Methods and systems for liquid desiccant air conditioning system retrofit
View Patent ↗Methods and systems are disclosed for utilizing liquid desiccant air conditioning systems in connection with existing HVAC equipment to achieve reductions in electricity consumption.
1. A method for increasing energy efficiency of an air conditioning system for a building, said air conditioning system comprising a plurality of existing air conditioning units mounted on a rooftop of the building, the method comprising:
(a) removing some, but not all, of the plurality of air conditioning units from the rooftop;
(b) installing a liquid desiccant air-conditioning unit on the rooftop in place of each removed air conditioning unit, said liquid desiccant air-conditioning unit being switchable between operating in a warm weather operation mode and in a cold weather operation mode, each liquid desiccant air-conditioning unit comprising:
a conditioner configured to expose a ventilation air stream entering the building from outside the building to a liquid desiccant such that the liquid desiccant dehumidifies the ventilation air stream in the warm weather operation mode and humidifies the ventilation air stream in the cold weather operation mode; and
a regenerator connected to the conditioner and configured to expose an air stream to the liquid desiccant such that the liquid desiccant humidifies the air stream in the warm weather operation mode and dehumidifies the air stream in the cold weather operation mode; and
(c) completely transferring a ventilation air stream treatment load from the one or more air conditioning units remaining on the rooftop to each liquid desiccant air-conditioning unit by reconfiguring the one or more air conditioning units remaining on the rooftop such that any intake of a ventilation air stream for the building in said one or more air conditioning units is eliminated by removing power to a damper motor of the one or more air-conditioning units remaining on the rooftop or removing a lever from a damper mechanism of the one or more air-conditioning units remaining on the rooftop.
2. The method of claim 1 , wherein the conditioner includes a plurality of structures arranged in a vertical orientation, each structure having at least one surface across which the liquid desiccant can flow, wherein the ventilation air stream flows between the structures, and wherein the regenerator includes a plurality of structures arranged in a vertical orientation, each structure having at least one surface across which the liquid desiccant can flow, wherein a return air stream flows between the structures.
3. The method of claim 2 , wherein each of the plurality of structures in the regenerator and conditioner includes an internal passage through which a heat transfer fluid can flow for transfer of heat between the heat transfer fluid and the liquid desiccant or the ventilation air stream or the return air stream.
4. The method of claim 3 , wherein each of the plurality of structures in the regenerator and conditioner includes a sheet of material positioned proximate to the outer surface of each structure between the liquid desiccant and an air stream, said sheet of material permitting transfer of water vapor between the liquid desiccant and the ventilation air stream or the return air stream.
5. The method of claim 4 , wherein the sheet of material comprises a membrane.
6. The method of claim 2 , wherein said plurality of structures in the regenerator and conditioner comprise a plurality of plate assemblies arranged in a vertical orientation and spaced apart to permit flow of the air stream between adjacent plate assemblies.
7. The method of claim 1 , wherein the ventilation air stream entering the building flows in a vertical direction through the conditioner and the air stream flowing in the regenerator flows in a vertical direction.
8. The method of claim 1 , wherein the ventilation air stream entering the building flows in a generally horizontal direction through the conditioner and the air stream flowing in the regenerator flows in a generally horizontal direction.
9. The method of claim 1 , wherein each liquid desiccant air-conditioning unit further comprises a heat pump for pumping heat from the conditioner to the regenerator in the warm weather operation mode and pumping heat from the regenerator to the conditioner in the cold weather operation mode.
10. The method of claim 9 , wherein the heat pump pumps heat from the liquid desiccant flowing in the conditioner to the liquid desiccant flowing in the regenerator in the warm weather operation mode, and wherein the heat pump pumps heat from the liquid desiccant flowing in the regenerator to the liquid desiccant flowing in the conditioner in the cold weather operation mode.
11. The method of claim 9 , wherein the heat pump pumps heat from a heat transfer fluid flowing in the conditioner to a heat transfer fluid flowing in the regenerator in the warm weather operation mode, and wherein the heat pump pumps heat from the heat transfer fluid flowing in the regenerator to the heat transfer fluid flowing in the conditioner in the cold weather operation mode.
12. The method of claim 1 , wherein each liquid desiccant air-conditioning unit further comprises a heat exchanger connected between the conditioner and the regenerator for transferring heat from the liquid desiccant flowing from one of the regenerator and the conditioner to the liquid desiccant flowing from the other of the regenerator and conditioner.
13. The method of claim 1 , wherein every one out of three to one out of five of the removed air conditioning units is replaced by a liquid desiccant air-conditioning unit.
14. The method of claim 1 , wherein reconfiguring the one or more air conditioning units comprises recirculating a return air stream from the building through a coil of an evaporator of each of said one or more air conditioning units, and increasing the operating temperature of the evaporator.
15. The method of claim 1 , reconfiguring the one or more air conditioning units remaining on the rooftop comprises closing a damper therein to reduce or eliminate intake of a ventilation air stream.
16. The method of claim 1 , wherein step (c) further comprises changing an evaporator temperature setting of the one or more air conditioning units remaining on the rooftop to a higher temperature setting.
17. The method of claim 16 , wherein the higher temperature setting increases the evaporator temperature such that substantially no condensation forms on the evaporator.
18. The method of claim 16 , wherein the higher temperature setting is 50-60° F.