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From: Hammo on 13 Feb 2007 01:26 On 13/2/07 5:04 PM, in article 45d15529$1(a)news.bekkers.com.au, "Theo Bekkers" <tbekkers(a)bekkers.com.au> wrote: > Hammo wrote: > >> I still argue thimbles, though no body cares, I'd go for an order of >> magnitude lower. I cannot differentiate between the fuel use with >> lights on vs lights off. > > So because you can't differentiate the fuel use there is none? On observation, that is currently true. However.......When I finish a PM shift and drive the 3 and bit hours home in the dark (headlights on) the fuel consumption has been equivalent if not better than during the day (headlights off). I change into top and then don't down change again until 3 kays from home where I need to negotiate a sharp turn. I've been looking to put a cruise control in so that human error can be minimised wrt throttle input. > >> (I'll post my calcs when I get back home, probably after I >> post the belated pics of roadside furniture to Theo). > > A lounge suite in a layby? No, that discussion about lamps, sign posts and road markers. They are all roadside furniture. I even went along to be involved with the taskforce that investigated and reported via the inquiry into road deaths in rural Victoria. I took some pics as I couldn't get hold of the photohgraphs I wanted to show you (i.e. Theo). Hammo > > Theo > >
From: jlittler on 13 Feb 2007 01:27 On Feb 13, 4:50 pm, Hammo <hbaj2...(a)aapt.net.au> wrote: > On 13/2/07 4:15 PM, in article > 1171343723.258542.248...(a)j27g2000cwj.googlegroups.com, > > > > > > "jlitt...(a)my-deja.com" <jlitt...(a)my-deja.com> wrote: > > On Feb 12, 6:15 pm, Hammo <hbaj2...(a)aapt.net.au> wrote: > >> On 12/2/07 10:43 AM, in article > > >> <jlitt...(a)my-deja.com> wrote: > >>> On Feb 11, 11:50 pm, Hammo <hbaj2...(a)aapt.net.au> wrote: > >>>> <knobdoo...(a)hotmail.com> wrote: > >>>>> "Hammo" <hbaj2...(a)aapt.net.au> wrote: > >>>> Now fuel systems are all about air to fuel ratio. Best situation is when > >>>> the ratio is adjusted for all situations. Hence EFI becoming better and > >>>> better wrt emissions. Why? It's not magic, it is due to the monitoring of > >>>> the system and adjustments that are made via many circuits many times per > >>>> second. What is based on? What measurement could possibly do this, what > >>>> principle? Stoichiometry. > > >>>> I.e. The equation for combustion wrt air:fuel ratio. That monitors how > >>>> much > >>>> fuel is required. It is calculated via moles of fuel based on the RON. > >>>> This is why some cars run better, or require higher octane fuels (wrt EFI). > > >>>> If you have a running total of fuel used based on the chemical reaction, > >>>> you > >>>> have a better indication than fuel flow as it relates to the chemistry, > >>>> i.e. > >>>> irreversible chemical reaction that converts fuel to energy. > > >>> <doubtful look> maybe the F1 teams do this, but too bloody expensive > >>> for a run of the mill road car. > > >> No, I don't think so, and I this is why the focus on the need for a "fuel > >> flow measure" to be utter bollocks. Clem claims it to be obfuscation. > > > <raised eyebrow> Who said you needed a fuel flow measurement to > > improve fuel economy/efficiency ? > > > JL > > (I've said repeatedly you can't make assumptions about a multitude of > > things, calculate a fuel flow and then claim you know it's > > particularly accurate though) > > Thank you, Mr Echo. Your support is much appreciated. > > Hammo Ahh I always knew you were a politician not a scientist - Howard really should employ you, I've never know such capability to ignore intent and pretend to hear something different to what was said. So I ask again WHO SAID you needed a fuel flow measurement to improve fuel economy/efficiency ? Knock that straw man down you set up Hammo. JL
From: Iain Chalmers on 13 Feb 2007 02:06 In article <C1F799F8.26483%hbaj2006(a)aapt.net.au>, Hammo <hbaj2006(a)aapt.net.au> wrote: > On 13/2/07 12:10 PM, in article > bigiain-3745C3.12100213022007(a)nasal.pacific.net.au, "Iain Chalmers" > <bigiain(a)mightymedia.com.au> wrote: > > > I calculated that 120W of headlights consumes something like 100mL > > per hour plus or minus 40%. > > > > Nobody has challenged those numbers, and my sanity check calculations > > seem to indicate I'm at least in the right order of magnitude with that > > figure... > > I still argue thimbles, though no body cares, I'd go for an order of > magnitude lower. > Hammo (I'll post my calcs when I get back home, probably after I post the > belated pics of roadside furniture to Theo). I'll be interested to see them. I'm still reasonably sure about my numbers, with the proviso that I'm basing them on a bunch of unsupported wikipedia values... The forst wikipedis value is for the energy content of petrol at ~32MJ/L: http://en.wikipedia.org/wiki/Gasoline#Energy_content Joules are easily expressed in Watt hours, so Watt hours can be expressed in L of petrol. 1 Watt Second = 1 joule 1 Watt Hour = 3600 Watt Seconds = 3600 joules. 