HEAT AND MASS TRANSFER ADDITIVES FOR IMPROVED AQUEOUS ABSORPTION FLUIDS

Abstract: The rate of water vapor sorption of an absorption cycle cooling and/or heating system using an aqueous alkali metal halide solution as the working fluid is increased by adding to the fluid an effective additive amount of at least 2 parts per million of an aliphatic, cycloaliphatic, or aromatic ketone or aldehyde capable of increasing the rate of water vapor absorption.

Description: HEAT AND MASS TRANSFER ADDITIVES FOR IMPROVED AQUEOUS ABSORPTION FLUIDS Summary of the Invention According to the present invention, aqueous absorption working fluids are improved by adding effective amounts of an aliphatic, cycloaliphatic or aromatic ketone or aldehyde having between 5 and 24 carbon atoms. The improved heat and mass transfer additives are used in aqueous metal salt solutions. The presence of the effective amount of ketone or aldehyde increases the rate of water vapor absorption by the absorption fluid thereby achieving important advantages and improvements in system performance. The improvements include absorber power load increases and improvements in the change of absorber fluid concentrations. Further improvements include increases in overall heat transfer coefficients and sorption fluid side film heat transfer coefficients. The advantage of such improved absorption fluid performance allows for reduction of sorber heat exchange surface areas needed to satisfy a given load resulting in reduction of absorber size and costs. These and other improvements and advantages will be evident from the following detailed description. Detailed Description of the Invention The specific improved aqueous absorption solutions used in the system of the present invention are aqueous solutions of metal salts. The preferred metal salts are alkali metal halides, particularly lithium bromide, lithium chloride and lithium iodide and mixtures of two or more of them. The most preferred working fluid is an aqueous solution of lithium bromide as the only substantial absorbent present in the aqueous solution as used in today's absorption chillers. In such solutions, a small amount of metal hydroxide may be present for pH corrosion control, typically between about .05 and about .15 normal. However, in addition to the preferred lithium bromide, one or more of the following salts may also be present: ZnCI 2 , ZnBr 2 , MnCI 2 , MnBr 2 , MgCI 2 , gBr 2 , SrCI 2 , SrBr 2 , CaCI 2 , CaBr 2 , FeCI 2 , FeBr 2 , LiCl, Lil, LiN0 2 , LiN0 3 , LiSCN and LiCI0 3 . The amount of salt present, whether lithium bromide alone or a mixture of two or more of the aforesaid salts is preferably between about 40% and about 85%, by weight. The aforesaid LiBr aqueous absorption solutions are well known to those skilled in the art as disclosed, for example, in U.S. Patent No. 3,478,530. Ketones may also be used with aqueous solutions containing alkali metal hydroxides. The alkali metal hydroxide absorption fluids are aqueous solutions of sodium hydroxide, potassium hydroxide or mixtures thereof. Preferred hydroxide compositions are those utilizing a mixture of the two hydroxides, and preferably those in which the total hydroxide concentration is between about 30% and about 80%, by weight. It has been found that optimum energy storage potentials are realized when sodium hydroxide is present between about 35% and about 75%, by weight, of the combined sodium hydroxide and potassium hydroxide weight. The amount of sodium hydroxide present in the salt mixture for systems at crystallization temperatures above 30°C is 50% or above, whereas for temperatures below 30°C, the preferred amount of sodium hydroxide is at or below 50% of the salt mixture. The most preferred amount of sodium hydroxide is between 40% and 55% of the combined weight of sodium hydroxide and potassium hydroxide for crystallization temperatures below 30°C. In addition to the aforesaid sodium and/or potassium hydroxide solutions, relatively small amounts of other alkali metal hydroxides may be added as well. Thus, the hydroxide solutions may contain up to about 50% cesium, rubidium, and/or about 35% lithium hydroxide, based on the weight of sodium and/or potassium hydroxides. It has been found that aldehydes are not effective heat and mass transfer