Heat storage system (Prius-like insulated coolant reservoir)

[skyking]

Originally Posted by Old Mechanic

You have nothing to worry about cracking anything engine wise.

regards
Mech

Frank and you both have this right, IMO. No worries at all. I think the whole thing can be totally passive on the heater hose circuit without pumps or controls. If you want an external heat source for really cold overnights, you can place a tank-type heater in a loop on your tank system, on a timer.
It won't heat your engine of you place it right, just your tank.
TANK TYPE ENGINE COOLANT BLOCK HEATER 1500W DIESEL | eBay

[meelis11]

Passive system (no extra pumps) with one electric valve is minimum I think.
About heat-storage - probably best would be to put second heater core into insulated container and fill container with wax (keep some air room for expansion)

If you add electric pump then you can release that heat before starting a car. But first you can probably get away without it.

[rainagain]

What a great idea! I'm sure BMW did something similar but they used a material similar to the bricks you get in overnight electric storage heaters to store the heat. This might give you a more compact setup.

[Demolite]

Thanks for the good ideas! I'm currently fabricating parts for my next attempt at a "passive" system. It does still have a valve controlled by a microcontroller based on two temperature sensors. Anyone have ideas on cheap electric valves that can take the pressure of a cooling system (1-2 bar max.)? I have some car vacuum solenoids, but I'm yet to test how they hold up to coolant and pressure. They are also quite small so they may resist flow. As for heat storage, I'm still staying with water. With no additional material in between the heat transfer is faster and this is key to the efficiency of the system. It's also cheaper to make.

[California98Civic]

Originally Posted by rainagain

I'm sure BMW did something similar but they used a material similar to the bricks you get in overnight electric storage heaters to store the heat.

"Bricks?" What sort of bricks?

[meelis11]

Originally Posted by Demolite

Thanks for the good ideas! I'm currently fabricating parts for my next attempt at a "passive" system. It does still have a valve controlled by a microcontroller based on two temperature sensors. Anyone have ideas on cheap electric valves that can take the pressure of a cooling system (1-2 bar max.)? I have some car vacuum solenoids, but I'm yet to test how they hold up to coolant and pressure. They are also quite small so they may resist flow. As for heat storage, I'm still staying with water. With no additional material in between the heat transfer is faster and this is key to the efficiency of the system. It's also cheaper to make.

Search ebay for "Electric Solenoid Valve".
I found some:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

[Demolite]

Yeah, I looked at those valves too but it says max water temp 95 C so it might not last too long as coolant temperatures stay quite near the max limit. I'll have to see if i can salvage a old electric heater valve from some car at the breakers.

[meelis11]

Originally Posted by Demolite

Yeah, I looked at those valves too but it says max water temp 95 C so it might not last too long as coolant temperatures stay quite near the max limit. I'll have to see if i can salvage a old electric heater valve from some car at the breakers.

Second is max 100 C so should be ok?

[rainagain]

Originally Posted by California98Civic

"Bricks?" What sort of bricks?

the bricks used in these heaters
Storage Heaters Advice

pic of the BMW latent heat store

bmwfans.info/parts/catalog/E39/Sedan/Europe/523i-M52/LHD/M/2000/march/browse/heater_and_air_conditioning/latent_heat_accumulator/

[retepsnikrep]

We have discussed this at some length on the Insight forum as well.

Insight Thermos Modification - Insight Central: Honda Insight Forum

I went as far as to get the special prius three way valve and pump and a stainless steel 2-3l thermos but never installed it. I added a 12v heating element into my thermos so you could boost the coolant temp with a very low current heater (even a solar panel on back shelf) as the the mod is not limited to winter use. I even knocked up few bits on the bench and bought some paraffin wax granules. i think the wax does expand a bit so you would have to leave a bit of room for that.

I think the thermos needs to be in the engine comp and hoses as short as possible, only one pump is reqd. There is a diagram of the prius system on the Insight thread.

I like the phase change fluid/wax idea and if you used a vacum bowl or wide neck flask you could incorporate a large surface area heat exchanger into it before soldering on a cover/end plate and insutalting that.

I was going to use simple pic12F683 and a couple of I2C temp sensors to monitor thermos internal temp and engine block temp and control pumping/valve with that.

Please post some pics of your setup.