methods of producing mechanical energy from heat are compositions comprising from about 10 to 99 weight percent HFO- 1225yeE and about 90 to 1 weight percent HFO-1234zeE. In another embodiment, for use in methods of producing mechanical energy from heat are compositions comprising from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134. Of particular utility in methods for producing mechanical energy from heat are non-flammable compositions comprising HFO-1225yeE, HFO-1234zeE, and optionally, HFC-134. It was shown in International Patent Application PCT/US2022/042675, that compositions with 64 weight percent HFO-1234zeE when combined with HFO- 1225yeE and optionally HFC-134 are non-flammable when tested with ASTM (American Society of Testing Materials) E-681 . Therefore, of particular utility in the present method are nonflammable compositions consisting essentially of from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134.

[0054] In another embodiment, for use in methods of producing mechanical energy from heat are compositions comprising from about 10 to 78 weight percent HFO-1225yeE, about 11 to 64 weight percent HFO-1234zeE, and about 11 to 27 weight percent HFC-134. In another embodiment, for use in methods of producing mechanical energy from heat are compositions comprising from about 40 to 78 weight percent HFO-1225yeE, from about 11 to 62 weight percent HFO-1234zeE, and from about 0 to 27 weight percent HFC-134.

[0055] Of particular utility, in methods for producing mechanical energy from heat are compositions consisting essentially of about 40 weight percent HFO-1225yeE and about 60 weight percent HFO-1234zeE. Additionally, of note for use in methods for producing mechanical energy from heat is a composition comprising about 26 weight percent HFO-1225yeE, about 62 weight percent HFO-1234zeE, and about 12 weight percent HFC-134.

[0056] Compositions for use in the method for producing mechanical energy from heat are those with GWP less than 150, preferably, GWP less than 100, and also GWP less than 10.

[0057] In one embodiment, the present invention relates to a method for converting heat from a heat source to mechanical energy using a sub-critical cycle. This method comprises the following steps:

(a) compressing a liquid working fluid to a pressure below its critical pressure;

(b) heating compressed liquid working fluid from (a) using heat supplied by the heat source to form vapor working fluid;

(c) expanding heated working fluid from (b) to lower the pressure of the working fluid and generate mechanical energy;

(d) cooling expanded working fluid from (c) to form a cooled liquid working fluid; and (e) cycling cooled liquid working fluid from (d) to (a) for compression.

[0058] In the first step of the sub-critical Organic Rankine Cycle (ORC) system, described above, the working fluid in liquid phase comprising HFO-1225yeE and HFO-1234zeE or working fluids comprising HFO-1225yeE, HFO-1234zeE, and HFC- 134 is compressed to a pressure below its critical pressure. In a second step, said working fluid is passed through a heat exchanger to be vaporized to a higher temperature before the entering the expander wherein said heat exchanger is in thermal communication with said heat source. The heat exchanger receives heat energy from the heat source by any known means of thermal transfer. The ORC system working fluid circulates through the heat supply heat exchanger where it gains heat.

[0059] Embodiments including use of one or more internal heat exchangers (e.g., a recuperator), and/or use of more than one cycle in a cascade system are intended to fall within the scope of the sub-critical ORC power cycles of the present invention.

[0060] In one embodiment, the present invention relates to a method for converting heat from a heat source to mechanical energy using a trans-critical cycle. This method comprises the following steps:

(a) compressing a liquid working fluid above said working fluid’s critical pressure;

(b) heating compressed working fluid from (a) using heat supplied by the heat source;

(c) expanding heated working fluid from (b) to lower the pressure of the working fluid below its critical pressure and generate mechanical energy;

(d) cooling expanded working fluid from (c) to form a cooled liquid working fluid; and

(e) cycling cooled liquid working fluid from (d) to (a) for compression.

[0061] In the first step of the trans-critical Organic Rankine Cycle (ORC) system, described above, the working fluid in liquid phase comprising HFO-1225yeE and HFO-1234zeE or working fluids comprising HFO-1225yeE, HFO-1234zeE, and HFC- 134 is compressed to above its critical pressure. In a second step, said working fluid is passed through a heat exchanger to be heated to a higher temperature before the fluid enters the expander wherein said heat exchanger is in thermal communication with said heat source. The heat exchanger receives heat energy from the heat source by any known means of thermal transfer. The ORC system working fluid circulates through the heat supply heat exchanger where it gains heat.

[0062] In the next step, at least a portion of the heated working fluid is removed from said heat exchanger and is routed to the expander where the expansion process results in conversion of at least portion of the heat energy content of the working fluid into mechanical shaft energy. The shaft energy can be used to do any mechanical work by employing conventional arrangements of belts, pulleys, gears, transmissions or similar devices depending on the desired speed and torque required. In one embodiment, the shaft can also be connected to an electric powergenerating device such as an induction generator. The electricity produced can be used locally or delivered to the grid. The pressure of the working fluid is reduced to below critical pressure of said working fluid, thereby producing vapor phase working fluid.

