WO2014080868A1 - Working medium for rankine cycle, and rankine cycle system - Google Patents

Abstract

Provided are: a working medium for the Rankine cycle, having reduced flammability, minimal effect on the ozone layer, minimal effect on global warming, and excellent cyclic performance (efficiency and capacity), and which yields a Rankine cycle system; and a Rankine cycle system having excellent cyclic performance (efficiency and capacity), in which safety is maintained. In the present invention, a working medium for the Rankine cycle including 1-chloro-2, 3, 3, 3-tetrafluoropropene and/or 1,1-dichloro-2,3,3,3-tetrafluoropropene is used in a Rankine cycle system.

Description

Rankine cycle working medium and Rankine cycle system

The present invention relates to a Rankine cycle working medium, a Rankine cycle system using the Rankine cycle working medium, and a composition containing the Rankine cycle working medium.

Advancement in technology to recover energy from heat sources in the low and medium temperature range lower than the temperature obtained by burning fuels such as heavy oil and oil using Rankine cycle, waste heat recovery power generation, ocean temperature difference power generation, geothermal binary Power generation, etc. has been put into practical use or tested.
Conventionally, working media used for power generation, heat pumps, and the like include water; hydrocarbons such as propane and butane; trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), and chlorodifluoromethane (HCFC-22). ), Fluorocarbons such as trichlorotrifluoroethane (CFC-113) and dichlorotetrafluoroethane (CFC-114); ammonia and the like are known.
Among them, CFC-11 and CFC-113 are used as working media for waste heat recovery power generation by Rankine cycle, and HCFC-22, propane, and ammonia are used for geothermal power generation as working media used for ocean temperature difference power generation. Isobutane or the like is used as the working medium.

Ammonia and hydrocarbons are limited in commercial use due to safety problems such as toxicity, flammability, and corrosivity, and inferior energy efficiency.
In contrast, many of the fluorocarbons have attracted attention as Rankine cycle working media because of their advantages such as low toxicity, non-flammability, chemical stability, and easy availability of various fluorocarbons with different standard boiling points. Yes.

However, among fluorocarbons, compounds containing chlorine atoms have environmental persistence and are considered to be related to ozone layer destruction, and are being progressively reduced and eliminated. For example, chlorofluorocarbons (hereinafter referred to as “CFC”) containing chlorine atoms and halogenated in all hydrogen atoms have already been abolished in developed countries such as Japan, the United States and Europe.
Among fluorocarbons, hydrochlorofluorocarbons (hereinafter referred to as “HCFC”) containing hydrogen atoms and chlorine atoms are being promoted to be completely eliminated in 2020 in developed countries.

Further, perfluorocarbon (hereinafter referred to as “PFC”) in which all hydrogen atoms of hydrocarbons are substituted with fluorine atoms, and hydrofluorocarbon (hereinafter referred to as “PFC”) in which some of the hydrogen atoms of hydrocarbons are substituted with fluorine atoms. HFC ") does not contain chlorine atoms, so there is no impact on the ozone layer, but it has been pointed out that it has an impact on global warming and is regulated as a warming compound that should suppress emissions into the atmosphere. .
For example, 1,1,1,2-tetrafluoroethane (HFC-134a) used as a refrigerant for automobile air conditioning equipment has a large global warming potential of 1430 (100-year value).

As a refrigerant replacing HFC-134a, carbon dioxide and 1,1-difluoroethane (HFC-152a), which has a global warming potential of 124 (100-year value) smaller than that of HFC-134a, are being studied.
However, carbon dioxide has many problems to be solved, such as an extremely high equipment pressure compared to HFC-134a. HFC-152a has a combustion range and has a problem of ensuring safety.
On the other hand, it has also been proposed to use 1-chloro-3,3,3-trifluoropropene (hereinafter referred to as “1233zd”) as a Rankine cycle working medium (Patent Document 1). However, the cycle performance (efficiency and capacity) was not always sufficient.

Special table 2012-51087 gazette

The present invention has been made in view of the above circumstances, has a low flammability, has little influence on the ozone layer, has little influence on global warming, and has excellent cycle performance (efficiency and ability). Provided is a Rankine cycle working medium that provides a cycle system, and a Rankine cycle system in which safety is ensured and cycle performance (efficiency and capacity) is excellent. Furthermore, this invention provides the working-medium composition for Rankine cycles containing the said working medium for Rankine cycles.
Hereinafter, the Rankine cycle working medium is also referred to as a working medium.

The working medium for Rankine cycle of the present invention includes 1-chloro-2,3,3,3-tetrafluoropropene (hereinafter referred to as “HCFO-1224yd”) and 1,1-dichloro-2,3,3,3. -One or both of tetrafluoropropene (hereinafter referred to as "CFO-1214ya").
In the Rankine cycle working medium of the present invention, the total ratio of HCFO-1224yd and CFO-1214ya in 100% by mass of the Rankine cycle working medium is preferably 60% by mass or more.
HCFO-1224yd and CFO-1214ya are both compounds belonging to chlorofluoroolefin. Hereinafter, chlorofluoroolefin including these compounds is referred to as “CFO”.

