|
|
re: heat storage vault
13 oct 2001
john canivan wrote:
>how large should a heat storage vault be to keep my 2,000 sq feet of living
>space at a minimum temperature of 65 f.
that depends on the outdoor temp. nrel's average jan temp is 31.5 f in nyc.
how long do you want to keep the house at 65 f? say 5 cloudy 31.5 f days.
say initial and final tank water temps are 200 and 100 f, with 1 ach of air
leaks and 20 kwh/day of internal gain with a 600 kwh/mo electric bill.
>the walls have an insulation value of r19.
say the ceiling does too.
>i do have a number of thermo pane windows with curtains, perhaps r3.
say 8% of the floorspace.
>lets say for simplicity sake that i live in a two story box with
>a full basement. my basement has a floor area of 1000 sq feet.
the house has a ceiling conductance of 1000ft^2/r19 plus 80 ft^2/r3
for windows plus 1944ft^2/r19 for walls plus 1x1000x16/60 = 267 cfm
of air leakage with an equivalent conductance of about 267 btu/h-f,
for a total conductance of 449 btu/h-f, so it needs 24h(65-31.5)449
= 360.7k btu/day to stay 65 f, or 292.4k more than the internal gain.
it needs 1462k btu for 5 cloudy 31.5 f days. if c pounds of water
cooling from 200 to 100 f stores (200-100)c = 1462k, c = 14.6k lb,
ie 1827 gallons or 228 ft^3, eg a 6.1' cube.
alternatively, you might keep the house air at 50% rh with a humidistat
and a soaker hose in the basement and use a thermostat to turn on an
upstairs fountain (or flood a pond below the basement ceiling) containing
a 50% licl solution that releases 1260 btu for every pound of water vapor
absorbed, as a "chemical heat pump," and absorb 1462k/1260 = 1158 pounds
or 145 gallons of water vapor over 5 days...
nick
nicholson l. pine system design and consulting
pine associates, ltd. (610) 489-1475/0545
821 collegeville road fax: (610) 489-7057
collegeville, pa 19426 email: nick@ece.vill.edu
computer simulation and modeling. high performance, low cost, solar heating
and cogeneration system design. bsee, msee. senior member, ieee. registered
us patent agent. web site: http://www.ece.vill.edu/~nick
|
|
