I've been thinking about recovering exhaust heat again. As I've stated many times on the forum, I have a short commute of 7 miles. Engine warm up is critical for me. In winter, its not uncommon for the engine not even to get up to full operating temp, especially if I want heat. This really takes its toll on my fuel mileage. Thus, I love thinking about ideas on how to use wasted exhaust heat. So, here is my latest idea.
We've talked a LOT about exhaust heat recovery to heat the coolant here in my other thread on
Mimicking Gen3 Prius Exhaust Heat Recovery. However, we really never came to a good conclusion on how to mimic it. IMO all the ideas were too complex or too expensive to be worth the time. So, whatever approach I took, it had to be simple, very simple.
This idea is pretty simple. We have a fan, an airbox around the exhaust manifold, and a radiator to transfer the hot air into the coolant. A lot of these parts can be salvaged from random junk, so a near zero cost system shouldn't be impossible to put together. The fan could be activated by a snap switch fixed to the block. No fancy electrical work, just simple. Yes, it will require a decent amount of fabrication to make the airbox and ducting. IMO that is the fun part.
There are no pumps, no coolant or exhaust diverter valves, no pressurized systems to deal with. You want heat, the fan turns on, you don't need heat anymore, it turns off. Air isn't going to break down if it gets too hot, or turn into steam and blow something up.
My main concern is pulling enough useful heat off the manifold. So, I'll be testing the warm up time on it when I get a chance.
Thoughts?