The shower needs of a small cabin are met with a 9-gal propane hot water heater that transfers 12000 Btu/h of thermal energy to the water in the...
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not getting any numbers close to what are meant to be the answers. Tau should be around 7.5 minutes, the mass of the tank should be around 75 lbm and the time it takes to drop from 110F to 100F should be around 5.2 minutes.

The shower needs of a small cabin are met with a 9-gal propane hot water heater that
transfers 12000 Btu/h of thermal energy to the water in the tank. The water heater's
tank is initially filled with hot water at 110 F. The flow rate of the water in the shower
is 1.2 gpm, and as water is drawn from the water heater's tank for the shower it is
replaced by 70 F water flowing into the tank at 1.2 gpm. Assume the temperature of
the water leaving the hot water heater is the same as the temperature of the water in
the hot water heater's tank. Find how long it will take for the temperature of the water
in the shower to drop from 110 F to 100 F. 7= 7.5 min, my x75 1bm =7 t x 5.2 min toget
to TT = 100 #F
1.2 gpm at Tin = 70.F
- 1.2 gpm to Shower
assume Tour =T,
OfI = Qtmcp ( Tin- T. )
m, cp de
Water
in Bhu /min
Heater
9 gal
find Cp in US units
dTE thinke Ty = Q +mcp Tin
= const
my in 15m
12,000 Btu/h

The way to answer this question is ... View the full answer

Rate I water mylow = 1.28 pm
Rate I waken onethow = 1. 25m.
Rate I hear supply to heater
8 = 12000 Bru/ h
2 200 Bru/ min .
12000 Bru/h
mass I flow / outflow 2 water
( 1 gal of with = 8: 35 lb. )...

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