Page 162 - Biosystems Engineering

Models for Heat Transfer in Heated Substrates 141

and moisture content in greenhouse soils. Chen et al. (2006) analyzed
the variation of the temperature and moisture content in soil with the
increase in depth, and found that the appearance of the peak tem-
perature in soil postponed with increase in depth. In greenhouse soils
covered with rice husks, Tuntiwaranuruk et al. (2006) simulated the
complexity of the temperature and moisture of a greenhouse. Nebbali
et al. (2006) were concerned with estimating the ground response for
some known transient ambient environment conditions (solar radia-
tion, temperature, hygrometry, and wind speed) using a semianalyti-
cal method.
Other models have focused on situations with abnormally high
soil temperatures, such as solarized soils (Cenis 1989), fires (Campbell
et al. 1994), or volcanic soils (Antilen et al. 2006). These situations, in
which the soil is subjected to high temperatures, occur also in thermal
modeling of heated substrates (Alvarez 1996; Kurpaska and Slipek
1996; de la Plaza et al. 1999; Guaraglia and Pousa 1999; Rodriguez
et al. 2004; Fernandez et al. 2005a, 2005b; Kurpaska et al. 2005;
Fernandez and Rodriguez 2006; Rodriguez et al. 2006; Fernandez
et al. 2007). Further research concerned with air-conditioning systems
was developed by Wu et al. (2007), who analyzed earth–air–pipe
systems that could be used to reduce the cooling load of buildings in
summer.
The models discussed above focused on soils subjected to mod-
erate or high temperatures, characteristic of temperate or warm cli-
mates. However, many efforts have focused on low-temperature
conditions in which the water phase change has a strong impact.
Hansson et al. (2004) developed a new method to account for phase
changes in a fully implicit numerical model for coupled heat trans-
port and variably saturated water flow involving conditions both
above and below zero. The new function was proposed to better
describe the dependency of thermal conductivity on the ice and
water contents of frozen soils.
The influence of unfrozen water on the thermal properties of
soils was accounted for in the one-dimensional heat-transfer model
based on the finite-difference method by Ling and Zhang (2004).
This method was also used by Zhang et al. (2008). The model
included dynamic layering of snow, user-adjustable layering of soil,
snow cover compaction and destructive metamorphisms, distinct
parameterizations of the surface organic layer, and unfrozen water
in frozen soil. For a freezing granite soil medium with an embedded
pipeline in a closed system, Song (2006) analyzed the unsteady-state
heat transfer using the commercial code ABAQUS, code that has
recently transitioned to SIMULIA. These studies were focused on
the development of a computational scheme by applying the effective
heat capacity model to numerical procedures for predicting tem-
perature profiles along a buried pipeline and the frozen penetration
depth.