U.S. patent application number 14/007057 was filed with the patent office on 2014-10-23 for fluorinated oxiranes as organic rankine cycle working fluids and methods of using same.
This patent application is currently assigned to 3M INNOVATIVE PROPERTIES COMPANY. The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Michael J. Bulinski, Michael G. Costello, Bamidele Fayemi, Richard M. Flynn, Richard M. Minday, John G. Owens, Phillip E. Tuma, Zhongxing Zhang.
Application Number | 20140311146 14/007057 |
Document ID | / |
Family ID | 45929014 |
Filed Date | 2014-10-23 |
United States Patent
Application |
20140311146 |
Kind Code |
A1 |
Fayemi; Bamidele ; et
al. |
October 23, 2014 |
FLUORINATED OXIRANES AS ORGANIC RANKINE CYCLE WORKING FLUIDS AND
METHODS OF USING SAME
Abstract
A process and an apparatus for converting thermal energy into
mechanical energy in a Rankine cycle is provided. The process and
apparatus include a working fluid that comprises a fluorinated
oxirane. The fluorinated oxirane can contain substantially no
hydrogen atoms bonded to carbon atoms and can have from about 4 to
about 9 carbon atoms. The process can drive a turbine and, in some
embodiments, generate electricity.
Inventors: |
Fayemi; Bamidele; (St. Paul,
MN) ; Zhang; Zhongxing; (Woodbury, MN) ;
Costello; Michael G.; (Afton, MN) ; Bulinski; Michael
J.; (Houlton, WI) ; Owens; John G.; (Woodbury,
MN) ; Tuma; Phillip E.; (Faribault, MN) ;
Minday; Richard M.; (Stillwater, MN) ; Flynn; Richard
M.; (Mahtomedi, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Assignee: |
3M INNOVATIVE PROPERTIES
COMPANY
St. Paul
MN
|
Family ID: |
45929014 |
Appl. No.: |
14/007057 |
Filed: |
March 13, 2012 |
PCT Filed: |
March 13, 2012 |
PCT NO: |
PCT/US2012/028855 |
371 Date: |
September 24, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61467452 |
Mar 25, 2011 |
|
|
|
Current U.S.
Class: |
60/651 ;
60/671 |
Current CPC
Class: |
F01K 25/08 20130101;
C07D 303/08 20130101; F01K 25/10 20130101; C09K 5/04 20130101; C07D
303/48 20130101 |
Class at
Publication: |
60/651 ;
60/671 |
International
Class: |
F01K 25/08 20060101
F01K025/08 |
Claims
1. A process for converting thermal energy into mechanical energy
in a Rankine cycle comprising: vaporizing a working fluid with a
heat source to form a vaporized working fluid; expanding the
vaporized working fluid through a turbine; cooling the vaporized
working fluid using a cooling source to form a condensed working
fluid; and pumping the condensed working fluid; wherein the working
fluid comprises a fluorinated oxirane.
2. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 1, wherein the fluorinated
oxirane compound includes up to a maximum of three hydrogen
atoms.
3. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 1, wherein the fluorinated
oxirane compound contains substantially no hydrogen atoms bonded to
carbon atoms.
4. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 1, wherein the fluorinated
oxirane has a total of from about 4 to about 9 carbon atoms.
5. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 4, wherein the fluorinated
oxirane contains 6 carbon atoms.
6. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 1, wherein the fluorinated
oxirane has a critical temperature greater than about 150.degree.
C.
7. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 1, wherein the turbine
generates electrical energy.
8. A process for converting thermal energy into mechanical energy
in a Rankine cycle according to claim 1, wherein the vaporized
working fluid is at a pressure greater than ambient pressure.
9. A process for recovering waste heat comprising: passing a liquid
working fluid through a heat exchanger in communication with a
process that produces waste heat to produce a vaporized working
fluid; removing the vaporized working fluid from the heat
exchanger; passing the vaporized working fluid through an expander,
wherein the waste heat is converted into mechanical energy; and
cooling the vaporized working fluid after it has been passed
through the expander, wherein the fluorinated oxirane compound
contains substantially no hydrogen atoms bonded to carbon
atoms.
10. A process for recovering waste heat comprising according to
claim 9, wherein the fluorinated oxirane has a total of from about
4 to about 9 carbon atoms.
11. A process for recovering waste heat comprising according to
claim 10, wherein the fluorinated oxirane contains 6 carbon
atoms.
12. A process for recovering waste heat comprising according to
claim 10, wherein the fluorinated oxirane has a critical
temperature of greater than about 150.degree. C.
13. An apparatus for converting thermal energy into mechanical
energy in a Rankine cycle comprising: a working fluid; a heat
source to vaporize the working fluid and form a vaporized working
fluid; a turbine through which the vaporized working fluid is
passed thereby converting thermal energy into mechanical energy; a
condenser to cool the vaporized working fluid after it is passed
through the turbine; and a pump to recirculate the working fluid,
wherein the working fluid comprises a fluorinated oxirane.
14. An apparatus for converting thermal energy into mechanical
energy in a Rankine cycle according to claim 13, wherein the
working fluid is in a closed loop.
15. An apparatus for converting thermal energy into mechanical
energy in a Rankine cycle according to claim 13, wherein the
fluorinated oxirane contains substantially no hydrogen atoms bonded
to carbon atoms.
16. An apparatus for converting thermal energy into mechanical
energy in a Rankine cycle according to claim 15, wherein the
fluorinated oxirane has a total of from about 4 to about 9 carbon
atoms.
17. An apparatus for converting thermal energy into mechanical
energy in a Rankine cycle according to claim 16, wherein the
fluorinated oxirane contains 6 carbon atoms.
18. An apparatus for converting thermal energy into mechanical
energy in a Rankine cycle according to claim 13, wherein the
fluorinated oxirane has a critical temperature greater than about
150.degree. C.
Description
FIELD
[0001] This disclosure relates to the use of fluorinated oxiranes
as Rankine cycle working fluids.
BACKGROUND
[0002] Rankine cycle systems are commonly used for generating
electrical power that can then be provided to a power distribution
system, or grid for residential and commercial use. The electrical
power is generated by converting thermal energy into mechanical
energy and then mechanical energy into electrical energy. Closed
Rankine systems are known that include a heat source such as a
boiler or evaporator of a motive fluid (working fluid), a turbine
fed with the vapor from the boiler to drive a generator or other
load, a condenser for condensing the exhaust vapors from the
turbine, and a means to pump the recycled condensed fluid back to
the heat source. U.S. Pat. No. 3,393,515 (Tabor et al.) describes a
self-starting power generating unit which operates on a closed
Rankine cycle. The motive fluid that has been used in such systems
has often been water. The heat source has been any form of fossil
fuel, e.g., oil, coal, or natural gas.