additives with metal hydroxides. The heat and mass transfer additives of the invention are aliphatic, cycloaliphatic, and aromatic ketones and aldehydes having between 5 and 24 carbon atoms. Preferred additives are normally liquid at system operating conditions, for example, between about 30°C and up to 100°C or more. Normal boiling points of 180°C or higher are particularly preferred. The additives may be soluble or insoluble in the brine working fluid. However, insoluble compounds must be liquid at 20° and above, whereas soluble additives may be solid as a pure compound at ambient temperatures but must fully dissolve and not form precipitates at 20° or higher. Additives of the present invention may be used in systems with absorber temperatures down to about 15°C if they are selected from compounds having a melting point less than the absorber temperature. The additives may be liquid over a wider temperature range, both higher and lower, without adversely affecting the operation of the invention. The ketones are of the formula R 1 (C-0)R 2 wherein R, and/or R 2 are aliphatic or substituted aliphatic groups of from 1 to 12 carbon atoms or are cycloaliphatic or aromatic or substituted cycloaliphatic or aromatic groups of from 6 to 12 carbon atoms, respectively. Where the hydrocarbon groups are alkyl groups, and wherein R, or R 2 is a methyl group, the carbon atom of the other alkyl group attached to the carbonyl group is a pπmary or tertiary carbon atom. Thus, ketones having R, as a methyl group and the other alkyl group R 2 having a secondary carbon atom attached to the carbonyl group such as 3-methyl-2-heptanone as disclosed in U.S. patent No. 3,609,087 have inferior heat and mass transfer properties in LiBr absorption fluids as compared to ketones of the present invention, and are thus excluded. Preferred aliphatic ketones are those in which R, and R 2 are alkyl groups having from 1 to 8 carbon atoms, and wherein either or both of the alkyl groups are substituted, preferably halogen substituted, and more preferably fluoro substituted. Examples of preferred aliphatic ketones include 4-methyl-2-pentanone, 5-methyl-2-hexanone, 3,3-dimethyl-2-hexanone, 2-pentaπone, 3-pentanone, 2,4-dimethyl-3-pentaπone, 2-hexanone, 4 methyl-2 hexanone, 5-methyI-2-hexaπone, 2- heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, 4-octanone, noπanone and decanone. Cycloaliphatic ketones, and particulariy cyclohexanone and alkyl and halogen substituted derivatives are also effective additives. Aromatic ketones include acetophenone (methyl phenyl ketone) and benzophenone (phenyl ketone) and their alkyl and halogen substituted derivatives. The aldehydes used as heat and mass transfer additives within the scope of the invention are aliphatic aldehydes having from 5 to 24 carbon atoms, and more preferably from 6 to 14 carbon atoms in the aliphatic or alkyl chain, which also may be halogen substituted. Specific aliphatic aldehydes are hexanal, heptanal, octanal, nonanal, decanal, etc. and longer chain aldehydes for example, lauryl aldehyde (C-12) and myristic aldehyde (C-14). Useful aromatic aldehydes include benzaldehyde, anisaldehyde and substituted aromatic aldehydes including ether and hydroxy substituted compounds such as vanillin (3-methoxy-4-hydroxy benzaldehyde). The ketones and aldehydes may also include one or more other functional groups, particularly halogens and more preferably chlorine or fluorine substituted molecules as previously disclosed. In addition, the molecules may also contain alcohol, thiol, amine, and ether groups, provided such functional groups do not cause the additive to form a precipitate or otherwise induce chemical instability in the presence of the metal salt solutions. Combinations of ketones and/or aldehydes may also be found suitable for different salts or salt combinations. Effective additive amounts of ketone or aldehyde added to the aqueous salt solutions for the purpose of improving heat and mass transfer are from at least about two parts per million preferably up to about 20,000 ppm, by weight. Preferred concentrations are between about 2 ppm and 10,000 ppm and more preferably between about 5 ppm and about 5,000 ppm, although amounts in excess of this range up to 20,000 ppm or more will not adversely affect the