The working medium for Rankine cycle of the present invention may further contain CFO other than HCFO-1224yd and CFO-1214ya (hereinafter referred to as “other CFO”). The proportion of other CFO in the total is preferably 40% by mass or less.
The Rankine cycle working medium of the present invention may further contain a hydrocarbon. In that case, the proportion of hydrocarbons in 100% by mass of the Rankine cycle working medium is preferably 40% by mass or less.
The Rankine cycle working medium of the present invention may further contain HFC. In this case, the proportion of HFC in 100% by mass of the Rankine cycle working medium is preferably 40% by mass or less.
The working fluid for Rankine cycle of the present invention may further contain a hydrofluoroolefin having no chlorine atom (hereinafter referred to as “HFO”), and in that case, the HFO occupying in 100% by mass of the working fluid for Rankine cycle. The ratio is preferably 40% by mass or less.
The Rankine cycle system of the present invention is characterized by using the Rankine cycle working medium of the present invention.
The working medium composition for Rankine cycle of the present invention comprises the working medium for Rankine cycle of the present invention and at least one selected from a lubricant, a stabilizer and a leak detection substance.

The working medium for Rankine cycle of the present invention provides a Rankine cycle system that has low flammability, little influence on the ozone layer, little influence on global warming, and excellent cycle performance (efficiency and ability).
The Rankine cycle system of the present invention ensures safety and is excellent in cycle performance (efficiency and capacity).

It is a schematic structure figure showing an example of a Rankine cycle system. FIG. 6 is a cycle diagram in which a state change of a Rankine cycle working medium in the Rankine cycle system is described on a temperature-entropy diagram. FIG. 6 is a cycle diagram in which a change in the state of a Rankine cycle working medium in the Rankine cycle system is described on a pressure-enthalpy diagram. It is a graph which shows the relative capability on the basis of HCFO-1224yd of each working medium in each evaporation temperature when a condensation temperature is 25 degreeC. It is a graph which shows the relative capability on the basis of HCFO-1224yd of each working medium in each evaporation temperature when a condensation temperature is 50 degreeC. It is a graph which shows the relative efficiency on the basis of HCFO-1224yd of each working medium in each evaporation temperature in case a condensation temperature is 25 degreeC. It is a graph which shows the relative efficiency on the basis of HCFO-1224yd of each working medium in each evaporation temperature in case a condensation temperature is 50 degreeC.

<Working medium for Rankine cycle>
The working medium for Rankine cycle of the present invention includes one or both of HCFO-1224yd and CFO-1214ya. The working medium for Rankine cycle of the present invention may contain working media other than the above, such as other CFOs, hydrocarbons, HFCs, and HFOs, as necessary.
In addition, the working medium of the present invention can be used in combination with components other than the working medium used together with the working medium (hereinafter, a composition containing the working medium and components other than the working medium is referred to as a working medium-containing composition). Examples of components other than the working medium include lubricants, stabilizers, leak detection substances, desiccants, and other additives.

(HCFO-1224yd and CFO-1214ya)
The working medium for Rankine cycle of the present invention contains one or both of HCFO-1224yd and CFO-1214ya, which are chlorofluoroolefins (hereinafter also referred to as “CFO”). CFO means that two or more hydrogen atoms of an unsaturated chain hydrocarbon containing one or more carbon-carbon double bonds in the molecule are substituted with chlorine atoms or fluorine atoms, and 1 chlorine atom and fluorine atom is substituted. It is a compound containing two or more. There are CFOs having no hydrogen atom and those having a hydrogen atom, and CFO having a hydrogen atom is hereinafter referred to as “HCFO”.

The working medium of the present invention may include one of HCFO-1224yd and CFO-1214ya, or may include both. When both are included, there is no limitation in particular in the mixture ratio of both. Both can provide a Rankine cycle system with excellent cycle performance (efficiency and capacity) at any blending ratio.
When the working medium of the present invention contains one of HCFO-1224yd and CFO-1214ya, the proportion of HCFO-1224yd or CFO-1214ya in 100% by mass of the working medium of the present invention is preferably 60% by mass or more, and 70% by mass. The above is more preferable, 80% by mass or more is further preferable, and 100% by mass is particularly preferable.
When the working medium of the present invention contains both HCFO-1224yd and CFO-1214ya, the total proportion of HCFO-1224yd and CFO-1214ya in 100% by weight of the working medium of the present invention is preferably 60% by weight or more. 70 mass% or more is more preferable, 80 mass% or more is further more preferable, and 100 mass% is especially preferable.
HCFO-1224yd has E form and Z form, both of which have similar physical properties and almost the same boiling point. Therefore, as the HCFO-1224yd, the E isomer and the Z isomer may be used alone, or HCFO-1224yd containing both in an appropriate ratio may be used.