[0003] Organic working fluids can boil at temperatures up to the
critical temperature above which there is no boiling, fluids with
higher critical temperatures result in higher Rankine cycle
efficiency. Typically, fluids such as 1,1,1,3,3-pentafluoropropane
(R245fa Refrigerant, available from Honeywell, Morristown, N.J.
under the trade designation GENETRON) has been used in Rankine
cycle system devices. More recently, other perfluorinated ketones
having a higher critical temperature than R245fa (critical
temperature of 150.degree. C.) have been considered for use in
Rankine cycle devices since these materials have a higher critical
temperature than R245fa. For example, U.S. Pat. No. 7,100,380
(Brasz et al.) discloses organic Rankine cycle systems that use
other perfluorinated ketones with higher thermodynamic Rankine
cycle efficiency than R245fa. For example, Brasz et al. discloses
the use of CF.sub.3CF.sub.2C(O)CF(CF.sub.3).sub.2 and other related
compounds as Rankine working fluids.
[0004] The use of fluorinated oxiranes for fire extinguishing has
been disclosed, for example, in U.S. Ser. No. 61/431,119 entitled
"Fluorinated Oxiranes as Fire Extinguishing Compositions and
Methods of Extinguishing Fires Therewith", filed Jan. 10, 2011. The
use of fluorinated oxiranes as dielectric fluids has been
disclosed, for example, in U.S. Ser. No. 61/435,867 entitled
"Fluorinated Oxiranes as Dielectric Fluids", filed Jan. 25, 2011.
Lubricants containing fluorinated oxiranes has been disclosed, for
example, in U.S. Ser. No. 61/448,826 entitled "Lubricant
Compositions Containing Fluorooxiranes", filed Mar. 10, 2011. The
use of fluorinated oxiranes as heat transfer fluids is disclosed in
Applicants' copending application, U.S. Attorney Docket No.,
67218US002, entitled "Fluorinated Oxiranes as Heat Transfer
Fluids", which was filed on the same date herewith.
SUMMARY
[0005] There continues to be a need for organic Rankine cycle
working fluids that have ever higher critical pressures and
temperatures as well as good thermal stabilities. There is a need
for working fluids that are less harmful to the environment and
that have acceptable environmental properties and are nonflammable.
There is also a need for working fluids that are more efficient in
energy transfer and can still be used in systems that have simple
equipment design.
[0006] In one aspect, a process for converting thermal energy into
mechanical energy in a Rankine cycle is provided that includes the
steps of vaporizing a working fluid with a heat source to form a
vaporized working fluid, expanding the vaporized working fluid
through a turbine, cooling the vaporized working fluid using a
cooling source to form a condensed working fluid, and pumping the
condensed working fluid, wherein the working fluid comprises a
fluorinated oxirane. The fluorinated oxirane can contain
substantially no hydrogen atoms bonded to carbon atoms and can have
a total of from about 4 to about 9 carbon atoms. In some
embodiments, the fluorinated oxirane can contain 6 carbon atoms.
The fluorinated oxirane can have a critical temperature of greater
than about 150.degree. C.
[0007] In another aspect, a process for recovering waste heat is
provided that includes passing a liquid working fluid through a
heat exchanger in communication with a process that produces waste
heat to produce a vaporized working fluid, removing the vaporized
working fluid from the heat exchanger, passing the vaporized
working fluid through an expander, wherein the waste heat is
converted into mechanical energy, and cooling the vaporized working
fluid after it has been passed through the expander, wherein the
fluorinated oxirane compound contains substantially no hydrogen
atoms bonded to carbon atoms.
[0008] Finally, in another aspect, an apparatus for converting
thermal energy into mechanical energy in a Rankine cycle is
provided that includes a working fluid, a heat source to vaporize
the working fluid and form a vaporized working fluid, a turbine
through which the vaporized working fluid is passed thereby
converting thermal energy into mechanical energy, a condenser to
cool the vaporized working fluid after it is passed through the
turbine, and a pump to recirculate the working fluid, wherein the
working fluid comprises a fluorinated oxirane.
[0009] In this disclosure:
[0010] "critical temperature and critical pressure" refers to the
temperature and pressure at which the density of the vapor of a
liquid in a sealed system is the same as that of the liquid.
[0011] "in-chain heteroatom" refers to an atom other than carbon
(for example, oxygen and nitrogen) that is bonded to carbon atoms
in a carbon chain so as to form a carbon-heteroatom-carbon
chain;
[0012] "device" refers to an object or contrivance which is heated,
cooled, or maintained at a predetermined temperature;
[0013] "inert" refers to chemical compositions that are generally
not chemically reactive under normal conditions of use;
[0014] "fluorinated" refers to hydrocarbon compounds that have one
or more C--H bonds replaced by C--F bonds;
[0015] "oxirane" refers to a substituted hydrocarbon that contains
at least one epoxy group, and
[0016] "perfluoro-" (for example, in reference to a group or
moiety, such as in the case of "perfluoroalkylene" or
"perfluoroalkylcarbonyl" or "perfluorinated") means completely
fluorinated such that, except as may be otherwise indicated, there
are no carbon-bonded hydrogen atoms replaceable with fluorine.
[0017] The provided processes and apparatuses that include
fluorinated oxiranes as organic Rankine cycle working fluids can
have ever lower boiling points, higher critical pressures and
temperatures as well as good thermal stabilities compared to
conventionally used fluorinated compositions with comparable
numbers of carbon atoms. The provided Rankine cycle working fluids
can be more efficient in energy transfer and can still be used in
systems that have simple equipment design.
[0018] The above summary is not intended to describe each disclosed
embodiment of every implementation of the present invention. The
brief description of the drawings and the detailed description
which follows more particularly exemplify illustrative
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic illustration of an apparatus for
converting thermal energy into mechanical energy in a Rankine
cycle.
[0020] FIG. 2 is a schematic illustration of a Rankine cycle
apparatus that includes a recuperator.
[0021] FIG. 3 is a graph (Temperature-Entropy Diagram) for an
embodiment of the provided process.
DETAILED DESCRIPTION
[0022] In the following description, reference is made to the
accompanying set of drawings that form a part of the description
hereof and in which are shown by way of illustration several
specific embodiments. It is to be understood that other embodiments
are contemplated and may be made without departing from the scope
or spirit of the present invention. The following detailed
description, therefore, is not to be taken in a limiting sense.
[0023] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties used in the specification
and claims are to be understood as being modified in all instances
by the term "about" Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the foregoing specification
and attached claims are approximations that can vary depending upon
the desired properties sought to be obtained by those skilled in
the art utilizing the teachings disclosed herein. The use of
numerical ranges by endpoints includes all numbers within that
range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and
any range within that range.
