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Diesel Dynamometer Testing Analysis

 

         

          In the past few days I have had more time to analyze in depth the dynamometer testing results from Purdue University that is reported on in our May 2007 newsletter.  Review that report at

http://www.hydrogen-boost.com/May%202007.html .

 

          Initially when I examined the charts below, supplied to me by the Purdue University team, I focused mostly on the black torque curves and was impressed with the increase in torque with Hydrogen Boost across most of the operating range of the engine, especially with the Vegetable oil as fuel tests. 

 

          This week I had more time to examine the blue dotted curves corresponding to the fuel used per horsepower hour, which is basically the inverse of the work done per gallon used that I reported on in the May 2007 newsletter mentioned above.  So these blue dotted lines indicate fuel used per unit of work performed.  Since we want to use less fuel to do the same amount of work, the lower the lines are on the chart the better.

 

Close examination of these curves on the Petroleum Diesel chart shows that as the RPM increase (as you move from left to the right of the chart) these lb/hphr curves first go up slightly then gradually go down steadily.  When looking at the Chart labeled Diesel Fuel With Hydrogen we see that to the far left the curves are actually higher than on the Petroleum Diesel chart, but as you move to the right (increase RPM and throttle setting) the curves drop quickly so that after 1100 RPM the curves are usually below those of the Petroleum Diesel Chart.  The further to the right you go on the chart for Diesel Fuel with Hydrogen (increasing RPM and throttle setting) the lower the curves go.

 

More importantly when you compare the curves on both charts you will find that the further you go to the right (higher RPM and throttle setting) the greater the difference between them (the greater the benefits of the hydrogen).  This only makes sense because the more fuel there is in the combustion chamber the more the benefits that can be achieved by making it combust better (the purpose of the hydrogen).  However, since more fuel is combusting better and releasing its energy, I would expect a higher exhaust gas temperature, and hence a higher possibility of NOx emissions, especially during these higher RPM and throttle settings.  Hydrocarbons and Carbon Monoxide emissions should be lower however.  I am expecting future Dynomometer emissions test to bare this out but I expect the emissions to still meet EPA standards.

 

Conclusions:

 

What does this mean to those who are mostly concerned with fuel economy?  Is Hydrogen Boost a benefit or not?  My answer to that is that it depends on the operating condition of the engine.  Obviously at idle and below 1100 RPM our fuel used per unit of work done were actually higher with Hydrogen Boost than without.  But for the vast majority of the operating range of the engine the effects of Hydrogen Boost were to reduce the fuel used to accomplish the same work. 

 

So, what if we apply this to driving a diesel car or diesel pickup, or even a diesel tractor trailer pulling an empty trailer, or no trailer at all?  Will we get better mileage with hydrogen Boost?  The answer as usual is, “It depends.”  If your normal driving is just putt-putting around at near idle and never getting into high throttle settings, then you might actually reduce your mileage with Hydrogen Boost.  But if you normal driving it above 1100 RPM and at medium to heavy throttle settings I would expect a reduction in fuel used and an increase in fuel mileage.  If your vehicle is pulling heavy loads or going at high speed and high wind resistance, I would expect an outstanding improvement in mileage with Hydrogen Boost. 

 

Now that I look back on our testing history with Hydrogen Boost, with gasoline vehicles as well as diesel vehicles, I can say that this is consistent with what we already know.  I have typically seen a greater % increase in mileage at 70 mph on a vehicle with Hydrogen Boost that at 45 mph.  And the two customers who surprised me early in our presentation of Hydrogen Boost systems for diesel vehicles, showing 20% and 25% increases in mileage were indeed correct, while I doubted their results.  Both were testing with diesel pickup trucks hauling heavy loads at high speeds.  These are the conditions under which Hydrogen Boost can really perform amazing achievements.

 

As a result of the analysis of these results we are recommending a small change in our installation instructions and may add a few components to our wiring kit.  The addition of a couple more relays and a couple large resisters and a set of throttle position micro-switches would allow us to produce hydrogen at 3 or 4 rates so we only produce the hydrogen needed at any particular engine operation condition.  Later on we may add to our welded hydrogen generators a capability to safely accumulate the hydrogen under some pressure and a way to meter the delivery of that hydrogen to match the need during different engine operating conditions.

