FINAL STATUS REPORT SUBMITTED BY

MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT                         SUBMITTED  BY   Senior  Design  Team  4   Alyssa  Eng,  C...
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MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

                   

SUBMITTED  BY   Senior  Design  Team  4   Alyssa  Eng,  Cesar  Gutierrez,  Annie  Mroz   May  6,  2013  

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MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

 

TABLE  OF  CONTENTS    

PROJECT  OVERVIEW  ...............................................................................................................................................................  3   OVERALL  DESIGN  ....................................................................................................................................................................  3   TESTING/PROTOTYPING  RESULTS  ..........................................................................................................................................  3   PROPOSED  IMPROVEMENTS/LESSONS  LEARNED  ..................................................................................................................  3   REQUIREMENTS  COMPLIANCE  ...............................................................................................................................................  3   COST  .......................................................................................................................................................................................  4  

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MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

 

PROJECT  OVERVIEW   PROBLEM STATEMENT Lack  of  access  to  water  presents  significant  barriers  to  growth  and  opportunity  in  developing  countries.  People   who  live  in  rural  areas  often  have  to  spend  several  hours  each  day  collecting  water,  due  to  the  fact  that  their  water   source  is  very  far  from  where  they  live  and  they  are  limited  to  what  they  can  physically  carry.  These  hours  spent   collecting  water  take  away  time  from  work,  leisure,  and  study.  Current  solutions  to  the  problem  such  as  hand   pumps  or  boreholes  are  typically  expensive,  complex,  and  fragile.  Water  access  without  electric  power  or   expensive  water  infrastructure  could  be  an  optimal  solution  to  this  problem.   HIGH LEVEL CONCEPT To  address  these  issues,  our  project  simultaneously  solves  the  problem  of  lack  of  water  and  of  electrical   infrastructure  by  providing  both  the  ability  to  move  water  and  charge  small  devices.  This  is  accomplished  with  a   self-­‐contained  bike  system  in  which  the  user  provides  manual  power  to  both  applications  by  pedaling.  To  charge   devices,  the  user  pedals  and  the  back  wheel  of  the  bicycle  turns  a  roller  via  friction  contact.  This  roller  is  connected   to  a  generator  that  provides  electric  power  to  charge  a  battery  or  power  small  USB  devices.  To  move  water,  the   bike  transmits  pedal  power  to  an  external  gear  via  an  extra  bike  chain,  and  this  extra  gear  powers  a  pump.   REVISED PROJECT METRICS Flow Rate

3 GPM

Pump Head

15 m

Generator

Charge 12 Volt Battery Charge cell phone or small appliances via USB

Cost

$20 - $100

Materials

Incorporate recycled materials where possible. Use as many recycled bike parts as possible.

Additional Goals

Portability, usability, ability to use any bike, ease of set up

NOVELTY After  much  research,  we  realized  that  bike-­‐water  projects  abound,  and  that  several  others  have  already  attempted   this.  However,  our  product  is  different  than  existing  bike-­‐water  projects  in  several  ways.  The  main  differentiation   between  our  project  and  others  is  that  the  bike  can  still  be  ridden  and  as  such,  the  entire  system  is  portable.  Any   bike  can  easily  be  dropped  into  our  system  without  any  significant  modifications  and  that  bike  can  be  as  easily   removed.  In  addition,  the  entire  product  is  inexpensive  and  made  primarily  from  recycled  bicycle  components.     3  |  P a g e    