[0024] A process for converting thermal energy into mechanical
energy in a Rankine cycle is provided that includes a working fluid
comprising a fluorinated oxirane. Referring to FIG. 1, typical
Rankine cycle system 100 is shown that includes evaporator/boiler
120 which receives heat from an external source. Evaporator/boiler
120 vaporizes an organic Rankine working fluid contained within
closed system 100. Rankine cycle system 100 also includes turbine
160 which is driven by the vaporized working fluid in the system
and is used to turn generator 180 thus producing electrical power.
The vaporized working fluid is then channeled though condenser 140
removing excess heat and reliquifying the liquid working fluid.
Power pump 130 increases the pressure of liquid leaving condenser
140 and also pumps it back into evaporator/boiler 120 for further
use in the cycle. Heat released from condenser 140 can then be used
for other purposes including driving a secondary Rankine system
(not shown).
[0025] It is generally desirable to have fluids with saturated
vapor curves that are either isentropic or have positive slope. In
cases where the saturated vapor curve has a positive slope, Rankine
cycle efficiency can be improved through the use of an extra heat
exchanger (or recuperator) to recover heat from vapor exiting the
expander and using the recovered heat to pre-heat liquid coming out
of the pump. FIG. 2 is an illustration of Rankine cycle system that
includes a recuperator.
[0026] Referring to FIG. 2, Rankine cycle system 200 is shown that
includes evaporator/boiler 220 which receives heat from an external
source. Evaporator/boiler 220 vaporizes an organic Rankine working
fluid contained within closed system 200. Rankine cycle system 200
also includes turbine 260 which is driven by the vaporized working
fluid in the system and is used to turn generator 270 thus
producing electrical power. The vaporized working fluid is then
channeled though recuperator 280 removing some excess heat and from
there to the condenser 250, where the working fluid condenses back
to liquid. Power pump 240 increases the pressure of liquid leaving
condenser 250 and also pumps it back into recuperator 280, where it
is preheated before going back into the evaporator/boiler 220 for
further use in the cycle. Heat released from condenser 250 can then
be used for other purposes including driving a secondary Rankine
system (not shown).
[0027] The provided apparatuses and processes include fluorinated
oxiranes. Fluorinated oxiranes useful in the provided compositions
and processes can be oxiranes that have a carbon backbone which is
fully fluorinated (perfluorinated), i.e., substantially all of the
hydrogen atoms in the carbon backbone have been replaced with
fluorine or oxiranes that can have a carbon backbone which is fully
or partially fluorinated having, in some embodiments, up to a
maximum of three hydrogen atoms, or a combination thereof. The use
of fluorinated oxiranes in an apparatus that includes a device and
a mechanism for transferring heat to or from the device is
disclosed in Applicants' copending application, U.S. Attorney
Docket No. 67218US002, which has been filed on the same day
herewith.
[0028] In addition to providing the required thermophysical
properties for use in organic Rankine systems, the fluorinated
oxiranes also demonstrate desirable environmental benefits. Many
compounds that display high stability in use have also been found
to be quite stable in the environment. Perfluorocarbons and
perfluoropolyethers exhibit high stability but also have been shown
to have long atmospheric lifetimes which result in high global
warming potentials. The atmospheric lifetimes of C.sub.6F.sub.14
and CF.sub.3OCF(CF.sub.3)CF.sub.2OCF.sub.2OCF.sub.3 are reported as
3200 years and 800 years, respectively (see Climate Change 2007:
The Physical Science Basis. Contribution of Working Group I to the
Fourth Assessment Report of the Intergovernmental Panel on Climate
Change, Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K. B.
Averyt, M. Tignor and H. L. Miller (eds.), Cambridge University
Press, Cambridge, United Kingdom and New York, N.Y., USA, 996 pp,
2007.). The fluorinated oxiranes have been found to degrade in the
environment on timescales that result in significantly reduced
atmospheric lifetimes and lower global warming potentials compared
to perfluorocarbons and perfluoropolyethers. Based on kinetic
studies for reaction with hydroxyl radical,
2,3-difluoro-2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-3-t-
rifluoromethyl-oxirane has an estimated atmospheric lifetime of 20
years. In similar kinetic studies,
2-fluoro-2-pentafluoroethyl-3,3-bis-trifluoromethyl-oxirane
demonstrates an estimated atmospheric lifetime of 77 years. As a
result of their shorter atmospheric lifetimes, fluorinated oxiranes
have lower global warming potentials and would be expected to make
significantly less contribution to global warming as compared to
perfluorocarbons and perfluoropolyethers.
[0029] The provided fluorinated oxiranes can be derived from
fluorinated olefins that have been oxidized with epoxidizing
agents. In the provided fluorinated oxirane compositions the carbon
backbone includes the whole carbon framework including the longest
hydrocarbon chain (main chain) and any carbon chains branching off
of the main chain. In addition, there can be one or more catenated
heteroatoms interrupting the carbon backbone such as oxygen and
nitrogen, for example ether or trivalent amine functionalities. The
catenated heteroatoms are typically not directly bonded to the
oxirane ring. In these cases the carbon backbone includes the
heteroatoms and the carbon framework attached to the
heteroatom.
[0030] Typically, the majority of halogen atoms attached to the
carbon backbone are fluorine; most typically, substantially all of
the halogen atoms are fluorine so that the oxirane is a
perfluorinated oxirane. The provided fluorinated oxiranes can have
a total of 4 to 12 carbon atoms. Representative examples of
fluorinated oxirane compounds suitable for use in the provided
processes and compositions include
2,3-difluoro-2,3-bis-trifluoromethyl-oxirane,
2,2,3-trifluoro-3-pentafluoroethyl-oxirane,
2,3-difluoro-2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-3-trifluorom-
ethyl-oxirane,
2-fluoro-2-pentafluoroethyl-3,3-bis-trifluoromethyl-oxirane,
1,2,2,3,3,4,4,5,5,6-decafluoro-7-oxa-bicyclo[4.1.0]heptane,
2,3-difluoro-2-trifluoromethyl-3-pentafluoroethyl-oxirane,
2,3-difluoro-2-nonafluorobutyl-3-trifluoromethyl-oxirane,
2,3-difluoro-2-heptafluoropropyl-3-pentafluoroethyl-oxirane,
2-fluoro-3-pentafluoroethyl-2,3-bis-trifluoromethyl-oxirane,
2,3-bis-pentafluoroethyl-2,3-bistrifluoromethyl-oxirane,
2,3-bis-trifluoromethyl-oxirane,
2-pentafluoroethyl-3-trifluoromethyl-oxirane,
2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-3-trifluoromethyl-oxirane-
, 2-nonafluorobutyl-3-pentafluoroethyl-oxirane,
2-fluoro-2-trifluoromethyl-oxirane,
2,2-bis-trifluoromethyl-oxirane,
2-fluoro-3-trifluoromethyl-oxirane, 2-heptafluoroisopropyloxirane,
2-heptafluoropropyloxirane,
[0031] 2-nonafluorobutyloxirane, 2-tridecafluorohexyloxirane, and
oxiranes of HFP trimer including
2-pentafluoroethyl-2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-3,3-bi-
s-trifluoromethyl-oxirane,
2-fluoro-3,3-bis-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-2-trifluor-
omethyl-oxirane,
2-fluoro-3-heptafluoropropyl-2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-eth-
yl)-3-trifluoromethyl-oxirane,
2-(1,2,2,3,3,3-hexafluoro-1-trifluoromethyl-propyl)-2,3,3-tris-trifluorom-
ethyl-oxirane and
2-[1,1,2,3,3,3-hexafluoro-2-(trifluoromethyl)propyl]-2-(trifluoromethyl)o-
xirane.
