Yesterday we started digging. I say 'we' - I actually mean one or two of the workshop guys. It's not that I don't want to help dig; it's mainly that they won't let me. I would actually quite like to help dig, but I have a suspicion that they take my suggestions of helping out as a kind of mild insult to their ability to get the job done. I wonder how they would take it if I just grab a spade from somewhere and join in. I digress.
But it would be faster if I joined in. Just saying.
Anyway, we started digging foundations for our forthcoming batch of solar panels. Having dubbed the prototype a success, for the last few weeks I've been working on the design of the bigger system, which should provide around 1000 litres of hot water to the laundry.
It might end up looking something a little like this:
The design work is very much an iterative process, as I keep having to alter the design to accommodate that material that is only available in this size, always assuming of course that you actually know what you've bought. But we seem to now be at a point of more-or-less being able to start building. I expect that as we build we'll get through a couple more design iterations.
Here is one of my friends not letting me dig:
They've also been cutting blocks of wood into planks to build the frames of the panels. The planer leaves something of a mess:
Drilling holes for bolts in the angle-iron leg. The 1/2" drill doesn't want to go through 1/4" steel. As usual, safety gear is optional - even if you could find some:
And welding parts of the legs together. At least he's wearing his sunglasses:
7 comments:
jo,
i've had digging issues with locals before, can relate.
I'm really looking forward to your next posting, I like the 3d image you've made, google sketchup was it?
with sourcing materials its hard to get certificates that will tell you their properties, it might be quicker to test the different materials yourself and create 'jo-certs' for them. Just a thought.
Take it is, be mighty.
Paul
Yep, Sketchup's the way forward when you have zero budget for a nice CAD program! It's actually not bad through...
Certificates? We have a hard enough time figuring out what kind of material it is, let alone its properties! Think we're getting there slowly on the procurement front though. Now we begin to wade into the realms of inaccurate measurements and sawing :o)
How's it going? Up to anything exciting yourself?
J
Nothing as exciting as what you're doing, i'm still in the 'learning stage' at work.
That is a lot of copper. Do you have to filter the water first? Have you thought of corrosion inhibitors, what sort of shelf life do you think your SWH will have?, you can get some great compression fittings for copper pipe over here, good luck with soldering the pipe together.
Paul
You have work? What work? Something more lucrative than building fences? :o)
Corrosion inhibitors: probably not, esp. given the likelihood of being able to find such a thing here.
My reading so far leads me to believe that copper is pretty stable in water, with corrosion usually of the order of 10s of µm/year (so several decades, if not 100 years, to get through a pipe wall).
Obviously that depends very much on the water chemistry, which I have no way of measuring here (other than "it's drinkable"). Often, a thin layer of carbonate or oxide scale can build up, which can help inhibit further corrosion.
The exceptions to that are:
1. where erosion-corrosion can cause faster wear in localised areas, particularly at high flow rates at sharp corners or joints where the flow is particularly turbulent. The water in the panels won't be moving anywhere near fast enough under thermosyphon flow.
2. galvanic corrosion as a result of unalike metals being electrically coupled and in contact with the water. All of the metalwork which will be in contact with the water will be copper. The exception, which we'll have to watch out for, is where the copper heat exchanger meets the galvanised steel supply pipe - so we'll need to get our hands on some dielectric unions, or failing that, a short length of non-conductive tube.
For the prevention of galvanic corrosion between the copper tubes and aluminium fins, we just have to do a good job of keeping rainwater out of the enclosures.
I seen anything to worry me unduly so far, but if there's anything obvious I've missed, please point it out!
J
Yes I have work, pipeline integrity.
Put an isolation valve in somewhere.
sounds like you have everything else well in control jo.
P
Is there a way of working out the thermal expansion of the water as its temperature increases, presumably there is a max temperature that thermosyphon systems will work to effectively, based on the temperature difference of inlet/outlet.
P
Isolation valves: planned!
Thermal expansion: I'm sure there's an expansion coefficient for that somewhere. Not too bothered as the tank will be unpressurised (with a lid, but effectively open to the air), so it can expand as much as it wishes.
Max temp: As the system gets hotter it does tend to hit an equilibrium point when the losses are as big as the input, but where exactly that is depends on the system (surface areas, pipe and tank insulation, etc) and its operating conditions (ambient temp, rate of heat extraction). The first tiny tank levelled out around 63°C, the larger one got to around 75°C. In summer time with better insulation I'd expect it to go higher.
This is one outstanding problem to solve actually - the laundry doesn't run on Sundays, which will mean a whole extra day of heating with no hot water being used. I'd love to have some automatic shading mechanism that would activate above a certain temperature, but that may be pushing it a bit. Or air vents in the panel enclosures that open up automatically.
May your pipelines be ever... integral? Or integrated?
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