Re: Ceiling mass air heater options

On 3 Dec 2003 08:59:52 -0500,
[EMAIL PROTECTED] (Nick Pine) wrote:

>David Delaney  <[EMAIL PROTECTED]> wrote:
>
>>Hi Nick
>
>Hi David...
>
>>>Would an unstratified mass (eg a poly film duct containing 1" of water over
>>>a shiny ceiling, with insulation above that) be warmer with David Delaney's
>>>flow separator 
>>
>>See "Solar air heater with flow organizer baffle array for right-angle
>>crossing of hot and cold air sheets",
><http://geocities.com/davidmdelaney/flow-organiser/flow-organiser.html>
>>
>>>or 70 F house return air filling a sunspace/air heater?
>>>
>>>Consider 2 steady-state 8' R10 cubes with 64 ft^2 of R2 glazing with 80%
>>>solar transmission, after a long string of 30 F average January days in
>>>Phila, with 1000 Btu/ft^2 of sun on a south wall...
>>>
>>>1.  --------------
>>>   |fs|    Tc     |       Cube 1 has a flow separator and a transpired
>>>   | .|           | R10   mesh collector. We might assume the air hear the 
>>>   | .|           |       glazing is about the same as the ceiling temp Tc. 
>>>S  | .|   70 F    | 30 F  This sunspace might be uncomfortably hot, but the
>>>   | .|           |       amount of airflow is not limited by the cube temp.
>>>   | .|           |       How does the ceiling keep the cube 70 F? 
>>>   | .|           |        
>>>    --------------   
>> 
>>I don't understand why Cube 1 is worth analysing.
>
>Its one way to store overnight heat from a sunspace, with a solar closet
>or shelfbox on the ground for cloudy-day heat. Putting a little flat mass
>above a ceiling seems a lot simpler than building the tall overhead
>block/drum structure you have in mind.
>
>>If I understand your text and drawing, the flow
>>separator (I prefer "flow organiser", hmmm...
>>perhaps "flow intersector" would be even better)
>>can have no useful effect because there are not
>>two moving sheets of air of different temperatures
>>that need the flow organiser in order to cross
>>through each other.
>
>It seems to me your flow organizer would help here. Without it, the air
>near the glazing would be warmer, and it's likely there would be less flow.
>I remember some pictures of how hot and cold fluids mixed in an hourglass-
>shaped container with the hot fluid below. Very slowly, as they fought
>each other in the narrow part. Adding a small dip tube through the neck
>helped a lot...
>

OK, then I guess it's your analysis rather than
mine that says that the whole Cube 1 configuration
is not a very good idea. :-)

David