[0032] The provided fluorinated oxirane compounds can be prepared
by epoxidation of the corresponding fluorinated olefin using an
oxidizing agent such as sodium hypochlorite, hydrogen peroxide or
other well known epoxidizing agent such as peroxycarboxylic acids
such as meta-chloroperoxybenzoic acid or peracetic acid. The
fluorinated olefinic precursors can be directly available as, for
example, in the cases of 1,1,1,2,3,4,4,4-octafluoro-but-2-ene (for
making 2,3-difluoro-2,3-bis-trifluoromethyl oxirane),
1,1,1,2,3,4,4,5,5,5-decafluoro-pent-2-ene or 1,2,3,3,4,4,5,5,6,6
decafluoro-cyclohexene (for making
1,2,2,3,3,4,4,5,5,6-decafluoro-7-oxa-bicyclo[4.1.0]heptane). Other
useful fluorinated olefinic precursors can include oligomers of
hexafluoropropene (HFP) and tetrafluoroethylene (TFE) such as
dimers and trimers. The HFP oligomers can be prepared by contacting
1,1,2,3,3,3-hexafluoro-1-propene (hexafluoropropene) with a
catalyst or mixture of catalysts selected from the group consisting
of cyanide, cyanate, and thiocyanate salts of alkali metals,
quaternary ammonium, and quaternary phosphonium in the presence of
polar, aprotic solvents such as, for example, acetonitrile. The
preparation of these HFP oligomers is disclosed, for example, in
U.S. Pat. No. 5,254,774 (Prokop). Useful oligomers include HFP
trimers or HFP dimers. HFP dimers include a mixture of cis- and
trans-isomers of perfluoro-4-methyl-2-pentene as indicated in Table
1 in the Example section below. HFP trimers include a mixture of
isomers of C.sub.9F.sub.18. This mixture has six main components
that are also listed in Table 1 in the Example section.
[0033] The provided fluorinated oxirane compounds can have a
boiling point in a range of from about -10.degree. C. to about
150.degree. C. In some embodiments, the fluorinated oxirane
compounds can have a boiling point in the range of from about
0.degree. C. to about 55.degree. C. Some exemplary materials and
their boiling point ranges are disclosed in the Examples section
below.
[0034] The provided process for converting thermal energy into
mechanical energy in a Rankine cycle includes using a heat source
to vaporize a working fluid comprising fluorinated oxiranes to form
a vaporized working fluid. In some embodiments, the heat is
transferred from the heat source to the working fluid in an
evaporator or boiler. The vaporized working fluid is pressurized
and can be used to do work by expansion. The heat source can be of
any form such as from fossil fuels, e.g., oil, coal, or natural
gas. Additionally, in some embodiments, the heat source can come
from nuclear power, solar power, or fuel cells. In other
embodiments, the heat can be "waste heat" from other heat transfer
systems that would otherwise be lost to the atmosphere. The "waste
heat", in some embodiments, can be heat that is recovered from a
second Rankine cycle system from the condenser or other cooling
device in the second Rankine cycle.
[0035] An additional source of "waste heat" can be found at
landfills where methane gas is flared off. In order to prevent
methane gas from entering the environment and thus contributing to
global warming, the methane gas generated by the landfills can be
burned by way of "flares" producing carbon dioxide and water which
are both less harmful to the environment in terms of global warming
potential than methane. Other sources of "waste heat" that can be
useful in the provided processes are geothermal sources and heat
from other types of engines such as gas turbine engines that give
off significant heat in their exhaust gases and to cooling liquids
such as water and lubricants.
[0036] In the provided process, the vaporized working fluid is
expanded though a device that can convert the pressurized working
fluid into mechanical energy. In some embodiments, the vaporized
working fluid is expanded through a turbine which can cause a shaft
to rotate from the pressure of the vaporized working fluid
expanding. The turbine can then be used to do mechanical work such
as, in some embodiments, operate a generator, thus generating
electricity. In other embodiments, the turbine can be used to drive
belts, wheels, gears, or other devices that can transfer mechanical
work or energy for use in attached or linked devices.
[0037] After the vaporized working fluid has been converted to
mechanical energy the vaporized (and now expanded) working fluid
can be condensed using a cooling source to liquefy for reuse. The
heat released by the condenser can be used for other purposes
including being recycled into the same or another Rankine cycle
system, thus saving energy. Finally, the condensed working fluid
can be pumped by way of a pump back into the boiler or evaporator
for reuse in a closed system.
[0038] The desired thermodynamic characteristics of organic Rankine
cycle working fluids are well known to those of ordinary skill and
are discussed, for example, in U.S. Pat. Appl. Publ. No.
2010/0139274 (Zyhowski et al.). The greater the difference between
the temperature of the heat source and the temperature of the
condensed liquid or a provided heat sink after condensation, the
higher the Rankine cycle thermodynamic efficiency. The
thermodynamic efficiency is influenced by matching the working
fluid to the heat source temperature. The closer the evaporating
temperature of the working fluid to the source temperature, the
higher the efficiency of the system. Toluene can be used, for
example, in the temperature range of 79.degree. C. (boiling point
of toluene) to about 260.degree. C., however toluene has
toxicological and flammability concerns. Fluids such as
1,1-dichloro-2,2,2-trifluoroethane and 1,1,1,3,3-pentafluoropropane
can be used in this temperature range as an alternative. But
1,1-dichloro-2,2,2-trifluoroethane can form toxic compounds below
300.degree. C. and need to be limited to an evaporating temperature
of about 93.degree. C. to about 121.degree. C. Thus, there is a
desire for other environmentally-friendly Rankine cycle working
fluids with higher critical temperatures so that source
temperatures such as gas turbine and internal combustion engine
exhaust can be better matched to the working fluid. Additionally,
fluids with higher heat capacities contribute to higher Rankine
cycle efficiencies due to increases thermal energy
utilization--greater energy recovery from expansion.
