MIL-HDBK-1003/13A
.
(mCp)c
Heat capacity flow rate
through collector (Btu/hr deg. F)
.
(mCp)min
The lesser of the two heat
capacity flow rates in the
collector-tank heat exchanger
No
Number of days in month
NI
Number of days in computation
period
P
Degree days
qc
Solar heat collected per ft2
of collector per month
(Btu/ft2-mo)
Qd
DHW heating load (Btu/day)
Qdt
Yearly total load (DHW only)
(Btu/yr)
QL
Total heat load (space + DHW)
per month (Btu/mo)
QLt
Yearly total heat load
(space + DHW) (Btu/yr)
Qu
Useful heat collected =
Acqc (Btu/mo)
R
Gross space heat load =
LxMxP
S
Slope factor = ratio of
direct solar radiation on a
tilted surface to that on a
horizontal surface
Ta
Average ambient air
temperature (deg. F)
Ti
Collector inlet fluid
temperature (deg. F)
To
Collector outlet fluid
temperature (deg. F)
Tref
212 deg. F, a reference temperature
151
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