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Aaron9890
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Thermodynamics question help?? is this right??
A boiler is supplied with water at a rate of 0.3 kg/s through a pipe of diameter 50mm
a) calculate the energy per second that must be supplied to the boiler,raising the water temperature to 100C, when the water is supplied at 15C
b) If the input power to the boiler is 3.1GJ/h, Calculate the efficiency of the boiler and heat transfer process
The density of water - 1000kg/m^3
specific heat capacity for water - 4.7kj/kgK
latent heat evaporation for water - 2.26MJj /kg
steam pipe outside diameter - 55mm
steam pipe wall thickness - 2.5mm
modulus of elasticity for steel - 210GPA
coefficient of linear expansion of steel - 18 x 10^-6/C
Q = MCAO + ML (mass flow rate x heat capacity x change in temp) + (mass flow rate x latent heat for evaporation of water)
Thermal efficiency = Q out / Q in
M = 0.3 kg/s
c = 4.7 KJ/kgK in J = 4700J/kgK
AO = 100C - 15C = 85C
L -= 2.26MJ/KgK in J = 2260000J/kgK
so Q = MCAO + ML
Q = (0.3)x(4700)x(85) + (0.3) x (2260000)
Q = 797 850 J/s or 0.79785MJ/s
Thermal Efficency = Qout / Qin
Thermal Efficency = 797.850J / 3100000000J
=? (please help me out on this one)
Homework Statement
A boiler is supplied with water at a rate of 0.3 kg/s through a pipe of diameter 50mm
a) calculate the energy per second that must be supplied to the boiler,raising the water temperature to 100C, when the water is supplied at 15C
b) If the input power to the boiler is 3.1GJ/h, Calculate the efficiency of the boiler and heat transfer process
The density of water - 1000kg/m^3
specific heat capacity for water - 4.7kj/kgK
latent heat evaporation for water - 2.26MJj /kg
steam pipe outside diameter - 55mm
steam pipe wall thickness - 2.5mm
modulus of elasticity for steel - 210GPA
coefficient of linear expansion of steel - 18 x 10^-6/C
Homework Equations
Q = MCAO + ML (mass flow rate x heat capacity x change in temp) + (mass flow rate x latent heat for evaporation of water)
Thermal efficiency = Q out / Q in
The Attempt at a Solution
M = 0.3 kg/s
c = 4.7 KJ/kgK in J = 4700J/kgK
AO = 100C - 15C = 85C
L -= 2.26MJ/KgK in J = 2260000J/kgK
so Q = MCAO + ML
Q = (0.3)x(4700)x(85) + (0.3) x (2260000)
Q = 797 850 J/s or 0.79785MJ/s
Thermal Efficency = Qout / Qin
Thermal Efficency = 797.850J / 3100000000J
=? (please help me out on this one)