[0039] Also provided is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle that includes a working
fluid that includes a fluorinated oxirane, a heat source to
vaporize the working fluid and form a vaporized working fluid, a
turbine to convert the thermal energy (and pressure) of the
vaporized working fluid into mechanical energy, a condenser to cool
the vaporized working fluid after it has transferred energy to the
turbine and a pump to recirculate the working fluid and to build
pressure. The recirculated working fluid can then be reheated in an
evaporator boiler in the provided method and as described
above.
[0040] Objects and advantages of this invention are further
illustrated by the following examples, but the particular materials
and amounts thereof recited in these examples, as well as other
conditions and details, should not be construed to unduly limit
this invention. The apparatus is typically a closed loop
EXAMPLES
TABLE-US-00001 [0041] TABLE 1 Materials Chemical Description Source
1,1,1,2,3,4,5,5,5-nonafluoro- 4-trifluoromethyl-pent-2-ene HFP
Dimer 2 isomers; ##STR00001## 3M Foam Additive FA-188, 3M, St.
Paul, MN. ##STR00002## 1,2,3,3,4,4,5,5,6,6 Available from Sigma-
decafluoro-cyclohexene Aldrich, St. Louis, MO. HFP Trimer HFP
Trimer 6 Isomers; ##STR00003## (45%), U.S. Pat. No. 5,254,774
##STR00004## (25%), ##STR00005## (14.5%), ##STR00006## (12%),
##STR00007## (3%), ##STR00008## (0.5%) Dodecafluoro-2-
C.sub.2F.sub.5C(O)CF(CF.sub.3).sub.2 3M NOVEC 649: 3M
methylpentan-3-one Company, St Paul, MN Sodium Hydroxide NaOH GFS
Chemicals, Inc., Powell, OH Sodium Hypochlorite Na.sup.+[ClO].sup.-
Alfa Aesar, Ward Hill, MA Potassium Hydroxide KOH Sigma Aldrich,
Milwaukee, WI Hydrogen Peroxide H.sub.2O.sub.2 GFS Chemicals, Inc.,
Powell, OH Acetonitrile CH.sub.3CN Honeywell Burdick & Jackson,
Morristown, NJ
Materials
Example 1
Synthesis of
2,3-difluoro-2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-3-trifluorom-
ethyl-oxirane. (C.sub.6F.sub.12O)
[0042] In a 1.5 liter glass reactor fitted with a mixer and a
cooling jacket, 400 grams of acetonitrile, 200 grams of
1,1,1,2,3,4,5,5,5-nonafluoro-4-trifluoromethyl-pent-2-ene and 150
grams of 50% potassium hydroxide were added. The reactor
temperature was controlled at 0.degree. C. using the reactor
cooling jacket. Then 100 grams of 50% hydrogen peroxide was slowly
added to the reactor under strong mixing while controlling the
reactor temperature at 0.degree. C. After all the hydrogen peroxide
was added within about 2 hours, the mixer was turned off to allow
the product crude to phase split from solvent and aqueous phases.
155 grams of the product crude was collected from the bottom
product phase. The product crude was then washed with 200 grams of
water to remove solvent acetonitrile and then purified in a 40-tray
Oldershaw fractionation column with condenser being cooled to
15.degree. C. The fractionation column was operated in such a way
so that the reflux ratio (the distillate flow rate going back to
the fractionation column to the distillate flow rate going to the
product collection cylinder) was at 10:1. The final product was
collected as the condensate when the head temperature in the
fractionation column was between 52.degree. C. and 53.degree.
C.
[0043] The 90 grams of the final product collected from the method
above was analyzed by 376.3 MHz .sup.19F-NMR spectra and identified
as a mixture of
2,3-difluoro-2-(1,2,2,2-tetrafluoro-1-trifluoro-methyl-ethyl)-3-trifluoro-
methyl-oxirane, 95.8% and 2.2% of
2-fluoro-2-pentafluoroethyl-3,3-bis-trifluoromethyl-oxirane.
Example 2
Oxirane Synthesis and Purification of
1,2,2,3,3,4,4,5,5,6-decafluoro-7-oxa-bicyclo[4.1.0]heptane.
c(C.sub.6F.sub.12O)
[0044] In a 1.5 liter glass reactor fitted with a mixer and a
cooling jacket, 400 grams of acetonitrile, 200 grams of
1,2,3,3,4,4,5,5,6,6-decafluoro-cyclohexene (89.3% purity) and 150
grams of 50% potassium hydroxide were added. The reactor
temperature was controlled at 0.degree. C. using the reactor
cooling jacket. Then 100 grams of 50% hydrogen peroxide was slowly
added to the reactor under strong mixing while controlling the
reactor temperature at 0.degree. C. After all the hydrogen peroxide
was added within about 2 hours, the mixer was turned off to allow
the product crude to phase split from solvent and aqueous phases.
100 grams of the product crude was collected from the bottom
product phase. The product crude was then washed with 100 grams of
water to remove solvent acetonitrile and then purified in a 40-tray
Oldershaw fractionation column with condenser being cooled to
15.degree. C. The fractionation column was operated in such a way
that the reflux ratio (the distillate flow rate going back to the
fractionation column to the distillate flow rate going to the
product collection cylinder) was at 10:1. The final product was
collected as the condensate when the head temperature in the
fractionation column was between 47.degree. C. and 55.degree.
C.
[0045] The 70 grams of the final product collected from the method
above was analyzed by 376.3 MHz .sup.19F-NMR spectra and identified
as 1,2,2,3,3,4,4,5,5,6-decafluoro-7-oxa-bicyclo[4.1.0]heptane with
a purity of 94.1% with an additional 2.6% isomers.
Example 3
C.sub.9 Oxirane Synthesis and Purification of HFP Trimer-oxirane
(C.sub.9F.sub.18O)
[0046] In a 1.5 liter glass reactor fitted with a mixer and a
cooling jacket, 400 grams of acetonitrile, 200 grams of HFP Trimer
(C.sub.9F.sub.18), and 150 grams of 50% potassium hydroxide were
added. The reactor temperature was controlled at 0.degree. C. using
the reactor cooling jacket. Then 100 grams of 50% hydrogen peroxide
was slowly added to the reactor under strong mixing while
controlling the reactor temperature between 0.degree. C. and
20.degree. C. After all the hydrogen peroxide was added within
about 2 hours, the mixer was turned off to allow the product crude
to phase split from solvent and aqueous phases. 180 grams of the
product crude was collected from the bottom product phase. The
product crude was then washed with 200 grams of water to remove
solvent acetonitrile and then purified in a 40-tray Oldershaw
fractionation column with condenser being cooled to 15.degree. C.
