JPS61255978A - Working medium - Google Patents

Abstract

PURPOSE:To provide a working medium having an improved efficiency, which comprises a specific perfluoro ether. CONSTITUTION:A working medium comprising a perfluoro ether of the formula (wherein n is an integer of 0-3). A mixture of the perfluoro ether with a halogenated hydrocarbon has further improved characteristics in respect of coefficient of performance on a heat pump etc. as compared with the perfluoro ether alone. The perfluoro ether of the formula can be obtd., e.g., by fluorinating the terminal of a hexafluoropropylene oxide in a polar solvent such as acetonitrile. In the formula, when n=0 the compd. is a perfluoro ether or perfluoro polyether having a b.p. of 29.4 deg.C, when n=1 the compd. is a perfluoro ether or perfluoro polyether having a b.p. of 96.4 deg.C, when n=2 the compd. is a perfluoro ether or perfluoro polyether having a b.p. of 146 deg.C, and when n=3 the compd. is a perfluoro ether or perfluoro polyether having a b.p. of 185.5 deg.C. A perfluoro ether to be used is selected from these perfluoro ethers having different b.p. taking into consideration the service temp.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a novel working medium (hereinafter sometimes referred to as working medium) that can be used in heat pumps and the like. [Conventional technology] Research is progressing to recover energy from heat sources in the medium and low temperature range, which is lower than the temperature obtained by burning fuels such as heavy oil and petroleum.
Ocean temperature difference power generation, geothermal binary power generation, waste heat recovery power generation,
Solar thermal power generation, temperature raising using heat pumps, heat exchange technology using heat pipes, etc. are being put into practical use or being tested. The working media used in these heat recovery technologies include water, hydrocarbons such as propane and butane, and trichloromonofluoromethane (R-11) and 1,2-dichlorotetrafluoroethane (R-114). Fluorocarbons, ammonia, etc. are known.

[Problems to be solved by the invention]

