Formatted Title
Harnessing Solar Energy for Sustainable In Situ Thermal Desorption of Contaminants with Parabolic Trough Concentrators
Background/Objectives
Solar energy, an abundant and cost-free form of thermal energy depending on regional availability, holds promise as a solution to reduce dependence on fossil fuels. Solar thermal technology, or solar thermal energy, utilizes the sun's heat to generate thermal energy. It employs solar collectors, such as flat-plate or concentrating systems, to capture sunlight and convert it into heat. The utilization of this technology offers an environmentally friendly approach, devoid of greenhouse gas emissions, contributing to the fight against climate change.
Approach/Activities
In situ thermal desorption (ISTD) is an effective technology for treating organic contaminants in soil. The primary principle involves heating the soil through a network of steel pipes functioning as heat exchangers. This process elevates the soil's temperature and pressure to the volatilization point of pollutants. This paper explores the novel concept of using solar energy to power the soil heating process in ISTD.
Of the various solar thermal technologies, parabolic trough concentrators emerge as particularly well-suited for achieving high-temperature soil heating. These concentrators operate based on the geometry of a large, curved parabolic mirror with an absorber tube along its focal line. All parallel light rays reflect to this line, heating a heat-transfer fluid within the receiver tube. Temperature levels of up to 1000°C can be attained depending on solar intensity, geographic location, fluid flow rate, and collector dimensions.
Once the heat-transfer fluid reaches high temperatures, it is injected into the soil via an exchanger tube, elevating the soil to a target temperature and vaporizing any contaminants. The fluid then returns to the parabolic concentrator, where it is reheated, and the process continues.
Results/Lessons Learned
Parabolic trough concentrators exhibit high efficiency and the capacity to store heat, enabling soil heating even in cloudy or nighttime conditions, making them suitable for thermal desorption applications. Thermal insulation tanks play a crucial role by storing some of the warm heat transfer fluids, ensuring continuous and stable soil heating, regardless of weather conditions. During periods when the sun isn't shining, the stored heat is redirected to maintain high soil temperatures, enhancing the technology's sustainability and operational reliability.