Posted by alexibu on February 21, 2007, 4:15 am
On Feb 21, 11:49 am, markz...@digiverse.net wrote:
> Just a thought...
> The average air conditioning heat pump will output over 3 times the
> input power in heat (in the heater configuration).
> So how about having the wind turbine run a heat pump compressor
> directly (no electricity)?
> Without the additional heat fom the motor, that would be over twice
> the rating of the wind turbine. IOW a 500 watt turbine should output
> 1kw of heat (or cold). Up to you wether it's used for heating water or
> air.
> The mast could double as the "radiator"/heat exchanger absorbing
> ambient heat and you could have a fridge at the bottom of the turbine
> as a bonus (with electrical backup for low wind days, obviously).
> The question is:
> How do heat pumps perform at variable speeds? Any refrigeration/ air
> conditioning techs out there?
> If the variable speed is a problem, any thoughts about solutions?
I think you are misunderstanding what a heat pump is - see
http://en.wikipedia.org/wiki/Heat_pump
The heat pump is not the actual compressor. It is the thermodynamic
cycle.
Therefore directly driving the compressor with wind turbine would not
have the benefits you are describing. They might have a small benefit,
but most likely it is beneficial to allow the wind turbine to run at
different speeds to the compressor.
Posted by Joe Fischer on February 21, 2007, 6:02 am
>On Feb 21, 11:49 am, markz...@digiverse.net wrote:
>> Just a thought...
>> The average air conditioning heat pump will output over 3 times the
>> input power in heat (in the heater configuration).
>> So how about having the wind turbine run a heat pump compressor
>> directly (no electricity)?
>I think you are misunderstanding what a heat pump is - see
>http://en.wikipedia.org/wiki/Heat_pump
>The heat pump is not the actual compressor. It is the thermodynamic
>cycle.
I think he knows what a heat pump is, he probably
owns 2 or 3. Your link says a heat pump is any machine
that cools or heats using a working fluid and radiators.
>Therefore directly driving the compressor with wind turbine would not
>have the benefits you are describing.
Can you explain why not? Any air conditioner
can be used as a heat pump if it is put in the window
backwards.
The big thing about a heat pump is that both
radiators need to be able to tolerate high pressure
depending on cool or heat mode, plus an additional
orifice with a valve to change modes.
>They might have a small benefit,
>but most likely it is beneficial to allow the wind turbine to run at
>different speeds to the compressor.
Some windmills do run at a different speed than
the output shaft.
There is a problem with a heat pump though,
usually they are undersized in heating mode, normally
the temperature difference wanted in heat mode is
more than in cool mode.
A simple solution to this problem is to have
more than one heat pump for the same space,
then both can be run in heat mode if needed,
and chance are only one will be needed in
cool mode.
Installers and manufacturers know that a heat
pump does not work well or at all below freezing, so
backup heat strips are used when outdoors
temperatures are low (for air to air heat pumps.
Even so, a heat pump still needs an alternate
heating system for real cold weather, a huge heat pump
is needed for heating loads of 20 or 30 kilowatts, and
that would be the equivalent of a very small gas furnace.
Joe Fischer
Posted by markzoom on February 21, 2007, 9:29 am
> >On Feb 21, 11:49 am, markz...@digiverse.net wrote:
> >> Just a thought...
> >> The average air conditioning heat pump will output over 3 times the
> >> input power in heat (in the heater configuration).
> >> So how about having the wind turbine run a heat pump compressor
> >> directly (no electricity)?
> >I think you are misunderstanding what a heat pump is - see
> >http://en.wikipedia.org/wiki/Heat_pump
> >The heat pump is not the actual compressor. It is the thermodynamic
> >cycle.
> I think he knows what a heat pump is, he probably
> owns 2 or 3. Your link says a heat pump is any machine
> that cools or heats using a working fluid and radiators.
> >Therefore directly driving the compressor with wind turbine would not
> >have the benefits you are describing.
> Can you explain why not? Any air conditioner
> can be used as a heat pump if it is put in the window
> backwards.
Exactly. In my case I'm more interested in the heating configuration,
though I could run the cold end of the cool pipe through my
refrigerator as a bonus.
> The big thing about a heat pump is that both
> radiators need to be able to tolerate high pressure
> depending on cool or heat mode, plus an additional
> orifice with a valve to change modes.
Point taken. I envisage the mast (scaffolding tube?) to play a part in
it.
> >They might have a small benefit,
> >but most likely it is beneficial to allow the wind turbine to run at
> >different speeds to the compressor.
> Some windmills do run at a different speed than
> the output shaft.
> There is a problem with a heat pump though,
> usually they are undersized in heating mode, normally
> the temperature difference wanted in heat mode is
> more than in cool mode.
Personally I don't need the cooling, so it will be designed for
heating.
> A simple solution to this problem is to have
> more than one heat pump for the same space,
> then both can be run in heat mode if needed,
> and chance are only one will be needed in
> cool mode.
> Installers and manufacturers know that a heat
> pump does not work well or at all below freezing, so
> backup heat strips are used when outdoors
> temperatures are low (for air to air heat pumps.
Not a problem here in the Azores but would be elsewhere.
> Even so, a heat pump still needs an alternate
> heating system for real cold weather, a huge heat pump
> is needed for heating loads of 20 or 30 kilowatts, and
> that would be the equivalent of a very small gas furnace.
My house only needs a measly 4kw to be comfortable in the winter,
there is not much temperature variance on Islands, the air is pretty
much the same as the sea temperature +/- land heating/radiance day/
night.
> Joe Fischer
Posted by Joe Fischer on February 21, 2007, 11:27 am
On 21 Feb 2007 06:29:44 -0800, markzoom@digiverse.net wrote:
>Not a problem here in the Azores but would be elsewhere.
The biggest problem is buying, begging, or borrowing
a good enough oil induction vacuum pump to vaporize all
moisture in the system and suck it all out to get it dry before
putting the freon in.
Otherwise, the orifice will freeze up constantly.
Joe Fischer
Posted by gfretwell on February 21, 2007, 12:13 pm
On Wed, 21 Feb 2007 11:27:25 -0500, Joe Fischer
> The biggest problem is buying, begging, or borrowing
>a good enough oil induction vacuum pump to vaporize all
>moisture in the system and suck it all out to get it dry before
>putting the freon in.
> Otherwise, the orifice will freeze up constantly.
If you don't mind "venting" a little into the air all you really need
to do is purge the system and use a new dryer. Turn the can over and
shoot liquid in the high side until it comes out the other end. HVAC
techs used to do that all the time before the rules about discharging
changed.
If you use R134 it is not prohibitively expensive.
That is not as good as using the proper vacuum pump but millions of
systems were charged that way and worked.
A new dryer will take out all of the moisture normally in a system but
that still doesn't do anything for the inert air.
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> The average air conditioning heat pump will output over 3 times the
> input power in heat (in the heater configuration).
> So how about having the wind turbine run a heat pump compressor
> directly (no electricity)?
> Without the additional heat fom the motor, that would be over twice
> the rating of the wind turbine. IOW a 500 watt turbine should output
> 1kw of heat (or cold). Up to you wether it's used for heating water or
> air.
> The mast could double as the "radiator"/heat exchanger absorbing
> ambient heat and you could have a fridge at the bottom of the turbine
> as a bonus (with electrical backup for low wind days, obviously).
> The question is:
> How do heat pumps perform at variable speeds? Any refrigeration/ air
> conditioning techs out there?
> If the variable speed is a problem, any thoughts about solutions?