Answer:
a) 512.5 KW/m2
b) 40.75 KW/m2
c) 2 KW/m2
Explanation:
Given data;
T_2 = 325 K
T_1 = 275 K
dx = 0.20 mm
a) for aluminium K = 205 W/m k
heat flux
= 512.5 KW/m2
b) for AISI 316 stainless steel
k = 16.3 W/ m k
heat flux
= 40.75 KW/m2
C) for Concrete
k = 0.8 W/ m k
heat flux
= 2 KW/m2
Answer:
net boiler heat = 301.94 kW
Explanation:
given data
saturated steam = 6.0 bars
temperature = 18°C
flow rate = 115 m³/h = 0.03194 m³/s
heat use by boiler = 90 %
to find out
rate of heat does the boiler output
solution
we can say saturated steam is produce at 6 bar from liquid water 18°C
we know at 6 bar from steam table
hg = 2756 kJ/kg
and
enthalpy of water at 18°C
hf = 75.64 kJ/kg
so heat required for 1 kg is
=hg - hf
= 2680.36 kJ/kg
and
from steam table specific volume of saturated steam at 6 bar is 0.315 m³/kg
so here mass flow rate is
mass flow rate =
mass flow rate m = 0.10139 kg/s
so heat required is
H = h × m
here h is heat required and m is mass flow rate
H = 2680.36 × 0.10139
H = 271.75 kJ/s = 271.75 kW
now 90 % of boiler heat is used for generate saturated stream
so net boiler heat =
net boiler heat =
net boiler heat = 301.94 kW