Compositions – Vaporization – or expansion – refrigeration or heat or energy... – With low-volatile solvent or absorbent
Patent
1995-06-15
1998-03-10
Lieberman, Paul
Compositions
Vaporization, or expansion, refrigeration or heat or energy...
With low-volatile solvent or absorbent
252 73, 252 77, C10M17302, C09K 502, C09K 504
Patent
active
057257930
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to agents for absorption machines according to the introductory part of claim 1.
In particular, agents respectively agents systems can be utilized in absorption machines such as absorption heat pumps, absorption refrigerating machines, absorption heat transformers and absorption compression heat pumps and absorption compression refrigerating machines.
2. State of the Art
With the regard to the state of the art, reference is made to the following literature: 1954, Absorptionskaltemachine. Plank, Hsg., Bd. 7, Springer, Berlin, etc., 1959. Absorptions-Kalteanlagen, Verfahrenstechnik 6 (1972), 390-399. Stoffpaar Ammoniak-Wasser, Dissertation, ETH Nr. 7070, Zurich, 1982. Brennstoff-Warme-Kraft, 40 (1988), 250-55. Chem.-Ing.-Techn., 60 (1988), 335-48. der Sicht des Anwenders, Chem.-Ing.-Tech., 60 (1988), 103-8.
Reference is explicitly made to this state of the art with regard to all terms not made more apparent herein.
Absorption machines are very environmental friendly, but relatively complicated and expensive machines for producing effective heat and refrigeration. The high investment costs, the control difficulties, the unfavorable partial load behavior and the relatively low thermal output figures, which are, in the case of heat pumps, usually little above 1, have hitherto stood in the way of more widespread use. This, however, is not true for small refrigerating aggregates for home, hotel and leisure time use, such as for cold water sets and air-conditioning devices used in countries such as the USA and Japan.
As the output figures, i.e., the ratio of effective heat respectively refrigeration to the applied heat, decisively depends on the choice of a "suited" pair of agents, work began early on new relatively optimum pairs of agents. In the field of refrigerating machines and low-temperature heat pumps, the agent pair ammonia (NH.sub.3) as the refrigerant with water (H.sub.2 O) as the solvent has proven itself in small plants as well as in large plants up to a power of several megawatts. Certain drawbacks of this pair of agents are that certain of parts water evaporate along with the ammonia when expelling the ammonia in the generator of a machine.
Since as pure as possible agents are required for obtaining low temperatures, it is necessary to provide a agent vapor purifier (dephlegmator) in the plant. This naturally raises the investment costs as well as the operation costs respectively lowers the output figures of the overall process.
Moreover, the high vapor pressure of ammonia has an unfavorable effect on dimensioning the heat exchangers and pipe lines and on the heat transition figures. In addition, aqueous ammonia solutions are corrosive, in particular, at high temperatures, i.e. require the use of corrosion inhibitors, such as, e.g., chromic salt (Na.sub.2 Cro.sub.4).
Various authors have proposed raising the output figures of absorption machines employing the technically proven agent system ammonia (NH.sub.3)-water (H.sub.2) by adding various types of salt.
With regard to this, reference is made to EP-A-O 012 856 as well as the literature mentioned in DE-PS 28 55 434 of the same priority or to A. Zimmermann, Experimentelle Untersuchung der Dampf-Flussigkeit-Phasengleichgewichte im Stoffsystem NH.sub.3 --H.sub.2 O--LiBr, dissertation, University of Siegen, GH, 1991.
The addition of salts to the solvent water, however, presents problems. Often the so-called solution range of ammonia is greatly reduced in the pressure-temperature-diagram, i.e., there is a danger that solid phases, e.g. ammonia salt compounds precipitate during the absorption process in the solution and cause serious disturbances.
Such results were published by R. Peters, R. Busse, J. U. Keller in "Solid-Liquid Equilibria in the Systems NH.sub.3 --H.sub.2 O--LiBr and H.sub.2 O--LiBr at p=1 atm in the Range from -35.degree. to 80.degree. C.", (Journal of Thermophysics, Vol. 14, No. 4, 1993).
Furthermore, it was discovered that, e.g., although the large addition of LiBr to NH.s
REFERENCES:
patent: 4614605 (1986-09-01), Erickson
patent: 5186009 (1993-02-01), Rockenfeller
Keller Jurgen
Peters Ralf
Kopec Mark
Lieberman Paul
Universitat Siegan
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