[0063] In the next step, the working fluid is passed from the expander to a condenser, wherein the vapor phase working fluid is condensed to produce liquid phase working fluid. The above steps form a loop system and can be repeated many times.

[0064] Embodiments including use of one or more internal heat exchangers (e.g., a recuperator), and/or use of more than one cycle in a cascade system are intended to fall within the scope of the trans-critical ORC power cycles of the present invention.

[0065] Additionally, for a trans-critical organic Rankine cycle, there are several different modes of operation.

[0066] In one mode of operation, in the first step of a trans-critical organic Rankine cycle, the working fluid is compressed above the critical pressure of the working fluid substantially isentropically. In the next step, the working fluid is heated under a constant pressure (isobaric) condition to above its critical temperature. In the next step, the working fluid is expanded substantially isentropically at a temperature that maintains the working fluid in the vapor phase. At the end of the expansion the working fluid is a superheated vapor at a temperature below its critical temperature. In the last step of this cycle, the working fluid is cooled and condensed while heat is rejected to a cooling medium. During this step the working fluid condensed to a liquid. The working fluid could be subcooled at the end of this cooling step.

[0067] In another mode of operation of a trans-critical ORC power cycle, in the first step, the working fluid is compressed above the critical pressure of the working fluid, substantially isentropically. In the next step the working fluid is then heated under a constant pressure condition to above its critical temperature, but only to such an extent that in the next step, when the working fluid is expanded substantially isentropically, and its temperature is reduced, the working fluid is close enough to the conditions for a saturated vapor that partial condensation or misting of the working fluid may occur during the expansion process. At the end of this step, however, the working fluid is still a slightly superheated vapor. In the last step, the working fluid is cooled and condensed while heat is rejected to a cooling medium. During this step the working fluid condensed to a liquid. The working fluid could be subcooled at the end of this cooling/condensing step.

[0068] In another mode of operation of a trans-critical ORC power cycle, in the first step, the working fluid is compressed above the critical pressure of the working fluid, substantially isentropically. In the next step, the working fluid is heated under a constant pressure condition to a temperature either below or only slightly above its critical temperature. At this stage, the working fluid temperature is such that when the working fluid is expanded substantially isentropically in the next step, the working fluid is partially condensed. In the last step, the working fluid is cooled and fully condensed and heat is rejected to a cooling medium. The working fluid could be subcooled at the end of this step.

[0069] While the above embodiments for a trans-critical ORC cycle show substantially isentropic expansions and compressions, and isobaric heating or cooling, other cycles wherein such isentropic or isobaric conditions are not maintained but the cycle is nevertheless accomplished, are within the scope of the present invention.

[0070] In one embodiment, the present invention relates to a method for converting heat from a heat source to mechanical energy using a super-critical cycle. This method comprises the following steps:

(a) compressing a working fluid from a pressure above its critical pressure to a higher pressure;

(c) expanding heated working fluid from (b) to lower the pressure of the working fluid to a pressure above its critical pressure and generate mechanical energy; (d) cooling expanded working fluid from (c) to form a cooled working fluid above its critical pressure; and

(e) cycling cooled liquid working fluid from (d) to (a) for compression.

[0071] Embodiments including use of one or more internal heat exchangers (e.g., a recuperator), and/or use of more than one cycle in a cascade system are intended to fall within the scope of the super-critical ORC power cycles of the present invention.

[0072] Typically, in the case of sub-critical Rankine cycle operation, most of the heat supplied to the working fluid is supplied during the evaporation of the working fluid. As a result, the working fluid temperature is essentially constant during the transfer of heat from the heat source to the working fluid. In contrast, the working fluid temperature can vary when the fluid is heated isobarically without phase change at a pressure above its critical pressure. Accordingly, when the heat source temperature varies, the use of a fluid above its critical pressure to extract heat from a heat source allows better matching between the heat source temperature and the working fluid temperature compared to the case of sub-critical heat extraction. As a result, the efficiency of the heat exchange process in a super-critical cycle or a trans- critical cycle is often higher than that of the sub-critical cycle (see Chen et al, Energy, 36, (2011) 549-555 and references therein).

[0073] The compositions containing HFO-1225yeE, HFO-1234zeE, and optionally, HFC-134a have been found to produce power within 10% of that for HFO-1234zeE alone; or within 5% of that for HFO-1234zeE alone.

[0074] Additionally, the compositions containing HFO-1225yeE, HFO-1234zeE, and optionally, HFC-134a have been found to produce efficiency within 2% of that for HFO-1234zeE alone; or efficiency within 1 % of that for HFO-1234zeE alone.

[0075] The working fluids of the present invention may be used in an ORC system to generate mechanical energy from heat extracted or received from relatively low temperature heat sources such as low pressure steam, industrial waste heat, solar energy, geothermal hot water, low-pressure geothermal steam, or distributed power generation equipment utilizing fuel cells or turbines, including microturbines, or internal combustion engines. One source of low-pressure steam could be the process known as a binary geothermal Rankine cycle. Large quantities of low- pressure steam can be found in numerous locations, such as in fossil fuel powered electrical generating power plants.