(Other CFO)
When the working medium for Rankine cycle of the present invention contains other CFO (CFO other than HCFO-1224yd and CFO-1214ya), it is preferable that the other CFO has only one carbon-carbon double bond. The carbon number is preferably 2 to 3 because it has a boiling point suitable as a working medium. The number of fluorine atoms (N) and the number of chlorine atoms (N _Cl ) are each preferably 1 to 5. The total number of fluorine atoms (N _F ) and chlorine atoms (N _Cl ) (N _{F + Cl} ) is 2 or more, preferably 2 to 6, and more preferably 4 to 6. The ratio of the total number of fluorine atoms and chlorine atoms to the total number of hydrogen atoms, fluorine atoms and chlorine atoms (N _{F + Cl} / N _{H + F + Cl} ) is preferably 0.5 to 1.0, and 0 More preferably, it is 7 to 1.0. If the total (N _{F + Cl} ) or the ratio (N _{F + Cl} / N _{H + F + Cl} ) is equal to or higher than the lower limit value, the combustibility is more easily suppressed.
Further, the ratio of the number of fluorine atoms to the number of chlorine atoms (N _F / N _Cl ) is preferably 0.1 to 0.8, and more preferably 0.5 to 0.8.
Another CFO may be used individually by 1 type, and may be used in combination of 2 or more type.
When other CFO is used, the proportion of the other CFO in 100% by mass of the Rankine cycle working medium of the present invention is preferably 1 to 40% by mass, and more preferably 5 to 20% by mass.

(hydrocarbon)
The hydrocarbon is a component that improves the solubility of the working medium in the below-described lubricating oil, particularly mineral oil.
Examples of the hydrocarbon include propane, propylene, cyclopropane, butane, isobutane, pentane, isopentane and the like.
A hydrocarbon may be used individually by 1 type and may be used in combination of 2 or more type.
When a hydrocarbon is used, the proportion of the hydrocarbon in 100% by mass of the working medium of the present invention is preferably 1 to 40% by mass, and more preferably 2 to 10% by mass. If the hydrocarbon is at least the preferred lower limit, it is easy to improve the solubility of the lubricating oil in the working medium. If the hydrocarbon is less than or equal to the preferable upper limit value, it is effective to suppress the combustibility of the working medium.

(HFC)
HFC is a component that improves the cycle performance (capacity) of the Rankine cycle system.
As the HFC, an HFC that has little influence on the ozone layer and little influence on global warming is preferable.
Examples of HFC include difluoromethane, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, pentafluorobutane, heptafluorocyclopentane, and the like. Difluoromethane (HFC-32), 1,1-difluoromethane (HFC-152a), 1,1,2,2-tetrafluoroethane (HFC-) because of its low impact and low impact on global warming 134), 1,1,1,2-tetrafluoroethane (HFC-134a) or pentafluoroethane (HFC-125) is particularly preferred.

One HFC may be used alone, or two or more HFCs may be used in combination.
When HFC is used, the proportion of HFC in 100% by mass of the working medium of the present invention is preferably 1 to 40% by mass, and more preferably 5 to 20% by mass.

(HFO)
HFO is a compound in which a part of hydrogen atoms of an unsaturated chain hydrocarbon containing one or more carbon-carbon double bonds in its molecule is replaced with a fluorine atom and does not contain a chlorine atom. HFO is a component that improves the cycle performance (capacity) of the Rankine cycle system.
As HFO, HFO which has little influence on the ozone layer and has little influence on global warming is preferable. Further, it is preferable that the HFO has only one carbon-carbon double bond. The carbon number is preferably 2 to 4 because it has a boiling point suitable for a working medium.
Examples of HFO include difluoroethylene, trifluoroethylene, trifluoropropylene, tetrafluoropropylene, and pentafluoropropylene. From the viewpoint of little influence on the ozone layer and little influence on global warming, 1,1 -Difluoroethylene (HFO-1132a), 1,2-difluoroethylene (HFO-1132), 1,1,2-trifluoroethylene (HFO-1123), 2,3,3,3-tetrafluoroolefin (HFO- 1234yf) and 1,3,3,3-tetrafluoroolefin (HFO-1234ze) are particularly preferred.

HFO may be used individually by 1 type and may be used in combination of 2 or more type.
When HFO is used, the proportion of HFO in 100% by mass of the working medium of the present invention is preferably 1 to 40% by mass, and more preferably 5 to 20% by mass.