system operation. Mixtures of the aforesaid additives may also be used. In addition to mixtures of the ketones and aldehydes, the additives may be used with other known heat and mass transfer additives which may be present or added to the absorption fluid. Examples of such known additives are alcohols, particularly those having 6-10 carbon atoms such as 2-ethylhexanol or n-octanol and amines disclosed in U.S. Patent No. 5,419,145 and application serial No. 08/443,707, the descriptions of which are incorporated herein by reference. According to the invention, it has been found that the presence of one or more ketones or aldehydes in the aforesaid aqueous absorption fluids results in substantially improved heat and mass transfer performance of the absorption working fluid composition. Specifically, the performance of the system improves in the following manner: water cooling temperature change in the absorber, for a constant water flow rate, rises significantly; the absorber power load increases proportional to the change in water cooling temperature; the steady state process vapor pressure drops, and if brought back to its initial value to achieve a constant evaporator temperature, the change in concentration of the absorber fluid increases significantly; the absorber solution subcooling, i.e., the difference between the maximum temperature at equilibrium (saturation) and the actual solution temperature, is decreased by several degrees; the absorber heat exchanger tube (solution side) interface comprises a highly agitated turbulent film as compared to a generally laminar flow pattern without presence of the additive; and overall heat transfer coefficients and sorption fluid film heat transfer coefficients are increased. As previously noted, water vapor absorption systems incorporating the heat and mass transfer additives in the aqueous alkali metal absorption solutions of the invention include a number of different types of systems incorporating one or more absorbers in which water vapor absorption solutions are typically used. Such equipment includes absorption chillers and refrigeration systems as disclosed in U.S. Patents 4,966,007, 5,038,574 and 5,186,009, thermal energy storage systems as disclosed in U.S. Patent 4,823,864, as well as multiple effect absorption systems, for example, double effect and dual loop systems disclosed in U.S. patents 3,266,266 and 4,542,628, triple effect systems disclosed in U.S. patents 5,335,515 and 5,390,509 and multiple effect systems resulting from a combination of single or double effect apparatus such as the triple effect system comprising combined single effect circuits as described in U.S. Patent No. 5,205,136 as well as single effect chillers and commonly used double effect chillers and heat transformers. The aqueous working fluids of the invention may also contain a corrosion inhibitor such a chromate, nitrate, tungstate or molybdate, as disclosed for example in U.S. patents 5,186,009 and 5,335,515 or any other suitable corrosion inhibitors. Where aldehydes are present, the use of certain corrosion inhibitors may be restricted to avoid aldehyde oxidation. To illustrate the improvement of system performance by using the heat and mass transfer additives of the present invention, the following examples are provided. In the Table, additives within the scope of the present invention are shown by way of example. The results given are for a constant set of operating conditions and include: initial cooling water ("Tube") temperature of 30°C, a system water vapor pressure of 10 mbar, 7°C dew point (evaporator temperature), initial aqueous solution concentration of 60% LiBr, initial solution flow rate of 400 grams/min, and initial solution temperature of 48°C entering the absorber, using a special bench test absorption machine. The solution flow rate used with the cyclohexanone additive is 500 grams/min. The water and solution temperatures, flow rates and vapor pressures are taken from monitor readings during operation. The concentrations are determined from fluid samples taken from the machine. The results are based on heat transfer equations well known to practitioners of the art. The absorber load dQ/dt, shown as W, is calculated from the water temperature, heat capacity of water, and water flow