Guarded hot plate apparatus design and construction for thermal conductivity measurements

A Guarded Hot Plate (GHP) appartus was designed and built for high temperatue applications, consistent with or better than the established standards. This apparatus consists of a hot and a cold plate, attached to a frame, which allows the plates to be tilted from horizontal to vertical and configured for heating from the top to the bottom. The plates are independently heated by passing heat transfer fluid through a flow distribution system consisting of manifolds and internal flow passages, machined in each plate. Attached to the hot plate are an electrically heated heater plate and a heat flux meter, configured consistent with the hybrid method for measuring heat flux. This apparatus is designed to measure thermal conductivity of soils at different moisture contents and for temperatures ranging from -20⁰C to 200⁰C. An error analysis for the thermal conductivity measurement shows a conservative estimate of the bias error to be around [plus or minus] 2%.