Sunday, April 1, 2012

Intermittency and Insulated cap

1 April 2012: The Tubes system is working (with the swimming pool configuration) although it is very intermittent. the tube manifold warms up in the sun and starts the pump. A very short while after that cold liquid goes up, the Delta-T closes and it turns off. But the Sun is shining, the air temperature is very cold (freezing overnight, perhaps), and it is an ideal time to observe the operation. So the tube sensor warms up quickly and runs liquid for another minute, then closes. This intermittency is a problem which could be solved with a heat exchanger. However, I would be interested to find out if we still get an energy capture even if it is intermittent.
    I have noticed that as the solar altitude increases, the intermittency is reducing - i.e. the heat arriving at the tubes is almost enough to maintain the flow (at slow speed) with cold liquid coming up from below - the period of action before it turns off is getting longer. Logically, the slowest pump speed is preferable, to allow the tubes manifold to stay hot for longer.
Tubes fitting on the roof between roof lights
I want to insulate this end. It was insulated at the Ecobuild model
    I cannot know if energy is being captured in significant quantity as the energy meter was fitted the wrong way round, so i will have to turn the system off and turn the meter round. It should be on the flow to the tubes, not the return. This isn't the fault of the guys, it's just that they didn't ask which way round it should be.
    Also, I noticed at the Kingspan stand at Ecobuild that the ends of the array had insulated cap-ends, and this insulation does not. I shall either have to ask KS for some cap-ends if such a thing exists as a manufactured item, or make one myself from insulation and aluminium boxing. This may seem small, but there must be a system loss on cold days from having exposed metalwork.

1 comment:

  1. Hi David

    Is it really possible to assembly tubes in horizontal position?

    Or have I forgot my medicine :)


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