rates, -g dQj. _ " ( { τ ■L H 2 0 , out _ τ 1 H 2 Q . i .n )> * c ^p (H l -2O u )' * d — t (1) For the heat transfer coefficients, the temperature change is treated as the log mean differential temperature, where LMDT ~ l n ( τ — ψ ) - i t r X~T T The outside film heat transfer coefficient h„ is calculated from 1 (3) -ϋo ' Ri 'm where dQ dt (4) £/- - = ° LMDT * ( tube area) and where R ιm is the thermal resistivity of the inside cooling water and copper metal tube wall. Solution subcooling is the temperature difference (ΔT) between the actual solution temperature leaving the absorber and the calculated absorber solution equilibrium temperature at the measured concentration and system vapor pressure values. Thus, lower subcooling temperature values reflect greater system efficiency as do increased outside film heat transfer coefficients, h 0 . The value calculated for solution subcooling is one measure of the efficiency of the system for water vapor absorption, with lower subcooling temperatures indicating an improvement. However, under certain b conditions, the derived subcooling numbers may be contrary to other direct measurements of water vapor absorption. In the Table some data show higher calculated solution subcooling while also showing increased water vapor absorption rates by increases in absorber loads, and increases in heat transfer coefficients. Thus, the derived subcooling results are to be checked against other direct evidence of increased absorption rates. TABLE Load ho Subcooling Additive ppm W W/m2K °C 2-octanone 0 900 1110 6.03 0 880 976 4.41 0 915 996 3.69 0 914 1011 3.99 0 835 920 5.39 0 921 1068 4.43 5.3 1784 3591 4.73 5.3 1773 3105 3.49 5.3 1739 2897 3.17 5.3 1735 2795 2.96 5.3 1596 2309 2.55 11.9 1866 3809 4.13 11.9 1866 3641 3.66 11.9 1866 3768 3.97 19.7 1908 4333 4.56 19.7 1872 4225 4.69 19.7 1893 4083 4.56 47.3 1878 4803 5.51 47.3 1960 4862 4.94 47.3 1953 4948 5.02 47.3 1919 4555 4.91 47.3 1902 4356 4.75 93.4 1946 4977 5.36 93.4 1927 4752 4.63 93.4 1914 4651 4.61 191.6 1770 4425 5.70 191.6 1833 4726 5.48 191.6 1791 5420 6.73 300 1848 5168 6.22 300 1848 5168 6.22 Load ho Subcooling A nruiriuiituivvpG pom W W|m2K °C 2-octanone (con't) 300 1799 4754 6.52 300 1858 5218 6.00 300 1893 5160 5.80 i 300 1965 5295 5.58 400 1819 4497 5.33 400 1923 4805 5.03 400 1925 4752 5.00 400 1959 4778 5.17 ) 400 1917 4632 5.46 400 1924 4711 5.44 500 1805 4494 5.66 500 1813 4430 5.63 500 1872 4756 5.39 ϊ 500 1895 4762 5.36 500 1936 5090 5.44 500 1909 4845 5.33 750 1768 4228 5.82 750 1824 4402 5.83 3 750 1959 4737 5.17 750 1853 4792 5.28 Load ho Subcooling Additive ppm W W/m2K °C 4-methyl-2-pentanone 0 938 997 2.29 0 837 952 3.60 0 879 961 3.10 0 978 1154 5.02 0 901 1041 4.88 0 960 1133 4.83 5 1272 1788 2.79 5 1331 1795 3.51 5 1300 1770 3.64 10 1344 2152 4.47 10 1401 2199 4.61 10 1366 2173 4.59 20 1431 2384 4.69 20 1450 2198 3.58 20 1430 2203 3.68 50 1466 3211 6.81 50 1516 3246 6.14 50 1502 3245 6.02 100 1497 3575 6.98 100 1519 3459 7.11 100 1502 3399 6.69 200 1256 2849 8.02 200 1370 2978 7.61 200 1418 3100 7.23 500 1252 2750 8.53 500 1346 2877 7.64 500 1375 2874 7.09 1 9 Load ho Subcooling Additive ppm W W/m2K °C cyclohexanone 0 1063 1379 5.1 0 1074 1369 4.7 0 1072 1383 4.8 5.1 1175 1443 3.3 5.1 1176 1426 3.2 5.1 1171 1419 3.2 10.4 1319 1560 1.6 10.4 1316 1563 1.7 10.4 1331 1688 2.9 20.5 1536 2087 2.0 20.5 1556 2095 1.9 20.5 1547 2066 1.8 50.2 1804 2731 1.4 50.2 1844 2632 0.9 50.2 1814 2584 0.7 100 1989 2977 0.5 100 2009 3037 0.7 200 1967 3203 1.1 200 1965 3122 0.8 200 1963 3094 0.8 348 1953 3378 1.8 348 1980 3222 0.9 348 1991 3196 0.8 501 1971 3411 1.7 501 1971 3420 1.6 501 1966 3264 1.2 100 1892 3134 1.8 100 1888 3081 1.5 100 1872 3022 1.5 1500 1811 2927 2.1 1500 1786 2861 1.9 1500 1808 2878 1.9 From the test results given in the Table, utilizing representative examples of ketones according to the invention, the improvements of the operating condition performance, taken from actual measurements of the laboratory bench test system as well as calculated values for fluid film heat transfer coefficients (h„) are shown. Additionally, the absorber power load increases are shown as are the significant decreases in solution subcooling at the operating conditions. Calculated values of film heat transfer coefficients (h„) are also increased.

