Experimental Research Of Thermal Conductivity Measuring Instrument For Building Insulation Material Based On The Guarded Hot Plate Method

The rapid development of the construction industry makes it difficult for the traditional insulation materials to serve for it.It is one of the urgent problems to be solved in the construction industry to find efficient and environmentally friendly new insulation materials.In-depth understanding of the commonly used insulation material characteristics is not only great significance for the energy efficiency,but also for the new insulation materials research.The thermal conductivity is directly affects and determines the thermal efficiency and performance parameters of the building structure.The main purpose of this paper is to develop thermal conductivity measurement instrument based on the guarded hot plate,the main work as follows:The research status of the guarded hot plate device at home and abroad is studied in detail.According to the thermal insulation-Determination of steady state thermal resistance and related properties-Guarded hot plate apparatus,a double specimen structure of the guarded hot plate apparatus was developed.The new device uses the double specimen structure to make the test result more accurate;the cold plate and the hot plate all use of the high thermal conductivity aluminum plate,causes the heating speed to be quicker;the hot plate is heated using a polyimide film heater,the advantage of the polyimide film heater is that the insulation is good,the heat conduction is high,the resistance stability and the temperature control precision are high.The cold plate is designed as a counter-current cold labyrinth structure to ensure uniform heating of the plate;the fastening device is designed so that the specimen is closely fitted with the plate,which effectively eliminates the possible air layer between the sample and theboar;high precision thermostat bath and Agilent 34970 A data acquisition instrument greatly improving the measurement accuracy.In the temperature range of 20~70 ℃,measuring the thermal conductivity of the polymethyl methacrylate by the newly established thermal conductivity measuring device.The maximum deviation between the resulting thermal conductivity coefficient and the reference value is 1.11% and the average deviation is 0.25%,the repeatability is less than 1%.;The uncertainty of the new test device is analyzed,the results show that the maximum uncertainty for measuring the thermal conductivity of this experimental system is ± 1%.The thermal conductivity of foam glass,polyurethane insulation board,phenolic insulation board and rubber insulation cotton were tested by using the new thermal conductivity measuring device.The overall deviation of the test is less than ±2% and the repeatability is within 1%.The experimental study on the thermal conductivity of some building insulation materials provides a reference for the further application of the existing insulation materials,the development of low cost and efficient insulation materials and the further study of the advanced technology.