ENERGY VAPOR EXCHANGER WITH AN INLET VORTEX GENERATOR
A membrane assembly of an energy and vapor exchanger includes a gas-permeable membrane having a first major surface that faces a gas flow and a second major surface that faces a liquid desiccant flow. An inlet region is proximate an inlet edge of the gas-permeable membrane. The inlet region includes a vortex generator that creates a vortex in the gas flow as it moves from the inlet edge to an outlet edge of the gas-permeable membrane. The vortex enhances mixing of fluids along the gas-permeable membrane.
1 . A membrane assembly for an energy and vapor exchanger, comprising:
a gas-permeable membrane having a first major surface that faces a gas flow and a second major surface that faces a liquid desiccant flow; and
an inlet region proximate an inlet edge of the gas-permeable membrane, the inlet region comprising a vortex generator that creates a vortex in the gas flow as it moves from the inlet edge to an outlet edge of the gas-permeable membrane, the vortex enhancing mixing of fluids along the gas-permeable membrane and convectively replacing gas that has dried out near the gas-permeable membrane with wetter gas from the gas flow.
2 . The membrane assembly of claim 1 , wherein the gas-permeable membrane comprises a sheet that forms a first side of a gas flow path through which the gas flow moves, a plate facing the sheet forming a second side of the gas flow path.
3 . The membrane assembly of claim 2 , wherein the vortex generator is located away from the sheet and the plate.
4 . The membrane assembly of claim 2 , wherein the inlet region comprises a planar structure parallel to and aligned with the gas-permeable membrane, the vortex generator protruding from the planar structure.
5 . The membrane assembly of claim 2 , wherein the vortex generator comprises a three-dimensional polygonal structure protruding from the inlet region.
6 . The membrane assembly of claim 1 , wherein the gas-permeable membrane comprises a tube, an inner surface of the tube forming a gas flow path through which the gas flow moves.
7 . The membrane assembly of claim 1 , wherein the gas-permeable membrane comprises a tube, an outer surface of the tube being exposed in an gas flow path through which the gas flow moves.
8 . The membrane assembly of claim 1 , wherein the vortex generator creates two counter-rotating vortex pairs in the gas flow.
9 . The membrane assembly of claim 1 , wherein the gas-permeable membrane is hydrophobic.
10 . The membrane assembly of claim 9 , wherein the gas-permeable membrane comprises expanded polytetrafluoroethylene.
11 . The membrane assembly of claim 10 , wherein the expanded polytetrafluoroethylene is bonded to a non-porous, plastic support.
12 . The membrane assembly of claim 1 , wherein the liquid desiccant flow comprises a lithium salt solution.
13 . A gas-to-liquid vapor exchanger, comprising:
a gas flow path comprising a gas-permeable membrane having a first major surface that faces a gas flow;
a fluid flow path formed at least in part by a second major surface of the gas-permeable membrane, a liquid desiccant moving through the flow path, the gas-permeable membrane transferring water vapor between the gas flow path and the fluid flow path; and
an inlet region of the gas flow path comprising a vortex generator that creates a vortex in the gas flow as it moves from the inlet to an outlet of the gas flow path, the vortex increasing a transfer of the water vapor through the gas-permeable membrane.
14 . The gas-to-liquid vapor exchanger of claim 13 , wherein the gas-permeable membrane comprises a sheet that forms a first side of the gas flow path, a plate facing the sheet forming a second side of the gas flow path, wherein the vortex generator is located away from the sheet and the plate.
15 . The gas-to-liquid vapor exchanger of claim 14 , wherein the inlet region comprises a planar structure parallel to and aligned with the gas-permeable membrane, the vortex generator protruding from the planar structure.
16 . The gas-to-liquid vapor exchanger of claim 14 , wherein the gas flow in the gas flow path has a laminar Reynolds number.
17 . The gas-to-liquid vapor exchanger of claim 13 , wherein the vortex generator creates two counter-rotating vortex pairs.
18 . The gas-to-liquid vapor exchanger of claim 13 , wherein the gas-permeable membrane comprises expanded polytetrafluoroethylene.
19 . The gas-to-liquid vapor exchanger of claim 18 , wherein the expanded polytetrafluoroethylene is bonded to a polypropylene support.
20 . A method comprising:
driving a gas flow across a gas-permeable membrane having a first major surface;
driving a liquid desiccant flow across a second major surface of the gas-permeable membrane;
transferring water vapor through the gas-permeable membrane between the gas flow and the desiccant flow; and
inducing a vortex in the gas flow via a vortex generator as the gas flow moves from an inlet edge to an outlet edge of the gas-permeable membrane, the vortex enhancing mixing of fluids along the gas-permeable membrane.