The fractionation column was operated in such a way so that the
reflux ratio (the distillate flow rate going back to the
fractionation column to the distillate flow rate going to the
product collection cylinder) was at 10:1. The final product was
collected as the condensate when the head temperature in the
fractionation column was between 120.degree. C. and 122.degree.
C.
[0047] The 150 grams of the final product collected from the method
above was analyzed by 376.3 MHz .sup.19F-NMR spectra and identified
as oxiranes of HFP trimer (C.sub.9F.sub.18O) with 5 isomeric forms.
The sum of all 5 isomers had a purity of 99.4%.
[0048] Table II shows some thermophysical properties of exemplary
fluorinated oxiranes and a comparative material
(docecafluoro-2-methylpentan-3-one).
Example 4
Synthesis of 2-nonafluorobutyloxirane
(C.sub.4F.sub.9CH(O)CH.sub.2)
[0049] The oxirane was prepared according to a modification of the
procedure of WO2009/096265 (Daikin Industries Ltd.). A 500 mL,
magnetically stirred, three-necked round bottom flask was equipped
with a water condensor, thermocouple and an addition funnel. The
flask was cooled in a water bath. Into the flask were placed
C.sub.4F.sub.9CH.dbd.CH.sub.2 (50 g, 0.2 mol, Alfa Aesar),
N-bromosuccinimide (40 g, 0.22 mol, Aldrich Chemical Company) and
dichloromethane as the solvent (250 mL). Chlorosulfonic acid (50 g,
0.43 mol, Alfa Aesar) was placed in the addition funnel and added
slowly to the stirred reaction mixture while keeping the reaction
temperature below 30.degree. C. After the addition was completed
the reaction mixture was held at ambient temperature for 16 hours.
The entire reaction mixture was then poured carefully onto ice, the
lower dichloromethane phase separated and washed once more with an
equal volume of water and the solvent removed by rotary evaporation
yielding 82 g of the chlorosulfite
C.sub.4F.sub.9CHBrCH.sub.2OSO.sub.2Cl in about 65% purity by glc
and which contained some C.sub.4F.sub.9CHBrCH.sub.2Br. The
chlorosulfite mixture was used without further purification in the
next step.
[0050] The chlorosulfite, benzyltrimethylammonium chloride (0.6 g,
0.003 mol, Alfa Aesar) and water (350 mL) were placed in a 1 L,
magnetically stirred, three-necked round bottom flask which was
equipped with a water condensor, thermocouple and an addition
funnel A solution of potassium iodide (66.3 g, 0.4 mol, EMD
Chemicals Inc.) dissolved in water (66 mL) was placed in the
separatory funnel and added to the chlorosulfite solution dropwise
over about 1.5 hours and the mixture stirred for 16 hours at
ambient temperature. Dichloromethane (300 mL) was then added, the
mixture filtered and the filter cake washed with an additional 100
mL of dichloromethane. The dichloromethane layer was separated and
the remaining aqueous layer extracted with an additional 200 mL of
dichloromethane. The dichloromethane solvent was then removed by
rotary evaporation. The residue, combined with material from
another preparation, was distilled bp=66-70.degree. C./20 ton and
the distillate once again dissolved in dichloromethane and washed
one time with 5% aqueous sodium bisulfite to remove iodine and the
solvent removed by rotary evaporation. At this stage the desired
product bromohydrin (82 g) C.sub.4F.sub.9CHBrCH.sub.2OH had a
purity of 87% and contained about 5% C.sub.4F.sub.9CHBrCH.sub.2Br
and 8% C.sub.4F.sub.9CHClCH.sub.2Br.
[0051] The bromohydrin (82 g), diethyl ether solvent (200 mL) and
tetrabutylammonium bromide (3.0 g, 0.009 mol, Aldrich) were placed
in a 500 mL, magnetically stirred, round bottom flask equipped with
a condensor and thermocouple. To this mixture was added all at once
a solution of sodium hydroxide (24 g, 0.6 mol) in water (33 g). The
mixture was stirred vigorously for four hours. The ether solution
was then washed once with saturated sodium chloride solution and
once with 5% HCl solution and subsequently dried over magnesium
sulfate and the residue fractionally distilled through a concentric
tube column with the fraction boiling at 101.degree. C. collected
to give a product (40.9 g) which was 88.5% the desired oxirane
C.sub.4F.sub.9CH(O)CH.sub.2 and 7.3% bromoolefin
C.sub.4F.sub.9CBr.dbd.CH.sub.2. Final purification of the epoxide
by removal of most of the bromoolefin was carried out by reaction
of the oxirane/bromoolefin mixture, which was degassed three times
under nitrogen using a Firestone valve connected to a source of dry
nitrogen and mineral oil bubbler, with
2,2'-azobis(2-methylpropionitrile) [0.5 g, 0.003 mol, Aldrich] and
bromine [4.0 g, 0.025 mol, Aldrich] at 65.degree. C. for eight
hours. The reaction mixture was treated with an aqueous solution of
5% by weight sodium bisulfite to remove the excess bromine, the
phases were separated and the lower phase fractionally distilled
through a concentric tube column to afford the final oxirane (25 g)
in 97.9% purity (b.p.=102.degree. C.). The product identity was
confirmed by GCMS, H-1 and F-19 NMR spectroscopy.
Example 5
Synthesis of 2-tridecafluorohexyloxirane
(C.sub.6F.sub.13CH(O)CH.sub.2)
[0052] A 1L, magnetically stirred, three-necked round bottom flask
was equipped with a water condensor, thermocouple and an addition
funnel. The flask was cooled in a water bath. Into the flask were
placed fuming sulfuric acid (20% SO.sub.3 content) (345 g, 0.86 mol
SO.sub.3, Aldrich) and bromine (34.6 g, 0.216 mol, Aldrich). Into
the addition funnel was placed C.sub.6F.sub.13CH.dbd.CH.sub.2 (150
g, 0.433 mol, Alfa Aesar) which was added to the acid solution over
a two hour period. There was no noticeable exotherm. The reaction
mixture was stirred at ambient temperature for 16 hours. Water (125
g) was placed in the separatory funnel and added very cautiously
over about a two hour period. The initial 5-10 g addition was
extremely exothermic. Once the addition was complete, more water
(50 g) was added all at once and the reaction mixture heated to
90.degree. C. for 16 hours. Diethyl ether (300 mL) was added to the
reaction mixture and the two phases separated with the lower phase
containing the product. The remaining aqueous phase was extracted
once more with ether (150 mL), the upper ether phase separated and
combined with the previous lower phase. The ether layer was washed
with 5% by weight aqueous potassium hydroxide solution and the
solvent removed by rotary evaporation to give 112 g of a white
crystalline solid which was about 72%
C.sub.6F.sub.13CHBrCH.sub.2OH, 8% C.sub.6F.sub.13CHBrCH.sub.2Br and
19% (C.sub.6F.sub.13CHBrCH.sub.2O)SO.sub.2. This solid was
distilled and the fraction collected (36 g) of boiling
range=68-74.degree. C./6 torr which was found to be 90.7% the
desired bromohydrin and 9.3% the dibromide.
