Method for use of liquid/vapor ammonia absorption systems in unitary HVAC systems

Abstract

A liquid vapor absorption system comprises: one or more absorbers, one or more generators, and a fluid loop for directing refrigerant absorption fluid between the absorbers and generators, heat exchangers for selectively functioning as an evaporator or a condenser and cooperating with an indoor coil for recovering thermal energy, a reservoir for condensed refrigerant, a phase-change thermosyphon loop for directing condensed refrigerant from the reservoir to the heat exchange section of an absorber for removing heat of absorption, and a reversing valve means for selectively directing gaseous refrigerant to the heat exchangers functioning as a condenser, and for simultaneously directing gaseous refrigerant from the heat exchangers functioning as an evaporator to the absorber.

Description

BACKGROUND OF THE INVENTIONThe invention relates to absorption beat pump systems and particularly to liquid / vapor absorption systems using ammonia refrigerant and water, salt, or salt and water absorbents. Thermal efficiencies of such systems have been improved during the past years by use of innovative heat recuperation within the absorber as well as between the one or more absorbers and the generator. Such improvements use absorber heat exchangers as well as generator / absorber heat exchange facilitated by use of the rich or weak absorption working fluid or by separate heat exchange loop. Detailed descriptions on the use and implementation can be found in U.S. Pat. Nos. 4,311,019, 5,024,063, 5,271,235, 5,367,884; R. J. Modahl and F. C. Hayes, "Evaluation of Commercial Advanced Absorption Heat Pump Breadboard", The Trane Company pp. 117-125, 1988, as well as numerous other publications. While all of the above improvements are intended to increase the rating or seasonal thermal effic...

AI Technical Summary

Benefits of technology

The separation of indoor and outdoor unit heat transfer interface not only eliminates the need for a secondary brine between the sorption cycle and the outdoor coil, but also allows for use of a more efficient brine for interface with the indoor coil only since the operating temperature range of the indoor coil is limited to about 33.degree. F. to 140.degree. F. Freeze point protection is only required for safety without need to operate at low temperatures, and less viscous fluids can be employed. It is also possible to use an environmentally acceptable phase change material, e.g. HFC, for heat transfer in this secondary loop even though such material may not be generally suitable in vapor compression processes.

a reversing valve means, e.g. four way valve, to facilitate the switching of evaporator and condenser function,

Problems solved by technology

While vapor compression systems are designed to exchange useful heat via condenser and evaporator only, absorption systems have the complication that a good portion of the heat is generated in the absorber.

It is also possible to use an environmentally acceptable phase change material, e.g. HFC, for heat transfer in this secondary loop even though such material may not be generally suitable in vapor compression processes.

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