摘要：Much effort has been devoted recently to deter-mine conditions which guarantee that the assumption oflocal thermal equilibrium (LTE) is accurate when model-ing of heat transfer in porous media. When it is accurate,then the thermal field is well-approximated by a singlethermal energy equation. An excellent review of conduc-tive effects in a stagnant porous medium may be found inCheng and Hsu [1]. In their chapter these authors considerperiodic media and their aim is to determine the effectivethermal conductivity of the combined medium in the termsof the conductivities of the constituent phases. ThereforeCheng and Hsu provide important information for thosewishing to use a single temperature field to model a two-phase saturated porous medium, or equivalently a compo-site solid consisting of two different constituents. In othercircumstances, local thermal nonequilibrium (LTNE) pre-vails and it is necessary to employ two energy equations,one for each phase. The first papers which used two differ-ent temperature fields presented by Anzelius [2] andSchumann [3], and they were both published about eightyyears ago. In their presented energy equations, we see thatdiffusion and advective (u ∂T/∂x) terms have been ne-glected in the work of Anzelius. The numerical study byCombarnous [4] predated by a couple of decades furtherwork on fully nonlinear convection using this model.Nakayama et al. [5] have proposed the nonthermal equilib-rium two-energy equations model for conduction and con-vection, in which the two-energy equations for the individ-ual phases at constant porosity are combined together andsolved analytically. Neild and Bejan [6] stated the simplestequations which are generally regarded as modeling un-steady heat transfer in a saturated porous medium whereLTE does not apply.
