Hi Alan, I hope you see this as there hasn't been any activity on this thread for a while.- I found it while looking at ice bank thermal storage, which is why this is my first post!
I am seriously considering an ice bank storage for my truck. I have been living off grid (mostly in vehicles) for a number of years. The last few months ive been settling down in a new project, a Ford Trader duel cab Ex CFA pumper/tanker, which i have installed 1400w of PV as a roof. Im also looking at potentially another Kw as fold out 'gull wings'.
I have been running a fairly small lead acid battery bank -which totally sucks, and have every intention of upgrading to lithium when i can. This is most important for mobile systems.
However, i really dont want to draw on these for refrigeration. I am currently running a 40L Engel and have also been trialling a 150L chest freezer, both as a freezer and as a fridge (with a digital thermostat conversion).
The conditions have been fairly tough on them lately. Driving them across western Queensland in the low 40s and now in central Australia where high 30s and low 40s are normal.
Both are coping (my inverters as well), but it has highlighted serious limitations.
These are particularly to do with the location of both units and there respective compressors and condensers. Basically having to ditch heat into what can be a high low 50s environment.
Also having to rely on batteries and functioning inverters at all times,and regularly wasting large amounts of power as the batteries go into float early in the day.
i just don't like it, and i think it is unnecessary.
What i would like to do is completely de-couple the cool boxes from the heat pump. By using a 300L ice bank that would circulate its water through a heat exchange jacket in highly insulated top opening boxes or draws that can slide out the side of the truck. The ice bank would have coiled evaporators throughout its volume, much the same as the Ice Bear. http://www.ice-energy.com/technology/ic ... ge-system/
The heat pump would be a small Inverter based air-conditioning compressor. Maybe around 1kw.
The idea would be to make sure that a small lithium battery bank was charged (which would mostly be used for lighting, telecommunications, and entertainment), then continuously dump what ever excess is available into the ice bank.
The key as i see it would be controlling the inverter heat pump so as to exactly match the pv output. This should be possible, as they are designed to run at part load when a room has been drawn down to a desirable temperature.
Small dc pumps would be used to circulate icy water through plates in cool boxes(the fridge space) and maybe even some chilled beam cooling in my sleeping/living space.
Its a bit to to set up and a bit to learn but it would make a very high value load dump for excess PV and also address the insufficiencies in my current fridges compressors/condenser configurations.
What do you reckon? any idea of the control circuitry needed for this one?