[0053] The bromohydrin mixture was then placed in a 250 mL,
magnetically stirred, round bottom flask equipped with a water
condensor and thermocouple along with tetrabutylammonium bromide
(1.5 g, 0.005 mol, Aldrich) dissolved in 5 g water and a solution
of 8.2 g of sodium hydroxide (0.2 mol) dissolved in 15 g water.
After one hour of vigorous stirring the reaction mixture was
analyzed by glc which showed about a 40% conversion of the
bromohydrin to the oxirane. The reaction was stirred for an
additional 5 hours. The lower aqueous phase was separated and the
remaining ether phase washed once with dilute aqueous hydrochloric
acid, prepared by adding a few drops of 2N aqueous HCl to 50 mL
water, dried over magnesium sulfate and distilled to afford the
product oxirane (12 g) C.sub.6F.sub.13CH(O)CH.sub.2 in 98.3% purity
(b.p.=144.degree. C.) and 1.5% bromoolefin
C.sub.6F.sub.13CBr.dbd.CH.sub.2. The product structure was
confirmed by GCMS, H-1 and F-19 NMR.
Example 6
Preparation of
2-[1,1,2,3,3,3-hexafluoro-2-(trifluoromethyl)propyl]-2-(trifluoromethyl)o-
xirane ((CF.sub.3).sub.2CFCF.sub.2C(CF.sub.3)OCH.sub.2)
[0054] In a 600 mL Parr reactor, hexafluoropropene dimer (300 g,
1.0 mol 3M Company), methanol (100 g, 3.12 mol, Aldrich) and TAPEH
(t-amylperoxy-2-ethylhexanoate) (4 g, 0.017 mol) were charged. The
reactor was sealed and the temperature was set to 75 deg. C. After
stirring for 16 hours at temperature the reactor contents were
emptied and washed with water to remove excess methanol. The
fluorochemical phase that was recovered was dried over anhydrous
magnesium sulfate and then filtered. This reaction was repeated two
additional times to generate a total of 500 g of product
(2,3,4,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)pentan-1-ol). The
crude reaction product was then purified by fractional distillation
using a 15-tray Oldershaw column. The fluorinated alcohol product,
2,3,4,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)pentan-1-ol (257 g
0.77 mol) was charged to a 1L round bottom flask equipped with
magnetic stirring, cold water condenser, thermocouple (J-Kem
controller) and an addition funnel Thionyl chloride (202.25 g, 1.7
mol, Aldrich) was charged via the addition funnel to the
fluorinated alcohol at room temperature. Once the addition was
complete the temperature was increased to 85 deg. C. until no more
offgas was observed. The water condenser was removed and a 1-plate
distillation apparatus was put in place. The excess thionyl
chloride was then distilled from the reaction mixture. 300 g of the
product was collected. This product was charged to a flask
containing 150 g of potassium fluoride in 500 mL of
N-methyl-pyrrolidinone solvent. The reaction mixture was then
stirred overnight at 35 deg. C. The following day the reaction
flask was set up for distillation and the product
3,3,4,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)pent-1-ene was
distilled from the reaction flask. A total of 140 g was
collected.
[0055] In a 500 mL jacketed reaction flask equipped with overhead
stirring, cold water condenser, N2 bubbler and thermocouple, sodium
hydroxide (2.5 g, 0.0636 mol, Aldrich), sodium hypocholorite (12%
concentration 80 g, 0.127 mol), Aliquat 336 (1 g, Alfa-Aesar) were
charged. The flask was cooled to 4 deg. C. The olefin,
3,3,4,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)pent-1-ene (20 g
0.0636 mol) was charged to the mixture which was then stirred for 2
hours. After 2 hours, stirring was stopped and a lower FC phase was
separated from the mixture. A total of 20 g of FC was collected. A
sample of this was analyzed by .sup.19F, .sup.1H and .sup.13C NMR
which confirmed the product structure for
2-[1,1,2,3,3,3-hexafluoro-2-(trifluoromethyl)propyl]-2-(trifluoromethyl)o-
xirane.
TABLE-US-00002 TABLE II Thermophysical Properties of Fluorinated
Oxiranes and Comparative Materials Normal Heat of Specific Boiling
Pour Viscosity Vaporization Heat Critical Critical Critical Point
Point @ 25.degree. C. @ 25.degree. C. Capacity Temperature Pressure
Density Example Material (.degree. C.) (.degree. C.)
(.times.10.sup.-7 m.sup.2/s) (kJ/kg) (J/kg-K) (.degree. C.) (kPa)
(kg/m.sup.3) Comparative 1 C.sub.2F.sub.5C(O)CF(CF.sub.3).sub.2
49.3 -108 4.0 94.3 1103 168.7 1865 594.2 Example 1 C.sub.6F.sub.12O
51.7 -145 3.7 99.2 1145 180.0 2386 611.9 Example 2
cC.sub.6F.sub.12O 56.1 -88 6.6 109.8 1083 200.3 2615 601.2 Example
3 C.sub.9F.sub.18O 121.9 -103 12.5 96.9 869 236.9 1421 613.6
[0056] The critical temperature and pressure of the fluorinated
oxiranes in Table II were determined from their molecular
structures using the method of Wilson-Jasperson given in Reid,
Prausnitz and Poling, The Properties of Gases and Liquids, 5.sup.th
ed., McGraw-Hill, 2000. The critical densities were calculated
using the method of Joback given in Reid, Prausnitz and Poling, The
Properties of Gases and Liquids, 5.sup.th edition, McGraw-Hill,
2000. Exemplary fluorinated oxirane thermodynamic properties were
derived using the Peng-Robinsion equation of state (Peng, D. Y.,
and Robinson, D. B., Ind. & Eng. Chem. Fund. 15: 59-64., 1976),
with an applied volume shift for liquid densities. Inputs required
for the equation of state were critical temperature, critical
density, critical pressure, acentric factor, molecular weight and
ideal gas heat capacity. Ideal gas heat capacity was calculated
using a group contribution method (Rihani, D., Doraiswamy, L., Ind.
& Eng. Chem. Fund., 4, 17, 1965). For Comparative Example 1,
thermophysical property data were fitted to a Helmholtz equation of
state, with the functional form described in Lemmon E. W., Mclinden
M. O., and Wagner W., J. Chem. & Eng. Data, 54: 3141-3180.,
2009.
