Date of Award
Master of Science (MS)
Environmental Engineering and Earth Science
Dr. Ronald Falta
Dr. Lawrence Murdoch
Low temperature solar thermal remediation is designed to accelerate ongoing biotic and abiotic treatment processes at a much lower temperature and cost than high temperature thermal remediation strategies. An array of borehole heat exchangers are used to circulate a solar-heated fluid through a closed-loop system of thermally conductive pipes. Thermal energy heats the surrounding contaminated zone through the process of thermal conduction which serves to enhance the degradation of the contaminant.
A three dimensional analytical solution was previously constructed to model heat propagation from borehole heat exchangers into the surrounding subsurface. The model utilizes a system of finite line sources to describe the borehole heat exchangers while accounting for variable borehole heating rates as well as multiple borehole heaters. This user-friendly simulation model can calculate subsurface temperature change at a low computation time, and is currently being used as a guidance tool for designing and optimizing solar thermal remediation systems. The analytical design tool has been validated by comparison with field data from a solar thermal remediation test site in Colorado, and is currently being used to optimize a detailed field test on Vandenberg Space Force Base in Southern California. The analytical model is compared to high-resolution temperature data during early stages of the test, and then used to predict the longer-term performance of the solar thermal remediation system.
A new feature has been added to the analytical design tool to estimate the thermal-enhanced decay of a contaminant using a modified first-order decay solution. This new capability uses temperature-dependent decay rates to project the thermal-enhanced decay of volatile organic compounds (VOC’s) over time, and is used to model VOC destruction at Vandenberg Space Force Base. With the ability to analyze the impact of increasing subsurface temperature on the duration of bioremediation projects, the decay tool offers an additional advantage in optimizing these types of remediation systems.
Trainor, Justin, "Modeling Heat Propagation and Thermal Enhanced Decay in a Solar Thermal Remediation System" (2023). All Theses. 4116.