Re: Suspension losses

On 1/16/2025 1:38 PM, Radey Shouman wrote:

Frank Krygowski <frkrygow@gXXmail.com> writes:
 

On 1/15/2025 1:28 PM, Zen Cycle wrote:

On 1/15/2025 1:16 PM, Frank Krygowski wrote:

On 1/15/2025 1:05 PM, Zen Cycle wrote:

On 1/13/2025 11:03 AM, Frank Krygowski wrote:

>
It's certainly true that 100% of the electricity consumed by an
electric blanket becomes heat.

>
No, that isn't true either.

>
Please explain. What electrical energy goes elsewhere?

A very small amount of power is used for the indicator lighting and
electronic controls.
>

>

I write "either" because even _if_ it were true that electric
heaters are 100% efficient (which isn't true), saying 100% of the
electricity consumed by the device become heat is very different
than saying it's 100% efficient.

>
What's your definition of "efficiency?" As I said earlier, I think
a common one used for engineering matters is Desired Output divided
by Required Input, or something similar.
>
Do you have a different one?

Nope, it's the notion that every watt of power directly goes into
heating the targeted space that I'm stuck on.

>
You're moving goalposts. You objected to my statement "It's certainly
true that 100% of the electricity consumed by an electric blanket
becomes heat."
>

There are other losses in the cabling and plug interface which -
while realized as heat - do not contribute the heating of the
targeted space. The heat generated by the plug and cord are rather
well insulated.

>
But it's still heat, delivered into the room. It's not lost elsewhere.

 Not necessarily true.  Heat is conducted thermally into the electrical
wires, which often run inside exterior walls, and can thus be conducted
to the outdoors without heating a room.
 But these are quibbles.  The definition of efficiency depends on the
purpose of the device, and the theoretical model used to compute the
minimum energy (or whatever) required to achieve that purpose.
 The purpose of an electric blanket is *not* to heat a room, it is to
make an individual human being more comfortable *without* heating the
room. 

I guess it's possible to define the Desired Output more and more narrowly, down to "The heat delivered to the parts of the body that have nerve endings that detect temperature." IOW, if Grandpa's hair and toenails get warmer, that's wasted heat. But I think few people want to go to that extreme.
Slightly more reasonable would be to demand wrapping the electric blanket around Grandpa, like a sleeping bag, then wrapping that with a perfectly adiabatic blanket. All the heat would eventually go into Grandpa.
--
- Frank Krygowski