discussing this with a motor engineer who really knows about lpg/propane this
was his response
How far below ground level do you need to go to get away from the
atmospheric temperature variation? Enough distance below ground with an
insulated door will see a temperature consistently over 0C.
If it's on a hill, go part way down the side of the hill and do a
horizontal bore shaft and put the tank in the end of the shaft or a small
carved room if in rock. The shaft only needs to be big enough to crawl
into or for the diameter of the tank, whichever is larger. If the ground
is unstable, large diameter concrete drain pipes can be used to form the
shaft.
All of the pipework including the outlet of the relief should be piped
away in hose, with lagging if necessary. The idea is to make sure that
cooling such as from conduction of heat away along the lines does not
exceed the rate at which heat in the ground is able to transfer into the
tank to maintain a consistent "off" temperature.
Is it going to be liquid withdrawal or vapour? Small engines will be
vapour, while bigger ones will be liquid. The difference is important
because it affects the rate of tank cooling while the genset is running.
In a vapour withdrawal system, the liquid in the tank is continually
boiling off to maintain vapour pressure and the latent heat of
vaporisation of that has to be compensated for by heat going into the
tank from outside. Liquid withdrawal has a proportionally smaller rate
of vapourisation relative to rate of fuel withdrawal as it only has to
vapourise a quantity of liquid proportional to the liquid withdrawal to
maintain vapour pressure.
In a vapour withdrawal system, you'd virtually have to heat the tank
from the waste heat (not exhaust) of the genset. With liquid withdrawal,
the majority of the latent heat of vapourisation is handled in the
convertor at the engine. An engine oil cooler under the tank would be an
effective form of heating, but might need a pair of bypass thermostats,
one to stop excessively cold flow and another to stop excessive heating
of the tank...
hope that helps
To: Repeater-Builder@yahoogroups.com
From: [EMAIL PROTECTED]
Date: Fri, 9 May 2008 07:34:05 -0500
Subject: Re: [Repeater-Builder] DTMF controllable propane generators
Tony,
Wonder why the commercial power would cost that much. Is it because of the
wiring installation cost???
73, ron, n9ee/r
>From: Tony VE6MVP <[EMAIL PROTECTED]>
>Date: 2008/05/08 Thu PM 11:55:23 CDT
>To: Repeater-Builder@yahoogroups.com
>Subject: [Repeater-Builder] DTMF controllable propane generators
>
>Folks
>
>We're moving a VHF MSR2000 repeater and two UHF GMR300 linking radso's toa
>site where commercial power will cost $5000 plus monthly fees. Sowe're
>looking at various options such as solar, wind and so forth. The land owner
>might not appreciate another wind turbine so one ideawe're thinking about is a
>DTMF controlled propane generator. Has anyone experimented with such? I see
>mention of remote controlgenerators so figure it should be doable. The
>current controller isa RLC-3 but that could be changed if it would help.
>
>The other obvious answer is to have the generator automatically come onwhen
>the voltage gets too low but I wonder how well that willwork.
>
>We're in central Alberta, Canada so the days in winter are quite shortand we
>can get 20 or 25 cloudy days in a row. We either need to putin a *lot* of
>solar panels or some other form of auxiliary power. Also the site may be
>accessible only by snowmobile for a number of monthsin the winter. We also
>will have to ensure that if thetemperature looks like it's going to get colder
>than -35 for an extendedperiod of time we'd better have the batteries charged
>right up as propanewon't "gasify" colder than that.
>
>Thanks, Tony
>
Ron Wright, N9EE
727-376-6575
MICRO COMPUTER CONCEPTS
Owner 146.64 repeater Tampa Bay, FL
No tone, all are welcome.
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