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OVERALL  DESIGN    As  mentioned  before,  the  goal  we  pursued  with  our  project  is  solving  the  problem  of  lack  of  access  to  water  in   developing  countries,  as  well  as  providing  a  inexpensive  and  reliable  source  of  electrical  power  for  small  electronic   devices  such  as  cellphones  or  LED  lights.  The  ultimate  purpose  being  to  improve  the  quality  of  life  of  people   (specifically  kids)  in  developing  countries,  by  allowing  them  to  save  time  doing  chores  for  study  or  play.     To  accomplish  this,  we  designed  a  universal,  portable  power  providing  system  consisting  of  a  bike  stand  in  which   you  can  drop  any  multi-­‐gear  bike.  This  stand  can  easily  be  attached  to  any  bike,  and  the  bike  does  not  require  any   complex  modification.  The  only  modification  to  the  bike  consists  of  adding  a  second  chain  to  the  rear  gear.  This  is   required  to  implement  the  double  chain  system  which  powers  the  water  pump.  This  task  can  be  done  in  less  than   10  minutes  and  without  the  need  of  any  specialized  or  expensive  tools.   Once  the  stand  is  attached  to  the  bike,  the  bike  can  be  ridden  as  usual  (so  the  entire  system  is  portable)  but  at  the   same  time  has  the  capacity  of  pumping  water  and  generating  electricity.  The  setup  of  the  generator  system  takes   no  longer  than  10  seconds,  and  the  setup  of  the  water  pump  takes  about  one  and  a  half  minutes.   With  our  portable  power  providing  system  we  are  simultaneously  tackling  many  of  the  problems  mentioned   before.  First  and  foremost,  we  hope  to  provide  people  with  more  convenient  access  to  water  and  electricity.  This   will  give  people  the  opportunity  to  use  their  extra  time  for  work,  study  or  leisure.  Besides  this,  we  are  creating   work  for  an  enterprising  entrepreneur,  not  only  for  the  owner  of  our  device  but  also  for  a  mechanic  or  welder  who   can  build  and  sell  our  design.  We  envision  an  entrepreneur  in  Kenya  could  make  an  initial  investment  to  purchase   or  fabricate  the  device  and  then  provide  a  service  for  his  fellow  villagers.  This  model  of  single  ownership  will   ensure  that  the  device  and  all  its  subsystems  are  well  maintained.  Additionally,  we  hope  that  this  model  will  enable   an  unemployed  villager  to  earn  additional  income.     If  the  concept  of  bike  power  were  to  become  a  business,  it  could  be  used  to  solve  a  number  of  problems  in  Kenya.   With  the  help  of  our  advisor  Dr.  Jackson,  who  has  in-­‐field  experience,  we  learned  that  villagers  often  collect   rainwater  but  have  no  way  of  pressurizing  it  for  sinks  and  faucets.  Our  product  could  easily  address  this  need  by   pumping  water  from  a  ground-­‐level  rain  barrel  to  a  secondary  storage  container  5-­‐10  m  off  the  ground.   These  issues  were  present  in  every  step  of  our  design  and  redesign  processes,  and  we  made  several  major  changes   in  our  design  with  portability  and  simplicity  being  our  priorities  until  we  reached  the  final  optimal  solution.  To   achieve  these  goals,  our  project  is  designed  to  be  easy  to  build  with  the  resources  available  in  Kenya.  For  this   reason,  we  decided  to  use  as  many  old  bike  parts  as  possible,  since  bikes  are  very  common  there.  Welding  is  also  a   common  resource  in  Kenya,  where  it  is  not  difficult  to  find  a  welder  in  any  village.  They  also  have  access  to  scrap   metal  which  can  be  welded  together  to  construct  most  of  the  structures  required  by  our  design.  Although  we  aimed   to  use  as  many  recycled  components  as  possible,  we  did  not  limit  ourselves  to  using  recycled  parts  when  it  was   impractical  or  unnecessary.          

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Detailed  Overview     Bike  stand:  The  stand  is  the  base  of  our  system.  It´s  main  purpose  is  holding  the  bike  stationary  while  the  user   pumps  water.  It  flips  up  to  form  a  rack  when  the  bike  is  being  ridden  as  a  regular  bike.  It  is  also  the  support  for  the   two  main  subsystems:  the  water  pump  and  the  electric  generator.  The  bike  stand  functions  as  follows:   Although  our  first  idea  was  manufacturing  our  own  bike  stand  out  of  repurposed  metal  bars  obtained  from  an  old   bicycle,  the  lack  of  access  to  welding  resources  and  the  delays  that  would  entail  by  having  it  welded  by  an  external   source  were  prohibitive.  We  decided  instead  to  buy  the  bike  stand  to  save  time.  This  stand  is  originally  a  bike   trainer  for  at-­‐home  cyclists.  This  triangular  structure  has  2  screws  on  the  top  corner  of  the  triangle.  These  screws   attach  to  the  axle  of  the  rear  wheel  of  the  bike  lifting  the  rear  wheel  to  make  the  bike  stationary.  The  screws  allow   the  stand  to  rotate  around  the  point  of  contact  with  the  bike.  We  took  advantage  of  this  feature  to  design  our   system  in  such  a  way  that  the  stand  can  be  flipped  up  and  be  held  in  that  vertical  position  via  a  bungee  system.  By   doing  this,  the  stand  that  originally  provided  a  stable  platform  to  hold  the  bike  now  provides  a  flat  surface  on  the   back  of  the  bike,  similar  to  a  rack.  This  surface  can  be  used  to  accommodate  a  crate  in  which  the  user  can  carry  all   the  tools  needed,  as  well  as  the  main  components  of  the  other  subsystems:  the  water  pump,  the  battery,  the  inlet   and  outlet  hoses  that  will  be  connected  to  the  pump,  and  tools.     Rack  and  crate:  In  order  to  take  advantage  of  the  flat  surface  that  provides  the  stand  when  it  is  flipped  up,  we   created  a  quick  release  system  to  accommodate  the  crate  in  a  secure  way.  To  do  so,  we  used  a  repurposed  the  seat   stays  (piece  of  tubing  connecting  the  main  frame  to  the  rear  axle)  of  an  old  bike.  The  shape  of  this  part  makes  it   ideal  to  mate  with  the  stand,  and  it  is  secured  in  place  via  a  bungee  cord  as  well  as  a  peg  and  slot  system.  The   assembly  and  disassembly  of  this  system  takes  no  longer  than  10-­‐15  seconds,  and  its  utility  resides  in  its  ability  to   carry  all  the  tools  and  components  in  an  easy  way,  keeping  the  bike  balanced  and  not  interfering  with  the  natural   pedaling  motion.  To  absorb  the  vibration  that  may  be  caused  by  riding  the  bike  in  rural  areas,  all  the  contact  points   are  cushioned  with  rubber.  This  also  increases  the  grip  between  removable  parts.   Water  pump  subsystem:  The  purpose  of  this  subsystem  is  transmitting  the  power  from  the  pedals  to  a  secondary   output  shaft  that  drives  the  water  pump.  After  several  iterations  and  redesign  steps,  we  decided  to  create  a  double   chain  system  because  it  was  the  most  optimal  solution  that  fulfilled  our  requirements  of  efficiency,  portability  and   simplicity.   The  benefits  of  using  this  double  chain  design  are  as  follows:   The  power  transmission  has  high  efficiency  in  chain  systems,  up  to  95%  in  well-­‐lubricated  and  tensioned  systems.   The  design  is  robust  and  compact.  The  second  chain  is  permanently  attached  to  the  output  shaft,  even  when  the   pump  is  not  connected  and  the  stand  is  flipped  up.  Thanks  to  this,  the  device  is  portable  and  the  setup  time  is   drastically  reduced,  to  the  point  that  it  takes  no  more  than  1  minute  and  30  seconds  from  the  moment  the  user   arrives  to  his  destination  riding  the  bike  until  the  moment  he  is  actually  pumping  water.  Since  the  output  shaft  is   well  lubricated,  the  power  loss  due  to  friction  when  it  is  freewheeling  (with  the  pump  disconnected)  is  negligible.   In  addition,  the  second  chain  can  be  obtained  from  and  old  bike.  The  output  shaft,  which  is  welded  into  the  stand,  is   a  repurposed  bottom  bracket  (the  axle  that  the  pedals  rotate  on)  of  an  old  bike.  Custom-­‐made  couplers  attach  to   both  sides  of  this  axle.  The  couplers  connect  the  water  pump  on  the  outer  side  and  the  extra  gear  system  on  the   5  |  P a g e    