Claims: WE CLAIM: I . A water vapor absorption cycle cooling and/or heating system containing a working fluid comprising an aqueous solution of a metal salt comprising lithium bromide, lithium chloride, lithium iodide, or mixtures of two or more thereof, and an effective additive amount of at least 2 parts per million, by weight of an aliphatic, cycloaliphatic or aromatic ketone or aldehyde having between 5 and 24 carbon atoms for increasing the rate of water vapor sorption of said working fluid, said aliphatic ketone being of the formula R,(C-0)R 2 wherein R, and R 2 are the same or different alkyl and substituted alkyl groups of from 1 to 12 carbon atoms and wherein when R, is a methyl group the carbon atom of the other alkyl group R 2 attached to the carbonyl group is a primary or tertiary carbon atom. 2. A system of Claim 1 wherein said ketone and said aldehyde are insoluble or slightly soluble in said working fluid and are liquid at 100°C and at 20°C or below. 3. A system of Claim 1 wherein the additive in said working fluid is an aliphatic ketone wherein said R, and R 2 are alkyl groups having from 1 to 8 carbon atoms. 4. A system of Claim 3 wherein either or both of said alkyl groups are halogen substituted. 5. A system of Claim 3 wherein either or both of said alkyl groups are fluoro substituted. 6. A system of Claim 1 wherein said working fluid contains a mixture of said ketones. 7. A system of Claim 1 wherein said working fluid contains a mixture of said aldehydes. 8. A system of Claim 1 wherein said working fluid contains a mixture of one or more of said ketones and one or more of said aldehydes. 9. A system of Claim 1 wherein said ketone and said aldehyde are substantially completely soluble in said working fluid at 20°C and above. 10. A system of Claim 1 wherein said working fluid contains between 2 ppm and about 20,000 ppm, by weight of said additive. II. A system of Claim 1 wherein said working fluid contains between 2 ppm and about 10,000 ppm, by weight of said additive. 12. A system of Claim 1 wherein the additive is a ketone selected from the group consisting of 2- pentanone, 3-pentanone, 4-methyl-2-pentanone, 2,4-dimethyl-3-pentanone, 2-hexanone, 3,3-dimethyl-2-hexanone, 4- methyl-2-hexanone, 5-methyl-2-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-octanone, 3-octaπone, 4-octanone, cyclohexanone, benzophenone and acetophenone. 13. A system of Claim 1 wherein the additive is an aliphatic aldehyde having between 6 and 14 carbon atoms. 14. A system of Claim 13 wherein said aldehyde is halogen substituted. 15. A system of Claim 1 wherein said working fluid contains lithium bromide and one or more salts selected from the group consisting of ZnCl ZnBr 2 , MnCI 2 , MnBr 2 , MgCI 2 , MgBr 2 , SrCI 2 , SrBr 2 , FeCI 2 , FeBr 2 , CaCI 2 , CaBr 2 , LiCl, Ul, LiN0 2 , LiN0 3 , LiSCN and LiCI0 3 . 16. A system of Claim 1 wherein said cooling and/or heating system comprises a single or double effect absorption apparatus and wherein said metal salt comprises lithium bromide. 17. A system of Claim 1 wherein said additive is a ketone, and wherein said metal salt includes sodium hydroxide, potassium hydroxide or mixtures thereof. 18. A system of Claim 1 wherein said additive is a ketone, and wherein said metal salt is a hydroxide comprising one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, rubidium hydroxide or lithium hydroxide. 19. A system of Ciaim 1 wherein said working fluid contains in addition to said ketone or said aldehyde, an additive amount of an alcohol or an amine heat and mass transfer additive. 20. A water vapor absorption cycle cooling and/or heating system containing a working fluid comprising an aqueous solution of a metal salt selected from the group consisting of lithium bromide, lithium chloride, lithium iodide, and mixtures of two or more thereof, and sodium hydroxide, potassium hydroxide and mixtures of said hydroxides, and an effective additive amount of at least 2 parts per million, by weight of an aliphatic, cycloaliphatic or aromatic ketone having between 5 and 24 carbon atoms for increasing the rate of water vapor sorption of said working fluid, said aliphatic ketone being of the formula R,(C-0)R 2 wherein R, and R 2 are the same or different alkyl and substituted alkyl groups of from 1 to 12 carbon atoms and wherein when R, is a methyl group the carbon atom of the other alkyl group R 2 attached to the carbonyl group is a primary or tertiary carbon atom. 21. A system of Claim 20, wherein said working fluid contains in addition to said ketone, an additive amount of an alcohol or an amine heat and mass transfer additive. 