Nando,
Just to get an idea--at what rpm does an ordinary small car alternator start
producing a substantial part of its potential output? And how much would that
be?
HYDRO <[EMAIL PROTECTED]> wrote:
It is a common occurrence the use of water turbines to drive refrigeration
compressors either directly or via electricity.
Walk in refrigeration units with great levels of insulation ( R60+), permits
the use of small to medium refrigeration compressors to maintain the food
and other elements cold or even frozen.
It is, many times, necessary to have electricity for secondary uses, like
fans for cold air circulation or even illumination and electric circuits for
cold room protection and temperature regulation.
The main problem driving the compressor directly is the starting torque of
the compressor that many times is in charge mode, requiring maximum torque
that the Turbine may not be able to generate from stand still.
For this reason, some have used a good size flywheel coupled to an electric
clutch attaching the turbine to the compressor ( the same type that the
automobile air conditioning units use), that sometimes have the winding
changed for much higher voltage, like for 115 volts or even 2230 volts DC.
A friend of mine made one for a site in Center America that could generate
compression and electricity with the electric clutch and the fly wheel --
the turbine did not have enough torque to start a compressor using
electricity -- Electric motor starting energy plus compressor charged or
semi-charged --He even tried the compressor delayed until the compressor
discharged and pressure equalized--- end up getting a compressor with belt
driven external motor.
The cold room wall thickness, I believe was about 50 to 60 cms ( 19 to 24
inches) including semi-underground construction, I do not recall the heat
losses per hour, it was very low.
External metal construction is not a good idea since the metal has the heat
absorption -- it is best to have reflecting energy material and a lot of
shading to reduce the solar insolation of the surfaces.
One thing that was done to reduce solar insolation was the planting vines to
cover the walls with greenery, a good way to reduce solar insolation.
Ideally to have a R 60 or better rating for reduced heat transfer.
Car alternators are very in-efficient, less than 50 %, the only benefit is
that one can get one anywhere because all cars must have one -- and junk
yards all over the world TERRA --- they are built in-efficient by design for
easy manufacturing, like the stator-rotor gap too large that causes a lot of
power losses and the rotor field with in-efficient inter-digitated
alternating magnetic flux generating sharp fingers that have a very
distorted magnetic field reducing the electric energy transfer-- It as
assumed that the power source is many, many times over than the power that
the alternator can produce.
Some of the late built alternators may have rotors with permanent high field
magnets with external charger controllers --those are available in some
expensive cars, also those cars may have now ECM motors ( Electronic
Commutated Motors) for the air blowers and other uses --ideal for small
turbines in the 100 to 300 watts.
Nando.
----- Original Message -----
From: "davis ron" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Saturday, October 08, 2005 7:05 AM
Subject: Re: [microhydro] Re:> Refrigeration compressor directly driven by
Microhydro
>
>> Refrigeration directly
>> driven by microhydro turbines
>>
>> Microhydro turbines would be a practical means to
>> directly drive mid-size refrigeration compressors
> for
>> walk-in refrigerators in remote areas, especially
>> where there is no electricity.
>> This would be a way to keep local food and produce
>> fresh until it could be used or taken to market,
> such
>> as fish. It would also upgrade the local diet.
>> It would mean that local people wouldn't have to eat
> a
>> whole cow a day or two after it is killed, as now
> must
>> be done in warmer areas. I think that from one to
> 2.5
>> h.p. would be sufficient for this.
>> A turbine has very high start-up torque--good for
>> running compressors. The refrigeration box could be
> a
>> prefab made from styrofoam blocks with galvanized
>> sheet metal glued on the outside, and assembled on
>> site.
>> Inside lights and an air circulation fan could be
> run
>> by electricity from a car alternator.
>> I think that such a unit could go a long way toward
>> making some rural areas more self reliant and
>> improving diet.
>> Anyone interested?
>>
>> Ron Davis, watermotor.net
>
>
>
>
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