The Stored Energy Dance (Octovalve)

[SageBrush]

I was thinking about the beauty of the Octovalve after I watched a Bjorn Nyland video that showed the car using heat accumulated in the battery after a Supercharging event to keep the cabin warm.

*Sweet!*, thought I, but that takes an hour or two and in the meantime the battery is hotter than ideal.
Could the motor(s) be an interim heat sink ? how much heat capacity do they have ?
Are there other heat sinks that can be utilized, or added to the system ? Perhaps a PCM ? Or a larger anti-freeze reservoir ?

 

[Brando]

I was thinking about the beauty of the Octovalve after I watched a Bjorn Nyland video that showed the car using heat accumulated in the battery after a Supercharging event to keep the cabin warm.

*Sweet!*, thought I, but that takes an hour or two and in the meantime the battery is hotter than ideal.
Could the motor(s) be an interim heat sink ? how much heat capacity do they have ?
Are there other heat sinks that can be utilized, or added to the system ? Perhaps a PCM ? Or a larger anti-freeze reservoir ?

octo as you know = 8
consider 8 heat sources in a Tesla
I can't imagine any sources Tesla engineers missed.

 

[SageBrush]

octo as you know = 8
consider 8 heat sources in a Tesla
I can't imagine any sources Tesla engineers missed.

Sink, not source.

---
The 'octo' name comes from the unit having 4 inputs and 4 outputs. To balance flow, an input is matched to an output. This allows up to a theoretical 2^4 = 16 pairings. IIRC, Tesla uses twelve.

 

[ItsNotAboutTheMoney]

I was thinking about the beauty of the Octovalve after I watched a Bjorn Nyland video that showed the car using heat accumulated in the battery after a Supercharging event to keep the cabin warm.

*Sweet!*, thought I, but that takes an hour or two and in the meantime the battery is hotter than ideal.
Could the motor(s) be an interim heat sink ? how much heat capacity do they have ?
Are there other heat sinks that can be utilized, or added to the system ? Perhaps a PCM ? Or a larger anti-freeze reservoir ?

Maybe they could have a built-in kettle.

 

[CYBER_Y]

octo as you know = 8
consider 8 heat sources in a Tesla
I can't imagine any sources Tesla engineers missed.

Are all 8 used for heat? Are any used for cooling?

 

[mongo]

I was thinking about the beauty of the Octovalve after I watched a Bjorn Nyland video that showed the car using heat accumulated in the battery after a Supercharging event to keep the cabin warm.

*Sweet!*, thought I, but that takes an hour or two and in the meantime the battery is hotter than ideal.
Could the motor(s) be an interim heat sink ? how much heat capacity do they have ?
Are there other heat sinks that can be utilized, or added to the system ? Perhaps a PCM ? Or a larger anti-freeze reservoir ?

Thermal mass of the pack is huge ~85wH/C , there is nothing in the car that can offset that (in a storage way) significantly.
https://patentimages.storage.googleapis.com/58/eb/22/870827f4b9f611/US20190070924A1.pdf
Motor wants to be cool (winding less resistivity, electronics like cool).
It would require 73 kg of pure water (no antifreeze) to equal the thermal mass (1C up for 1C down).

 

[Needsdecaf]

Ya'll are making me re-live my 8:00 AM thermodynamics classes with Professor Ulucacli and I don't like it one bit.

 

[mongo]

Ya'll are making me re-live my 8:00 AM thermodynamics classes with Professor Ulucacli and I don't like it one bit.

Sorry, I tried to keep it at the Chem 101 level

 

[SageBrush]

Thermal mass of the pack is huge ~85wH/C , there is nothing in the car that can offset that (in a storage way) significantly.
https://patentimages.storage.googleapis.com/58/eb/22/870827f4b9f611/US20190070924A1.pdf
Motor wants to be cool (winding less resistivity, electronics like cool).
It would require 73 kg of pure water (no antifreeze) to equal the thermal mass (1C up for 1C down).

Fair enough.

PCM ?
It would not be necessary to suck all the heat out of battery -- just get it off the 50C+ plateau into the low 40s C

And we could always call on the heat pump if we wanted more heat transfer than a heat exchanger provides.

 

[rypalmer]

Thermal mass of the pack is huge ~85wH/C , there is nothing in the car that can offset that (in a storage way) significantly.
https://patentimages.storage.googleapis.com/58/eb/22/870827f4b9f611/US20190070924A1.pdf
Motor wants to be cool (winding less resistivity, electronics like cool).
It would require 73 kg of pure water (no antifreeze) to equal the thermal mass (1C up for 1C down).

That's significant - 2.55kWh of equivalent energy assuming a 30ºC swing - even more considering the efficiency of the heat pump. But it would be interesting to do the math on the electrical energy lost due to heat harvesting for the cabin.

 

[Brando]

Are all 8 used for heat? Are any used for cooling?

a continuum from (-) ... cold ... io ... hot ... (+)

HeatPump moves heat from one place to another place

 

[mongo]

That's significant - 2.55kWh of equivalent energy assuming a 30ºC swing - even more considering the efficiency of the heat pump. But it would be interesting to do the math on the electrical energy lost due to heat harvesting for the cabin.

Watch out, you don't get to multiplly the pack heat energy by the heat pump coefficient of performance, there is only 2.55kWh of heat available. Rather, the amount of energy the heat pump needs to use to move the pack heat is divided by the COP (add added to the total).