Freon, which has traditionally been used as a working medium, is particularly unstable in the presence of lubricating oil. It is unsuitable for heat pumps operating at high discharge temperatures in the compressor. On the other hand, water has no problems in terms of stability, but when used at low temperatures, the specific volume of steam is large, which increases the size of the equipment and reduces efficiency. Furthermore, since it has a high freezing point, it condenses when operated at low temperatures, so there is a limit to the temperature at which it can be used. Furthermore, from the perspective of energy conservation, improvements in efficiency are expected through the development of new operating media. It also improves the capacity (heating and cooling capacity) of the working medium per compressor suction volume. It is desired to develop a new working medium that improves the shortcomings of the working medium that has been conventionally used. [Means for Solving the Problems] The present inventors have conducted various studies in order to meet such demands, and as a result, perfluoroethers represented by the following general formula (C3F7O- [CF CCF3 ) CFzol n-
It has been found that C2F5 (1)n θ~3 has excellent properties as a working medium. Furthermore, it has been found that a mixed system of perfluoroethers and halogenated hydrocarbons has even better properties than perfluoroethers. That is, the present invention relates to a working medium containing a perfluoroether represented by the general formula (1) as an essential component, and a working medium containing a perfluoroether and a halogenated hydrocarbon as essential components. . The perfluoroethers in the present invention are... For example, it can be obtained by polymerizing B fluorinated propylene oxide (hereinafter abbreviated as θFPO) in a polar solvent such as acetonitrile in the presence of silver nitrate at a low temperature of θ to IQ''O, and further fluorinating the terminals. In formula (1), n=0 is the boiling point of 28.4°C, and nJ is the boiling point of 88.4
°C, nm2 has a boiling point of 14 B'O, nm3 has a boiling point of 185.5
These perfluoroethers with different boiling points may be used depending on the operating temperature of the working medium, which is a perfluoroether or a perfluoropolyether of °C.
Compounds where n is 4 or more have too high a boiling point and are therefore unsuitable for use as a normal working medium. Perfluoroethers are nonflammable, thermally and chemically stable, and are not easily affected by operating temperature or coexisting substances, so they are suitable as working media that can be operated for long periods of time. The combined use of perfluoroethers and halogenated hydrocarbons improves the coefficient of performance of heat pumps, for example. The halogenated hydrocarbon preferably has a boiling point close to that of perfluoroethers, and is a compound in which hydrogen in an aliphatic or cyclic hydrocarbon compound having 1 to 4 carbon atoms is replaced with a halogen atom such as chlorine, fluorine, or bromine. It is. Preferred examples include compounds in which part or all of the hydrogen in methane or ethane is replaced with at least one selected from chlorine, fluorine, or bromine atoms, or in cyclic saturated hydrocarbon compounds having 93 to 4 carbon atoms. It is a compound in which part or all of hydrogen has been replaced with chlorine and/or fluorine atoms. Specifically, to C 14 e CG Is F e C
C12F 2 @CHCIs *CHCItF, C
HClh, CH2C1teCHsO1, CBr2Fz,
CBrh. CChF-CG12F, CC1zF-CCIFr,
CCIFr-CCIFr. CBrF2-CBrF2. CCIFz-CFs, C
;HClz-CCIFz, CHCh-CFs, CH
CIF-CClF2. CHCIF-CFs, CCI
Ft-CjHh. CHF2-CFs, CH2Cl-CF3. CCh-
CHs, CC1h-CH3*CHh- to Hs, Ch-
Examples include Ch-Ch-Ch, an azeotrope of CCIzh and CHh-C1h, and an azeotrope of CHCIFz and CC1h-CF3. The preferred mixing molar ratio of perfluoroethers and halogenated hydrocarbons varies depending on the type of halogenated hydrocarbon used in combination, as can be understood based on the dLm coefficients in Tables 3 to 9 attached. - not determined by law. The case where the working medium of the present invention is applied to a heat pump system will be described below. Figures 1 and 2 show flow sheets of a heat pump using the working medium of the present invention, where l is a compressor, 2 is a condenser, 3 and 3' are load fluid piping, and 4 is a pressure reducing device. , 5
is an evaporator, e and e' are heat source fluid pipes, and 7 is an intermediate heat exchanger. In the heat pump cycle shown in FIG. 1, the working medium is compressed by a compressor 1 and then led to a condenser 2, where it is cooled and condensed by a high heat source fluid introduced from a pipe 3. on the other hand. The load fluid is inversely heated in the condenser 2 and subjected to load heating via the tube 3'. Next, the condensed working medium is transferred to the pressure reducing device 4
After the pressure is reduced, the fluid is introduced into the evaporator 5, where it is heated and evaporated by the heat source fluid discharged from the pipe B introduced through the pipe 6, and then sucked into the compressor 1 again to repeat the above cycle. In the heat pump cycle shown in FIG. 2, the working medium is compressed in the compression 411 and then led to the intermediate heat exchanger 7, in which it is superheated by the working medium condensed in the condenser 2, and then condensed. Guided by Vessel 2. On the other hand, the working medium introduced from the W1 compressor 2 is supercooled by the heat exchanger 7 and then reduced in pressure by the pressure reducing device 4. Thereafter, the cycle is repeated in the same way as in the case of FIG. Figure 3 is a pressure-enthalpy diagram showing the cycle of the working medium in the heat pump system shown in Figure 1 and Figure 4 is shown in Figure 2.0 When saturated vapor of the working medium is adiabatically compressed , the dry state is shown in Figure 1.
