Descriptors of Forced Convection Heat Transfer Invariant with Thermal Boundary Conditions. Ph.D. Thesis
This work examines descriptors of forced convection heat transfer that are invariant with thermal boundary conditions in temperature superposition analyses for discrete and continuous temperature distributions. The heat transfer coefficient, is not invariant with thermal boundary conditions, and must be redetermined for each heat flux distribution for a given hydrodynamic situation. This redetermination can be avoided if descriptors invariant to thermal boundary conditions are measured and used. These descriptors are useful in discrete and continuous temperature predictions with arbitrary heat flux distributions, conjugate heat transfer problems, and benchmark convection studies. A heat flux invariant descriptor for discrete systems is the adiabatic heat transfer coefficient. It was developed for electronics cooling situations, which are essentially channel flows with a nonuniformly heated array of discrete elements on one wall. Data from the current study of geometrically similar arrays of cubes in a channel flow were used with data in the literature of other discrete systems to examine correlations schemes. Nusselt-Reynolds number type correlations were successful at collapsing data from a limited range of geometries if the inlet velocity was used in the definition of the Reynolds number. The most general correlation used an estimate of the turbulent fluctuations as the velocity scale in the Reynolds number, and correlated all of the geometrically diverse data examined within +/- 15%. A heat flux invariant descriptor for continuous systems is the continuous kernel function. Currently, the known kernel functions are limited to analytical and computational solutions of relatively simple problems, such as hydrodynamically fully developed regions of laminar and turbulent duct flows. As a first step towards extending the use of the kernel functions to more complex flows, the authors have developed an experimental technique to measure it for developing internal flows.
- Research Organization:
- Stanford Univ., CA (United States)
- OSTI ID:
- 236775
- Report Number(s):
- N-96-21513; NIPS-96-33355; TRN: 9621513
- Resource Relation:
- Other Information: TH: Ph.D. Thesis; PBD: Jan 1995
- Country of Publication:
- United States
- Language:
- English
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