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  inner  side.  These  couplers  have  been  machined  with  a  tapered  hole  that  mates  perfectly  with  the  shape  of  the  axle   from  the  old  bike  making  it  easy  to  attach  or  remove  them.   The  quick  connection  of  the  pump  consists  of  a  setscrew  through  the  axle  of  the  pump  and  a  wing  nut.  In  order  to   prevent  the  pump  from  freewheeling,  we  designed  a  small  stand  for  the  pump  that  sits  on  the  ground  and   accommodates  the  circular  shape  of  the  pump.   The  pump  is  a  positive  displacement  pump,  specifically  a  rotary  vane  pump.  We  chose  plastic  because  it  is  light,   durable,  resistant  to  corrosion  and  inexpensive.   The  tubing  is  the  same  for  the  inlet  and  the  outlet.  We  used  ¾”    clear,  vinyl  tubing.  The  ¾”  hose  diameter  was   chosen  based  on  the  results  of  our  Matlab  model  (implementing  the  Colebrook  equation  for  frictional  losses).  The   model  predicts  the  pressure  lost  depending  on  the  flowrate,  distance  and  height  to  which  you  are  pumping.   Another  important  parameter  that  was  taken  into  account  was  the  weight  of  the  hose.  The  inlet  tubing  is  15  feet   long  and  the  outlet  is  90  feet.  Minimizing  weight  was  important  so  that  the  user  could  have  a  long  enough  hose  to   make  it  useful  for  pumping  distances  but  at  the  same  time  practical  and  portable.  To  make  the  transportation  of  the   hose  easier,  there  is  enough  clearance  between  the  crate  and  the  seat  of  the  bike  so  that  the  hose  can  be  coiled   around  the  crate.  The  connection  between  the  pump  and  the  tubing  is  made  via  standard  gardening  hose   connections.    A  check  valve  is  attached  to  the  outlet  of  the  pump  to  prevent  back  flow  allowing  the  user  to  take  a  break  without   losing  pressure.   In  the  inlet  hose  we  attached  a  small  filter  to  prevent  debris  from  getting  into  the  pump,   damaging  the  mechanism.  The  inlet  of  the  hose  is  weighted,  so  that  it  stays  submerged  preventing  dry-­‐running  of   the  pump.   On  the  other  side  of  the  output  shaft  we  have  an  extra  gear  system,  entirely  made  out  of  repurposed  bike  parts.  The   main  part  is  the  rear  gear  hub,  which  is  screwed  to  the  coupler  mentioned  before.  This  rear  gear  hub   accommodates  several  laser  cut  spacers  and  the  biggest  gear  of  an  old  bike  cassette.  The  spacers  allow  the  user  to   place  the  gear  in  the  desired  position.  This  is  important  as  the  second  gear  needs  to  be  in  the  same  plane  as  the   biggest  gear  of  the  cassette  of  the  main  bike  so  that  the  second  chain  is  aligned,  reducing  friction  and  consequently   increasing  efficiency.   The  second  chain  links  the  biggest  gear  of  the  cassette  of  the  bike  with  the  gear  on  the  output  shaft.  With  this  setup,   the  gear  ratio  between  the  pedaling  motion  and  the  RPM  in  the  output  shaft,  and  consequently  in  the  pump  is  3/2   (assuming  that  the  user  chooses  the  recommended  gear  ratio).    The  placement  of  the  second  chain  is  such  that   does  not  interfere  with  the  derailleur  of  the  bike,  so  the  user  can  still  switch  gears  as  desired,  except  for  the  biggest   two  gears  in  the  cassette,  which  are  occupied  by  the  second  chain.  This  exception,  however,  is  not  a  big   inconvenience  since  those  are  less-­‐commonly  used  gears.   It  should  be  noted  that  although  the  primary  purpose  of  this  extra  axle  is  to  pump  water,  it  could  easily  be  used  for   any  other  application  that  requires  rotary  motion,  such  as  a  grinding  mill  or  knife  sharpener.      

