info on exterior insulation/filling material, etc.-1999

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Report A3132.1 Page 11 Heat Flux Profiles Temperature differences across the thermally calibrated insulation layer at the inner face of the wall were calculated at 4 vertical locations with thermocouple and three vertical locations with heat flux meters shown in Figures Al and A2. Example profiles of heat flux into the basement wall are shown in Figure 12. The smoothness or regularity of these curves attest to the fact that the seven vertical readings are consistent with one another. These weekly averaged heat flux profiles have the highest level of accuracy associated with them. Each heat flux meter reading is the result of the average of 5 EMF readings. Part 3 - Analysis and Discussion Method to Measure Thermal Resistance In Situ A test method, developed at NRC during previous project (Muzychka, 1992; Bomberg and Kumaran 1994)2'3, involves testing two materials placed in contact With each other- a reference material whose thermal conductivity and specific heat are known as a function of temperature, and a test specimen whose _. thermal properties are unknown. Because of its comparative character, this method has been called a heat flow comparator(HFC). In a previous experiment involving roof insulation, the reference and tested specimens were placed in the exposure box representing a conventional roofing assembly. Thermocouples were placed on each surface of the standard and reference materials to measyre temperatures, which then were used as the boundary conditions in the heat flow calculations. The beat flux across the boundary surface between reference and tested specimen is calculated using a numerical algorithm to solve the heat transfer equation through the reference material. Imposing the requirement of heat flux continuity at the contact boundary between test and reference materials, corresponding values of thermal conductivity and heat capacity of the tested specimens are found with an iterative technigwe.- Performing these calculations for each subsequent data averaging period Wirt"result in a set of thermal properties of the test material which, over the period of measurements, give the best match with its boundary conditions (temperatures and heat flux). Since thermal conductivity of the specimen is a function of its temperature, the solution of the heat transfer equation is based on central finite difference calculations that include Kirchoff's potential function (integral of thermal conductivity over the range of temperature) and uses a Taylor's series to calculate heat flux through the surface. Subsequent developments improved the stability of the numerical solution and produced a user friendly computer code Lj