[0076] Of note are sources of heat including waste heat recovered from gases exhausted from mobile internal combustion engines (e.g. truck or ship or rail Diesel engines), waste heat from exhaust gases from stationary internal combustion engines (e.g. stationary Diesel engine power generators), waste heat from fuel cells, heat available at Combined Heating, Cooling and Power or District Heating and Cooling plants, waste heat from biomass fueled engines, heat from natural gas or methane gas burners or methane-fired boilers or methane fuel cells (e.g. at distributed power generation facilities) operated with methane from various sources including biogas, landfill gas and coal-bed methane, heat from combustion of bark and lignin at paper/pulp mills, heat from incinerators, heat from low pressure steam at conventional steam power plants (to drive "bottoming" Rankine cycles), and geothermal heat.

[0077] Also of note are sources of heat including solar heat from solar panel arrays including parabolic solar panel arrays, solar heat from Concentrated Solar Power plants, heat removed from photovoltaic (PV) solar systems to cool the PV system to maintain a high PV system efficiency.

[0078] Also of note are sources of heat including at least one operation associated with at least one industry selected from the group consisting of: oil refineries, petrochemical plants, oil and gas pipelines, chemical industry, commercial buildings, hotels, shopping malls, supermarkets, bakeries, food processing industries, restaurants, paint curing ovens, furniture making, plastics molders, cement kilns, lumber kilns, calcining operations, steel industry, glass industry, foundries, smelting, air-conditioning, refrigeration, and central heating.

[0079] In one embodiment of the Rankine cycles of this invention, geothermal heat is supplied to the working fluid circulating above ground (e.g., binary cycle geothermal power plants). In another embodiment of the Rankine cycles of this invention, the working fluid is used both as the Rankine cycle working fluid and as a geothermal heat carrier circulating underground in deep wells with the flow largely or exclusively driven by temperature-induced fluid density variations, known as "the thermosyphon effect".

[0080] In other embodiments, the present invention also uses other types of ORC systems, for example, small scale (e.g., 1 - 500 kw, preferably 5-250 kw) Rankine cycle systems using micro-turbines or small size positive displacement expanders, combined, multistage, and cascade Rankine Cycles, and Rankine Cycle systems with recuperators to recover heat from the vapor exiting the expander.

[0081] Other sources of heat include at least one operation associated with at least one industry selected from the group consisting of: oil refineries, petrochemical plants, oil and gas pipelines, chemical industry, commercial buildings, hotels, shopping malls, supermarkets, bakeries, food processing industries, restaurants, paint curing ovens, furniture making, plastics molders, cement kilns, lumber kilns, calcining operations, steel industry, glass industry, foundries, smelting, air- conditioning, refrigeration, and central heating.

Power Cycle Apparatus

[0082] In accordance with this invention, a power cycle apparatus for converting heat to mechanical energy is provided. The apparatus contains a working fluid comprising HFO-1225yeE and HFO-1234zeE or a working fluid comprising HFO- 1225yeE, HFO-1234zeE, and HFC-134. Typically, the apparatus of this invention includes a heat exchange unit where the working fluid can be heated and an expander where mechanical energy can be generated by expanding the heated working fluid by lowering its pressure. Expanders include turbo or dynamic expanders, such as turbines, and positive displacement expanders, such as screw expanders, scroll expanders, piston expanders and rotary vane expanders.

Mechanical power can be used directly (e.g., to drive a compressor) or be converted to electrical power through the use of electrical power generators. Typically, the apparatus also includes a working fluid cooling unit (e.g., condenser or heat exchanger) for cooling the expanded working fluid and a compressor for compressing the cooled working fluid.

[0083] In one embodiment, the power cycle apparatus of the present invention comprises (a) a heat exchange unit; (b) an expander in fluid communication with the heat exchange unit; (c) a working fluid cooling unit in fluid communication with the expander; and (d) a compressor in fluid communication with the working fluid cooler; wherein the compressor is further being in fluid communication with the heat exchange unit such that the working fluid then repeats flow through components (a), (b), (c) and (d) in a repeating cycle; wherein the working fluid comprises HFO- 1225yeE and HFO-1234zeE or a working fluid comprising HFO-1225yeE, HFO- 1234zeE, and HFC-134.

[0084] In one embodiment, the power cycle apparatus uses a working fluid comprising HFO-1225yeE and HFO-1234zeE or a working fluid comprising HFO- 1225yeE, HFO-1234zeE, and HFC-134. Of note are working fluids that consist essentially of HFO-1225yeE and HFO-1234zeE or a working fluid consisting essentially of HFO-1225yeE, HFO-1234zeE, and HFC-134. Also, of note, are working fluids that consist of HFO-1225yeE and HFO-1234zeE or a working fluid consisting of HFO-1225yeE, HFO-1234zeE, and HFC-134.

