How to temporary chill a car with non-working AC.

"Threeducks" > wrote in message
...
|
| A system does not contain "heat". Heat is simply a method of
| transfering energy between the system and it's surroundings.

I thought that *any* material with a temperature above "absolute zero" contains
"heat".

"Daniel J. Stern" > wrote in message
n.umich.edu...
| On Fri, 24 Sep 2004, Kathy and Erich Coiner wrote:
|
| > > An air conditioner generates neither heat nor cold. All it does is *move*
| > > heat.
|
| > But it moves the energy at less than 100% efficiency. That means there is
| > some extra work that shows up as heat.
|
| Sure, but the fact remains, an aircon does not "generate" heat or cold.
|
| > You have a closed,well insulated room with a refrigerator in it. It is
| > running and you hold the door open. What happens to the air temp in the
| > room?
|
| Of course the ambient temp increases.
|
| Now here's a fun one: It is common knowledge that there is no such thing
| as a 100 percent efficient machine. Given that, consider an electric space
| heater with a 20-foot electric cord and a high-speed motor-driven blower.
| Is the efficiency of such a device 100 percent, or some lesser figure?
| Support your answer.

No for several reasons:

o Losses in the generation of electricity at the power plant
o Losses due to electrical transmission line losses between the
generator and the heater
o Losses in step-down transformers along the electrical
transmission route.
o Losses at each connection point, switch/fuse/breaker

Daniel J. Stern wrote:
> On Thu, 23 Sep 2004, motsco_ _ wrote:
>
>
>>An air conditioner generates more HEAT than COLD
>
>
> An air conditioner generates neither heat nor cold. All it does is *move*
> heat.
>
>

It does naturally generate heat due to the energy lost in moving the
energy in the hot air.

Otherwise it would consume almost zero watts...

On Fri, 24 Sep 2004, James C. Reeves wrote:

> | Now here's a fun one: It is common knowledge that there is no such thing
> | as a 100 percent efficient machine. Given that, consider an electric space
> | heater with a 20-foot electric cord and a high-speed motor-driven blower.
> | Is the efficiency of such a device 100 percent, or some lesser figure?
> | Support your answer.
>
> No for several reasons:
>
> o Losses in the generation of electricity at the power plant
> o Losses due to electrical transmission line losses between the
> generator and the heater
> o Losses in step-down transformers along the electrical
> transmission route.
> o Losses at each connection point, switch/fuse/breaker

"No" is not a valid answer; the question is not of the yes/no variety.
Also, we're talking about efficiency at converting the electricity *at the
wall socket* into heat.

On Fri, 24 Sep 2004, James C. Reeves wrote:

> |
> | On Wed, 22 Sep 2004, Burt Squareman wrote:
> |
> | > The A/C system in an `89 old Honda is completely dead.

> | Find and get an automotive swamp cooler. They were popular before car A/C
> | became common.

> Swamp coolers are relatively ineffective

So are clapped-out '89 Hondas. Perfect match.

"Daniel J. Stern" > wrote in message
n.umich.edu...
| On Fri, 24 Sep 2004, James C. Reeves wrote:
|
| > |
| > | On Wed, 22 Sep 2004, Burt Squareman wrote:
| > |
| > | > The A/C system in an `89 old Honda is completely dead.
|
| > | Find and get an automotive swamp cooler. They were popular before car A/C
| > | became common.
|
| > Swamp coolers are relatively ineffective
|
| So are clapped-out '89 Hondas. Perfect match.
|

Good point! ;-)

"James C. Reeves" > wrote >

I thought that *any* material with a temperature above "absolute zero"
contains
> "heat".


Except for my ex-wife.

On Fri, 24 Sep 2004 03:54:20 GMT, "Kathy and Erich Coiner"
> wrote:

>This is a thought problem we sometimes give to mechanical engineering job
>applicants.
>
>You have a closed,well insulated room with a refrigerator in it. It is
>running and you hold the door open.
>What happens to the air temp in the room?
>
>Erich

If you let the condensate down the drain instead of evaporating inside
the room, you have the most efficient heater.

Bye,
Leon

On Fri, 24 Sep 2004 19:18:42 -0400, Max > wrote:

>Daniel J. Stern wrote:
>> On Thu, 23 Sep 2004, motsco_ _ wrote:
>>
>>
>>>An air conditioner generates more HEAT than COLD
>>
>>
>> An air conditioner generates neither heat nor cold. All it does is *move*
>> heat.
>>
>>
>
>It does naturally generate heat due to the energy lost in moving the
>energy in the hot air.
>
>Otherwise it would consume almost zero watts...

No, the a/c is a heat pump. Think about it as a pump pumping water
between two tanks. It takes energy to pump water up to the higher
tank. The pump is also inefficient.

Bye,
Leon

"James C. Reeves" wrote:
>
> "Threeducks" > wrote in message
> ...
> |
> | A system does not contain "heat". Heat is simply a method of
> | transfering energy between the system and it's surroundings.
>
> I thought that *any* material with a temperature above "absolute zero" contains
> "heat".

No, a material can not contain heat. Heat, as Threeducks said, applies
only to thermal energy in transit. From Halliday / Resnick: Fundamentals
of Physics, 3rd edition, Wiley 1988:

Page 464: "Heat is energy that flows between a system and its
environment by virtue of a temperature difference that exists between
them"

Page 465: "Both heat and work represents energy-in-transit between a
system and its environment. Heat and work, unlike temperature, pressure
and volume, are not intrinsic properties of a system. They have meaning
only as they describe energy transfers into or out of a system, adding
or subtracting from the system's store of internal energy. (...) It is
without meaning to say: "This system contains 450 J of heat" or "This
system contains 385 J of work""