Fuel economy/Heat recovery
Posted: January 16th, 2010, 7:12 pm
Hi all,
Im interested in tuning and achieving excellent fuel economy.
I have a 1994 Auto-V6 running duel fuel LPG system.(sequential multipoint injection)
Atm i have a dying auto trans so fuel econ isnt that good due to clutch slippage
Im getting 12.5L/100km on lpg eqivalent to about 9.5L/100km on petrol
(235.2146 รท x L/100km = y MPG (US liquid gallon)) - Conversion factor for those familiar with mpg
I have installed a fuel controller that voltage modulates the VAF sensor so i can lean out the mixtures slightly. It works reasonably well but there are a few problems with regards to, after a while the ecu runs back to stoic mixtures due to closed loop operation (input from O2 sensors)
1- if the O2 sensors are unplugged the system will go into open loop mode, i assume and possibly very rich
In this mode, will the ecu still make calculations based on VAF???
If so this would mean that i would be able to correctly adjust mixtures via VAF modulation without closed loop operation interfering
I monitor the mixtures via the the stock narrowband o2 sensor.
I monitor egts (pyrometer is located about 100mm past the 02 sensor on the front bank)
2- Is this to far down the exhaust manifold to give a correct readng?
would it loose approx 100K between extractors and current pyrometer location?
temps fluctuate between 300 to 400C under normal drving conditions and max out at 500C when flogging it.
There are no noticeable power losses when running lean, but throttle response is a little poorer. but i am getting fuel savings of about 10% with no real aggressive tuning. Also lpg has a high RON rating in excess of 100 hence it can be leaned out with out pre detonation occurring.
3-From a safety perspective how far can i push the lean mixtures? Will i be able to hear if knocking occurs or will it be inaudible because of the small engine components? Is it safe to lean it out to the point where any leaner could affect drivability?
HEAT RECOVERY TOPIC
IC engines are only ~30% max efficiency with the other 70% lost as heat. 30% power at the crank (very optimistic), 30% out radiator and 30% out Exhaust.
So when cruising the engine does output about 20Hp. This means there 40-50 Hp of heat in generated.
I have been thinking about some mechanism to transfer this heat into usable energy and have up with ideas that use steam to either provides power and/or increase FE
There would be a water tank onboard. Water passes through a heat exchanger with the radiator Heating from say 20C to 90C. This water is passed through a secondary heat exchanger with the exhaust creating a high pressure steam. This high tmp/pressure steam will spool a turbo that spins and runs an large alternator( complication: gearing would be required)
The alternators output could
-a- replace the alternator the runs off the engine (possibly reducing 1-2 hp worth of drag)
-b- power electric motors mounted in the wheels. complicated, but a host of information at http://www.evalbum.com/" onclick="window.open(this.href);return false; This option would be a way to increase your vehicles power output with no increase in fuel consumption
-c- alternator electrical output is consumed within a electrolysis cell where the resulting H2 and O2 are fed back-into the IC engine.
Option -c- has 2 advantages
1- range and mpg can be significantly improved as fuel is supplemented
2- Hydrogen catalyzed combustion in spark ignition engine increases combustion efficiency and improves emissions quality
Looking from a efficincy perspective
option -a- would have maybe a 5% increase in FE due to no alternator drag on engine
option -b- would have a round trip efficiency(heat to mechanical) of say
- 70% heat recovery
- 40% turbine efficiency
- 80% alternator efficiency
- 90% motor eff.
= 20% overall eff.
so when cruising you would have 0.2*50HP = 10Hp extra
thats a 50% increase in power!!!!!!!!!
what about when flooring it
for my klde 130HP (mechanical)
means 325 heat is generated
At 20% efficiency thats 65HP extra at no increase in fuel consumption
Option -c-
- 70% heat recovery
- 40% turbine efficiency
- 80% alternator efficiency
- 50% electrolysis eff.
= 11 % overall eff.
At 20Hp load when cruising 0.11*50Hp(heat)
= 5.5 Hp extra(in terms of fuel energy)
thats a 27.5 % increase in MPG or range
Please feel free to comment/ question
thanks
Im interested in tuning and achieving excellent fuel economy.