[0085] In one embodiment, for use in power cycle apparatus are compositions comprising from about 10 to 99 weight percent HFO-1225yeE and about 90 to 1 weight percent HFO-1234zeE. In another embodiment, for use in power cycle apparatus are compositions comprising from about 10 to 99 weight percent HFO- 1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134. Of particular utility in power cycle apparatus are non-flammable compositions comprising HFO-1225yeE, HFO-1234zeE, and optionally, HFC-134. It was shown in International Patent Application PCT/US2022/042675 (attorney docket number FL2014), that compositions with 64 weight percent HFO-1234zeE when combined with HFO-1225yeE and optionally HFC-134 are non-flammable when tested with ASTM (American Society of Testing Materials) E-681. Therefore, of particular utility in the power cycle apparatus are nonflammable compositions consisting essentially of from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134.

[0086] In another embodiment, for use in power cycle apparatus are compositions comprising from about 10 to 78 weight percent HFO-1225yeE, about 11 to 64 weight percent HFO-1234zeE, and about 11 to 27 weight percent HFC-134. In another embodiment, for use in methods of producing mechanical energy from heat are compositions comprising from about 40 to 78 weight percent HFO-1225yeE, from about 11 to 62 weight percent HFO-1234zeE, and from about 0 to 27 weight percent HFC-134.

[0087] Of particular utility, in power cycle apparatus are compositions consisting essentially of about 40 weight percent HFO-1225yeE and about 60 weight percent HFO-1234zeE. Additionally, of note for use in methods for producing mechanical energy from heat is a composition comprising about 26 weight percent HFO- 1225yeE, about 62 weight percent HFO-1234zeE, and about 12 weight percent HFC-134.

[0088] Compositions for use in power cycle apparatus are those with GWP less than 150, preferably, GWP less than 100, and also GWP less than 10.

[0089] FIG. 1 shows a schematic of one embodiment of the ORC system for using heat from a heat source. Heat supply heat exchanger 40 transfers heat supplied from heat source 46 to the working fluid entering heat supply heat exchanger 40 in liquid phase. Heat supply heat exchanger 40 is in thermal communication with the source of heat (the communication may be by direct contact or another means). In other words, heat supply heat exchanger 40 receives heat energy from heat source 46 by any known means of thermal transfer. The ORC system working fluid circulates through heat supply heat exchanger 40 where it gains heat. At least a portion of the liquid working fluid converts to vapor in heat supply heat exchanger (e.g., evaporator) 40.

[0090] The working fluid now in vapor form is routed to expander 32 where the expansion process results in conversion of at least a portion of the heat energy supplied from the heat source into mechanical shaft power. The shaft power can be used to do any mechanical work by employing conventional arrangements of belts, pulleys, gears, transmissions or similar devices depending on the desired speed and torque required. In one embodiment, the shaft can also be connected to electric power-generating device 30 such as an induction generator. The electricity produced can be used locally or delivered to a grid.

[0091] The working fluid still in vapor form that exits expander 32 continues to condenser 34 where adequate heat rejection causes the fluid to condense to liquid. [0092] It is also desirable to have liquid surge tank 36 located between condenser 34 and pump 38 to ensure there is always an adequate supply of working fluid in liquid form to the pump suction. The working fluid in liquid form flows to pump 38 that elevates the pressure of the fluid so that it can be introduced back into heat supply heat exchanger 40 thus completing the Rankine cycle loop.

[0093] In an alternative embodiment, a secondary heat exchange loop operating between the heat source and the ORC system can also be used. In FIG. 2, an organic Rankine cycle system is shown, in particular for a system using a secondary heat exchange loop. The main organic Rankine cycle operates as described above for FIG. 1 . The secondary heat exchange loop is shown in FIG. 2 as follows: the heat from heat source 46' is transported to heat supply heat exchanger 40' using a heat transfer medium (i.e., secondary heat exchange loop fluid). The heat transfer medium flows from heat supply heat exchanger 40' to pump 42' that pumps the heat transfer medium back to heat source 46'. This arrangement offers another means of removing heat from the heat source and delivering it to the ORC system.

[0094] In fact, the working fluids of this invention can be used as secondary heat exchange loop fluids provided the pressure in the loop is maintained at or above the fluid saturation pressure at the temperature of the fluid in the loop. Alternatively, the working fluids of this invention can be used as secondary heat exchange loop fluids or heat carrier fluids to extract heat from heat sources in a mode of operation in which the working fluids are allowed to evaporate during the heat exchange process thereby generating large fluid density differences sufficient to sustain fluid flow (thermosyphon effect). Additionally, high-boiling point fluids such as glycols, brines, silicones, or other essentially non-volatile fluids may be used for sensible heat transfer in the secondary loop arrangement described. A secondary heat exchange loop can make servicing of either the heat source or the ORC system easier since the two systems can be more easily isolated or separated. This approach can simplify the heat exchanger design as compared to the case of having a heat exchanger with a high mass flow/low heat flux portion followed by a high heat flux/low mass flow portion.

[0095] Organic compounds often have an upper temperature limit above which thermal decomposition will occur. The onset of thermal decomposition relates to the particular structure of the chemical and thus varies for different compounds. In order to access a high-temperature source using direct heat exchange with the working fluid, design considerations for heat flux and mass flow, as mentioned above, can be employed to facilitate heat exchange while maintaining the working fluid below its thermal decomposition onset temperature. Direct heat exchange in such a situation typically requires additional engineering and mechanical features which drive up cost. In such situations, a secondary loop design may facilitate access to the high- temperature heat source by managing temperatures while circumventing the concerns enumerated for the direct heat exchange case.

