Design and Construction of a Guarded Hot Plate Apparatus for Thermal Conductivity Measurements

摘要

Steady state techniques (either absolute or comparative) for measuring heat flows operate on a simple theory, which requires carefully monitored heat input, accurate temperature measurement and a well-controlled pattern of heat flow. Although these techniques demand care in lengthy experiments, they are the benchmark for transient techniques and industrial measurements. Hence, a single specimen guarded hot plate (GHP) apparatus was designed and built at Ryerson University.The principle of this technique is to generate a steady known heat flux in a metering device that flows unidirectionally through a specimen between the planes of hot and cold plates. The hot plate consists of a main plate (178 × 178 × 19 mm) and a heater plate (metering device) embedded in a recess (78 × 78 × 6.4 mm). The main plate forms a guard around the metering device embedded in the centre separated by an air gap of 0.80 mm, which acts as a thermal barrier (Fig. 1). The hot and cold plates are maintained at different temperatures, each uniform within 0.03°C.