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Hybrid Block Heater

Use some of that HUGE battery capacity to help out the engine
  [vote for,

Gasoline engines work best when they are at their ideal operating temperature, for lots of reasons. The various gaps and tolerances are designed with an operating temperature in mind and other components, like the oil, are optimized for a given temperature also. Furthermore, most engine wear occurs on startup when the oil can't do its job.

In cold regions, people use simple plug-in resistive block heaters to offset some of the negative effects. Why not add this to a hybrid? Only cleverer. Some hybrids already use electric water and oil pumps. Simply adding the heater to the oil circuit, you could pre-heat and circulate the oil using the not-inconsiderable battery reserve. Your engine may then be designed to have much tighter tolerances (F1 car engines won't crank while cold, their tolerances are so tight that they are effectively seized until warm) and the oil could be designed with a much narrower range of operating temperatures. The engine should then be more efficient by not having to run on choke, which is essentially just over fueling. It should also last longer.

It might be a bit annoying to wait for the engine to be warmed up before it can start, but the initial portion of most car journeys is slow speed, getting-out-of-the- driveway type stuff, which can be done entirely on electric anyway.

bs0u0155, Sep 04 2014

Prius Heat Storage Tank https://www.youtube...watch?v=vpx6M8us0eU
[bs0u0155, Sep 05 2014]

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       Choke? The wasted fuel is lost to heating a large lump of metal. It might seem odd, but it actually makes sense to use thermal losses from combustion to do that rather than the very high order of energy found in the battery.
WcW, Sep 04 2014

       Well, I understand that using combustion heat to warm the block is sort of neat, as it would otherwise be wasted. I have no issue with the waste heat be used to MAINTAIN* block temp.   

       Electrical preheating allows the initial combustion to be as efficient as possible, for example, the 1.3l Nissan Micra I used to own would do about 16 mpg for the first 10 mins on a cold morning and 55 mpg when warmed up at the same speed. That's a 1/3rd of a gallon wasted. Also, you can make the whole engine so much tighter, much smaller piston rings can be used, gaining efficiency. The oil can be more specific.   

       * italics would be better here
bs0u0155, Sep 04 2014

       Doesn't battery discharge already generate heat? You could use that heat to warm the engine block, when running electric first thing. I suspect this may already be done, as some hybrids have integrated cooling systems.   

       Also, this idea is similar to glowplugs in diesel engines.
the porpoise, Sep 04 2014

       //That's a 1/3rd of a gallon wasted.// Wow - seriously? That's about £1.80... ouch. Hate to think what it is for a 4.2 v6...
MaxwellBuchanan, Sep 04 2014

       This would be especially good on a plug-in hybrid. you could schedule it to preheat the engine using grid power before you leave. Grid electricity is even cheaper than gas.   

       I worry somewhat about this concept in a situation where the car is stopped when the battery is largely depleted or if the car is left parked for along time. Currently, you can get enough power to get the engine running in a couple seconds with jumper cables, but you'd need a bit more to preheat the engine. I suppose you could design it so that another similar hybrid could provide a jump start, though that would require however many minutes are needed to heat the engine.   

       How much energy does it actually take to warm up an engine block? And if it's too cold out, and the heater isn't powerful enough, you could end up not being able to get it up to temperature at all.   

       Especially on a non plug-in hybrid, it seems like you'd want some mechanism that allows you to heat the engine by burning fuel.
scad mientist, Sep 04 2014

       //How much energy does it actually take to warm up an engine block?//   

       Assuming an engine mass of 200kg (I am guessing) and a heat capacity of about 1kJ/kg/°C, and assuming you need to heat it by 100°C, that's 200*100*1000=20MJ, or about half a litre of petrol.   

       So, if what [bs] said is correct, it's much more efficient to burn fuel solely to heat the engine before starting it, than it is to run the engine from cold and let it warm up naturally.
MaxwellBuchanan, Sep 04 2014

       Yes, maybe, but a low-grade fuel. Liquid fuels are too useful for vehicles to waste on simple heating applications. A "cartridge" system using biomass would be good. But there'd be a significant lead time on startup.   

       Using electrical energy from the traction battery is inherently inefficient.   

       The powerplant has a well-defined mass and specific heat. By adding a heat reservoir in the form of a water tank, heat could be collected from the exhaust gases and cooling system during normal running. When the engine is cold, simply recirculate the coolant through the heavily-insulated tank of hot water.   

       A tank of liquid about 200% of the volume of the coolant circuit should be enough. For a small engine, that's likely to be about 20 litres.
8th of 7, Sep 04 2014


       Run with what 8th said, using stored warm coolant to defreeze the engine and oil, then...   

       Having previously shut down the 4-banger with all pistons at half-mast, run the injectors at very low fuel flow to hot up the cylinder and piston heads from the inside, without cranking the engine. Requires an independent valve-train and a small amount of forced induction.
FlyingToaster, Sep 04 2014

       Diesel engines like the Perkins 4.108 use an intake air heater for starting, instead of glowplugs. Now, with a valve lifter and an air preheater, a small fan would be enough to blow hot air through the pots and warm the block and coolant for a quick and easy start.
8th of 7, Sep 04 2014

       //heat could be collected from the exhaust gases and cooling system during normal running//   

       That's a very good idea, so good Toyota did it in the Prius <link> (video warning).
bs0u0155, Sep 05 2014

       ////That's a 1/3rd of a gallon wasted.// Wow - seriously? That's about £1.80... ouch. Hate to think what it is for a 4.2 v6...//   

       hmm. 4.2 litre V6 you say? nah. The only 4.2 litre V6 I'm aware of is a godawful Ford unit fitted to the F150/Explorer over here. you either have a 4.2 litre V8, in either an Audi or a Jag. Or a 3.2 litre V6 in a VW/Audi or possibly an oldish Honda. Either way, bigger engines have a more optimal surface area volume ratio and heat up faster. If you like, you can locate your OBD2 port, plug in a laptop and get every parameter of your engine, dumped at 10Hz. A real exercise in data wrangling after that. Changes the way you drive... or it did me.   

       Either way, engines rarely weigh 200kg, and they're aluminium mostly, quite a low specific heat capacity. Also, many parts of the "Engine" are to some extent thermally isolated when the thermostat is closed. It's really about getting the chamber temperatures up to the point where the fuel mixes well.
bs0u0155, Sep 05 2014


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