Quote:
Originally Posted by Phase
So everyone knows that short trips with the engine cold give you horrible mpgs...
Heck in my ioniq today, a 5 mile short trip to get groceries and back with ''hypermiling'' netted me 29mpg. and its a HYBRID! obviously this was because the engine was cold and none of the fluids or parts were warmed up and at the best operating temp...
IS THERE A WAY to speed up this warming up cycle or get better gas mileage for shorter trips? would a winter heat block still help the engine warm up during hot summer months? does parking in the sun help the engine warm up faster? what other things or '' hacks'' can someone do to get better short trip driving fuel economy?
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Hey again Phase!
So I see that warming your car quickly *has* been on your mind already! The insulation mentioned in the other thread is one route and a good one for short trips. It definitely reduces warmup times and improves FE, but for a 5 minute trip it would be maybe a +10%, or +3 mpg in your example. Worthwhile but not spectacular.
Another route is using the Toyota Prius trick. They take the hot coolant fluid and shunt it to a thermos when the car shuts off. Then they put it back into the coolant reservoir when you start up again. This only helps between multiple quick trips, i.e. the car doesn't warm up faster, it "loses heat slower", so to speak.
Engine block warmers, the glowplugs mentioned earlier, etc. will all work. They will give you a better mpg reading on your dash, but won't necessarily be more efficient. Meaning, you still need to spend energy to power the heaters, and (if factored into the mpg equation) is still crap net fuel economy. It's just consuming two different types: gas and electricity. To truly get more efficiency one would want to harness some natural or ambient resource for "free".
If we want the coolant to always be at operating temperature near start, then a crazy but workable solution is to use the solar oven effect. Trap a dark fluid under a clear surface and it will raise temperature quickly. Then circulate it with a heat exchanger to your coolant fluid. Some simple electronics could ensure the right temperature, and making it solar powered ensures it only comes on when the sun is out.
The main potential drawback is thermal expansion issues between the engine and coolant. Meaning, if the coolant is too hot and the engine is too cold, they might be out of spec relative to each other on startup. So it might make sense to run the "heater fluid" through the oil and across the engine as well, to try to warm up everything "evenly". The best solution here would be to find a way to use the actual coolant pump while the car is off. That may not be possible with some engines; some use the stroke cycle itself to circulate fluids. Fortunately, every hybrid I've ever seen has a separate coolant pump, because they want fine control for efficiency reasons.
Alternatively, you could use a fluidless solution, go full solar, and use something iike the Glowplug heaters mentioned earlier. Basically harvest sun for electricity to directly convert into heat. That has possibilities if you ever plan on using the electricity for anything else, whereas the fluid solution is effectively a secondary radiator.
Huh. This could actually have real applicability. If we were to view this purely as a heating problem, then the most efficient solution is to use a heat pump. So you'd use the solar power to extract heat from the heating fluid and force it into the relevant components. That not only gains the COP factor for efficiency, it means the solution would work to much lower temperatures than the solar solution alone. The heat pump could also have dual use to heat the cabin, which is much needed in cold climes.
Cheers.