Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

dcb · 01-22-2010, 04:32 PM

Neil, in all three examples you increase the size of the engines for a simple parallel setup when you should be reducing them. That is misinformaton posing as fact. Peak efficiency is improved in an optimized parallel setup for a target load/speed, by a good %20 over a series hybrid.

At some point efficiency will fall off as you leave the target speed(or speeds if you make an efficient trans) and load, but you (the driver) have options then as well, i.e. recharge the battery/supercap if the load isn't sufficient, or discharge the battery if you need more power.

So the range where optimized series *might* surpass a well managed optimized parallel system is much smaller than you might think.

But storage, again, is not Germaine to this discussion, they both have it, leave it out. Focus on the transmission losses between the ICE and wheels in BOTH cases. I can operate near bscf all day with enough gears, albeit not at constant speed, but I don't care about that.

Mech, chill out and answer a straight question. We have to eliminate some variables and look at the component parts here.

Q. MECH, assume you are operating a vehicle at a constant speed and load, with an ICE that has a 98% efficient transmission that is cheap and lightweight, and the engine is operating at bsfc. Lets assume a fairly clean design and the engine only needs to put out 15hp to cruise @55 mph.

It isn't directly relevant to the question, but this is where the bar for peak parallel/direct drive efficiency is at and these are not part of the variables for this question.

Can you give accurate assessments of how converting this relatively constant speed/load operation to a hydraulic will affect:
1. efficiency, in terms of how much power leaving the engine shaft gets to the wheels.
2. weight at the efficiency.
3. cost that weight/efficiency
4. additional space needed in cubic feet to house the components at that weight/cost/efficiency/no word games/ etc.

Also I would say the assume you have a hydraulic transformer in there (you neglected to mention its efficiency) if you wish to also claim the benefits of having a hydraulic system, but I don't care about storage right now, we will come to that, but it isn't a factor in extended constant load/speed operation.

01-22-2010, 04:32 PM	#76 (permalink)
dcb needs more cowbell Join Date: Feb 2008 Location: ÿ Posts: 5,038 pimp mobile - '81 suzuki gs 250 t 90 day: 96.29 mpg (US) schnitzel - '01 Volkswagen Golf TDI 90 day: 53.56 mpg (US) Thanks: 158 Thanked 269 Times in 212 Posts	Neil, in all three examples you increase the size of the engines for a simple parallel setup when you should be reducing them. That is misinformaton posing as fact. Peak efficiency is improved in an optimized parallel setup for a target load/speed, by a good %20 over a series hybrid. At some point efficiency will fall off as you leave the target speed(or speeds if you make an efficient trans) and load, but you (the driver) have options then as well, i.e. recharge the battery/supercap if the load isn't sufficient, or discharge the battery if you need more power. So the range where optimized series might surpass a well managed optimized parallel system is much smaller than you might think. But storage, again, is not Germaine to this discussion, they both have it, leave it out. Focus on the transmission losses between the ICE and wheels in BOTH cases. I can operate near bscf all day with enough gears, albeit not at constant speed, but I don't care about that. Mech, chill out and answer a straight question. We have to eliminate some variables and look at the component parts here. Q. MECH, assume you are operating a vehicle at a constant speed and load, with an ICE that has a 98% efficient transmission that is cheap and lightweight, and the engine is operating at bsfc. Lets assume a fairly clean design and the engine only needs to put out 15hp to cruise @55 mph. It isn't directly relevant to the question, but this is where the bar for peak parallel/direct drive efficiency is at and these are not part of the variables for this question. Can you give accurate assessments of how converting this relatively constant speed/load operation to a hydraulic will affect: 1. efficiency, in terms of how much power leaving the engine shaft gets to the wheels. 2. weight at the efficiency. 3. cost that weight/efficiency 4. additional space needed in cubic feet to house the components at that weight/cost/efficiency/no word games/ etc. Also I would say the assume you have a hydraulic transformer in there (you neglected to mention its efficiency) if you wish to also claim the benefits of having a hydraulic system, but I don't care about storage right now, we will come to that, but it isn't a factor in extended constant load/speed operation. __________________ WINDMILLS DO NOT WORK THAT WAY!!!