Numerical Study of Heat Pipe Heat Spreaders with Large Periodic Heat Input

Abstract

Thestabilityofatransientcomputational analysisofthevaporcorein large flat plateheatpipeheatspreadershas beeninvestigatedusinganexplicittwo-dimensional finitedifferenceprocedure.Thecalculationprocedureemployed a highly underrelaxed scheme to suppress instabilities arising from the transient computation of a series of interdependent, nonlinear equations that comprised the transient numerical model. Investigations were performed using various combinations of time step size and relaxation parameters, to obtain a stable, converged result. This result was then validated against a set of bulk thermodynamic calculations for the heat pipe operating under similar conditions. The computational model used an explicit scheme to minimize roundoff errors, while simultaneously overcoming the inherent instabilities occurring during the transient period of interest. The time step size and relaxation parameters for optimal and stable computation in a typical case are obtained and presented in the paper. Typical distributions of the field variables in the vapor core of large flat plate heat pipe of the type analyzed are also presented and discussed.