22. In operation of an absorption cycle cooling and/or heating system including an absorber containing an aqueous metal salt absorption solution for absorbing water vapor therein and wherein said metal salt comprises an alkali metal halide, a method of improving the rate of water vapor absorption in said absorption solution comprising adding thereto an effective additive amount of at least 2 parts per million, by weight, of an aliphatic, cycloaliphatic, or aromatic ketone or aldehyde having between 5 and 24 carbon atoms and capable of increasing said rate of water vapor absorption, said aliphatic ketone being of the formula R,(C=0)R 2 wherein R, and R 2 are the same or different alkyl and substituted alkyl groups of from 1 to 12 carbon atoms and wherein when R, is a methyl group the carbon atom of the other alkyl group R 2 attached to the carbonyl group is a primary or tertiary carbon atom. 23. A method of Claim 22 wherein said ketone and said aldehyde are insoluble or slightly soluble in said working fluid and are liquid at 100°C and at 20°C or below. 24. A method of Claim 22 wherein the additive in said working fluid is an aliphatic ketone wherein said R, and R 2 are alkyl groups having from 1 to 8 carbon atoms. 25. A method of Claim 22 wherein either or both of said alkyl groups are halogen substituted. 26. A method of Claim 22 wherein either or both of said alkyl groups are fluoro substituted. 27. A method of Ciaim 22 wherein said working fluid contains a mixture of said ketones. 28. A method of Claim 22 wherein said working fluid contains a mixture of said aldehydes. 29. A method of Claim 22 wherein said working fluid contains a mixture of one or more of said ketones and one or more of said aldehydes. 30. A method of Claim 22 wherein said ketone and said aldehyde are substantially completely soluble in said working fluid at 20°C and above. 31. A method of Claim 22 wherein said working fluid contains between 2 ppm and about 20,000 ppm, by weight of said additive. 32. A method of Claim 22 wherein said working fluid contains between 2 ppm and about 10,000 ppm, by weight of said additive. 33. A method of Claim 22 wherein the additive is a ketone selected from the group consisting of 2- pentanone, 3-pentanone, 4-methyl-2-pentanone, 2,4-dimethyl-3-pentanone, 2-hexanone, 3,3-dimethyI-2-hexanone, 4- methyl-2-hexanone, 5-methyl-2-hexanone, 2-heptanoπe, 3-heptanone, 4-heptanone, 2-octanone, 3-octanone, and 4- octanone, cyclohexanone, benzophenone and acetophenone. 34. A method of Claim 22 wherein the additive is an aliphatic aldehyde having between 6 and 14 carbon atoms. 35. A method of Ciaim 22 wherein said aldehyde is halogen substituted. 36. A method of Claim 22 wherein said working fluid contains lithium bromide and one or more salts selected from the group consisting of ZnCl ZnBr 2 , MnCI 2 , MnBr 2 , MgCI 2 , MgBr 2 , SrCI 2 , SrBr 2 , FeCI 2 , FeBr 2 , CaCI 2 , CaBr 2 , LiCl, Lil, LiN0 2 , UNO* LiSCN and LiCI0 3 . 37. A method of Claim 22 wherein said cooling and/or heating system comprises a single or double effect absorption apparatus and wherein said metal salt comprises lithium bromide. 38. A method of Claim 22 wherein said additive is a ketone, and wherein said metal salt includes sodium hydroxide, potassium hydroxide or mixtures thereof. 39. A method of Claim 22 wherein said additive is a ketone, and wherein said metal salt is a hydroxide comprising one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, rubidium hydroxide or lithium hydroxide. 40. In operation of an absorption cycle cooling and/or heating system including an absorber containing an aqueous metal salt absorption solution for absorbing water vapor therein and wherein said metal salt is selected from the group consisting of an alkali metal halide, sodium hydroxide, potassium hydroxide and mixtures of said hydroxides, a method of improving the rate of water vapor absorption in said absorption solution comprising adding thereto an effective additive amount of at least 2 parts per million, by weight, of an aliphatic, cycloaliphatic, or aromatic ketone having between 5 and 24 carbon atoms and capable of increasing said rate of water vapor absorption, said aliphatic ketone being of the formula R,(C-0)R 2 wherein R, and R 2 are the same or different alkyl and substituted alkyl groups of from 1 to 12 carbon atoms and wherein when R, is a methyl group, the carbon atom of the other alkyl group R 2 attached to the carbonyl group is a primary or tertiary carbon atom.

Inventors: CHANDLER TRAVIS, ROCKENFELLER UWE, CHANDLER, TRAVIS, ROCKENFELLER, UWE
Applicants: ROCKY RESEARCH
Application year: 1996
Main classification: C09K5
IPC codes: C09K5, F25B15