[0096] Other ORC system components for the secondary heat exchange loop embodiment are essentially the same as described for FIG. 1. In FIG. 2, Liquid pump 42’ circulates the secondary fluid (e.g., heat transfer medium) through the secondary loop so that it enters the portion of the loop in heat source 46’ where it gains heat. The fluid then passes to heat exchanger 40’ where the secondary fluid gives up heat to the ORC working fluid.

[0097] The apparatus may include molecular sieves to aid in removal of moisture. Desiccants may be composed of activated alumina, silica gel, or zeolite-based molecular sieves. In some embodiments, the molecular sieves are most useful with a pore size of approximately 3 Angstroms, 4 Angstroms, or 5 Angstroms.

Representative molecular sieves include MOLSIV XH-7, XH-6, XH-9 and XH-11 (UOP LLC, Des Plaines, IL).

Power cycle compositions

[0098] In some embodiments, the compositions comprising HFO-1225yeE and HFO-1234zeE or a working fluid comprising HFO-1225yeE, HFO-1234zeE, and HFC-134 that are particularly useful in power cycles including organic Rankine cycles will be combined with additional components.

[0099] In one embodiment, the compositions useful in methods of producing mechanical energy from heat or in power cycle apparatus comprising HFO-1225yeE and HFO-1234zeE or a working fluid comprising HFO-1225yeE, HFO-1234zeE, and HFC-134 also comprise a lubricant. [0100] In one embodiment, any of the working fluids comprising HFO-1225yeE and HFO-1234zeE or a working fluid comprising HFO-1225yeE, HFO-1234zeE, and HFC-134 may be used in combination with at least one lubricant selected from the group consisting of polyalkylene glycols, polyol esters, polyvinyl ethers, polycarbonates, perfluoropolyethers, mineral oils, alkylbenzenes, synthetic paraffins, synthetic naphthenes, poly(alpha)olefins, and combinations thereof. Representative conventional lubricants are the commercially available BVM 100 N (paraffinic mineral oil sold by BVA Oils), naphthenic mineral oil commercially available from Crompton Co. under the trademarks Suniso® 3GS and Suniso® 5GS, naphthenic mineral oil commercially available from Pennzoil under the trademark Sontex® 372LT, naphthenic mineral oil commercially available from Calumet Lubricants under the trademark Calumet® RO-30, linear alkylbenzenes commercially available from Shrieve Chemicals under the trademarks Zerol® 75, Zerol® 150 and Zerol® 500, and HAB 22 (branched alkylbenzene sold by Nippon Oil). Perfluoropolyether (PFPE) lubricants include those sold under the trademark Krytox® by E. I. du Pont de Nemours; sold under the trademark Fomblin® by Ausimont; or sold under the trademark Demnum® by Daikin Industries.

[0101] In another embodiment is provided composition suitable for use in organic Rankine apparatus, comprising a working fluid containing HFO-1225yeE and HFO- 1234zeE or a working fluid comprising HFO-1225yeE, HFO-1234zeE, and HFC-134 and at least one other component selected from the group consisting of stabilizers, compatibilizers and tracers.

[0102] Optionally, in another embodiment, certain refrigeration, air-conditioning, or heat pump system additives may be added, as desired, to the working fluids as disclosed herein in order to enhance performance and system stability. These additives are known in the field of refrigeration and air-conditioning, and include, but are not limited to, anti-wear agents, extreme pressure lubricants, corrosion and oxidation inhibitors, metal surface deactivators, free radical scavengers, and foam control agents. In general, these additives may be present in the working fluids in small amounts relative to the overall composition. Typically, concentrations of from less than about 0.1 weight percent to as much as about 3 weight percent of each additive are used. These additives are selected on the basis of the individual system requirements. These additives include members of the triaryl phosphate family of EP (extreme pressure) lubricity additives, such as butylated triphenyl phosphates (BTPP), or other alkylated triaryl phosphate esters, e.g., Syn-O-Ad 8478 from Akzo Chemicals, tricresyl phosphates and related compounds. Additionally, the metal dialkyl dithiophosphates (e.g., zinc dialkyl dithiophosphate (or ZDDP); Lubrizol 1375 and other members of this family of chemicals may be used in compositions of the present invention. Other antiwear additives include natural product oils and asymmetrical polyhydroxyl lubrication additives, such as Synergol TMS (International Lubricants). Similarly, stabilizers such as antioxidants, free radical scavengers, and water scavengers may be employed. Compounds in this category can include, but are not limited to, butylated hydroxy toluene (BHT), epoxides, and mixtures thereof. Corrosion inhibitors include dodecyl succinic acid (DDSA), amine phosphate (AP), oleoyl sarcosine, imidazone derivatives and substituted sulfphonates. Metal surface deactivators include areoxalyl bis (benzylidene) hydrazide, N, N'-bis(3,5-di-tert-butyl- 4-hydroxyhydrocinnamoylhydrazine, 2,2,' - oxamidobis-ethyl-(3,5-di-tert-butyl-4- hydroxyhydrocinnamate, N,N'-(disalicyclidene)-1 ,2-diaminopropane and ethylenediaminetetra-acetic acid and its salts, and mixtures thereof.

