|
Fire Tube Heat Duty(Q, MMBtu/hr): |
|
|
| Pipe Outside Temperature (To, oF) |
|
| Fluid Temperature(Tf, oF) |
|
| Excess Air(%): |
|
| Flue Gas Rate(r,lb/MMBtu): |
|
| Pipe ID(ID, ft): |
|
| Flue Gas Specific Heat(Cp, Btu/(lb.oF) |
|
| Flue Gas Thermal Conductivity (k, Btu/[(hr. sq ft.oF)/ft]) |
|
| Flue Gas Bulk Viscosity (μb, cp) |
|
| Flue Gas Viscosity at Pipe Wall (μw, cp) |
|
| Convective Heat Flux(Hfc, Btu/(hr.ft2)) |
Refer Example 8-6 |
|
Result |
| Flue Gas Mass Flow(Ma, lb/hr) |
|
| ΔT(oF) |
|
| Reynolds Number(Re) |
|
| Prandtl Number(Pr) |
|
| C |
per Fig 8-5 |
| m |
per Fig 8-5 |
|
Result |
| Heat Transfer Coefficient (hi, Btu/(hr.ft2.oF)) |
|
| Convective Heat Flux(Hfc, Btu/(hr.ft2)) |
|
| Total Heat Flux(Hf, Btu/(hr.ft2)) |
|
Example 8-3; Heat transfer coefficient for forced convection
Step 1: Calculate Re, Pr, select C and M for Fig 8-5
Re =
1488*D*V*ρ
/
μ
=
0.5263 * M
/
D * μ
Eq8-9a
Pr =
2.419*Cp*μ
/
k
Eq 8-7
Fig 8-5 from GPSA Section 8
Step 2: Calculate ho
Nu = C * Rem * Pr0.33 * (μb/μw)0.14 =
hi * di
/
12 * k
Eq8-5b
Convective Heat Flux = Q / Ac = hi * ΔT
Total Heat Flux = Convective Heat Flux + Radiant Heat Flux
|