Heat-pump driven desiccant regeneration
Disclosed herein are systems and processes to thermally regenerate and re-concentrate a liquid desiccant (absorbent) with an electrically driven heat pump. The regeneration and re-concentration may be performed in a cost and energy efficient manner.
1. A method comprising:
removing a moisture from a first air stream using a desiccant to absorb the moisture;
operating a heat pump comprising a refrigerant stream circulating through an evaporator, a compressor, a valve, and a condenser;
routing the desiccant that is diluted with the moisture through the condenser to heat the desiccant and evaporate the moisture;
collecting the evaporated moisture using a second air stream also routed through the condenser; and
depositing the evaporated moisture in the evaporator by routing the second air stream through the evaporator.
2. The method of claim 1 , further comprising cooling the first air stream using evaporative cooling.
3. The method of claim 2 , wherein the evaporated moisture collected in the evaporator is used to provide the evaporative cooling.
4. The method of claim 1 , wherein:
the second air stream is routed through an air-to-refrigerant heat exchanger prior to entering the condenser, and
the refrigerant is routed through the air-to-refrigerant heat exchanger after exiting the condenser.
5. The method of claim 1 , wherein the second air stream is routed through an air-to-air heat exchanger after exiting the condenser but prior to entering the evaporator.
6. The method of claim 5 , wherein the second air stream is routed through the air-to-air heat exchanger prior to entering the condenser.
7. The method of claim 5 , wherein the second air stream is routed through the air-to-air heat exchanger after exiting the evaporator.
8. The method of claim 1 , further comprising:
splitting the refrigerant stream exiting the compressor into a first refrigerant stream and a second refrigerant stream using a three-way valve;
routing the first refrigerant stream through the condenser;
routing the second refrigerant stream and the first air stream through a first air-to-refrigerant heat exchanger;
combining the first refrigerant stream and the second refrigerant stream into a unified refrigerant stream;
routing the unified refrigerant stream through a second air-to-refrigerant heat exchanger; and
routing the second air stream through the second air-to-refrigerant heat exchanger prior to entering the condenser.
9. The method of claim 8 , wherein the first air stream is heated by the first air-to-refrigerant heat exchanger.
10. The method of claim 1 , wherein:
the refrigerant stream bypasses the condenser,
the refrigerant stream is used to heat a secondary fluid in a refrigerant-to-secondary fluid heat exchanger, and
the secondary fluid is routed through the condenser.
11. The method of claim 10 , wherein the secondary fluid is water.
12. The method of claim 10 , wherein:
the refrigerant is routed through an air-to-refrigerant heat exchanger after exiting the refrigerant-to-secondary fluid heat exchanger, and
the second air stream passes through the air-to-refrigerant heat exchanger prior to entering the condenser.
13. The method of claim 1 , wherein the operation of the heat pump occurs when a majority of the desiccant is diluted with the moisture.
14. The method of claim 1 , further comprising storing the desiccant and the moisture in a tank.
15. The method of claim 14 , wherein the tank contains a device configured to measure the volume of the desiccant and the moisture in the tank.
16. The method of claim 15 , wherein the heat pump is operated when the volume of the desiccant and the moisture in the tank reaches a pre-determined level.
17. The method of claim 1 , wherein the heat pump is operated until a majority of the desiccant is not diluted with the moisture.