(Other working media)
The working medium of the present invention is an alcohol having 1 to 4 carbon atoms, or a compound used as a conventional working medium, refrigerant, or heat transfer medium (hereinafter, the alcohol and the compound are collectively referred to as “other working medium”). May be included).
Other working media include the following compounds.
Fluorine-containing ether: perfluoropropyl methyl ether (C ₃ F ₇ OCH ₃ ), perfluorobutyl methyl ether (C ₄ F ₉ OCH ₃ ), perfluorobutyl ethyl ether (C ₄ F ₉ OC ₂ H ₅ ), 1, 1, 2 , 2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (CF ₂ HCF ₂ OCH ₂ CF ₃ , manufactured by Asahi Glass Co., Ltd., AE-3000).

The proportion of the other working medium in 100% by mass of the working medium of the present invention may be in a range that does not significantly reduce the effect of the present invention, preferably 30% by mass or less, more preferably 20% by mass or less, and 15% by mass. % Or less is particularly preferable.

(Function and effect)
HCFO-1224yd and CFO-1214ya have a high proportion of halogen that suppresses combustibility. Moreover, since it has a carbon-carbon double bond, it is easily decomposed by OH radicals in the atmosphere. Therefore, the Rankine cycle working medium of the present invention containing one or both of HCFO-1224yd and CFO-1214ya has low combustibility, little influence on the ozone layer, and little influence on global warming.
Further, as a result of examination by the present inventors, it has been found that a working medium containing HCFO-1224yd or CFO-1214ya, or a working medium containing both of them provides a Rankine cycle system having excellent cycle performance (efficiency and capacity). .

<Lubricating oil, etc.>
The working medium for Rankine cycle of the present invention can be further used as a working medium-containing composition containing components other than the working medium. Examples of components other than the working medium include known additives such as lubricants, stabilizers, leak detection substances, and desiccants.

(Lubricant)
As the lubricating oil used in the working medium-containing composition, a known lubricating oil used in the Rankine cycle system is used.
Examples of the lubricating oil include oxygen-containing synthetic oils (such as ester-based lubricating oils and ether-based lubricating oils), fluorine-based lubricating oils, mineral oils, and hydrocarbon-based synthetic oils.

Examples of the ester-based lubricating oil include dibasic acid ester oil, polyol ester oil, complex ester oil, and polyol carbonate oil.

Examples of the dibasic acid ester include dibasic acids having 5 to 10 carbon atoms (glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.) and 1 carbon atom having a linear or branched alkyl group. Esters with ˜15 monohydric alcohols (methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, etc.) are preferred. Specific examples include ditridecyl glutarate, di (2-ethylhexyl) adipate, diisodecyl adipate, ditridecyl adipate, di (3-ethylhexyl) sebacate and the like.

Polyol ester oils include diols (ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 1,5-pentadiol, neopentyl glycol, 1,7- Heptanediol, 1,12-dodecanediol, etc.) or polyol having 3 to 20 hydroxyl groups (trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, glycerin, sorbitol, sorbitan, sorbitol glycerin condensate, etc.), Fatty acids having 6 to 20 carbon atoms (hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, eicosanoic acid, oleic acid and other straight chain or branched fatty acids, or 4 carbon atoms. So-called neo Etc.), esters of is preferable.
The polyol ester oil may have a free hydroxyl group.
Polyol ester oils include esters of hindered alcohols (neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, pentaerythritol, etc.) (trimethylol propane tripelargonate, pentaerythritol 2-ethylhexanoate). And pentaerythritol tetrapelargonate) are preferred.

The complex ester oil is an ester of a fatty acid and a dibasic acid, a monohydric alcohol and a polyol. As the fatty acid, dibasic acid, monohydric alcohol, and polyol, the same ones as described above can be used.

The polyol carbonate oil is an ester of carbonic acid and polyol.
Examples of the polyol include the same diol as described above and the same polyol as described above. Further, the polyol carbonate oil may be a ring-opening polymer of cyclic alkylene carbonate.

