Experimental Optimization of Forced Draft for PM2.5 Emissions Reduction

Colorado  State  University Kevin  Dischino,  John  Mizia

Project Overview

•  Program  Overview

–  RTI,  CSU  and  Envirofit  are  collabora=ng  under  a  DOE  grant  to  develop  novel  forced  draB  technology

•  Summarized  Program  Goals

–  Achieve  significant  emissions  reduc=ons  from  the  Envirofit  M-­‐5000  stove  (CSU)

–  Develop  robust  consumer  product  through  field  and  durability  tes=ng  

Project Goal: Emissions Reduction

•  Goal:    Tier  4  emissions  in  a  biomass  cookstove –  <  41  mg/MJ    of  PM  2.5  

–  <  8  g/MJ    CO  

•  Major  Approaches:     1.  Exhaust  Gas  Recircula=on  

2.  Air  Injec=on  

Testing Methodology: Chronological Overview

Baseline" Exhaust Gas Recirculation

(EGR)"

EGR/Air" Air"

Testing Methodology: Nozzle/Flow Rate Optimization Procedure

•  Developed  =me  efficient  Nozzle  and  Flow  Rate  Op=miza=on  Procedure: –  Design  nozzle  (vary  injec=on  loca=on,  nozzle  geometry)

–  Determine  op=mized  flow  rates  for  “startup”  and  “steady”  firepower  phases

–  Run  cold  start  water  boil  tests  at  op=mized  flow  rates

–  Repeat!

Major Results: EGR Stove Nozzle/Flow Rate Optimization

•  EGR  Stove  Nozzle/Flow  Rate  Op=miza=on:   –  4  nozzle  configura=ons  op=mized  

–  55%  reduc=on  in  PM  emissions  achieved  (compared  to  baseline  M-­‐5000  PM  emissions  of  275  mg/MJ)    with  Side  Injec=on  Nozzles  V1

Air Curtain" Side Injection Nozzles V1" Diffusion Nozzle" Chimney Ring"

Testing Methodology: Understanding EGR Stove PM Emissions Reduction

•  Tests  were  completed  to  determine  the  isolated  effect  of  the  following  mechanisms,  rela=ve  to  the  op=mized  configura=on: –  Chemical  Effect  of  op=mized  oxygen  concentra=on  in  oxida=on  region  of  flame

–  Chemical  Effect  of  elevated  carbon  dioxide  concentra=on

–  Increased  residence  =me  of  par=cles  in  the  oxida=on  zone  via  recircula=on    (used  replicate  EGR  gas)

–  Forced  mixing  (used  Argon)

–  Increased  fuel  consump=on  rate  (Compare  to  baseline  WBT  at  similar  fuel  consump=on  rate)

Major Results: Understanding EGR Stove PM Emissions Reduction

•  Understanding  EGR  Net  Emissions  Reduc=on:

–  Mechanisms  that  caused  a  reduc=on  in  PM:

•  Chemical  effect  of  injec=ng  op=mized  O2  concentra=on  

•  Increased  residence  =me  of  par=cles  via  recircula=on

•  Enhanced  Mixing

–  Mechanisms  that  had  no  significant  effect  on  PM:

•  Chemical  effect  of  elevated  CO2  concentra=on

–  Mechanisms  that  caused  an  increase  in  PM:

•  Increased  fuel  consump=on  rate

–  Overall  a  net  emissions  reduc=on  was  observed

Major Results: EGR and Air Stove Comparison

•  Tes=ng  Methodology: –  Direct  comparison  between  op=mized  PM  emissions  EGR  and  forced  air  using  the  

same  nozzle  configura=on

–  Completed  flow  rate  op=miza=on  for  both  EGR  and  Air  

•  Major  Results

–  67%  reduc=on  achieved  with  air  stove –  55%  reduc=on  achieved  with  EGR  stove –  Air  stove  outperformed  EGR  stove  of  the  same  configura=on  

Major Results: Air Stove Nozzle/Flow Rate Optimization

•  Air  Stove  Nozzle/Flow  Rate  Op=miza=on:   –  4  nozzle  configura=ons  op=mized

–  Focused  primarily  on  isola=ng  the  effect  of  forced  draB  velocity  on  PM  emissions

•  All  nozzle  configura=ons  were  “Side  Injec=on  Nozzles”  with  varied  hole  diameters

–  79%  reduc=on  in  PM  emissions  achieved  with  Side  Injec=on  Nozzles  V4

Impact

•  Current  laboratory  emissions  performance  is  compe==ve  with  best  stoves  available  (Tier  4  CO,  Tier  3.9  PM),  however  there  is  s=ll  poten=al  for  further  emissions  reduc=ons  

Significant human and environmental health impacts!!

Previous emissions performance!

Current emissions performance!

Future Work

•  Further  Air  Stove  Nozzle/Flow  Rate  Op=miza=on –  Determine  op=mized  flow  rate  as  func=on  of  firepower  with  greater  resolu=on

–  Develop  control  system  for  flow  rate •  Further  analysis  of  effect  on  PM  emissions

–  Par=cle  size  distribu=on –  EC/OC  

•  Field  tes=ng