[0057] FIG. 3 shows temperature-entropy diagrams for Examples 1, 2
and 3 (Ex. 1, Ex. 2, and Ex. 3), along with Comparative Example 1
(Comp. 1). Each plot was generated using the equations of state
described above for each fluid. Though all the fluids have
saturated vapor lines with a positive slope, Examples 1, 2 and 3
have greater positive slopes, thereby requiring less desuperheating
(or recuperation) after expansion, which could be advantageous when
sizing recuperator heat exchangers for the Rankine cycle
configuration of FIG. 2.
[0058] A Rankine cycle based on the configuration of FIG. 1, and
operating between 50.degree. C. and 140.degree. C., was used to
assess the performance of the exemplary fluorinated oxiranes and
the comparative example. The Rankine cycle was modeled using the
calculated thermodynamic properties from the equations of state and
the procedure described in Cengel Y. A. and Boles M. A.,
Thermodynamics: An Engineering Approach, 5.sup.th Edition; McGraw
Hill, 2006. The heat input for the cycle was 1000 kW, with working
fluid pump and expander efficiencies taken to be 60% and 80%
respectively. Results are shown in Table III. Thermal efficiencies
of the exemplary fluorinated oxiranes are greater than that of the
comparative example.
TABLE-US-00003 TABLE III Calculated Rankine Cycle Performance
Comparative Example Example 2 Example 3 Example 1 1
C.sub.6F.sub.12O cC.sub.6F.sub.12O C.sub.9F.sub.18O
C.sub.2F.sub.5C(O)CF(CF.sub.3).sub.2 Condenser Temperature
[.degree. C.] 50.0 50.0 50.0 50.0 Condenser Pressure [kPa] 97.0
82.2 6.4 103.9 Boiler Temperature [.degree. C.] 140 140 140 140
Boiler Pressure [kPa] 1114.8 893.2 177.0 1069.9 Fluid Flow [kg/s]
6.0 6.0 5.8 6.2 Pump Work [kJ/kg] 1.10 0.84 0.16 1.05 Q, Boiler
[kJ/kg] 168.0 166.4 173.5 161.4 Expander Work [kJ/kg] 18.14 20.30
18.32 16.71 Net Work [kJ/kg] 17.0 19.5 18.2 15.7 Net Work [kW]
101.4 117.0 104.6 97.0 Thermal Efficiency 0.101 0.117 0.105
0.097
[0059] As discussed above, for a given heat source, thermodynamic
efficiency in a Rankine cycle can be improved when the boiling
point of the working fluid is close to that of the temperature of
the heat source. Higher critical temperatures therefore lead to
greater thermodynamic efficiencies. Exemplary fluorinated oxiranes
can have critical temperatures of greater than 175.degree. C.,
greater than 200.degree. C., or even greater than 230.degree. C. as
shown in Table II.
[0060] Following are exemplary embodiments of fluorinated oxiranes
as organic rankine cycle working fluids and methods of using same
according to aspects of the present invention.
[0061] Embodiment 1 is a process for converting thermal energy into
mechanical energy in a Rankine cycle comprising: vaporizing a
working fluid with a heat source to form a vaporized working fluid;
expanding the vaporized working fluid through a turbine; cooling
the vaporized working fluid using a cooling source to form a
condensed working fluid; and pumping the condensed working fluid;
wherein the working fluid comprises a fluorinated oxirane.
[0062] Embodiment 2 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 1,
wherein the fluorinated oxirane compound includes up to a maximum
of three hydrogen atoms.
[0063] Embodiment 3 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 1,
wherein the fluorinated oxirane compound contains substantially no
hydrogen atoms bonded to carbon atoms.
[0064] Embodiment 4 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 1,
wherein the fluorinated oxirane has a total of from about 4 to
about 9 carbon atoms.
[0065] Embodiment 5 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 4,
wherein the fluorinated oxirane contains 6 carbon atoms.
[0066] Embodiment 6 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 1,
wherein the fluorinated oxirane has a critical temperature greater
than about 150.degree. C.
[0067] Embodiment 7 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 1,
wherein the turbine generates electrical energy.
[0068] Embodiment 8 is a process for converting thermal energy into
mechanical energy in a Rankine cycle according to embodiment 1,
wherein the vaporized working fluid is at a pressure greater than
ambient pressure.
[0069] Embodiment 9 is a process for recovering waste heat
comprising: passing a liquid working fluid through a heat exchanger
in communication with a process that produces waste heat to produce
a vaporized working fluid; removing the vaporized working fluid
from the heat exchanger; passing the vaporized working fluid
through an expander, wherein the waste heat is converted into
mechanical energy; and cooling the vaporized working fluid after it
has been passed through the expander, wherein the fluorinated
oxirane compound contains substantially no hydrogen atoms bonded to
carbon atoms.
[0070] Embodiment 10 is a process for recovering waste heat
comprising according to embodiment 9, wherein the fluorinated
oxirane has a total of from about 4 to about 9 carbon atoms.
[0071] Embodiment 11 is a process for recovering waste heat
comprising according to embodiment 10, wherein the fluorinated
oxirane contains 6 carbon atoms.
[0072] Embodiment 12 is a process for recovering waste heat
comprising according to embodiment 10, wherein the fluorinated
oxirane has a critical temperature of greater than about
150.degree. C.
[0073] Embodiment 13 is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle comprising: a working
fluid; a heat source to vaporize the working fluid and form a
vaporized working fluid; a turbine through which the vaporized
working fluid is passed thereby converting thermal energy into
mechanical energy; a condenser to cool the vaporized working fluid
after it is passed through the turbine; and a pump to recirculate
the working fluid, wherein the working fluid comprises a
fluorinated oxirane.
[0074] Embodiment 14 is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle according to embodiment
13, wherein the working fluid is in a closed loop.
[0075] Embodiment 15 is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle according to embodiment
13, wherein the fluorinated oxirane contains substantially no
hydrogen atoms bonded to carbon atoms.
[0076] Embodiment 16 is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle according to embodiment
15, wherein the fluorinated oxirane has a total of from about 4 to
about 9 carbon atoms.
[0077] Embodiment 17 is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle according to embodiment
16, wherein the fluorinated oxirane contains 6 carbon atoms.
[0078] Embodiment 18 is an apparatus for converting thermal energy
into mechanical energy in a Rankine cycle according to embodiment
13, wherein the fluorinated oxirane has a critical temperature
greater than about 150.degree. C.
[0079] Various modifications and alterations to this invention will
become apparent to those skilled in the art without departing from
the scope and spirit of this invention. It should be understood
that this invention is not intended to be unduly limited by the
illustrative embodiments and examples set forth herein and that
such examples and embodiments are presented by way of example only
with the scope of the invention intended to be limited only by the
claims set forth herein as follows. All references cited in this
disclosure are herein incorporated by reference in their
entirety.
* * * * *