DE2756470A1 - CONSTANT BOILING MIXTURES OF 1-CHLORINE-2,2,2-TRIFLUORAETHANE AND THEIR USE - Google Patents

Description

Constant boiling mixtures of 1-chloro-2,2,2-trifluoromethane

and their use

The invention relates to constant-boiling binary mixtures of 1-chloro-2,2,2-trifluoroethane in combination with certain hydrocarbons and halogenated hydrocarbons. Such mixtures are particularly useful as compression refrigerants, especially in systems using centrifugal or rotary compressors.

The coolant capacity per pumped volume of a coolant is largely a function of the boiling point, with the lower-boiling coolants generally giving the greater capacity at a certain evaporator temperature. This factor Greatly affects the design of the refrigeration system and affects capacity, energy requirements, the size and cost of the facility. Another important factor related to the boiling point of the coolant is the minimum cooling temperature desired during the cooling cycle with the lower boiling refrigerants being used to achieve the lower refrigeration temperatures. From these For reasons, a large number of coolants of varying boiling temperature and capacity are required to allow design flexibility, and technology is constantly evolving Faced problem of developing new coolants as the demand for new capacities and installation types grows.

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It

The low molecular weight aliphatic hydrocarbons substituted with fluorine and chlorine are known as refrigerants. Many of these fluorocarbons have certain desirable properties, such as lower toxicity and non-flammability, which has led to the extensive use of such compounds in a large number of refrigeration and freezing applications, respectively. Trichlorofluoromethane and dichlorodifluoromethane are two of the most common chlorofluorocarbon refrigerants available today. There is a recognized need of refrigerants with boiling points between the relatively high boiling point of trichlorofluoromethane (+ 23.78 C at atmospheric pressure) and the relatively low boiling point of dichlorodifluoromethane (-29.8 ⁰ C at atmospheric pressure), good to coolant performance in varying capacities available.

Various chlorofluorocarbons have boiling points in this range, but they suffer from other disadvantages such as flammability, poor stability or poor thermodynamic Power. Some examples of these types of refrigerants are tetrafluorodichloroethane, fluorodichloromethane, difluorochloroethane and fluorochloromethane.

It would also be possible to achieve the desired boiling point by mixing two coolants with boiling points above and below of the desired boiling point. In this case, for example, mixtures of trichlorofluoromethane and dichlorodifluoromethane could be used be used. However, it is known that simple mixtures cause problems in construction and operation because of the deposition of the components in the liquid and

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Cause vapor phase. This problem is particularly troublesome in systems using centrifugal compression, namely because of the large amounts of liquid usually found in the vaporizer.

To avoid such separation problems, technology is constantly looking for new azeotropic or constant boiling mixtures, such as the constant-boiling fluorocarbon devices disclosed in U.S. Patents 3,607,755, 3,470,101, 3,640,869, 3,505,232 and 3 634 255 and CA-PS 332 341 or the constant-boiling mixtures of fluorocarbons and hydrocarbons according to U.S. Patents 3,249,546 and 3,431,211, Canadian Patent 829,259, and Soap and Chemical Specialties, August 1964.

An object of the present invention is to provide new constant boiling binary mixtures with boiling points between that of trichlorofluoromethane and dichlorodifluoroethane, which are suitable for use as refrigerants.

More particularly, it is an object of the invention to provide refrigerant systems with a capacity between the refrigeration capacity of trichlorofluoromethane and dichlorodifluoroethane, which are used as compression refrigerants, are particularly useful in systems where a centrifugal or rotary compressor is used.

Another goal is to get new, low-boiling azeotropic or constant boiling mixtures that can be used in cooling those systems are useful in which the cooling by

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vaporization is achieved in the vicinity of the body to be cooled and in which, because of the nature of the system, the problem of separation or component separation is critical.

According to the invention, constant-boiling mixtures were found, which consist essentially of 1-chloro-2,2,2-trifluoroethane and a Hydrocarbon or halogenated hydrocarbon from the group Isopentane, n-pentane, η-butane, isobutane, 2,2-dimethylpropane, Octafluorocyclobutane and / or 2-chloroheptafluoropropane exist. The compositions are as follows:

Table I (Examples 1 - 5)

example
No.