Examples of the ether lubricant include polyvinyl ether oil and polyoxyalkylene lubricant.
As polyvinyl ether oil, those obtained by polymerizing vinyl ether monomers such as alkyl vinyl ether, those obtained by copolymerizing vinyl ether monomers and hydrocarbon monomers having olefinic double bonds, and polyvinyl ether, There are alkylene glycols or polyalkylene glycols, or copolymers thereof with monoethers.
A vinyl ether monomer may be used individually by 1 type, and may be used in combination of 2 or more type.
Examples of hydrocarbon monomers having an olefinic double bond include ethylene, propylene, various butenes, various pentenes, various hexenes, various heptenes, various octenes, diisobutylene, triisobutylene, styrene, α-methylstyrene, various alkyl-substituted styrenes, etc. Is mentioned. The hydrocarbon monomer which has an olefinic double bond may be used individually by 1 type, and may be used in combination of 2 or more type.
The polyvinyl ether copolymer may be either a block or a random copolymer.
A polyvinyl ether may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the polyoxyalkylene-based lubricating oil include polyoxyalkylene monool, polyoxyalkylene polyol, polyoxyalkylene monool and alkyl etherified product of polyoxyalkylene polyol, polyoxyalkylene monool and esterified product of polyoxyalkylene polyol, and the like. Can be mentioned. Polyoxyalkylene monools and polyoxyalkylene polyols are used to open a C 2-4 alkylene oxide (ethylene oxide, propylene oxide, etc.) in an initiator such as water or a hydroxyl group-containing compound in the presence of a catalyst such as an alkali hydroxide. Examples thereof include those obtained by a method of addition polymerization. Further, the oxyalkylene units in the polyalkylene chain may be the same in one molecule, or two or more oxyalkylene units may be included. It is preferable that at least an oxypropylene unit is contained in one molecule.
Examples of the initiator include water, monohydric alcohols such as methanol and butanol, and polyhydric alcohols such as ethylene glycol, propylene glycol, pentaerythritol, and glycerol.
The polyoxyalkylene-based lubricating oil is preferably an alkyl etherified product or an esterified product of polyoxyalkylene monool or polyoxyalkylene polyol. The polyoxyalkylene polyol is preferably polyoxyalkylene glycol. In particular, an alkyl etherified product of polyoxyalkylene glycol in which the terminal hydroxyl group of polyoxyalkylene glycol is capped with an alkyl group such as a methyl group, called polyglycol oil, is preferable.

Examples of fluorine-based lubricating oils include compounds in which hydrogen atoms of synthetic oils (mineral oils, polyα-olefins, alkylbenzenes, alkylnaphthalenes, etc. described later) are substituted with fluorine atoms, perfluoropolyether oils, fluorinated silicone oils, and the like. .

As mineral oil, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation or vacuum distillation is refined (solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, hydrorefining, And paraffinic mineral oils, naphthenic mineral oils, etc., which are refined by appropriately combining white clay treatment and the like.

Examples of the hydrocarbon synthetic oil include poly α-olefin, alkylbenzene, alkylnaphthalene and the like.
A lubricating oil may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the lubricating oil may be in a range that does not significantly reduce the effect of the present invention, and varies depending on the application, the type of the compressor, etc., but is usually 10 to 100 parts by mass with respect to the working medium (100 parts by mass). 20 to 50 parts by mass are preferable.

(Stabilizer)
The stabilizer used in the working medium-containing composition is a component that improves the stability of the working medium against heat and oxidation. Examples of the stabilizer include an oxidation resistance improver, a heat resistance improver, and a metal deactivator. Can be mentioned.

Examples of the oxidation resistance improver and heat resistance improver include N, N′-diphenylphenylenediamine, p-octyldiphenylamine, p, p′-dioctyldiphenylamine, N-phenyl-1-naphthylamine, and N-phenyl-2-naphthylamine. N- (p-dodecyl) phenyl-2-naphthylamine, di-1-naphthylamine, di-2-naphthylamine, N-alkylphenothiazine, 6- (t-butyl) phenol, 2,6-di- (t-butyl) ) Phenol, 4-methyl-2,6-di- (t-butyl) phenol, 4,4′-methylenebis (2,6-di-t-butylphenol) and the like. The oxidation resistance improver and the heat resistance improver may be used alone or in combination of two or more.

Examples of metal deactivators include imidazole, benzimidazole, 2-mercaptobenzthiazole, 2,5-dimethylcaptothiadiazole, salicylidine-propylenediamine, pyrazole, benzotriazole, toltriazole, 2-methylbenzamidazole, 3,5- Imethylpyrazole, methylenebis-benzotriazole, organic acids or their esters, primary, secondary or tertiary aliphatic amines, amine salts of organic or inorganic acids, heterocyclic nitrogen-containing compounds, alkyl acids Examples thereof include an amine salt of phosphate or a derivative thereof.

The content of the stabilizer may be in a range that does not significantly reduce the effect of the present invention, and is usually 5 parts by mass or less and preferably 1 part by mass or less with respect to the working medium-containing composition (100 parts by mass).

(Leak detection substance)
Examples of leak detection substances used in the working medium-containing composition include ultraviolet fluorescent dyes, odorous gases and odor masking agents.
The ultraviolet fluorescent dyes are described in U.S. Pat. No. 4,249,412, JP-T-10-502737, JP-T 2007-511645, JP-T 2008-500437, JP-T 2008-531836. And known ultraviolet fluorescent dyes.
Examples of the odor masking agent include known fragrances such as those described in JP-T-2008-500337 and JP-T-2008-531836.

