nickbone59
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Any suggestions anyone? Really struggling with this one !
A domestic radiator is 2.5 m long and 0.6m high and is sited in a room whose temperature is 14C. Hot water is circulating through the radiator at a temperature of 90c. The radiator is convecting heat from both sides but only radiating from one side. Given that the surface emissivity is 0.7, calculate the total heat transfer from radiator to the room.
Stefan-Boltzmann Constant = 5.67x10^-8
Nu = 0.59(Gr.Pr)^0.25 for laminar flow (GR.Pr)<10^9
Nu = 0.129(Gr.Pr)^0.33 for turbulent flow (GR.Pr)>10^9
where,
Grashof no. Gr= ([tex]\rho[/tex]^2[tex]\beta(\theta[/tex]1-[tex]\theta[/tex]2)l^3)/[tex]\mu[/tex]^3
Nusselt No. Nu= hl/k
Prandtl No. Pr=Cp[tex]\mu[/tex]/k
Q= [tex]\sigma\epsilon[/tex]A(T1^4-T2^4)
= 5.67x10^-8 x 0.7 x 1.5 x (1.736x10^10-6.785x10^9)
= 629.8W
Homework Statement
A domestic radiator is 2.5 m long and 0.6m high and is sited in a room whose temperature is 14C. Hot water is circulating through the radiator at a temperature of 90c. The radiator is convecting heat from both sides but only radiating from one side. Given that the surface emissivity is 0.7, calculate the total heat transfer from radiator to the room.
Homework Equations
Stefan-Boltzmann Constant = 5.67x10^-8
Nu = 0.59(Gr.Pr)^0.25 for laminar flow (GR.Pr)<10^9
Nu = 0.129(Gr.Pr)^0.33 for turbulent flow (GR.Pr)>10^9
where,
Grashof no. Gr= ([tex]\rho[/tex]^2[tex]\beta(\theta[/tex]1-[tex]\theta[/tex]2)l^3)/[tex]\mu[/tex]^3
Nusselt No. Nu= hl/k
Prandtl No. Pr=Cp[tex]\mu[/tex]/k
The Attempt at a Solution
Q= [tex]\sigma\epsilon[/tex]A(T1^4-T2^4)
= 5.67x10^-8 x 0.7 x 1.5 x (1.736x10^10-6.785x10^9)
= 629.8W