120 Watt hours = 432,000 joules (120*3600) So if everything was 100% efficient that'd be .0135L (432,000/32,000,000) But wikipedia says alternators have an efficiency "between 50 and 62%" http://en.wikipedia.org/wiki/Alternator#Automotive_alternators So lets use 55% and increase our fuel requirements by 1/0.55 to 0.0245L. Now we make one more trip to wikipedia to find out how efficient the internal combustion engine is, and they tell us "It is generally accepted that most gasoline fueled internal combustion engines, even when aided with turbochargers and stock efficiency aids, have a mechanical efficiency of about 20%." http://en.wikipedia.org/wiki/Internal_combustion#Engine_Efficiency So we need to multiply our fuel requirements by another factor of 5 to get 0.12L of fuel used for each hour of generating 120W of electrical power using an automotive alternator driven by an internal combustion engine. I'm guessing my errors are around +-40% (20% in the alternator efficiency figure and another 20 in engine efficiency one). Lets do a sanity check on that. Honda make little generators which are actually dc alternators with inverters (click the "Inverter" link in the left column of the webpage below for details). The 1000W model, http://www.hondapowerequipment.com/ModelDetail.asp?ModelName=eu1000i has got a 0.6gal/2.27L tank and they claim that it'll run for 3.8 hours @ rated load and 8.3 hours at 1/4 load" so they're saying 0.6L per hour for 1000W or 0.27L/hour for 250 Watts - that last figure looks pretty damed close to my calculation of 0.12L/hour for 120W... (the full load figure is clearly running somewhat more efficiently though, but still within my stated error range) I reckon you must have pretty big thimbles... :-) big -- "Everything you love, everything meaningful with depth and history, all passionate authentic experiences will be appropriated, mishandled, watered down, cheapened, repackaged, marketed and sold to the people you hate." Mr Jalopy quoting Hooptyrides (on jalopyjunktown.com)
From: Iain Chalmers on 13 Feb 2007 02:24 In article <C1F7A529.265C9%hbaj2006(a)aapt.net.au>, Hammo <hbaj2006(a)aapt.net.au> wrote: > On 13/2/07 5:04 PM, in article 45d15529$1(a)news.bekkers.com.au, "Theo > Bekkers" <tbekkers(a)bekkers.com.au> wrote: > > > Hammo wrote: > > > >> I still argue thimbles, though no body cares, I'd go for an order of > >> magnitude lower. I cannot differentiate between the fuel use with > >> lights on vs lights off. > > > > So because you can't differentiate the fuel use there is none? > > On observation, that is currently true. However.......When I finish a PM > shift and drive the 3 and bit hours home in the dark (headlights on) the > fuel consumption has been equivalent if not better than during the day > (headlights off). > > I change into top and then don't down change again until 3 kays from home > where I need to negotiate a sharp turn. > > I've been looking to put a cruise control in so that human error can be > minimised wrt throttle input. You've also accounted for different air temperatures and densities (both in terms of the engine combustion process and the aerodynamic effect)? You've averaged the observations over trips from home in the dark and light as well as to home in the dark and light (to remove any elevation changes)? If you've done this then presumably you've checked the tire pressures and wheel alignment regularly during the test procedure? And kept the air-con off so differing compressor cycle times due to different outside air temperatures wouldn't affect the results? Is there a typical prevailing wind speed and direction in the area of the trip, and is it the same for both day and night trips? My numbers suggest you're looking for something like a half or one percent increase in fuel consumption at highway speeds in a car that averages around 15L/100km. I think _lots_ of other things will have effects that overshadow it, but I honestly believe if you _were_ careful enough in your measurements you'd see a real-world cost of ~0.35L over your 3-ish hour trip if you do it with headlights on. My experience is that I never get repeatability to anything better than about 10 or 20% in my fuel useage even when I think I'm doing exactly the same trips, so I'd only expect it to show up "in observation" through application of some effective statistical methods over many many trips... big -- "Everything you love, everything meaningful with depth and history, all passionate authentic experiences will be appropriated, mishandled, watered down, cheapened, repackaged, marketed and sold to the people you hate." Mr Jalopy quoting Hooptyrides (on jalopyjunktown.com)
From: G-S on 13 Feb 2007 03:35
Nev.. wrote: > G-S wrote: >> Nev.. wrote: >>> Knobdoodle wrote: >>> >>>> [crinkles brow] >>>> What's this new diversion you're trying now Hammo? >>>> "the inefficiencies of the internal combustion engine."?!!? >>>> What the hell has that got to do with the fuel waste through >>>> unnecessary use of driving lights? >>> >>> Eh? I thought we'd already established that there was no waste, or, >>> if there was, it was only measurable at a theoretical level. >>> >> No we established that you car fuel measuring device wasn't sensitive >> enough to measure it but that practical measurment devices for >> measuring the effect did in fact exist :) > > No. I established 'facts' by gathering data, you made 'unsubstantiated > allegations' about the data collection method in order to discredit that > data. > So when I checked the reality of the effect we were discussing using a bus and a commercial quality calibrated fuel flow meter you think that constitutes an 'unsubstantiated allegation', but when you attempted to collect information about the reality of the effect we are discussing using the less sensitive and accurate device of 'your car' that is 'establishing facts' eh Nev... Well each to their own :) G-S |