Component A (mol %) ♦

1-chloro-2,2,2-trifluoroethane (88)

1-chloro-2,2,2-trifluoroethane (96)

1-chloro-2,2,2-trifluoroethane (39)

1-chloro-2,2,2-trifluoroethane (55)

1-chloro-2,2,2-trifluoroethane

Component B boiling point (mol%) * (760 mm Hg)

Isopentane (12)

n-pentane (4) 5 n-3utane (61) -5 2,2-dimethyl
propane (4 5) 1 Isobutane C-13 ° C.

♦ at 2CTC

Example 6

A phase study was carried out with 1-chloro-2,2,2-trifluoromethane

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(Kp._, = 6.1 ° C) and octafluorocyclobutane (Kp. _ _G = 6 ⁰ C) carried out, the composition was varied and the vapor pressures were measured ^{at a temperature of 20, 0 0 C.} An azeotropic composition at 20 ° C was obtained at the maximum pressure and was as follows:

1-chloro-2,2,2-trifluoroethane 22 mol% octafluorocyclobutane 78 mol%

The lower boiling point of the azeotrope compared to its components results in increased cooling capacity compared to both Components and to a new level of cooling capacity.

The novel azeotropic compositions of about 22 mole% of 1-chloro-2,2,2-trifluoroethane and about 78 mol% octafluorocyclobutane have a boiling point of about -8 ⁰ C at atmospheric pressure (760 mm Hg). 1-chloro-2,2,2-trifluoroethane has a boiling point of about 6, I ⁰ C at atmospheric pressure, and octafluorocyclobutane has a boiling point of -6 ⁰ C.

Example 7

A phase study was carried out with 1-chloro-2,2,2-trifluoromethane ( _{boiling point 76O} = 6.1 ° C.) and 2-chlorohaptafluoropropane (boiling point 750 mm ^β -2.6 ° C.), the composition being varied and the vapor pressures were measured at a temperature of 20.0 ° C. It became an azeotropic composition at 20 ° C

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received the maximum pressure and was the following:

1-chloro-2,2,2-trifluoroethane 29 mol% 2-chloroheptafluoropropane 71 mol%

The lower boiling point of the azeotrope compared to its components results in increased cooling capacity compared to both components and a new level of cooling capacity.

The new azeotropic compositions of about 29 mol% 1-chloro-2,2,2-trifluoroethane and about 71 mol% 2-chloroheptafluoropropane have a boiling point of about -5 C at atmospheric pressure (760 mm Hg). i-chloro-2,2,2-trifluoroethane has a boiling point of about 6.1 C at atmospheric pressure, and 2-chloroheptafluoropropane has a boiling point of about -2.6 C at atmospheric pressure.

For purposes of discussion, azeotropic or constant boiling is also intended to be essentially azeotropic or essentially mean constant boiling. In other words, within the meaning of these terms is not only the real azeotrope, which is described above at 20.0 C, but in these terms also include other compositions that have the same components in different proportions, which are true azeotropes at other temperatures and pressures, such as also those equivalent compositions which are part of the same azeotropic system and are azeotrope-like in their properties

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are to be recognized in the art, there is an area of compositions which contain the same components as the azeotrope and which are not just essentially equivalent Properties for cooling and other areas of application show, but also essentially equivalent properties such as the true azeotropic compositions in terms of constant boiling properties and tendency not to fractionate on boiling, to have.

The new azeotropic compositions according to the invention all have lower boiling points than their individual components the properties of the components alone could cause the degradation the boiling temperature and the azeotrope properties in the mixtures are not expected.

The new azeotropic mixtures result in increased cooling capacity compared to the components and represent new cooling mixtures, which are particularly useful in systems using centrifugal and rotary compressors. The use of the azeotropic Mixtures eliminates the problem of component separation and handling in the operation of the system, since the azeotropic

themselves
Mixtures behave essentially like a single component. The new azeotropic mixtures are essentially non-flammable.

