Transient heatpipe modeling. II
Abstract
This paper describes a continuation of work done to better understand numerical modeling of heatpipe transients. The most significant contribution discussed in the paper is a method of reducing the amount of computer time required to obtain a numerical solution. It was found that time accurate results could be obtained even if the heatpipe's wall model and the heatpipe's vapor model use different time steps to march through time. This leads to a reduction in computer time requirements by as much as a factor of 500. A second method of decreasing computer time requirements is briefly discussed. The method involves using an implicit solution algorithm instead of the explicit method used for most of this work. The implicit method was at least 10 times faster than the explicit method. Also in the paper two different methods for modeling the heatpipe wall transient are discussed and compared. Both methods gave comporable results; however, one method required less computer time than the other. A third area of discussion centers around the equation of state used in the vapor model. A real gas and an ideal gas model were studied. The real gas model could not be used in the vapor solution model because numerical instabilities resulted. It is believed that an ideal gas model is an accurate equation of state for the heatpipe's vapor. Supporting evidence for these views is presented.
 Publication:

AIAA, Aerospace Sciences Meeting
 Pub Date:
 January 1990
 Bibcode:
 1990aiaa.meetR....B
 Keywords:

 Computerized Simulation;
 Heat Pipes;
 Transient Heating;
 Boundary Value Problems;
 Mathematical Models;
 Time Marching;
 Vapor Phases;
 Wall Flow;
 Fluid Mechanics and Heat Transfer