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re: btu - formula
4 jan 1998
paul milligan wrote:
>nicksanspam@ece.vill.edu pondered briefly, and wrote:
>>...might come (at night) from 4 100 watt light bulbs, 4 100 watt people,
>>a 50 watt dog, 4 25 watt cats, and 5 10 watt rabbits...
> nick, i still need help here. i have no rabbits or dogs, and
>i can't seem to find the wattage rating on my cats. what now ?
get some ashrae standard cats (as described in table 7 on page 9.12 of
the 1993 handbook of fundamentals):
heat generation, btu/h per animal
-normally active(b, c)-
animal weight basal(a) sensible latent total
lb
...
mouse 0.046 0.66 1.11 0.54 1.65
cat 6.61 27.41 39.22 19.31 68.02
...
(a) based on standard metabolic rate m = 6.6w^0.75 watt per animal
(klieber 1961) or appropriate reference (w = animal mass, lb)
(b) referenced according to availability of heat generation data.
otherwise, heat generation is calculated on basis of athg = 2.5m
(borton _et al_. 1976.) latent heat is assumed to be approximately
33% of total; sensible heat, 67% of total heat (besch 1973, woods
_et al_. 1972.)
(c) data taken from runkle (1964), kleiber (1961), besch (1973), woods
and besch (1974), woods _et al_. (1959) and ota and mcnally (1961.)
a house requiring 750 gallons of oil burned at 80% efficiency over a
200 day heating season, ie 750/200/24x130,000x0.8 = 16,250 btu/h might be
heated with a herd of c cats and m mice (with a suitable condensing air-air
heat exchanger, and appropriate controls to avoid volterra instabilities),
where 68.02c + 1.65m = 16,250, and (assuming the cats eat 5 mice per day,
and each mouse produces a litter of 3 once a month) m = 50c, so
c(68.02+1.65(50)) = 16,250, and c = 108, and m = 5,400.
nick
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