[0103] Of note are stabilizers to prevent degradation at temperatures of 50°C or above. Also of note are stabilizers to prevent degradation at temperatures of 75°C or above. Also of note are stabilizers to prevent degradation at temperatures of 85°C or above. Also of note are stabilizers to prevent degradation at temperatures of 100°C or above. Also of note are stabilizers to prevent degradation at temperatures of 118°C or above. Also of note are stabilizers to prevent degradation at temperatures of 137°C or above.

[0104] Of note are stabilizers comprising at least one compound selected from the group consisting of hindered phenols, thiophosphates, butylated triphenylphosphorothionates, organo phosphates, or phosphites, aryl alkyl ethers, terpenes, terpenoids, epoxides, fluorinated epoxides, oxetanes, ascorbic acid, thiols, lactones, thioethers, amines, nitromethane, alkylsilanes, benzophenone derivatives, aryl sulfides, divinyl terephthalic acid, diphenyl terephthalic acid, ionic liquids, and mixtures thereof. Representative stabilizer compounds include but are not limited to tocopherol; hydroquinone; t-butyl hydroquinone; monothiophosphates; and dithiophosphates, commercially available from Ciba Specialty Chemicals, Basel, Switzerland, hereinafter “Ciba,” under the trademark Irgalube® 63; dialkylthiophosphate esters, commercially available from Ciba under the trademarks Irgalube® 353 and Irgalube® 350, respectively; butylated triphenylphosphorothionates, commercially available from Ciba under the trademark Irgalube® 232; amine phosphates, commercially available from Ciba under the trademark Irgalube® 349 (Ciba); hindered phosphites, commercially available from Ciba as Irgafos® 168; a phosphate such as (Tris-(di-tert-butylphenyl), commercially available from Ciba under the trademark Irgafos® OPH; (Di-n-octyl phosphite); and iso-decyl diphenyl phosphite, commercially available from Ciba under the trademark Irgafos® DDPP; anisole; 1 ,4-dimethoxybenzene; 1 ,4-diethoxybenzene; 1 ,3,5- tri methoxybenzene; d-limonene; retinal; pinene (a or p); menthol; Vitamin A; terpinene (a ory); dipentene; lycopene; beta carotene; bornane; 1 ,2-propylene oxide; 1 ,2-butylene oxide; n-butyl glycidyl ether; trifluoromethyloxirane;

1 ,1-bis(trifluoromethyl)oxirane; 3-ethyl-3-hydroxymethyl-oxetane, such as OXT-101 (Toagosei Co., Ltd); 3-ethyl-3-((phenoxy)methyl)-oxetane, such as OXT-211 (Toagosei Co., Ltd); 3-ethyl-3-((2-ethyl-hexyloxy)methyl)-oxetane, such as OXT-212 (Toagosei Co., Ltd); ascorbic acid; methanethiol (methyl mercaptan); ethanethiol (ethyl mercaptan); Coenzyme A; dimercaptosuccinic acid (DMSA); grapefruit mercaptan (( R)-2-(4-methylcyclohex-3-enyl)propane-2-thiol)); cysteine (( R)-2- amino-3-sulfanyl-propanoic acid); lipoamide (1 ,2-dithiolane-3-pentanamide); 5,7- bis(1 ,1-dimethylethyl)-3-[2,3(or 3,4)-dimethylphenyl]-2(3H)-benzofuranone, commercially available from Ciba under the trademark Irganox® HP-136; benzyl phenyl sulfide; diphenyl sulfide; diisopropylamine; dioctadecyl 3, 3’ -thiodipropionate, commercially available from Ciba under the trademark Irganox® PS 802 (Ciba); didodecyl 3,3’-thiopropionate, commercially available from Ciba under the trademark Irganox® PS 800; di-(2,2,6,6-tetramethyl-4-piperidyl)sebacate, commercially available from Ciba under the trademark Tinuvin® 770; poly-(N-hydroxyethyl-2, 2,6,6- tetramethyl-4-hydroxy-piperidyl succinate, commercially available from Ciba under the trademark Tinuvin® 622LD (Ciba); methyl bis tallow amine; bis tallow amine; phenol-alpha-naphthylamine; bis(dimethylamino)methylsilane (DMAMS); tris(trimethylsilyl)silane (TTMSS); vinyltriethoxysilane; vinyltrimethoxysilane; 2,5- difluorobenzophenone; 2’,5’-dihydroxyacetophenone; 2-aminobenzophenone; 2- chlorobenzophenone; benzyl phenyl sulfide; diphenyl sulfide; dibenzyl sulfide; ionic liquids; and others. [0105] Tracers that may be included in the working fluid compositions may be selected from the group consisting of hydrofluorocarbons (HFCs), deuterated hydrofluorocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodated compounds, alcohols, aldehydes and ketones, nitrous oxide and combinations thereof.

