Book Description

Abstract: There are two major aspects to this study: l) the modeling of simultaneous heat and mass transports in a porous medium, and 2) the problem of evaluating the feasibility of using buried pipe soil warming systems to meet agricultural and/or power plant needs. Both soil temperature and soil moisture have important influences upon meeting agricultural needs for high and uniform temperature and moisture and the power plant need to cool condenser water. Accordingly, a detailed variable property analysis of the simultaneous heat and mass transfer in soil has been derived, in order to predict temperature and moisture profiles in the vicinity of a buried pipe system. Differential equations for conservation of energy and mass in soil have been derived. While the forms of the equations are the same as ones appearing in the soil physics literature, the present development brings out clearly the volume-averaged nature of the equations as well as illuminates the underlying assumptions. When existing theories for obtaining soil transport coefficients are used in the analysis, the resulting predictions do not agree with available data within experimental accuracy. Consequently, an empirical method has been developed in order to obtain more accurate transport coefficients for soils. Concerning the feasibility of soil warming, it was determined that soil warming is technically feasible, without the introduction of moisture near the warm pipes, for some designs, when agriculture is the overriding concern. However, when systems are designed to meet both the agricultural needs and the power plant requirement to obtain significant water cooling in the pipes, the length of each pipe is likely to be excessive.