The Mechanism by which water moves through a porous material subjected to a temperature gradient: 2. Salt tracer and streaming potential to detect flow in the liquid phase

A temperature gradient across a partially saturated porous material produces a movement of water from the hot to the cold side. The controversy regarding the mechanism by which this water moves has been referred to in a previous paper ( NRCC-3453). If there is flow in the liquid phase toward the cold side, the liquid may be expected to carry along dissolved salt, and this flow may be expected to give rise to a streaming potential. This paper gives the results of experiments to detect flow in the liquid phase through a bed of sand by using a salt tracer and by measuring streaming potentials.Un gradient de temp\ue9rature de part et d?autre d?un mat\ue9riau poreux partiellement satur\ue9 entra\ueene une migration de l?eau du c\uf4t\ue9 chaud au c\uf4t\ue9 froid. On a fait r\ue9f\ue9rence, dans un document ant\ue9rieur (CNRC-3453), \ue0 la pol\ue9mique au sujet du m\ue9canisme par lequel cette eau migre. S?il y a migration dans la phase liquide vers le c\uf4t\ue9 froid, on s?attendrait \ue0 ce que le liquide transporte des sels dissous et \ue0 ce que cet \ue9coulement donne lieu \ue0 un potentiel d?\ue9lectrofiltration. Ce document fournit les r\ue9sultats d?exp\ue9riences men\ue9es en vue de d\ue9tecter la migration dans la phase liquide \ue0 travers un lit de sable, en utilisant un traceur de sel et en mesurant les potentiels d?\ue9lectrofiltration.Peer reviewed: NoNRC publication: Ye