LOW-COST DISTRIBUTED TEMPERATURE SENSOR USING ELECTRICAL TDR

Letters from leading researchers of subsurface hydrobiogeochemical processes, including Department of Energy researchers, confirm the need for low-cost, rugged distributed temperature sensing. Temperature and thermal gradients are critical drivers and state variables in many important subsurface hydrobiogeochemical processes, as well as indicators of hydrologic phenomena. In addition to helping understanding subsurface fluxes, surface water and groundwater interactions, and land-atmosphere interactions, spatially resolved temperature observations are important in critical zone biological activity, permafrost, thermal vent zones, gas hydrate formation and dissolution, and limnology. Current technology for distributed temperature sensing is not rugged or inexpensive enough for long- term remote field deployment, achieves a range that is often unnecessary, and a resolution that is often too coarse for many subsurface monitoring needs. Transcend Engineering and Technology propose a low-cost, rugged, field deployable distributed temperature sensor based on the established principle of electrical time domain reflectometry, that range and resolution capabilities of which will fill a currently unmet need in the research community. Phase I will prove the technical and commercial feasibility of the required temperature sensitive cable through analyses, numerical modeling, laboratory synthesis of novel materials, and measurement and assessment of their relevant properties for enabling development of the sensor we propose. Temperature variation over distance is critical to understanding many important underground processes. The sensor we propose will measure temperatures all along a thin cable over a hundred feet in length. It will cost much less and be far more suitable for long- term unattended deployment than existing sensors for this purpose. Commercial Applications and Other Benefits: The research will lead to a marketable product that will serve large commercial markets. The resultant rugged, field-portable instrument with embedded software for processing raw time domain reflectometry measurements from the temperature sensitive cable into spatial temperature profiles, would be useful for remote and portable field deployment by Federal Government researchers, regulators, and commercial applications such as quality assurance monitoring of cure-in-place piping and cure monitoring of concrete pavement and mass-pour structures. Other potential applications with public benefits include fire detection in special hazard buildings, perimeter leak monitoring of liquid natural gas and other storage vessels, and temperature monitoring in plant and process engineering.