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  Electric  generator  subsystem:  The  lack  of  electricity  inhibits  education  and  studying  for  young  people.  Children   often  must  spend  most  of  their  daylight  hours  doing  chores  (such  as  collecting  water)  and  by  the  time  they  are   done  with  their  work  it  is  already  dark  and  therefore  they  have  no  light  to  study  by.  For  this  reason,  we  added  a   small  electrical  generator  to  our  project.  The  generator  is  powered  by  the  wheel  of  the  bike  in  a  roller-­‐fashion.  The   generator  can  be  engaged  anytime,  not  only  when  riding  the  bike  from  one  place  to  the  other  but  also  when  the   bike  is  stationary  or  while  pumping  water.    It  can  be  connected  to  a  12V  battery  or  directly  to  any  electronic  device   that  uses  a  USB  port.  This  way,  the  battery  can  be  used  to  power  LED  lights  or  to  charge  cellphones,  or  the   cellphones  and  LED  lights  can  be  charged  directly.  The  user  can  decide  which  option  is  more  convenient  at  any   time  and  change  from  one  to  the  other  by  flicking  a  switch.   The  generator  is  supported  by  a  custom  aluminum  plate  which  is  screwed  into  the  back  of  the  bike  stand.  This   plate  can  rotate  around  a  fixed  point  in  the  stand  until  the  generator  gets  in  contact  with  the  wheel,  and  it  can  be   locked  in  place  by  adjusting  a  set  screw  with  a  wing  nut.  Power  is  transmitted  to  the  generator  in  a  roller-­‐fashion   because  it  gives  the  user  a  high  gear  ratio,  which  in  turn  allows  the  user  to  easily  generate  a  high  RPM  in  the   generator.  Consequently,  it  is  easy  for  the  user  to  generate  a  high  voltage  in  the  generator  even  while  pedaling  at   slow  speeds.         Because  the  generator  is  AC,  we  designed  a  compact  circuit  that  rectifies  the  voltage  via  a  bridge  rectifier.  It  also   allows  the  user  to  choose  between  “battery  mode”,  in  which  the  battery  can  be  directly  connected  to  power  and   ground  outputs  or  “USB  mode”,  which  can  be  used  to  connect  any  USB  device.  Cell  phones  are  quite  common  in   Kenya  but  charging  them  without  access  to  electricity  is  a  constant  struggle.  In  order  to  charge  their  phones,   owners  typically  have  to  leave  their  village  and  walk  a  long  way  until  they  have  access  to  the  grid  or  to  a  diesel   generator  where  they  can  pay  to  get  their  phone  charged.  The  entire  circuit  is  housed  in  a  small  box  which  remains   attached  to  the  bike  stand  but  that  can  be  disengaged  at  any  time.   The  whole  system  works  as  follows:   Once  the  owner  of  the  bike  arrives  to  the  place  where  he  would  like  to  pump  water,  he  flips  down  the  stand  to   make  the  bike  stationary  and  connects  the  water  pump  to  the  exterior  side  of  the  axle.  After  that,  he  has  to  connect   the  inlet  and  outlet  hose  and  place  the  pump  stand  right  under  the  pump.  Then,  the  last  step  is  to  drop  the  inlet   hose  into  the  water  source  and  the  outlet  hose  to  the  desired  storage  vessel.  After  that,  he  can  start  pedaling  to   pump  water.  This  whole  process  shouldn´t  take  more  than  one  and  a  half  minutes.   Also,  as  mentioned  before,  the  generator  can  be  engaged  at  any  time.  Since  the  amount  of  power  that  it  extracts  is   not  very  great,  it  can  be  engaged  when  riding  the  bike  from  one  place  to  the  other,  taking  advantage  of  the  time   spent  travelling.  Once  the  user  decides  to  start  pumping  water,  he  can  leave  the  generator  engaged  if  the  head  he   wants  to  pump  to  is  not  too  high,  or  he  can  just  disengage  it  to  transmit  all  the  power  to  the  pump.   Once  the  process  of  pumping  water  is  over,  the  packing  process  is  the  same  as  the  setup  process  but  in  the  opposite   direction:  he  has  to  disconnect  the  hoses  and  the  pump,  flip  up  the  stand  and  secure  it  with  the  bungee  system  and   place  the  rack  and  the  crate  on  top  of  it,  again  using  another  bungee  system.  To  conclude,  he  has  to  put  the  pump,   the  pump  stand  and  the  hose  in  and  around  the  crate  respectively  and  he  is  ready  to  ride  his  bike  to  a  different   location.     7  |  P a g e    

MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

 

TESTING/PROTOTYPING  RESULTS   Setup and Methods Numerous  rounds  of  testing  were  conducted  both  to  test  component  integration  and  system  performance.  Pump   testing  was  conducted  by  pedaling  the  bike  and  measuring  the  flow  rate  of  the  water  as  well  as  the  pressure  head   generated.  Testing  was  done  at  a  gentle  power  input  to  simulate  the  ability  of  someone  pedaling  for  an  extended   period.  We  tried  testing  with  two  different  pressure  gauges,  neither  of  which  provided  any  useful  measure  of   pressure  head  within  the  system  because  of  constant  fluctuations.  As  such,  we  resorted  to  calculating  the  pressure   head  based  on  pumping  to  different  vertical  heights.  This  is  not  truly  a  measure  of  the  pressure  built  up  in  the   pump  as  it  doesn’t  account  for  frictional  losses  in  the  tubing,  but  it  provides  a  good  lower  bound  of  pump   capabilities.     Testing  was  performed  in  Skirkanich,  with  the  bike  on  the  ground  floor  and  someone  on  a  different  floor   measuring  the  flow  rate.  We  also  tested  outside  near  Penn  Park  to  simulate  what  it  would  be  like  to  actually  use  the   bike  outdoors  up  a  more  sloping  hill.  We  set  up  the  bike  with  a  bucket  of  water  at  the  bottom  of  the  hill  and  again   had  someone  at  the  top  measuring  flow  rate.  The  height  of  the  hill  was  about  15  feet  and  at  a  leisurely  pace  we   achieved  a  flow  rate  of  about  4  GPM.     We  also  tested  the  electrical  components  of  our  product.  Current  and  voltage  output  from  the  generator  were   tested  with  a  digital  multimeter  while  one  person  pedaled.  The  generator  was  also  tested  by  charging  a  cell  phone,   both  while  stationary  and  riding.  Cell  phone  charge  time  was  measured  to  give  an  indication  of  generator   performance.   The  aspect  of  testing  that  we  struggled  the  most  with  was  that  we  couldn’t  measure  power  input.  There  was  no   way  for  us  to  practically  measure  power  output  of  the  person  pedaling,  so  we  had  no  way  to  validate  our  model.   The  best  we  could  do  were  smart  estimates.  However,  because  the  goal  of  our  project  was  to  pump  water  and   generate  electricity,  most  of  our  testing  focused  on  simply  getting  the  system  to  work.   Prototyping effect on design Doing  a  lot  of  testing  early  on  was  key  in  ensuring  system  functionality.  Our  initial  tests  were  promising  (we  were   able  to  pump  water  via  pedaling),  but  were  not  ideal.  As  of  the  submission  of  the  midterm  report,  our  design  made   use  of  an  extra  gear  engaged  with  the  main  bike  chain.  This  required  a  lot  of  tension  to  be  added  to  the  derailleur   (40-­‐60  lbs.)  which  was  more  than  was  practical  via  any  additional  tensioning  system.  All  of  the  designs  we  tested   to  add  tension  to  the  chain  were  bulky  and  awkward.  We  also  noticed  after  testing  our  system  several  times  that   applying  such  great  tension  to  our  derailleur  was  permanently  deforming  it,  and  we  nearly  broke  it.  Doing  a  lot  of   testing  and  playing  around  with  different  ideas  for  power  transmission  led  us  to  the  double  chain  system.     At  some  point  in  all  of  our  design  iterations,  we  had  been  contemplating  the  double  chain  system,  but  had   discounted  it.  We  were  doubtful  because  the  extra  chain  would  absorb  one  of  the  gears  rendering  it  unusable,  and   we  were  worried  about  space  constraints.  We  were  also  concerned  that  a  double  chain  system  would  require  the   user  to  remove  the  chain  with  every  setup  and  breakdown  of  the  pump.  Examining  the  bike,  we  realized  that  the   double  chain  could  be  permanently  engaged  with  the  back  gear  to  prevent  this  issue.  Prototyping  confirmed  that   8  |  P a g e    

MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

  this  designed  functioned  well  given  the  space  constraints  and  that  the  extra  chain  could  remain  on  the  back  gear   without  problems.     Leaking  was  also  an  important  factor  in  our  testing,  and  we  experimented  with  thread  tape  and  sealant  as  well  as   different  types  of  hose  connectors  to  see  which  ones  worked  the  best.   Results of Testing Our  final  round  of  testing  gave  us  the  following  results  for  our  pump:        

Height   (meters)  

Flow  Rate   (GPM)  

4.70  

6  

9.25  

4  

13.25  

2  

        From  our  initial  generator  testing,  it  was  clear  that  we  could  easily  output  over  12  Volts.  We  even  found  that  we   could  generate  voltages  larger  than  12  Volts  while  pedaling  at  an  easy  pace.  After  our  circuit  was  complete,  we   tested  it  by  charging  a  cell  phone.  Our  generator  was  able  to  charge  a  cell  phone  from  0%  battery  to  20%  in  20   minutes,  similar  to  charging  via  wall  outlet.  Additional  applications  such  as  a  bike  light  were  also  hooked  up  the   USB  port  and  charged  easily.                  

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MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

 

PROPOSED  IMPROVEMENTS/LESSONS  LEARNED   Along  the  process  of  designing  and  manufacturing  our  project  we  faced  different  problems  ranging  from  the  lack  of   access  to  some  resources  (as  welding)  to  the  strict  constraints  in  terms  of  cost  and  materials.  Because  simplicity,   reliability,  portability,  low  cost  and  manufacturability  in  developing  countries  were  our  main  goals,  we  struggled  to   find  materials  and  components  that  met  these  requirements  while  still  being  useful  in  our  design.  One  of  the   biggest  lessons  learnt  during  this  process  is  how  to  design  and  manufacture  what  we  had  in  our  minds  while  being   subject  to  the  constraints  mentioned.  We  realized  that  the  easier  design  is  usually  the  better  one.     One  major  breakthrough  that  we  had  is  that  using  repurposed  parts  from  old  bicycles  was  an  optimal  solution   balancing  practicality  and  our  initial  goals  of  using  all  recycled  material.  Bike  parts  are  cheap  and  easy  to  find  in   developing  countries.    They  are  universal  and  easy  to  understand  and  fix,  which  we  considered  really  important  to   implement  our  system.  Besides  this,  using  bike  parts  that  are  already  manufactured  drastically  reduces  the   complexity,  number  of  tools,  and  time  required  to  construct  the  system.  This  way,  the  whole  system  can  be  made   by  a  welder  by  just  using  and  old  bike  (from  which  he  would  take  the  bottom  bracket,  the  chain,  the  rear  gear  hub,   the  cassette  and  the  seat  stays).  The  frame  of  an  old  bike  or  scrap  metal  could  be  used  to  build  the  stand  instead  of   having  to  buy  one.   If  we  had  to  do  this  project  again,  we  would  make  several  changes.  Due  to  the  lack  of  access  to  welding  facilities,  we   decided  to  buy  a  bike  stand.  Although  this  stand  works  well,  it  is  heavy  and  expensive.  The  stand  alone  was  as   expensive  as  the  water  pump  and  the  generator  together,  and  it  represents  the  majority  of  the  extra  weight  added   to  our  design.  Since  the  design  of  the  stand  is  really  simple,  we  are  confident  that  it  could  be  made  from  the  frame   of  a  scrap  bike.  That  would  make  the  design  lighter  and  cheaper.   Another  feature  that  we  would  like  to  change  for  a  second  iteration  is  the  integration  of  the  output  shaft.  In  our   current  design,  the  shaft  is  welded  into  the  frame  in  a  fixed  position.  This  system  works  efficiently,  but  has  some   drawbacks,  mainly  the  initial  setup  and  adjustment  of  the  second  chain.  Because  the  shaft  is  fixed  in  place  in  our   current  design,  the  user  has  to  modify  the  length  of  the  second  chain  to  accommodate  whatever  extra  gear  he  uses.   In  some  instances,  he  may  not  be  able  to  use  the  gear  size  he  wishes  because  chains  come  with  a  discrete  number   of  links,  and  as  such  only  certain  size  gears  will  work.  Further,  although  this  is  a  setup  need  only  be  done  once   (since  after  the  first  setup  the  chain  is  going  to  be  permanently  engaged),  this  process  could  be  made  easier.  We   thought  that  having  the  output  shaft  mounted  in  a  rail  system  along  the  frame  of  the  stand  would  make  the  system   more  user-­‐friendly.  It  would  not  only  make  this  initial  setup  easier  but  it  would  allow  the  user  to  change  the  gear   on  the  shaft  fast  and  easily.  Although  the  current  gear  ratio  is  optimal  for  pumping  water,  the  user  may  be   interested  in  a  having  broader  range  in  order  to  power  other  potential  functions.   Other  improvements  that  could  be  proposed  for  a  second  iteration  of  this  project  are  the  implementation  of  a   compact  water  filtration  system  or  a  hose  system  that  could  be  used  for  irrigation.  Last  but  not  least,  another   improvement  that  would  like  to  propose  is  to  make  the  whole  electric  system  waterproof.  Although  we  know  that   our  generator  is  water  resistant  (it  is  meant  to  be  used  for  outdoor  purposes  such  as  wind  turbines),  we  could  not   verify  that  capability.  Further,  the  USB  port  and  the  connections  for  the  battery  are  exposed.  Although  the  whole   electric  system  can  me  removed  easily  to  prevent  it  from  corrosion  in  the  case  of  rain,  we  think  that  is  necessary  to   make  it  completely  waterproof  because  the  device  is  mainly  meant  for  outdoor  use.   10  |  P a g e    

MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

  In  terms  of  the  lessons  learnt,  apart  from  the  constrained  design  mentioned  before,  we  also  learnt  the  importance   of  system  integration.  The  fact  of  having  different  subsystems  working  smoothly  and  perfectly  does  not  imply  that   they  are  going  to  work  once  they  are  put  together.  That  was  one  of  the  main  challenges  we  faced  during  the  design   of  the  double  chain  system.  Due  to  the  presence  of  the  derailleur  and  the  tight  space  between  the  bike  and  the   stand  we  had  several  issues  with  parts  interfering  with  each  other,  which  made  us  make  several  redesigns  until  we   found  the  final  solution.                                          

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MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

 

REQUIREMENTS  COMPLIANCE   Initial Goals: Flow Rate

13 GPM

Pump Head

0.5 miles (horizontal)

Cost

$20 - $100

Materials

Entirely recycled or scrap

Our  initial  goals  were  set  before  we  fully  understood  the  needs  of  people  in  developing  countries  and  the  limits  of   human  abilities.  Because  of  this,  they  are  a  little  unrealistic.  They’ve  since  been  scaled  back  while  keeping  in  mind   customer’s  needs.  Furthermore,  we  added  in  several  new  quantitative  and  qualitative  metrics.   Revised Goals: Flow Rate

3 GPM

Pump Head

15 m

Generator

Charge 12 Volt Battery Charge cell phone or small appliances via USB

Cost

$20 - $100

Materials

Incorporate recycled materials where possible. Use as many recycled bike parts as possible.

Additional Goals

Portability, usability, ability to use any bike, ease of set up

As  our  design  went  through  several  iterations,  our  priorities  and  design  focus  changed.  We  abandoned  the  goal  of   making  the  project  from  completely  recycled  materials  for  several  reasons.  Requiring  that  the  entire  project  be   made  from  recycled  materials  came  to  be  viewed  as  an  impractical  and  unnecessary  constraint.  Instead,  we   attempted  to  incorporate  recycled  materials,  especially  any  type  of  bike  part,  when  practical  and  feasible.  The  team   decided  that  making  certain  components,  the  pump  for  instance,  out  of  recycled  material,  was  an  unnecessary  step   as  pumps  are  manufactured  to  specific  tolerances  which  is  especially  important  given  concerns  with  sealing,  and   manual  pumps  are  inexpensive  anyway.  Our  final  design  is  a  good  compromise  between  recycling  components,   functionality,  and  cost.    

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MECHANICAL  ENGINEERING  DESIGN  PROJECTS   FINAL  STATUS  REPORT    

  We  scaled  back  our  flowrate  goal  as  our  initial  estimate  of  13  GPM  was  probably  more  than  necessary  for  an   average  village  and  not  practically  possible.    Instead  of  focusing  on  horizontal  distances,  we  instead  used  vertical   distances  as  our  metric  for  pressure  due  to  the  impracticality  of  testing  over  long  distances.  We  were  successfully   able  to  pump  2  GPM  up  to  13.5  m.  Our  model  indicates  that  with  a  ¾”  diameter  pipe  about  15-­‐20%  of  pump  head  is   lost  to  frictional  losses  (depending  of  course  on  flowrate).  Conservatively  estimating  that  15%  of  our  pump  head   was  lost  to  friction,  13.5  m  of  vertical  head  would  give  a  total  pump  head  of  15.8  m.    As  such,  we  accomplished  just   under  our  revised  goal  of  3  GPM  and  a  little  bit  above  our  revised  goal  of  15  m  of  pump  head.  It  is  likely  that  we   could  have  hit  the  3  GPM  at  15  m  metric  had  we  tested  our  system  with  a  greater  power  input.    Many  qualitative  goals  were  added  into  the  project  between  the  beginning  of  the  year  and  now  including:   portability,  usability,  ability  to  use  any  bike,  and  ease  of  set  up.  We  feel  that  we  have  met  or  exceeded  all  of  these   qualitative  goals  as  discussed  in  detail  in  the  previous  sections.  In  terms  of  cost,  should  our  product  be   manufactured  at  scale  and  with  the  stand  made  from  scrap  metal  instead  of  purchased,  it  could  certainly  be   manufactured  for  around  $100.  The  bulk  of  the  cost  is  due  to  the  pump  ($66)  and  the  generator  ($40).  The  addition   of  the  generator,  which  was  not  part  of  the  design  with  the  initial  $20-­‐100  cost  estimate,  adds  a  lot  of  value  to  our   product  even  though  it  is  a  major  cost  driver.    

