System and method for photoelectrochemical air purification

Abstract

An air purification system including a housing defining a lumen, an inlet, an outlet, and a flow pathway between the inlet and the outlet and through the lumen; a filter assembly retained within the lumen and including a substrate defining an open three-dimensional volume, a photocatalytic material disposed on the substrate, and a photon source arranged to illuminate the photocatalytic material with optical radiation; and a flow control mechanism arranged along the flow pathway between the inlet and the outlet.

We claim: 
     
         1 . An air purification system, comprising:
 an enclosure enclosing an air purification volume;   a reactive filter within the air purification volume, the reactive filter comprising:
 a fibrous layer; 
 an active material attached to the fibrous layer, wherein the active material is configured to react with pollutants in the air purification volume when the active material is illuminated with optical radiation; and 
 a conductive material attached to the fibrous layer, wherein the conductive material is electrically coupled to the active material; 
   a photon source arranged inside the reactive filter, the photon source comprising a plurality of light emitters, wherein the plurality of light emitters is configured to illuminate the reactive filter with optical radiation; and   an impeller coupled to the enclosure, wherein the impeller is configured to urge air along an airflow path through the air purification volume,   
       wherein the photon source is separated from the reactive filter by a distance, wherein the distance is selected to generate a target irradiance of the optical radiation at the active material. 
     
     
         2 . The air purification system of  claim 1 , wherein photon source further comprises a support structure, wherein the support structure is a pentagonal prism, wherein a set of light emitters of the plurality of light emitters is arranged on each face of the support structure. 
     
     
         3 . The air purification system of  claim 2 , wherein the set of light emitters comprises at least three light emitters, wherein the set of light emitters are uniformly distributed along each face of the support structure. 
     
     
         4 . The air purification system of  claim 1 , wherein the target irradiance at the active material is at least about 25 W/m 2 . 
     
     
         5 . The air purification system of  claim 1 , further comprising a controller that is operable to modify the optical radiation of the photon source. 
     
     
         6 . The air purification system of  claim 5 , further comprising a sensor, communicatively coupled to the controller, that outputs a performance metric, wherein the controller is operable to modify an irradiance of the optical radiation between a first value and a second value based on the performance metric. 
     
     
         7 . The air purification system of  claim 5 , wherein the controller is operable to temporally modulate the optical radiation, wherein the optical radiation is modulated between a first irradiance and a second irradiance at a frequency. 
     
     
         8 . The air purification system of  claim 7 , wherein the frequency is selected based on a free carrier lifetime of the active material. 
     
     
         9 . The air purification system of  claim 1 , wherein the plurality of light emitters is in fluid communication with the airflow path, wherein a temperature of each light emitter of the plurality of light emitters is determined based on at least one of an air temperature and an airflow rate within the airflow path. 
     
     
         10 . The air purification system of  claim 1 , wherein the optical radiation comprises a minimum wavelength of at least 280 nanometers. 
     
     
         11 . An air purification system, comprising:
 an enclosure enclosing an air purification volume and separating the air purification volume from an environment proximal the enclosure, wherein the enclosure defines an intake proximal a bottom of the enclosure and an exhaust proximal a top of the enclosure, wherein the intake and the exhaust are in fluid communication with the environment and the air purification volume, wherein the enclosure defines an airflow pathway between the intake and the exhaust;   a reactive filter within the air purification volume, the reactive filter comprising:
 a fibrous layer, wherein the airflow pathway intersects the fibrous layer; and 
 an active material attached to the fibrous layer, wherein the active material is configured to react with pollutants in the air purification volume when the active material is illuminated with optical radiation; and 
   a fan proximal the top of the enclosure, wherein the fan is configured to urge air along the airflow pathway; and   a passive flow guide arranged between the fan and the reactive filter along the airflow path, wherein the passive flow guide comprises a fan cover configured to maintain the airflow within a predetermined flow regime.   
     
     
         12 . The air purification system of  claim 11 , wherein the passive flow guide comprises flow directing radial slats. 
     
     
         13 . The air purification system of  claim 12 , wherein the passive flow guide is domed, wherein a top of the dome is proximal the reactive filter. 
     
     
         14 . The air purification system of  claim 11 , wherein an internal surface of the enclosure, proximal the exhaust, comprises a convex shape. 
     
     
         15 . The air purification system of  claim 11 , further comprising a set of vanes proximal the exhaust, wherein the set of vanes is configured to generate a vorticity in the airflow pathway. 
     
     
         16 . The air purification system of  claim 15 , wherein each vane of the set of vanes is arranged at an oblique angle relative to the airflow pathway. 
     
     
         17 . The air purification system of  claim 11 , wherein the enclosure is configured to balance a load of the reactive filter. 
     
     
         18 . The air purification system of  claim 17 , wherein the enclosure is configured to equalize a pressure drop on a first end and a second end of the reactive filter. 
     
     
         19 . The air purification system of  claim 11 , wherein the airflow pathway enters the reactive filter at a nonzero angle to a longitudinal axis of the reactive filter and exits the reactive filter parallel the longitudinal axis. 
     
     
         20 . The system of  claim 11 , wherein the enclosure comprises a set of supports, wherein the set of supports are arranged along an internal surface of the enclosure, wherein the internal supports are arranged to minimize obstruction of the airflow path.