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Distributing hot water into a heat store while maintaining thermal stratification - Page 2

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Posted by DavidMDelaney on December 18, 2006, 8:02 pm

meow2222@care2.com wrote:


I don't know.

Posted by nicksanspam on December 18, 2006, 9:03 pm


Testing seems like a good idea, with a reservoir and filter
to slow incoming greywater flow.


Posted by DavidMDelaney on December 19, 2006, 5:17 am
nicksanspam@ece.villanova.edu wrote:

How about testing it with a three tank system, all of which could be
quite small?  Consider two tanks, H and T that are each somewhat less
than 1/4 the height of a third tank C and in total half of its volume.
The tank C may be configured with and without the horn. C is full of
uniform temperature cold water, H of uniform temperature hot water, and
T of uniform temperature tepid water. Arrange the tanks so that the
bottom of T is at the same height as the middle of C. H is above T with
the tops of H and C at equal heights. The tanks are plumbed together:
bottom of C to bottom of T, top of T to bottom of H, top of H to top of
C.  This arrangement insures that the hot and tepid water enter the
cold tank in the "wrong" order, and would allow accurate and rapid
repitition with and without the horn. Arrange valves to control
starting and stopping of natural convection, and ports for emptying and
refilling of the tanks.

For forced convection, as you indicate, a retarding chamber of some
kind would be needed.


Posted by Jeff on December 19, 2006, 7:25 am
 DavidMDelaney wrote:

All of this discussion makes me wonder about the efficiency of the
overall system. Certainly the lower flow rate of a thermosiphon (versus
active pumped) affects the system efficiency.

   Does where the water is being returned to the tank not affect the
volume of water pumped by thermosiphon? I can't help but wonder if
bringing the system to "equilibrium" does not slow  the thermosiphon
effect and lower the overall efficiency. Certainly a retarding chamber


Posted by DavidMDelaney on December 19, 2006, 4:23 pm
Jeff wrote:

A retarding chamer was suggested *only* for forced injection. A
retarding chamber would indeed be inappropriate for natural convection.

The rate of entry of water to the tank under natural convection is
driven entirely by the pressure difference due to the temperature
differential, and is restricted only by the shape and nature of the
channels up to the opening into the tank.


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