Passive recirculation device
The present disclosure provides a recirculation device comprising a body comprising at least one first passage configured to receive an exhaust, at least one second passage configured to receive a fuel, at least one third passage configured to receive a mixture of the exhaust and the fuel, and a longitudinal axis extending from the second passage to the third passage. The device can also comprise a nozzle comprising an inner cavity for directing fuel towards an orifice, located at the smallest cross-sectional area of the inner cavity and a piston slideably located within the body comprising a first end configured to receive the fuel and a second end configured to fuel to the nozzle cavity, whereby the piston can be actuated along the longitudinal axis of the body by the exhaust controlling the flow of fuel passing through the orifice. A mixing chamber located within the body can be configured to receive an exhaust and configured to receive fuel from the orifice.
1. A recirculation device, comprising:
a body defining an internal cavity, the body comprising a first passage configured to receive an exhaust into the body, a second passage configured to receive a fuel into the body, a third passage configured to discharge a mixture of the exhaust and the fuel from the body, and a longitudinal axis extending from the second passage to the third passage;
a piston slideably located within the body having a diaphragm seal fixed to an outer wall of the piston and an inner wall of the internal cavity, where the outer wall and diaphragm seal separate the internal cavity into a first cavity section that is exposed to the exhaust and a second cavity section separated from the exhaust, the piston comprises a piston cavity configured to receive a needle through the piston cavity, the piston cavity is configured to direct the fuel towards an orifice, the orifice is located at the smallest cross-sectional area of the piston cavity, whereby the piston is actuated along the longitudinal axis of the body toward the second passage by an exhaust force applied to the piston by the exhaust within the first cavity section of the body;
a mixing chamber located within the body configured to receive the exhaust and configured to receive the fuel from the orifice; and
the needle fixedly coupled to the body comprising:
a first end that receives the fuel from the second passage and feeds the fuel into a central cavity that extends towards a second end; and
in the general region of the second end an outlet passage discharges the fuel from the central cavity into the piston cavity;
a spring positioned within the second cavity section of the body that contacts the piston and applies a spring force on the piston, wherein the spring force opposes the exhaust force;
wherein the position of the piston is passively controlled by the exhaust force produced by a pressure of the exhaust within the body such that the sum of the exhaust force, the spring force, and a hydraulic force due to a pressure in the second cavity section determines the position of the piston and the flow rate of the fuel through the orifice into the mixing chamber.
2. A recirculation device according to claim 1 , wherein the device is configured to operate within a fuel cell system.
3. A recirculation device according to claim 1 , wherein the fuel ejected from the orifice and the exhaust is entrained and mixed within the mixing chamber.
4. A recirculation device according to claim 1 , wherein the exhaust is discharged from the anode compartment of a fuel cell and fuel is a hydrogen containing fluid.
5. A recirculation device according to claim 1 , wherein the exhaust inlet pressure supplied to the first passage of recirculation device ranges between about three to about 60 psig and the fuel pressure supplied to second passage of recirculation device ranges between about 30 to about 500 psig.
6. A recirculation device according to claim 1 , wherein at least one of the fuel and the mixture flow velocity is configured to operate at supersonic speed.
7. A recirculation device according to claim 1 , wherein as the needle enters the orifice, its area is reduced until the needle fills the orifice and seals off a flow of the fuel.