The Effect of Robust Thermowells on Thermocouple Response Time - 19 Appendix 1 Calculation of Convective Heat Transfer Coefficient All calculations are from the following source: Incropera, Frank, & DeWitt, David. (2007). Fundamentals of heat and mass transfer. Wiley. Given a number of fluid properties, the series of equations used to calculate the convective heat transfer coefficient of flow around a sphere are as follows, Where, Re D is the Reynolds Number, dimensionless, is the density of the fluid, lbm/in 3 , V is the velocity of the fluid, in/s, D is the diameter of the sphere, in, is the dynamic viscosity of the fluid, lbm/(in*s). Where, Pr is the Prandtl Number, dimensionless, c p is the specific heat of the fluid Btu/(lb*°F), k fluid is the thermal conductivity of the fluid, Btu/(in*s*°F). When, Where, Nu D is the Nusselt Number, dimensionless, is the viscosity ratio, dimensionless. Where, h is the convective heat transfer coefficient, Btu/(in 2 *s*°F).
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Appendix 1 - AC Controls · Appendix 1 Calculation of Convective Heat Transfer Coefficient All calculations are from the following source: Incropera, Frank, & DeWitt, David. (2007).
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The Effect of Robust Thermowells on Thermocouple Response Time - 19
Appendix 1 Calculation of Convective Heat Transfer Coefficient
All calculations are from the following source: Incropera, Frank, & DeWitt, David. (2007). Fundamentals of heat and mass transfer. Wiley.
Given a number of fluid properties, the series of equations used to calculate the convective heat transfer coefficient of flow around a sphere are as follows,
Where,
ReD is the Reynolds Number, dimensionless, is the density of the fluid, lbm/in3,
V is the velocity of the fluid, in/s, D is the diameter of the sphere, in,
is the dynamic viscosity of the fluid, lbm/(in*s).
Where, Pr is the Prandtl Number, dimensionless, cp is the specific heat of the fluid Btu/(lb*°F), kfluid is the thermal conductivity of the fluid, Btu/(in*s*°F).
When,
Where, NuD is the Nusselt Number, dimensionless,
is the viscosity ratio, dimensionless.
Where, h is the convective heat transfer coefficient, Btu/(in2*s*°F).
The Effect of Robust Thermowells on Thermocouple Response Time - 20
The conditions, intermediate values, and the convective heat transfer coefficients for each thermowell are provided in the table below.
Thermowell Type WIKA Thermowell WIKA Thermowell Bailey Pyrotron