Example 8

The azeotropes were determined in the following manner. Phase studies

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were made in which the composition of the various binary mixtures was varied and the vapor pressures at one
Temperature of 20.0 C were measured. In all cases were
obtained at 20 C azeotropic compositions at the maximum pressure as reported in the table above. The azeotrope of 1-chloro-2,2,2-trifluoroethane and isobutane was noted, but its exact composition was not determined.

All azeotropes have lower boiling points than the individual components thus providing higher cooling capacity for the azeotropes than the individual components as well as new levels of cooling capacity.

An evaluation of the cooling properties of the azeotrope of 1-chloro-2,2,2-trifluoroethane and isopentane according to the invention and its fluorocarbon component are shown in the following table. Isopentane alone is not suitable as a coolant because of its flammability.

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- V-

Table II Comparison of the cooling performance

1-chloro-2,2,2-trifluoroethane

Evaporator
pressure, psia 13.75 capacitor
pressure, psia 53.35 Evaporator-
temperature, F 40 capacitor
temperature, F 110 Discharge
temperature, F 116 Net cooling effect
(NRE), BTü / lb 69.9 Performance
coefficient (COP) 6.13 capacity ft / minute / ton 9.02 Compression
relationship 3.88

azeotropic composition of 88 mol% 1-chloro-2,2,2-trifluoroethane and 12 mol% isopentane

14.34

54.36

40 110 110

72.78 April 6

8.64 3.79

The change is understood as the net cooling effect (NRE) the enthalpy of the refrigerant in the evaporator or in other words the heat removed by the cooling in the evaporator.

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The coefficient of performance (COP) is the ratio from NRE to the compressor work. It is a measure of the effectiveness of the coolant.

The azeotrope shows a 4.4% increase in capacity versus 1-chloro-2,2,2-trifluoroethane.

Additives such as lubricants, corrosion inhibitors and others / can add to the new compositions according to the invention Purposes provided that they do not adversely affect the compositions for their intended uses.

Except for cooling purposes, the new compositions are constant boiling according to the invention also useful as heat transfer media, gaseous dielectrics, expanding agents, such as for polyolefins and polyurethanes, working fluids in force cycles, Solvents and aerosol propellants that are particularly environmentally friendly.

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Claims (7)

Dr. Hans-Heinrich Willrath t Dr. Dieter Weber Dipl.-Phys. Klaus Seiffert PATENTANWÄLTE D-62 WIESBADEN, December 16, 1977 Postfadi 6145 Gusnv-Frcyug-Strafe (S Dr. We / TU «(061« I 37 (7 «0 TeleKr.mni.dr.-Me! WILLPATENT Telex: 4 -186247 5400-1466 Allied Chemical Corporation, Morristown, New Jersey 07960, USA Constant-boiling devices of 1-chloro-2,2,2-trifluoroethane and their use priorities; Serial No. 753 054, 753 063, 753 064 respectively from 21 December 1976 in USA claims: 1. Constant boiling mixtures, consisting essentially of 1-chloro-2,2,2-trifluoroethane and a hydrocarbon or Halogenated hydrocarbons from the group isopentane, n-pentane, η-butane, 2,2-dimethylpropane, isobutane, octofluorocyclobutane and / or 2-chloroheptafluoropropane. OBCHNAL INSPECTED 809825/0963 2. Constant boiling mixtures according to claim 1, wherein the hydrocarbon is isopentane and the boiling at about 4 ° C at 760 now. 3. Constant boiling mixtures according to claim 1, wherein the Hydrocarbon is n-pentane and boil at about 5 C at 760 mm. 4. Constant boiling mixtures according to claim 1, wherein the hydrocarbon is η-butane and at about -5 C at 760 mm boil. 5. Constant boiling mixtures according to claim 1, wherein the Hydrocarbon is 2,2-dimethylpropane and which is at about Boil 1 ° C at 760 mm. 6. Constant boiling mixtures according to claim 1, wherein the halogenated hydrocarbon is octafluorocyclobutane and / or Is 2-chloroheptafluoropropane. 7. Use of constant boiling mixtures according to claim 1 to as a coolant. 809825/0963