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COST   In  terms  of  literal  expenses  throughout  the  entire  year,  we  spent  $814.84,  which  is  $81.16  under  our  allotted  $900   budget.  However  in  terms  of  what  we  spent  that  was  actually  used  in  our  final  project,  it  comes  out  to  be   significantly  cheaper.  The  actual  cost  of  everything  that  was  used  in  our  final  product  was  $448.  The  tubing  was  a   large  part  of  this  cost  at  $180.  The  generator,  pump,  and  stand  amounted  to  $177.  The  extra  $41  came  from   miscellaneous  expenses  like  screws,  bungee  cords,  nuts,  a  check  valve,  and  hose  connectors.  We  also  had  to  buy  a   bike,  however  we  bought  a  used  one  at  Neighborhood  Bike  Works  for  only  $50.       The  discrepancy  between  the  product  cost  and  the  total  cost  of  $914.84  comes  from  expenses  not  directly   toward  the  final  product,  such  as  costs  associated  with  prototyping,  development,  and  testing  equipment.  The  costs   associated  with  prototyping  and  development  were  for  items  that  were  ordered  but  ended  up  not  needing  due  to   design  changes.  Our  first  pump,  which  was  made  of  cast  iron,  rusted  and  was  too  heavy,  so  we  ordered  a  second,   plastic  pump  which  was  used  in  our  final  design.  We  also  ordered  two  generators  because  we  were  unsure  which   model  would  work  best  and  wanted  to  avoid  delays  due  to  ordering  a  second  generator.  We  only  ended  up  using   one,  however.  Miscellaneous  items  ordered  from  McMaster  in  the  beginning  of  the  year  when  we  wanted  to  make   the  pump  ourselves  amounted  to  another  $150.  About  $40  was  spent  on  accessories  for  the  bike  such  as  a  12  Volt   battery  and  a  bike  light.  Both  were  ordered  to  demonstrate  what  the  bike  was  capable  of  accomplishing.     The  remainder  of  the  costs  resulted  from  testing.  A  check  valve,  a  gate  valve,  a  pressure  gauge,  and  smaller   amounts  of  tubing  were  purchased  for  testing.  Things  like  thread  sealant,  latex  tape,  various  types  of  hose   connectors,  and  thread  connectors  were  also  used  for  testing.  We  really  used  these  items  primarily  in  testing,  so   they  were  a  necessary  cost,  but  didn’t  actually  go  into  the  final  product.  This  combined  with  smaller  expenses  like   tape,  spray  paint,  and  glue  made  up  for  the  rest  of  the  expenses.

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Summary  of  Expenses   Items  Ordered  Through  the  Business  Office   Cost   RAD  Cycle  Products  Indoor  Portable  Work  Out  Bicycle  Trainer   $75.18     Cast  Iron  Rotary  Drum  Pump,  10  GPM   $43.95     Plastic  Rotary  Polypropylene  Drum  Pump  For  Chemicals  #  4649-­‐99   $66.10     Small  Alternator,  Mini  Generator   $36.50     Small    Alternator,  Mini  Generator  for  Wind  Turbine   $49.00     EPDM  O-­‐Ring  AS568A  Dash  Number  242,  packs  of  10   $6.29     Sheet  Gasket  Assortment  Includes  14  Sheets,  6"  X  6"   $24.26     High-­‐Strength  Adhesive/Sealant  Marine,  10.2-­‐Ounce  Cartridge,  Clear   $9.74     Zinc-­‐Plated  Steel  Bolts  with  Two  Hex  Nuts  and  Washers   $9.33     Machine  Screw  Hex  Nuts,  Zinc-­‐Plated  Steel   $1.21     3/4"  Air  and  Water  Hose,  Black  Hose   $17.70     Two  Male  Fittings    for  3/4"  Air  and  Water  Hose,  Black  Hose   $16.24     Business  Office  Total   $355.50         Reimbursements   Home  Depot     $46.00     Bike  and  Parts     $60.00     Lowes  Mar  24     $34.39     Home  Depot  Mar  31     $9.66     Bike  Church  Mar  28     $5.00     Radioshack  Mar  29     $25.89     Lowes  Mar  31     $198.22     Dr.  Jackson  Hardware  Store,  Swing  Check  Valve   $11.76     Monarch  Hardware     $12.13     CVS  Pharmacy     $4.85     CVS  Pharmacy     $4.85     Radioshack  Apr  6     $4.53     Radioshack  Apr  9     $5.92     Hardware  Store  Apr  10     $4.96     Hardware  Store  Apr  11   $6.47     Lowes  April  8  (Alyssa)   $26.04     Home  Depot  Apr  8  (Alyssa)   $2.67     Reimbursement  Total   $463.34         Sum  of  Expenses   $818.84     Total  Budget   $900.00   Difference   -­‐81.16     15  |  P a g e    

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