DESIGN, CONSTRUCTION AND USE OF AN ASTM GUARDED-HOT-PLATE APPARATUS AS AN INDEPENDENT RESEARCH PROJECT

摘要

Thermal conductivity and/or R-value of materials may be measured using methods specified by American Society for Testing Materials (ASTM) or International Standards Organization (ISO). In general three methods are commonly used: the Hot Box, the Heat Flow Meter, and the Guarded Hot Plate. The project was assigned to a Mechanical Engineering Technology student as a research project to satisfy requirements for, senior level, "ETME-499-Independent Research in Mechanical Engineering Technology" course. Student was asked to do his own literature search for the available standard methods and select the most suitable standard method to design and construct an apparatus to measure thermal conductivity and/or R-value of insulating plane specimens. Student has decided to use the Guarded Hot Plate method since it did not require calibration and is simpler to construct. Before the standard was received, student has created some designs similar to the one described by the standard. Limited test runs indicate that polystyrene R-values were underestimated by 12-16%, and duct board R-vales were underestimated up to 22% at higher than 75 °F average specimen temperatures. Student has enjoyed designing, constructing and using the apparatus, which has real world applications. This project has forced him to use his machine design, strength of materials, thermodynamics, instrumentation, heat transfer and manufacturing processes knowledge. Paper will convey our design, construction and use experiences as well as the experience the primary author had in guiding the student towards a common goal in an "Independent Research" course.