The good, the bad, the ugly (or my 18 months with a GIII)

And of course, aluminum has a heat capacity that is somewhat less than iron....

 

The efficiency of the heat exchanger system is not 50 % after taking into account the additional losses of piping all the coolant everywhere from front to back of the vehicle, inverter, HSD, engine. With the heat exchanger (which is bad engineering BTW due to its extra weight, complexity and maintenance issues ... yet another "radiator" to corrode), it would be fair to say the Prius breaks even from the additional losses from the extra piping.

Below 2000rpm, the 2.5 in the Subaru generates 3X the HP of the Prius. In addition, once the battery reached operating temp, even less power is drawn from the Prius ICE. So if the 2.5 is running at 2000 rpm while the Prius ICE idles , the difference is even greater up to 5X.

So my claim still stands , unless the Prius is capable of changing the laws of physics...

Link ?

This appears at odds with the OP (which is a good one BTW).

 

Hi tpfun,

Its not how much HP the engine can generate, its how much traffic will actually let you use. Driving along in traffic, both cars are using about the same HP, if they are about the same weight. Which I believe is a close enough approximation for this discussion.

Of course 50 % is a number I pulled out of you know where based on my limited mechanical engineering experieince. I am an electrical engineer with 25 years of experience , and actually, in the long distant past have sized heat exchangers for various projects - that actually worked. The 3rd Genertion Prius exhaust heat exchanger could be much more efficient, as the exhaust gasses are pretty hot compared to the coolant temp. 70 % even - similar to the efficency of a hydronic household heating is possible. Yes, there will be more losses due to the asociated plumbing. But the magnitude of the heat energy in that exhaust flow makes up for this. As my back-of-the-envelope numbers above should have made abundantly clear.

Combined Heat and Power is a hot topic in mechanical engineering circles for remote location power generators. Ask our PC user Jayman about those. This is just the automotive version of such systems.

Not good engineering? By your same criterion, a Turbo charger would also be such poor engineering. BMW does not think so either, they have both been working on way to get that 78 % wasted energy at low speed back into the car, rather than pumped out the tail pipe. They have built prototype sterling engines powered by exhaust gasses as an alternative to the traditional alternator. Yea, all the stuff needed to recuperate that energy may not be elegant engineering, but the waste out the tail pipe of the internal combustion engine , even the Atkinson engine, makes it very much needed.

Well, the battery gets all its energy from the Engine and only the engine in the Toyota produced hybrids on the road today. Albeit, sometimes using the car as a big energy storage device as its driven up hill, and then down - regenerating the energy back into the battery. SO, no once warmed up, the energy still comes from the engine. Its just that the Prius need only produce half the energy to travel the same distance as cars of similar weight of more traditional design. Which I accounted for in my previous post. And the 3rd Prius still had twice the cabin heat available.

Here is a link to the magazine, and the PC thread where it first came up

http://tekniikanmaailma.fi/uutiset/vuoden-talviauto-2010-valittu

http://priuschat.com/forums/gen-iii...82-worried-about-snow-few-other-things-2.html