[0106] The compositions of the present invention can be prepared by any convenient method including mixing or combining the desired amounts. In one embodiment of this invention, a composition can be prepared by weighing the desired component amounts and thereafter combining them in an appropriate container.

EXAMPLES

Example 1

[0107] Power Generation through Subcritical Rankine Cycle Using an HFO- 1225yeE/HFO-1234zeE Blend as the Working Fluid

[0108] Heat at temperatures from about 110 to 132°C is available from various sources and can be converted to mechanical or electrical power using Rankine cycles. Heat can be captured as a byproduct from various industrial processes, it can be collected from solar irradiation through solar panels or it can be collected from diesel exhaust. An organic Rankine cycle has been modeled using compositions containing HFO-1225yeE and HFO-1234zeE.

[0109] Table 1 compares the cycle performance of the compositions of the present invention containing HFO-1225yeE and HFO-1234zeE relative to use of HFO- 1234zeE alone. Conditions for the calculations are as follows:

Table 1

[0110] The data illustrates that the compositions of the present invention provide power within 10% of that for HFO-1234zeE alone and efficiency within 2%. The compositions containing HFO-1225yeE and HFO-1234zeE would make useful, nonflammable working fluids to be used in place of HFO-1234zeE alone.

Example 2

[0111] Power Generation through Subcritical Rankine Cycle Using an HFO- 1225yeE/HFO-1234zeE/HFC-134 Blend as the Working Fluid

[0112] Heat at temperatures from about 120 to 132°C is available from various sources and can be converted to mechanical or electrical power using Rankine cycles. Heat can be captured as a byproduct from various industrial processes, it can be collected from solar irradiation through solar panels or it can be collected from diesel exhaust. An organic Rankine cycle has been modeled using compositions containing HFO-1225yeE, HFO-1234zeE, and HFC-134.

[0113] Table 2 compares the cycle performance of the compositions of the present invention containing HFO-1225yeE, HFO-1234zeE, and HFC-134 relative to use of HFO-1234zeE alone. Conditions for the calculations are as follows:

Table 2

[0114] The data illustrates that the compositions of the present invention provide power within 10% of that for HFO-1234zeE alone and efficiency within 2%. The compositions containing HFO-1225yeE, HFO-1234zeE, and HFC-134 would make useful, non-flammable working fluids to be used in place of HFO-1234zeE alone.

Example 3

[0115] Power Generation through Trans-critical Rankine Cycle Using an HFO- 1225yeE/HFO-1234zeE/HFC-134 Blend as the Working Fluid

[0116] Heat at temperatures from about 120 to 150°C is available from various sources and can be converted to mechanical or electrical power using Rankine cycles. Heat can be captured as a byproduct from various industrial processes, it can be collected from solar irradiation through solar panels or it can be collected from diesel exhaust. An organic trans-critical Rankine cycle has been modeled using compositions containing HFO-1225yeE, HFO-1234zeE, and HFC-134.

[0117] Table 3 summarizes the cycle performance of the compositions of the present invention containing HFO-1225yeE, HFO-1234zeE, and HFC-134 over a range of supercritical heat exchanger pressures and a range of temperatures for the supercritical inlet conditions to the expander. Conditions for the calculations are as follows:

Table 3

[0118] It can be observed from Table 3 that both the maximum power generation capacity (CAP) and efficiency are achievable at the maximum inlet temperature to the turbine, corresponding to a heat source of at least 145 C. Both performance metrics are also maximal at the largest supercritical heat exchanger pressure that avoids wet expansion in the turbine, 4.77 MPa. The composition for maximal CAP and efficiency are 22 wt% R-1225yeE, 65 wt% R-1234zeE and 13 wt% R-134 and 52 wt-% R-1225yeE, 35 wt-% R-1234zeE and 13 wt-% R-134 respectively. Although the composition of maximum power generating capacity corresponds with the maximum glide, this glide is still very low and permissible, <0.5 K in the condenser. These compositions are also < 150 GWP and do not propagate a flame.

[0119] Table 4 compares the trans-critical cycle performance of the compositions of the present invention containing HFO-1225yeE, HFO-1234zeE, and HFC-134 relative to use of HFO-1234zeE alone at the previously identified optimal supercritical heat exchanger pressure and inlet temperature to the turbine. Conditions for the calculations are as follows:

Table 4

[0120] Again, the data illustrates that the compositions of the present invention provide power within 10% of that for HFO-1234zeE alone and efficiency within 2%, where the optimal power generation capacity and optimal efficiencies occur at 23 wt% R-1225yeE, 64 wt% R-1234zeE and 13 wt% R-134 and 55 wt% R-1225yeE, 32 wt% R-1234zeE and 13 wt% R-134 respectively. The compositions containing HFO- 1225yeE, HFO-1234zeE, and HFC-134 would make useful, non-flammable working fluids to be used in place of HFO-1234zeE alone.

