American Society of Agricultural and Biological Engineers



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The Design and Fabrication of a Rotatable Guarded Hot Box (RGHB) Capable of Static Pressure Application

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  131578832,  2013 Kansas City, Missouri, July 21 - July 24, 2013. (doi: http://dx.doi.org/10.13031/aim.20131578832) @2013
Authors:   Andrew J Holstein, David R Bohnhoff
Keywords:   Building Envelope; Heat and Mass Transfer; Guarded Hot Box; Thermal Conductivity; Thermal Resistance; Air Infiltration

Abstract. A Rotatable Guarded Hot Box (RGHB) apparatus was designed and constructed on the University of Wisconsin- Madison campus for the large-scale thermal testing of post-frame building envelope designs. In addition to conducting standard thermal performance tests in accordance with ASTM C1363, the apparatus—capable of testing a wall or roof specimen up to 2.9 x 3.8 m—was designed to simulate the effects of air infiltration through the application of a static pressure differential across the test specimen. Utilizing a cable winch system and centralized pivot point, the entire apparatus may be rotated 360 degrees about its horizontal axis to test wall or roof specimens at any orientation. Using this apparatus, the thermal effect of various envelope design changes such as structural component placement and orientation, insulation type and geometry, and the inclusion and placement of air barriers may be studied.

This apparatus employs a state of the art wireless data acquisition system that collects and digitizes temperature, pressure, and air velocity data within inches of the sensors. This increases system flexibility while reducing system error, thermocouple material cost, and insulated envelope penetrations. These data are monitored by an automated computer control system that varies heater and fan output, calculates and records key variables, and determines the completion of experimental objectives. Using this system, it is possible to expedite the conduction of accurate thermal experiments with a minimum of human interaction.

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