When a leak detection substance is used, a solubilizing agent that improves the solubility of the leak detection substance in the Rankine cycle working medium may be used.
Examples of the solubilizer include those described in JP-T-2007-511645, JP-T-2008-500437, JP-T-2008-531836.
The content of the leak detection substance may be in a range that does not significantly reduce the effect of the present invention, and is usually 2 parts by mass or less and 0.5 parts by mass or less with respect to the working medium-containing composition (100 parts by mass). Is preferred.

<Rankin cycle system>
The Rankine cycle system of the present invention is a system using the working medium of the present invention.
A Rankine cycle system is a system that heats a working medium, adiabatically expands the working medium that has become steam in a high-temperature and high-pressure state, drives the generator by work generated by the adiabatic expansion, and generates power. is there.
As a heat source for heating the working medium, geothermal energy, solar heat, medium to high temperature waste heat of about 50 to 200 ° C., and the like can be suitably used.

FIG. 1 is a schematic configuration diagram showing an example of the Rankine cycle system of the present invention. Rankine cycle system 10 is driven by an expander 11 that expands high-temperature and high-pressure working medium vapor C into low-temperature and low-pressure working medium vapor D, and work generated by adiabatic expansion of working medium vapor C in expander 11. The working medium vapor D discharged from the generator 12 and the expander 11 is cooled, liquefied to form the working medium A, and the working medium A discharged from the condenser 13 is pressurized to operate at high pressure. A pump 14 serving as a medium B, an evaporator 15 that heats the working medium B discharged from the pump 14 to form a high-temperature and high-pressure working medium vapor C, a pump 16 that supplies a fluid E to the condenser 13, and an evaporator And a pump 17 that supplies a fluid F to 15.

In the Rankine cycle system 10, the following cycle is repeated.
(I) The high-temperature and high-pressure working medium vapor C discharged from the evaporator 15 is expanded by the expander 11 to obtain a low-temperature and low-pressure working medium vapor D for Rankine cycle. At this time, the generator 12 is driven by work generated by adiabatic expansion of the working medium vapor C in the expander 11 to generate electricity.
(Ii) The working medium vapor D discharged from the expander 11 is cooled by the fluid E in the condenser 13 and liquefied to obtain the working medium A. At this time, the fluid E is heated to become a fluid E ′ and is discharged from the condenser 13.
(Iii) The working medium A discharged from the condenser 13 is pressurized by the pump 14 to obtain a high-pressure working medium B.
(Iv) The working medium B discharged from the pump 14 is heated by the fluid F in the evaporator 15 to be a high-temperature and high-pressure working medium vapor C. At this time, the fluid F is cooled to become a fluid F ′ and discharged from the evaporator 15.

The Rankine cycle system 10 is a cycle composed of an adiabatic change and an isobaric change, and the state change of the working medium can be expressed as shown in FIG. 2 on a temperature-entropy diagram.
In FIG. 2, the AB′C′D ′ curve is a saturation line. The AB process is a process in which adiabatic compression is performed by the pump 14 so that the working medium A becomes a high-pressure working medium B. The BB′C′C process is a process in which the isobaric heating is performed by the evaporator 15 and the high-pressure working medium B is converted into the high-temperature and high-pressure working medium vapor C. The CD process is a process in which adiabatic expansion is performed by the expander 11 to change the high-temperature and high-pressure working medium vapor C into a low-temperature and low-pressure working medium vapor D to generate work. The DA process is a process in which isobaric cooling is performed by the condenser 13 and the low-temperature and low-pressure working medium vapor D is returned to the working medium A.
Similarly, when the state change of the working medium is described on the pressure-enthalpy diagram, it can be expressed as shown in FIG.

(Moisture concentration)
If water is mixed in the Rankine cycle system, problems may occur particularly when used at low temperatures. For example, there are problems such as freezing in the capillary tube, hydrolysis of the working medium and lubricating oil, material deterioration due to acid components generated in the thermal cycle, and generation of contamination. In particular, when the lubricating oil is an ester-based lubricating oil, an ether-based lubricating oil, etc., the hygroscopic property is extremely high, the hydrolysis reaction is liable to occur, the characteristics as a lubricating oil deteriorates, and the long-term reliability of the compressor It is a major cause of damage. Therefore, in order to suppress hydrolysis of the lubricating oil, it is necessary to suppress the water concentration in the Rankine cycle system.
The water concentration of the working medium in the Rankine cycle system is preferably 100 ppm or less, and more preferably 20 ppm or less.

Examples of a method for suppressing the water concentration in the Rankine cycle system include a method using a desiccant (silica gel, activated alumina, zeolite, etc.). The desiccant is preferably brought into contact with a liquid working medium from the viewpoint of dehydration efficiency. For example, it is preferable to place a desiccant at the outlet of the condenser 13 or the inlet of the evaporator 15 to contact the working medium.