 

 

Another In Depth Analysis

 

          Going back to the tables of raw data for the petroleum diesel tests with and without Hydrogen Boost, we once again take each data point and divide the torque by the fuel consumption to get the work done per gallon of fuel.  Below we put those results side by side in a table form so you can easily compare the diesel alone results with the hydrogen assist results for each data point individually. 

RPM

100% thrl

100%wHB

%change

 

 

 

2500

27.56

28.74

4.30%

 

 

 

2300

33.4

33.38

0%

75%thrtl

75%wHB

% change

2100

33.58

37.78

12.50%

21.08

34.06

61.60%

1900

35.35

41.57

17.60%

27.21

38.65

42.10%

1700

37.64

45.5

20.90%

36.27

41.52

14.50%

1500

41.92

51.43

22.70%

52.5

52.8

0.50%

1300

44.8

59.08

31.62%

58.7

59.25

1.01%

1100

67.06

74.45

11.02%

62.97

70

11.20%

900

70.31

75.7

7.70%

78.46

79.27

1.01%

 

 

 

 

 

 

 

RPM

50% thrtl

75%wHB

% change

 

 

 

1700

38.53

39.12

1.50%

 

 

 

1500

46.57

51.75

11.10%

25% thrtl

25%wHB

% change

1300

58.72

59.36

1.10%

14.89

0

0

1100

63.24

80.4

27.10%

58.5

45

-23%

900

70.55

79.38

12.50%

82

69.7

-16%

 

          Notice that the benefits of the hydrogen are really evident at high throttle settings, especially full throttle at less than 2300 RPM.  I have been told that accelerating a tractor trailer down the road and powering up hills, the RPM is usually kept 1300 and 1900 which happens to be the range where Hydrogen Boost gave a 17-31% increase in work done per gallon of fuel used at full throttle.  I am also told that cruising RPM is usually kept between 1100 and 1500 which in a range where Hydrogen Boost gave a 1-27% increase at 50% throttle.  So if we can shut off the Hydrogen boost at idle and low throttle, low RPM conditions we could expect to see even better improvements than the 15% overall average for the operating envelope of the engine.  Our plan is to make a change to our wiring kit to include a vacuum switch or throttle position switch that will turn on the hydrogen generator only at cruise and acceleration condition.  This should enable us to expect a 20% increase in mileage on tractor trailers if they are driven whenever they are running, and not sitting all night idling.

 

 

 

 

 

 

 

 

Possible Savings With Hydrogen Boost

 

          In the charts below notice that hydrogen production is not free.  It takes energy to produce the hydrogen and this energy does not always get compensated for with improved combustion and efficiency.  The key is to produce only the hydrogen you need to ignite the combustion mixture at the ultra lean mixture we produce with our electronic control circuit or the normal fuel mixture in a diesel engine.  If excess hydrogen is produced the improved mileage will be lower than what is possible at optimum hydrogen production. 

In the charts below the light blue shaded area represents the possible savings with Hydrogen Boost.  The yellow shaded areas represent the possible NEGATIVE savings with Hydrogen Boost.  Notice that at idle there is always a negative savings and at low cruise the savings may be negative or slightly positive.  As stated in recent newsletter and documents the Hydrogen Boost benefits are especially prevalent when high power and torque are being produced (when lots of fuel is being combusted).  This really shows that Hydrogen Boost can be most valuable with vehicles that are heavily loaded or underpowered. 

          The conditions where Hydrogen Boost may improve mileage the least is when the driver is already implementing driving tips like slow acceleration and cruising at low speeds and throttle settings.  It may be possible that the cost of the hydrogen production could be higher than the benefits of that hydrogen to the miniscule amounts of fuel that are being combusted while using these efficient driving techniques.  This is exaggerated when the operator sets his hydrogen production too high for the engine he is operating. 

          Our Model 20 is designed to produce enough hydrogen for even the largest gasoline engines including those of 8 liters displacement.  So those who are installing and operating on a one liter Geo Metro engine may be only preventing improved mileage when producing hydrogen at 20 amps.  

          Recent changes in installation instructions provide for installation of a throttle position switch or intake manifold vacuum switch that would only turn the hydrogen generator on during acceleration and high cruise throttle settings.  This will avoid most of the negative savings operations.  Adjusting the vacuum switch to optimum setting should practically eliminate the negative savings zones.

 

 

 

 

 

 

 

 

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