Refrigeration – Processes – Circulating external gas
Reexamination Certificate
2003-01-27
2004-07-06
Doerrler, William C. (Department: 3744)
Refrigeration
Processes
Circulating external gas
C062S238300, C062S480000, C062S271000
Reexamination Certificate
active
06758048
ABSTRACT:
BACKGROUND OF INVENTION
Technical Field
The present invention relates generally to an air-conditioning system and more particularly relates to an air-conditioning system using the waste heat from a microturbine to regenerate a desiccant system.
A HVAC system (Heating, Ventilating, and Air-conditioning) generally includes three components or goals: (1) temperature management, (2) humidity management, and (3) air quality management. Temperature management generally may be achieved with a basic dry bulb thermostat coupled to a furnace and an air-conditioning system. The thermostat may accurately indicate when the furnace or the air-conditioning system should be activated.
Although the thermostat may manage the temperature of the air, the thermostat generally does not take into account the humidity level. Rather, humidity control generally may be accomplished by cooling the intake air below its dew point. The humidity within the air may then be condensed and removed from the system as a liquid. Once the humidity has been condensed, however, the air generally should be reheated before use so as to bring the air back to a comfortable temperature. Although this technique may remove a sufficient amount of humidity from the air stream, the energy requirements may be significant given the need to lower the air temperature below the desired temperature and then reheat the air.
Similarly, exhausting the spent interior air or mixing only a portion of the interior air with the intake air, as opposed to reusing the conditioned air, generally accomplishes air quality management. Specifically, most of the spent interior air is exhausted back to the environment and fresh intake air is chilled as described above. Again, this method is effective in maintaining air quality although it may be energy intensive.
An alternative method of humidity control is the use of a desiccant system. In a desiccant system, the intake air may pass through a desiccant wheel before being cooled. The desiccant wheel may include a desiccant material such as a silica gel, titanium silicates, or some type of zeolite (hydrous silicates). The desiccant material absorbs all or part of the humidity in the air. As the desiccant material becomes saturated with the humidity in the incoming air stream, the wheel is rotated and the humidity may be expelled with an opposing stream of hot air. The hot air dries or “regenerates” the material such that it is again ready for use. A heating device of some sort generally may produce the hot air stream. The desiccant wheel may be continually rotated such that one portion is absorbing the humidity from the incoming air stream and one portion is releasing the humidity in the regeneration air stream.
Once the incoming air stream has been stripped of its humidity, the air stream then may be chilled to the desired temperature via a conventional cooling system. Because the temperature of the air need not be reduced as far as is required in traditional systems to reduce the humidity level, the air stream may not need to be reheated so as to bring the air back up to a comfortable temperature.
There is a desire therefore to provide a HVAC system with efficient use of a desiccant system so as to provide improved temperature and humidity control. The HVAC system preferably can provide these improvements in a less energy intensive manner than known systems while also being cost effective in terms of installation and use.
SUMMARY OF INVENTION
The present invention thus provides a system for conditioning air. The system may include a turbine for generating waste heat and a desiccant system for removing humidity from the air. The desiccant system may be in communication with the turbine so as to use the waste heat for regeneration. The system also may include a cooling system so as to cool the air after the air passes through the desiccant system.
The turbine may include a microturbine and may be driven by natural gas. The turbine may generate waste heat of about 150° to about 540° Celsius (about 300° to about 1000 F.). The turbine also may generate electrical power. The desiccant system may include a desiccant wheel. The desiccant system may include a humidity control system for adjusting the relative humidity level. The cooling system may include a cooling coil. The cooling system may include a temperature control system for adjusting the temperature level.
The system further may include one or more intake ducts so as to direct the air through the desiccant system and the cooling system and into a space for conditioning. Likewise, the system may include one or more return ducts so as to direct the air from the space. One or more recirculation ducts may be positioned so as to direct the air from the return ducts to the intake ducts. A heat exchanger may be positioned between the desiccant wheel and the cooling system so as to exchange heat between the air in the intake ducts and the recirculation ducts. The heat exchanger may include a heat wheel. The heat wheel may include a desiccant material.
A further embodiment of the present invention may provide an air system for conditioning ambient air for a predetermined space. The system may include microturbine generation means for generating waste heat and desiccant means for removing humidity from the ambient air. The desiccant means may be in communication with the generation means so as to use the waste heat for regeneration. The system also may include cooling means for cooling the ambient air after the ambient air passes through the desiccant means.
A further embodiment of the present invention may provide an air-conditioning system. The air conditioning system may a microturbine for generating electrical power and a waste heat stream and a desiccant wheel for removing humidity from an incoming air stream. The desiccant wheel may be in communication with the microturbine so as to use the waste heat for removing moisture therefrom. The system also may include a cooling system to cool the incoming air stream by a predetermined amount after the incoming air stream passes through the desiccant wheel.
A method of the present invention provides for conditioning ambient air. The method includes the steps of generating waste heat via a turbine, removing humidity from the ambient air with a desiccant system, regenerating the desiccant system with the waste heat, and cooling the ambient air to chilled air after the ambient air passes through the desiccant system. The method further may include the steps of conditioning a space with the chilled air and mixing the chilled air with the ambient air after the chilled air passes through the space.
These and other features of the present invention will become apparent upon review of the following detailed description of the invention when taken in conjunction with the drawings and the appended claims.
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1998 International Gas Research Conference, Title “Development of a Small-Scale Directly Gas-Fired Integrated HVAC System”, by Prof. Dr.-Ing. G. Schmitz and Dipl.-Ing. R. Mockel; pp. 771-777.
Doerrler William C.
General Electric Company
Sutherland & Asbill & Brennan LLP
Zec Filip
LandOfFree
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