wrote:

A very small percentaqe of the heat you radiate goes in any
one particular direction, and the amount that falls on the 'receiving
/ absorbing surface' will thusly decrease as the square of the
distance from it.

Not if the surface completely encloses you. The MRT is solid angles weighted
by their temperatures. Multiply each area your body sees by its temp, add
the products, and divide by the total area of a reference sphere surrounding
you, containing the individual areas. You might radiate 50% to a large close
wall. As you walk away from a large wall, the near-field view factor might
still be about 50%.

And we don't need liquid helium. The MRT graph he

http://heatkit.com/html/guide2.htm#MasonryHeating

says we can be comfy in 90 F air with 40 F walls, in a bunny-free room.

Some buildings have chilled beams and ceilings for cooling. A chilled
floor would make more sense, since warm air rises. A slow ceiling fan
with an occupancy sensor and a room temp thermostat could stir up some
floor air as needed for comfort.

Nick

On 16 Aug 2008 11:32:01 -0400, wrote:

wrote:

A very small percentaqe of the heat you radiate goes in any
one particular direction, and the amount that falls on the 'receiving
/ absorbing surface' will thusly decrease as the square of the
distance from it.

Not if the surface completely encloses you.

Good point, Nick.

If you happen to be sitting inside a radiant-absorptive ball (
a thermal variation of a Dyson Sphere, perhaps, Scotty ? ).

The MRT is solid angles weighted
by their temperatures. Multiply each area your body sees by its temp, add
the products, and divide by the total area of a reference sphere surrounding
you, containing the individual areas. You might radiate 50% to a large close
wall. As you walk away from a large wall, the near-field view factor might
still be about 50%.

And we don't need liquid helium. The MRT graph he

http://heatkit.com/html/guide2.htm#MasonryHeating

says we can be comfy in 90 F air with 40 F walls, in a bunny-free room.

Some buildings have chilled beams and ceilings for cooling. A chilled

So do many many cold rooms of various applications. Ever hear
of static-coil ammonia systems ? They do not work primarily by
raidant absorption, they work mainly by convection currents. If you
were to put the coils at the floor instead of the ceiling, they
wouldn't work worth a ****.


floor would make more sense, since warm air rises. A slow ceiling fan
with an occupancy sensor and a room temp thermostat could stir up some
floor air as needed for comfort.

And thus, it is no longer a radiant system, it is convective.

Hey, here's one to work on - what if you took a bunch of Bucky
Balls IE Fullerenes, and froze them, then dumped them all in a room ?

Pls post your code for designing it when you get a chance :-)


--
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wrote:

... Some buildings have chilled beams and ceilings for cooling.

So do many many cold rooms of various applications. Ever hear
of static-coil ammonia systems ?

No. I'm mainly interested in houses, altho I've read that a 70 F low-e
ceiling can reduce ice rink melting by 10 watts/ft^2...

They do not work primarily by raidant absorption, they work mainly by
convection currents.

Cool air falls...

If you were to put the coils at the floor instead of the ceiling, they
wouldn't work worth a ****.

There would be more cool surface, but maybe less cooling, with no slow
ceiling fan.

... a cool floor would make more sense, since warm air rises. A slow
ceiling fan with an occupancy sensor and a room temp thermostat could
stir up some floor air as needed for comfort.

And thus, it is no longer a radiant system, it is convective.

Most of the cooling might be convective, but consider that a) a ceiling
needs well-distributed cool sources in order to have a large radiant or
convective surface, but we might cool an entire floor with a single point
source, since cool air falls, and b) a slow ceiling fan can provide more
air velocity for useful low-energy cooling, allowing a higher room air
temp for the same comfort, and c) a radiant cool floor can allow a higher
air temp, for the same comfort, and d) with a slow ceiling fan, it's easier
to turn off the cooling when nobody's in the room.

Nick

On Aug 16, 8:51*am, wrote:
On 16 Aug 2008 11:32:01 -0400, wrote:

wrote:

* * * *A very small percentaqe of the heat you radiate goes in any
one particular direction, and the amount that falls on the 'receiving
/ absorbing surface' will thusly decrease as the square of the
distance from it.

Not if the surface completely encloses you.

* * * * Good point, Nick.

* * * * If you happen to be sitting inside a radiant-absorptive ball (
a thermal variation of a Dyson Sphere, perhaps, Scotty ? ).

The MRT is solid angles weighted
by their temperatures. Multiply each area your body sees by its temp, add
the products, and divide by the total area of a reference sphere surrounding
you, containing the individual areas. You might radiate 50% to a large close
wall. As you walk away from a large wall, the near-field view factor might
still be about 50%.

And we don't need liquid helium. The MRT graph he

http://heatkit.com/html/guide2.htm#MasonryHeating

says we can be comfy in 90 F air with 40 F walls, in a bunny-free room.

Some buildings have chilled beams and ceilings for cooling. A chilled

* * * * So do many many cold rooms of various applications. *Ever hear
of static-coil ammonia systems ? *They do not work primarily by
raidant absorption, they work mainly by convection currents. *If you
were to put the coils at the floor instead of the ceiling, they
wouldn't work worth a ****.

floor would make more sense, since warm air rises. A slow ceiling fan
with an occupancy sensor and a room temp thermostat could stir up some
floor air as needed for comfort.

* * * * And thus, it is no longer a radiant system, it is convective.

* * * * Hey, here's one to work on - what if you took a bunch of Bucky
Balls IE Fullerenes, and froze them, then dumped them all in a room ?

* * * * Pls post your code for designing it when you get a chance :-)

--
Click here every day to feed an animal that needs you today !!!www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo online atwww.pmilligan.net/palm/
Free 'People finder' program now atwww.pmilligan.net/finder.htm

this is correct... 40F walls in a warm room create convection... it is
conduction from skin to air that removes the highest percentage of
heat from a human body.... convection provides the air flow... same
with cold beams etc.... (and evaporation of water from the skin)...

radiation is a factor but its a minor factor n the termperature
differrential range are discussing....load calc books have the math
for all of this..... on a roof though with the hot sun, radiation is a
huge factor, same though glass, convection not withstanding.


Phil scott


Phil scott

phil scott wrote:

... The MRT graph he

http://heatkit.com/html/guide2.htm#MasonryHeating

says we can be comfy in 90 F air with 40 F walls...

this is correct... 40F walls in a warm room create convection... it is
conduction from skin to air that removes the highest percentage of
heat from a human body....

I disagree. You can't cool 92 F skin much with 90 F air.

Nick