Reduced Backpressure Combustion Purifier

Abstract

Reverse flow heat exchangers including one or more pairs of contiguous ducts are provided. An intake duct conveys particle laden air, such as engine exhaust, to a combustion chamber and an exit duct conveys the purified air away from the combustion chamber. The exit duct is shaped such that the cross sectional area thereof varies as function of the length thereof, for example, the cross sectional area can increase as a function of distance from the combustion chamber. The intake duct can also be shaped to have a varying cross sectional area. A combustion purifier is formed by the combination of the combustion chamber with the reverse flow heat exchanger. When used in combination with an engine, the shapes of the ducts can serve to increase the power or efficiency of the engine by further reducing backpressure, as compared to a reverse flow heat exchanger without the shaped ducts.

1 . A system comprising:
 a combustion chamber; and   a reverse flow heat exchanger including
 a first duct having
 a first end, and 
 a second end opening into the combustion chamber; and 
 
 a second duct, contiguous with the first duct, and having
 a first end opening into the combustion chamber, 
 a second end, and 
 a cross sectional area that increases between the first end and the second end. 
 
   
     
     
         2 . The system of  claim 1  wherein the first duct has a cross sectional area that decreases between the first end and the second end thereof. 
     
     
         3 . The system of  claim 1  wherein a width of the second duct increases linearly as a function of a length thereof. 
     
     
         4 . The system of  claim 1  wherein the first and second ducts are spiral-wound around the combustion chamber. 
     
     
         5 . The system of  claim 1  wherein the combustion chamber defines a first longitudinal axis and the reverse flow heat exchanger defines a second longitudinal axis approximately perpendicular to the first longitudinal axis. 
     
     
         6 . A vehicle comprising:
 an engine having an exhaust pipe; and   a combustion purifier including
 a combustion chamber, and 
 a reverse flow heat exchanger having
 a first duct having
 a first end in fluid communication with the exhaust pipe, and 
 a second end opening into the combustion chamber; and 
 
 a second duct, contiguous with the first duct, and having
 a first end opening into the combustion chamber, 
 a second end, and 
 a cross sectional area that increases between the first end and the second end. 
 
 
   
     
     
         7 . The vehicle of  claim 6  wherein the first duct has a cross sectional area that decreases between the first end and the second end thereof. 
     
     
         8 . The vehicle of  claim 6  wherein a width of the second duct increases linearly as a function of a length thereof. 
     
     
         9 . The vehicle of  claim 6  wherein the first and second ducts are spiral-wound around the combustion chamber. 
     
     
         10 . The vehicle of  claim 6  wherein the combustion chamber defines a first longitudinal axis and the reverse flow heat exchanger defines a second longitudinal axis approximately perpendicular to the first longitudinal axis. 
     
     
         11 . The vehicle of  claim 6  further comprising a turbo charger, the turbo charger including an impeller and a turbine, and the second end of the second duct being in fluid communication with the turbine of the turbo charger. 
     
     
         12 . A system comprising:
 a combustion chamber; and   a reverse flow heat exchanger including
 a first duct having
 a first end, and 
 a second end opening into the combustion chamber; and 
 
 a second duct, contiguous with the first duct, and having
 a first end opening into the combustion chamber, 
 a second end, and 
 a cross sectional area that decreases between the first end and the second end. 
 
   
     
     
         13 . The system of  claim 12  wherein the first duct has a cross sectional area that increases between the first end and the second end thereof. 
     
     
         14 . A vehicle comprising:
 an engine having an exhaust pipe; and   a combustion purifier including
 a combustion chamber, and 
 a reverse flow heat exchanger having
 a first duct having
 a first end in fluid communication with the exhaust pipe, and 
 a second end opening into the combustion chamber; and 
 
 a second duct, contiguous with the first duct, and having
 a first end opening into the combustion chamber, 
 a second end, and 
 a cross sectional area that decreases between the first end and the second end. 
 
 
   
     
     
         15 . The vehicle of  claim 14  wherein the first duct has a cross sectional area that decreases between the first end and the second end thereof. 
     
     
         16 . The vehicle of  claim 14  further comprising a turbo charger, the turbo charger including an impeller and a turbine, and the second end of the second duct being in fluid communication with the turbine of the turbo charger. 
     
     
         17 . An electricity generating system comprising:
 a burner having an exhaust; and   a combustion purifier including
 a combustion chamber, and 
 a reverse flow heat exchanger having
 a first duct having
 a first end in fluid communication with the exhaust, and 
 a second end opening into the combustion chamber; and 
 
 a second duct, contiguous with the first duct, and having
 a first end opening into the combustion chamber, 
 a second end, and 
 a cross sectional area that varies between the first end and the second end. 
 
 
   
     
     
         18 . The electricity generating system of  claim 17  wherein the cross sectional area of the second duct increases between the first end and the second end. 
     
     
         19 . The electricity generating system of  claim 17  wherein the cross sectional area of the second duct decreases between the first end and the second end. 
     
     
         20 . The electricity generating system of  claim 17  further comprising a turbo charger, the turbo charger including an impeller and a turbine, and the second end of the second duct being in fluid communication with the turbine of the turbo charger. 
     
     
         21 . A ramjet comprising:
 an intake duct;   a combustion chamber in fluid communication with the intake duct;   a nozzle in fluid communication with the combustion chamber; and   a reverse flow heat exchanger for regenerating heat from the nozzle to the intake duct, the reverse flow heat exchanger including a contiguous interface between the nozzle and the intake chamber,   where the ramjet does not include moving parts.   
     
     
         22 . The ramjet of  claim 21  wherein the intake duct and nozzle are spiral-wound around the combustion chamber. 
     
     
         23 . The ramjet of  claim 21  wherein the intake duct is symmetric around a longitudinal axis. 
     
     
         24 . The ramjet of  claim 21  wherein the intake duct has a cross sectional area that decreases between a first end and a second end thereof, where the second end of the intake duct opens into the combustion chamber. 
     
     
         25 . The ramjet of  claim 21  wherein the nozzle is characterized by a plurality of expansion regions separated by non-expansion regions. 
     
     
         26 . A method comprising:
 receiving an airflow in an intake duct;   receiving the airflow in a combustion chamber in fluid communication with the intake duct;   maintaining a continuous combustion in the combustion chamber to heat the airflow;   expanding the heated airflow through a nozzle in fluid communication with the combustion chamber; and   regenerating heat from the nozzle to the intake duct.   
     
     
         27 . The method of  claim 26  wherein maintaining the continuous combustion in the combustion chamber includes combusting particles in the airflow. 
     
     
         28 . The method of  claim 26  wherein regenerating heat from the nozzle to the intake duct includes conducting heat through a contiguous interface between the nozzle and the intake duct.