As the desiccant, a zeolitic desiccant is preferable from the viewpoint of the chemical reactivity between the desiccant and the working medium and the moisture absorption capacity of the desiccant.
As a zeolitic desiccant, when a lubricating oil having a higher moisture absorption than conventional mineral-based lubricating oils is used, the compound represented by the following formula (1) is used as a main component from the viewpoint of excellent hygroscopic capacity. Zeolite desiccants are preferred.
_{M 2 / n O · Al 2} O 3 · xSiO 2 · yH 2 O ··· (1).
However, M is a Group 1 element such as Na or K, or a Group 2 element such as Ca, n is a valence of M, and x and y are values determined by a crystal structure. By changing M, the pore diameter can be adjusted.

In selecting a desiccant, pore size and fracture strength are particularly important.
When a desiccant having a pore size larger than the molecular diameter of the working medium is used, the working medium for Rankine cycle is adsorbed in the desiccant, resulting in a chemical reaction between the working medium and the desiccant, and non-condensing Undesirable phenomena such as generation of gas, decrease in the strength of the desiccant, and decrease in adsorption ability will occur.
Therefore, it is preferable to use a zeolitic desiccant having a small pore size as the desiccant. In particular, a sodium / potassium A type synthetic zeolite having a pore diameter of 3.5 mm or less is preferable. By applying sodium / potassium type A synthetic zeolite having a pore diameter smaller than the molecular diameter of the working medium, only moisture in the thermal cycle system can be selectively adsorbed and removed without adsorbing the working medium. In other words, since the working medium is less likely to be adsorbed to the desiccant, thermal decomposition is less likely to occur, and as a result, deterioration of the materials constituting the Rankine cycle system and generation of contamination can be suppressed.

If the size of the zeolitic desiccant is too small, it will cause clogging of valves and piping details of the heat cycle system, and if it is too large, the drying ability will be reduced, so about 0.5 to 5 mm is preferable. The shape is preferably granular or cylindrical.
The zeolitic desiccant can be formed into an arbitrary shape by solidifying powdered zeolite with a binder (such as bentonite). As long as the zeolitic desiccant is mainly used, other desiccants (silica gel, activated alumina, etc.) may be used in combination.
The use ratio of the zeolitic desiccant with respect to the working medium is not particularly limited.

(Non-condensable gas concentration)
If a non-condensable gas is mixed in the Rankine cycle system, it adversely affects heat transfer in the condenser and the evaporator and an increase in operating pressure. Therefore, it is necessary to suppress the mixing as much as possible. In particular, oxygen, which is one of non-condensable gases, reacts with the working medium and lubricating oil to promote decomposition.
The non-condensable gas concentration is preferably 1.5% by volume or less, particularly preferably 0.5% by volume or less in terms of the volume ratio with respect to the Rankine cycle working medium in the gas phase portion of the working medium.

(Function and effect)
In the Rankine cycle system described above, since the working medium of the present invention with reduced combustibility is used, safety is ensured.
Moreover, since the working medium of the present invention having excellent thermodynamic properties is used, the cycle performance (efficiency and capacity) is excellent. Moreover, since the efficiency is excellent, a large amount of electric power can be obtained per recovered heat amount (heat receiving amount) and the capacity is excellent, so that the system can be downsized.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples.

<Evaluation method>
The power generation capacity L and Rankine cycle efficiency η when various working media are applied to the Rankine cycle system 10 of FIG. 1 were determined by the following formulas (2) and (3). In the following formulas (2) and (3), h is enthalpy, and the subscript represents the state of the Rankine cycle working medium in FIG. For example, h _C is the enthalpy of the Rankine cycle working medium vapor C in FIG.
In the evaluation, the condensation temperature of the Rankine cycle working medium in the condenser 13 is 25 ° C. or 50 ° C., and the evaporation temperature of the Rankine cycle working medium in the evaporator 15 is 60 ° C., 80 ° C., 100 ° C., 120 ° C., 140 ° C. Went as either.
In addition, there was no loss due to equipment efficiency and no pressure loss in piping and heat exchangers.

L = h _C -h _D (2)
η = effective work / heat receiving amount = (power generation capacity−pump work) / heat receiving amount = {(h _C −h _D ) − (h _B −h _A )) / (h _C −h _B )
Since the pump work is extremely small compared to the other items, if this is ignored, the Rankine cycle efficiency is as follows.
η = {(h _C −h _D ) − (h _B −h _A )) / {(h _C −h _A ) − (h _B −h _A )}
≒ (h _C -h _D ) / (h _C -h _A ) (3)

Each enthalpy of h _C , h _D , and h _A calculates the thermodynamic properties necessary for the calculation based on the generalized equation of state (Soave-Redrich-Kwong equation) based on the corresponding state principle and the thermodynamic relational equations. And asked. When characteristic values were not available, calculations were performed using an estimation method based on the group contribution method.