The items that become wet are shown in Fig. 2 and Fig. 4.
Corresponds to the figure. Changes in the working medium due to the compressor in Figures 1 and 2 are shown in Figure 3.
The change in the working medium due to the condenser is from 9 to 11 or 1 to the change from 8 to 9 or from 14 to 15 in Fig.
The change in working medium due to the pressure reducing device is from 11 to 12 or 17 to 18, and the change in working medium due to the evaporator is from 12 to 8 or 18 to 13.
The change in K, the change in the working medium due to the intermediate heat exchanger is 13
14 and 18 to 17, respectively. The working medium of the present invention is particularly effective when applied to a heat pump system using a medium-low temperature heat source, but it can also be used as a working medium for Rankine cycle or various other heat recovery technologies. The working medium has excellent thermal stability and does not require stabilizers under normal usage conditions, but when it is necessary to improve thermal stability due to severe usage conditions, dimethyl phosphite, diisopropyl Phosphite-based compounds such as phosphite and diphenylphosphite, or thiophosphite-based compounds, or triphenoxyphosphine sulfide,
A small amount of about 1 part by weight of a phosphine sulfide compound such as trimethylphosphine sulfide and other stabilizers may be added to 100 parts by weight of the working medium. [Example] The operating conditions for the heat pump system shown in FIG. 1 or 2 using the working medium of the present invention are as follows: the evaporator outlet temperature (the temperature indicated by code 8 or !3) is set at 50 or 100°C, and the condenser is set at 50 or 100°C. Temperature at the beginning of condensation of the working medium (symbol lO or 1
5) was set at 100°C to 150°C. Tables 1 to 9 show design parameters for the above-mentioned noheat pump system using the working medium of the present invention. Table 1 Table 3 Atsushi 50°C Atsushi 150°C 1st component 03F7O-CF (CF3) CF2 F5
2nd component circle 1: +F (R11) 4th expression 50℃ Body 1150℃ 1st component 0sFzO (F (03) CF stirrup QFs 2nd component CG12F2 (R12) 5th expression 50℃ IJjImJR150℃ 1st Component 03F7O (F (α3) σ2 can QFs 2nd component 12F (Ni 1) Table 6 Evaporation temperature 50℃ Condensation temperature 150℃ 1st component c
3 F7O(F(0'3)CF2O-Q F5 2nd component 01; l2F-CCIF2 (R113) Table 7 Rinxian 50℃ Hyunxian 150℃ 1st component 0zFy or σ(S3)σ2幀F5 2nd component 1F2-CClF2 (R114) Table 8 Rinju 50℃ -M 150℃ 1st weight QI F7 D-CF ((F3)CF2()
G F5 2nd component (M2-Oh (R152a) Table 9 Rinju 5G℃ m 150℃ 1st #03F7O-CF (CF3) σ2O-Q2
F5 Second component αrσrαz−CFz (RC318) [
Effect of the invention] Since the novel working fluid of the present invention has excellent thermal stability,
Conventionally known R11. It has an excellent effect that can be applied even in a high temperature range where fluorocarbons such as R113 cannot be applied in terms of thermal stability. Furthermore, when compared with water, which has excellent thermal stability, as can be understood from Table 1, when a heat pump cycle is applied under the same conditions, the novel working medium of the present invention can reduce the compression ratio and It has excellent properties such as lowering the discharge temperature of the compressor by more than 100°C and having a small specific volume of steam at the compressor inlet. The new working medium has excellent capabilities as a working medium for high temperature heat pumps. As can be understood from Tables 3 to 9, the working fluid mixture of the present invention in which a halogenated hydrocarbon is mixed with the novel working fluid does not increase the compressor discharge temperature and improves the coefficient of performance and heating capacity of the unit before mixing. For example, 03F7OCF (CF3)CF2OCzFs
In the system in which R21 is mixed with R21, the coefficient of performance is 03F7O0FCC
F3) Improved by 85% compared to CF2O1C2Fs and 46% compared to R21, and the heating capacity is also 5.
This is an improvement of 5 times and 1.9 times. In other words, it can be said that the working medium mixture of the present invention has characteristics that can improve the heating capacity and the coefficient of performance without increasing the compressor discharge temperature. As explained above, the new working fluid of the present invention can be applied to high temperature ranges that cannot be applied with conventional working fluids, and the compression ratio and the coefficient of performance of the mixed media containing compressed hydrocarbons are improved compared to water. Moreover, the heating capacity can be increased, which brings about an extremely useful effect in practice.

[Brief explanation of drawings]

Figures 1 and 2 are heat pump flow sheets for explaining one embodiment of the present invention, and Figures 3 and 4 are pressure-enthalpy diagrams showing a cycle using the medium of the present invention as a working medium for a heat pump. This is a diagram filled out in the figure. Figure 1

Claims (1)

[Claims] 1. A working medium comprising a perfluoroether represented by the following general formula (I) as an essential component. C_3F_7O-[CF(CF_3)CF_2O]n-
C_2F_5(1) n=0 to 3 2. A working medium comprising a perfluoroether represented by the general formula (1) and a halogenated hydrocarbon as essential components.