โ Scribed by T. VandenBerghe; T.E. Diller
No coin nor oath required. For personal study only.
IIA design method is presented to minimize experimental uncertainties and errors resulting from heat losses in a common type of constant-wall-temperature convection measurement system. The system consists of one or more thick, individually heated metallic plates that are exposed to convection on the top face, with electric heaters on the bottom surface, and are surrounded on all four sides by thermal insulation and/or guard heaters. A heat balance, which includes thermal losses, is applied to the measurement plate to determine the average heat transfer coefficient over the plate.
A generalized analysis was made of the convection and conduction heat transfer in the insulation strips separating heated plates. On the basis of this analysis, the correction for the heat lost from a measurement plate and an estimate of the uncertainty of the measurement are presented. The results are presented in the form of generalized (dimensionless) plots of insulation temperature drop, heat losses, and corrections for losses. The effect of an insulation temperature drop on the isothermal wall temperature boundary condition was also considered. It is shown how the results can be used to minimize the overall correction for losses and the experimental uncertainty by optimizing the design of the insulation strips between plates. As an example, the analytical and optimization methods are applied to a typical experimental system.
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