The following evaluation results are shown as relative values with respect to the power generation capacity L and Rankine cycle efficiency η of HCFO-1224yd determined under the same conditions (condensation temperature and evaporation temperature, equipment conditions, etc., other than the working medium are the same). That is, the relative capacity is the ratio of the power generation capacity L of the working medium to the power generation capacity L of the HCFO-1224yd determined under the same conditions, and the relative efficiency is the ratio of the Rankine cycle efficiency η of the HCFO-1224yd determined under the same conditions. It is the ratio of Rankine cycle efficiency η of the working medium.

<Target of evaluation>
The following three types of working media were evaluated. In addition, a working medium in which HCFO-1224yd and CFO-1214ya were mixed was also evaluated.
HCFO-1224yd (Molar ratio of E and Z forms is 1: 1)
・ CFO-1214ya
・ HFC-134a

<Evaluation results>
FIG. 4 shows the relative capacity of each working medium at each evaporation temperature when the condensation temperature is 25 ° C. FIG. 5 shows the relative capacities of each working medium at each evaporation temperature when the condensation temperature is 50 ° C.
From the results of FIG. 4 and FIG. 5, it can be understood that HCFO-1224yd and CFO-1214ya which are working media for Rankine cycle of the present invention have excellent power generation capability over a wide temperature range. In particular, it was found that the evaporation power is higher than that of HFC-134a at an evaporation temperature of 100 ° C. or higher.

FIG. 6 shows the relative efficiency of each working medium at each evaporation temperature when the condensation temperature is 25 ° C. FIG. 7 shows the relative efficiency of each working medium at each evaporation temperature when the condensation temperature is 50 ° C.
From the results of FIGS. 6 and 7, the HCFO-1224yd and CFO-1214ya, which are working media for Rankine cycle of the present invention, are superior to HFC-134a over a wide evaporation temperature range, particularly when the condensation temperature is 25 ° C. It was found to have efficiency.
It can be said that HCFO-1224yd and CFO-1214ya, which are working mediums for Rankine cycle of the present invention, are excellent in both efficiency and capacity.

Table 1 shows the relative capacities and relative efficiencies of HCFO-1224yd and CFO-1214ya and their mixed media under the conditions of a condensation temperature of 25 ° C and an evaporation temperature of 120 ° C. Note that “%” in Table 1 is mass% in the working medium.
As shown in Table 1, it was found that the mixed medium of HCFO-1224yd and CFO-1214ya is excellent in both efficiency and capacity at an arbitrary blending ratio.

The Rankine cycle working medium of the present invention is useful as a working fluid for a power generation system (waste heat recovery power generation or the like).
It should be noted that the entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2012-254494 filed on November 20, 2012 is cited herein as the disclosure of the specification of the present invention. Is to be incorporated

10 ... Rankine cycle system, 11 ... Expander, 12 ... Generator, 13 ... Condenser, 14 ... Pump, 15 ... Evaporator, 16 ... Pump, 17 ... Pump

Claims (12)

A Rankine cycle working medium comprising one or both of 1-chloro-2,3,3,3-tetrafluoropropene and 1,1-dichloro-2,3,3,3-tetrafluoropropene. The total proportion of 1-chloro-2,3,3,3-tetrafluoropropene and 1,1-dichloro-2,3,3,3-tetrafluoropropene in 100% by mass of the Rankine cycle working medium is The working medium for Rankine cycle according to claim 1, wherein the working medium is 60% by mass or more. The chlorofluoroolefin according to claim 1 or 2, further comprising chlorofluoroolefin other than 1-chloro-2,3,3,3-tetrafluoropropene and 1,1-dichloro-2,3,3,3-tetrafluoropropene. Working medium for Rankine cycle. 4. The Rankine cycle working medium according to claim 3, wherein a ratio of the chlorofluoroolefin in 100% by mass of the Rankine cycle working medium is 40% by mass or less. The working medium for Rankine cycle according to claim 1 or 2, further comprising a hydrocarbon. The working medium for Rankine cycle according to claim 5, wherein a ratio of the hydrocarbon in 100% by mass of the working medium for Rankine cycle is 40% by mass or less. The working medium for Rankine cycle according to claim 1 or 2, further comprising hydrofluorocarbon. The working medium for Rankine cycle according to claim 7, wherein a ratio of the hydrofluorocarbon in 100% by mass of the Rankine cycle working medium is 40% by mass or less. The working medium for Rankine cycle according to claim 1 or 2, further comprising a hydrofluoroolefin having no chlorine atom. The working medium for Rankine cycle according to claim 9, wherein a ratio of the hydrofluoroolefin occupying in 100% by mass of the working medium for Rankine cycle is 40% by mass or less. A Rankine cycle system using the Rankine cycle working medium according to any one of claims 1 to 10. A working medium composition for Rankine cycle, comprising the working medium for Rankine cycle according to any one of claims 1 to 10, and at least one selected from a lubricant, a stabilizer, and a leakage detection substance.

Images