Claims

CLAIMS What is claimed is:

1 . A method for converting heat from a heat source to mechanical energy, comprising heating a working fluid comprising HFO-1225yeE, HFO-1234zeE, and optionally HFC-134 using heat supplied from the heat source; and expanding the heated working fluid to lower the pressure of the working fluid and generate mechanical energy as the pressure of the working fluid is lowered.

2. The method of claim 1 , wherein the working fluid is compressed prior to heating; and the expanded working fluid is cooled and compressed for repeated cycles.

3. The method of claim 1 , wherein the working fluid is a nonflammable composition consisting essentially of HFO-1225yeE, HFO-1234zeE, and optionally HFC-134.

4. The method of claim 1 , wherein the working fluid consists essentially of from about 10 to 99 weight percent HFO-1225yeE and from about 90 to 1 weight percent HFO-1234zeE.

5. The method of claim 3, wherein the working fluid consists essentially of from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134.

6. The method of claim 3 or 5, wherein the working fluid consists essentially of from about 10 to 78 weight percent HFO-1225yeE, about 11 to 64 weight percent HFO-1234zeE, and about 11 to 27 weight percent HFC-134.

7. The method of claim 3 or 5, wherein the working fluid consists essentially of from about 40 to 78 weight percent HFO-1225yeE, from about 11 to 62 weight percent HFO-1234zeE, and from about 0 to 27 weight percent HFC-134.

8. The method of claim 1 , 3, 5, or 7, wherein the working fluid comprises about 40 weight percent HFO-1225yeE and about 60 weight percent HFO-1234zeE.

9. The method of claim 1 , 3, 5, 6 or 7, wherein the working fluid comprises about 26 weight percent HFO-1225yeE, about 62 weight percent HFO-1234zeE, and about 12 weight percent HFC-134.

10. The method of any of claims 2 to 9, wherein heat from a heat source is converted to mechanical energy using a sub-critical cycle comprising:

(e) cycling cooled liquid working fluid from (d) to (a) for compression.

11 . The method of any of claims 2 to 9 wherein heat from a heat source is converted to mechanical energy using a trans-critical cycle comprising:

(e) cycling cooled liquid working fluid from (d) to (a) for compression.

12. The method of any of claims 2 to 9, wherein heat from a heat source is converted to mechanical energy using a super-critical cycle comprising:

(a) compressing a working fluid from a pressure above its critical pressure to a higher pressure; (b) heating compressed working fluid from (a) using heat supplied by the heat source;

(c) expanding heated working fluid from (b) to lower the pressure of the working fluid to a pressure above its critical pressure and generate mechanical energy;

(d) cooling expanded working fluid from (c) to form a cooled working fluid above its critical pressure; and

(e) cycling cooled liquid working fluid from (d) to (a) for compression.

13. The method of any of claims 1 to 10, wherein said working fluid further comprises a lubricant.

14. The method of claim 13, wherein said lubricant is selected from the group consisting of polyalkylene glycols, polyol esters, polyvinyl ethers, perfluoropolyethers, polycarbonates, mineral oils, alkylbenzenes, synthetic paraffins, synthetic naphthenes, poly(alpha)olefins and combinations thereof.

15. A power cycle apparatus containing a working fluid comprising HFO-1225yeE, HFO-1234zeE, and optionally HFC-134.

16. The power cycle apparatus of claim 15 comprising (a) a heat exchange unit; (b) an expander in fluid communication with the heat exchange unit; (c) a working fluid cooling unit in fluid communication with the expander; and (d) a compressor in fluid communication with the working fluid cooler; wherein the compressor is further being in fluid communication with the heat exchange unit such that the working fluid then repeats flow through components (a), (b), (c) and (d) in a repeating cycle.

17. The power cycle apparatus of claim 15 or 16, wherein the working fluid comprises from about 10 to 99 weight percent HFO-1225yeE, about 1 to 64 weight percent HFO-1234zeE, and about 0 to 27 weight percent HFC-134.

18. The power cycle apparatus of claim 15 or 16, wherein the working fluid consists essentially of from about 10 to 78 weight percent HFO-1225yeE, about 11 to 64 weight percent HFO-1234zeE, and about 11 to 27 weight percent HFC-134.

19. The power cycle apparatus of any of claims 15, 16, or 17, wherein the working fluid comprises about 40 weight percent HFO-1225yeE and about 60 weight percent HFO-1234zeE.

20. The power cycle apparatus of any of claims 15 to 18, wherein the working fluid comprises about 26 weight percent HFO-1225yeE, about 62 weight percent HFO-1234zeE, and about 12 weight percent HFC-134.

21 . The power cycle apparatus of any of claims 15 to 20, wherein the working fluid further comprises a lubricant.

22. The power cycle apparatus of claim 21 , wherein said lubricant is selected from the group consisting of polyalkylene glycols, polyol esters, polyvinyl ethers, perfluoropolyethers, polycarbonates, mineral oils, alkylbenzenes, synthetic paraffins, synthetic naphthenes, poly(alpha)olefins and combinations thereof.