20050611

Steve replied Rick: my compliments for a superb site. I did not realize that you've setup such a sophisticated communication and record keeping system . How do I change the color of my sentences to make it easier to read who said what during a session?

Rick wrote

Hi Steve,

Your drawings are excellent. I have put them together in a PPT presentation. Then I have added some comments on each slide. I hope that you can work with the PPT file. Let me know if I should send it as a PDF.

I am confused because I thought that you had already built the cavity space. If you have not then it would be best to discuss the details. There are implications to every detail and I do have some suggestions. Tuisco showed me many photos and details of how the structure is fabricated and I think that you have done a great job of it - the structure is simple and the pipe assembly is nicely done. I would like to suggest that you install an interior layer to form the cavity space. This will decrease the interior volume and the working space inside - but it appears that your roof is high enough and that this could be a good option. The design that I would suggest will make it easier to work with the negative air pressure in the roof cavity.

I am working with a couple of other sites and I must direct my energy and advice to the Open Source projects that are willing to work with me on a "open" disclosure basis. Our communications can be more open when we collaborate on projects at the Sola Roof Wiki. I have set up a group for this purpose called Agro Best and we have a Blog and can develop many pages that will provide depth of knowledge on the processes as we go along. See: http://www.solaroof.org/wiki/AgroBest/WikiBlog

Regards,

Rick (see indented comments to your previous email below:)

Steve wrote:

Rick replied

Hi Steve, Tuisco,

I like Steve's suggestion for the adjustable vents around the edges of the roof cavity. I would suggest that you not remove the channel for the bubbles that was built along the ridge.

The ceiling of the roof is not installed yet. So there are no channels yet. I prefer to have a perfect picture first before I install the system.

You could also have a few liquid cooling nozzles in this channel (unless you think that it is too difficult for drainage) and you could then try just a straight flow in and out (going across the length in a straight duct. Then you could close inlet vents and get a much greater flow and air velocity to see what effect that might have. Or you could close the vents to one side and so with the same blower you would see the effect of exhausting one half the volume. This would be a higher air change on only one side. The degree of chilling can be evaluated in the portion of the roof that is is active. Air flowing into a larger shape and volume will not reach the same velocity as air that is channeling within modular sections of a roof. That is the main difference that the alternate structure design can provide.

Aha.... straight airflow and air velocity are the key words here. Thus dividing each side of the roof into two additional straight channels will improve the air velocity and thus improve the chilling of the ceiling. Each channel having is own set of liquid cooling nozzles. Drainage is no problem to setup. Yes, I can see that!

yes what is needed is a constant pressure drop along the flow path - it is not so much about high velocity but an "accelerating flow" that is partly due to the increasing RH of the air stream.

What I cannot picture clearly, at the moment, is how we will optimize the connection of these straight channels to the blower air intake space. Blower air intake space is the space where all (5) channels (the ridge channel and the two side channels) are coming together. Blower air suction in each channel should be regulated such that it is equal. See cavity_structure. gif

You are right about that and actually, I have not previously designed roof cavities that have that kind of structure. The duct-like roof cavity spaces in our Bio Synthesis ? structure design have long individual channels that have the air moving and precipitation devises at the ends. This assures that there is a perfect balance, without any flow complexity.

I know this is not answering your question (or observation) but I am not certain about the implication of the inflow into the exhaust plenum where a blower would exhaust the air to the outdoors. Actually there may not be any problem at all. The balancing of the flow can be done by adjusting inlet louvers on the intake end of the channels. There can be an adjustable inlet damper for the inlet plenum and then further vent adjustment to the inlet of each channel to adjust and balance the air flow.

Airflow circulation depicts an idea to improve chilling further by using dehumidified greenhouse air recognizing that the vegetations evapotranspiration in the greenhouse will influence greenhouse humidity. Still, what do you think??

I made a comment on that slide (see attached PPT) that offers some thoughts. I think it is okay to use the greenhouse air (if we are ventilating the greenhouse for supply of CO 2) but I would not use any humidifier screen at the inlet to the roof cavity. I would just let the air flow into the roof cavity and let it do the evaporative chilling in the roof space. This takes much less power. Wet screens will cause more back pressure and remember, we are not blowing into the roof cavity we are drawing (sucking) in the air at the inlet so that there is a negative air pressure within the roof space..

For your next step to a commercial scale I would like to see how the structure design and modular long panels that are used to form the roof - all aspects of the "package" would work together to make the chilling more effective.

We gladly keep you informed in detail.

This optimum structure design is the type that Ed will be building - we call it the pole structure, which is a very simple and cheap to build. It is a much beter layout then the "shed roof" style structure that you have built.

Then the next stage is the precipitation and separation of the vapor so that we generate dry air to recirculate into an adjoining roof panel. This air will flow to the far end of that panel and become saturated as it goes, then to enter the vortex precipitation/separation mechanism and the dry air exiting feeds into the adjoining panel. I hope you can visualize how this works and how it work more effectively with "channeled" air flow. However we can likely use the ridge channel to do the same thing with the exit (dry) air flowing into either side of the roof cavity.

See Richard_vortex_precipitation_separation_mechanism.jpg

This drawing shows a good layout of channels but the vortex system is not moving outside air through the roof. The chiller system is a closed, recirculation flow. We can talk more about that down the road - I think that the first step is to show the evaporative roof chiller system. By the way, you use the name DWC - what does that stand for?

So what I am saying is: don't remove the ridge duct that you made for a bubble flow path. We might still use it for bubbles or for the closed cycle chiller process that does not use the outside air but recirculates air within the cavity space. [Steve 1] WOW !! I tried to draw up this closed cycle chilled process but I am not satisfied with the result. Interesting, very interesting indeed !!!

Question: Can you sketch your ideas about the closed cycle chilled process applicable to our roof?

I added some sketch notes to your drawing that you can see in side 2 - please note also the comments on each slide click on them to open the comment.

Again, I repeat that this is pioneering work that we need to operate and measure the result - there are no guidelines to follow - this is new territory. Let me know if you have more questions. One air change per 4 minutes for the entire roof - or, half the roof can change in 2 minutes and the ridge duct would have an air change per 1 minute - these are our experimental modes of operation. There is no question that evaporative chilling will take place but the rate at which the process will work and the degree of chilling is something that we will need to observe from the actual operating result. OK!

Question: the vortex precipitation/separation mechanism, does such mechanism exist and if so can we build it? can we purchase it?

I will be prototyping this system in collaboration with Ed and later with Nottingham University. I have built some proof of concept test units years ago but the details are still in a development stage where we would custom fabricate the components. So there is no supplier yet - but it is possible that Ed might set up production of this equipment ant bubble generator units as well. In fact it is likely that we will offer a complete structural and mechanical kit for commercial greenhouse operators. You could also be a supplier of such kits (and perhaps turnkey projects) in your region. We can spread out the development cost and ease the burden of this pioneering work by letting each of our associated enterprises take a lead with areas that they have a specialty to handle.

Thanks for your efforts to build our knowledge; to go from vision to a proof of concept.

The same right back to you! Tuisco and I are determined to break a few barriers when it comes to Greenhouses for the Humid Tropics.

That's the spirit - we need to act with speed and determination because the time we have now is special and the future of the planet is in the balance. I believe a grass roots collaboration can make the difference.

I am really pleased to work with you - Rick

Regards, Rick

Steve & Tuisco