I have a 1994 Auto-V6 running duel fuel LPG system.(sequential multipoint injection)
Atm i have a dying auto trans so fuel econ isnt that good due to clutch slippage
Im getting 12.5L/100km on lpg eqivalent to about 9.5L/100km on petrol
(235.2146 รท x L/100km = y MPG (US liquid gallon)) - Conversion factor for those familiar with mpg
I have installed a fuel controller that voltage modulates the VAF sensor so i can lean out the mixtures slightly. It works reasonably well but there are a few problems with regards to, after a while the ecu runs back to stoic mixtures due to closed loop operation (input from O2 sensors)
1- if the O2 sensors are unplugged the system will go into open loop mode, i assume and possibly very rich
In this mode, will the ecu still make calculations based on VAF???
If so this would mean that i would be able to correctly adjust mixtures via VAF modulation without closed loop operation interfering
I monitor the mixtures via the the stock narrowband o2 sensor.
I monitor egts (pyrometer is located about 100mm past the 02 sensor on the front bank)
2- Is this to far down the exhaust manifold to give a correct readng?
would it loose approx 100K between extractors and current pyrometer location?
temps fluctuate between 300 to 400C under normal drving conditions and max out at 500C when flogging it.
There are no noticeable power losses when running lean, but throttle response is a little poorer. but i am getting fuel savings of about 10% with no real aggressive tuning. Also lpg has a high RON rating in excess of 100 hence it can be leaned out with out pre detonation occurring.
3-From a safety perspective how far can i push the lean mixtures? Will i be able to hear if knocking occurs or will it be inaudible because of the small engine components? Is it safe to lean it out to the point where any leaner could affect drivability?
HEAT RECOVERY TOPIC
IC engines are only ~30% max efficiency with the other 70% lost as heat. 30% power at the crank (very optimistic), 30% out radiator and 30% out Exhaust.
So when cruising the engine does output about 20Hp. This means there 40-50 Hp of heat in generated.
I have been thinking about some mechanism to transfer this heat into usable energy and have up with ideas that use steam to either provides power and/or increase FE
There would be a water tank onboard. Water passes through a heat exchanger with the radiator Heating from say 20C to 90C. This water is passed through a secondary heat exchanger with the exhaust creating a high pressure steam. This high tmp/pressure steam will spool a turbo that spins and runs an large alternator( complication: gearing would be required)
The alternators output could
-a- replace the alternator the runs off the engine (possibly reducing 1-2 hp worth of drag)
-b- power electric motors mounted in the wheels. complicated, but a host of information at http://www.evalbum.com/" onclick="window.open(this.href);return false; This option would be a way to increase your vehicles power output with no increase in fuel consumption
-c- alternator electrical output is consumed within a electrolysis cell where the resulting H2 and O2 are fed back-into the IC engine.
Option -c- has 2 advantages
1- range and mpg can be significantly improved as fuel is supplemented
2- Hydrogen catalyzed combustion in spark ignition engine increases combustion efficiency and improves emissions quality
Looking from a efficincy perspective
option -a- would have maybe a 5% increase in FE due to no alternator drag on engine
option -b- would have a round trip efficiency(heat to mechanical) of say
- 70% heat recovery
- 40% turbine efficiency
- 80% alternator efficiency
- 90% motor eff.
= 20% overall eff.
so when cruising you would have 0.2*50HP = 10Hp extra
thats a 50% increase in power!!!!!!!!!
what about when flooring it
for my klde 130HP (mechanical)
means 325 heat is generated
At 20% efficiency thats 65HP extra at no increase in fuel consumption
Option -c-
- 70% heat recovery
- 40% turbine efficiency
- 80% alternator efficiency
- 50% electrolysis eff.
= 11 % overall eff.
At 20Hp load when cruising 0.11*50Hp(heat)
= 5.5 Hp extra(in terms of fuel energy)
thats a 27.5 % increase in MPG or range
Please feel free to comment/ question
thanks