Patent ID: 9494024
Filing Date: 2016-11-15
CPC Classification: E21B

Claim Text:
1. A method of operating a heater having 1) a heater housing extending along a heater axis; 2) a fuel cell stack assembly disposed within said heater housing and having a plurality of fuel cells which convert chemical energy from a fuel into heat and electricity through a chemical reaction with an oxidizing agent, said fuel cell stack assembly having a fuel cell manifold for a) receiving said fuel within a fuel inlet of said fuel cell manifold and distributing said fuel to said plurality of fuel cells and b) receiving said oxidizing agent within an oxidizing agent inlet of said fuel cell manifold and distributing said oxidizing agent to said plurality of fuel cells; 3) a fuel supply conduit in fluid communication with said fuel cell manifold for communicating said fuel to said fuel inlet of said fuel cell manifold; 4) an oxidizing agent supply conduit in fluid communication with said fuel cell manifold for communicating said oxidizing agent to said oxidizing agent inlet of said fuel cell manifold; and 5) a sonic orifice disposed between said fuel supply conduit and said fuel inlet or between said oxidizing agent supply conduit and said oxidizing agent inlet; said method comprising: operating said heater to achieve a first pressure upstream of said sonic orifice; and operating said heater to achieve a second pressure downstream of said sonic orifice; wherein the ratio of said first pressure to said second pressure is at least 1.85:1, thereby limiting the velocity of said fuel or said oxidizing agent through said sonic orifice.