Research On Integral Calibration Techniques For Heat Flow Meter By Hot-Box Method

In order to achieve the goal of building energy efficiency, energy comprehensive utilization and development of energy-saving products had significant theoretical breakthroughs and progress. On this background, hollow block and its insulation technology were developed, for this non-homogeneous materials, energy-efficient detection requirement was not the same as other materials, which promoted the further development of detection.The features and weaknesses of all detection means were comprehensively analyzed and proposed that using heat flow meter which calibrated by heat box to detection hollow block wall. Physical and mathematical models were established for hollow block, then using numerical analysis methods with Discrete Ordinate radiation model, solar radiation model and fluid-solid coupling model to study temperature and heat flux field about hollow block.Temperature and heat flux were different with position, and which effected by thermal bridges. Using a particular value as the basis for calculating heat transfer coefficient, will inevitably lead to different results. Therefore, correction factor must be calibrated by heat box for truth values and application.Several group experimental results showed that the heat transfer coefficient that calculated by value of wattmeter in heat-box were accurate and credible, so it can be used as the calibration reference. When the hollow block has been insulated, the correction factors were significantly greater than without insulation. The correction factors were different according to different production or different place.Detection results were affected by several unsteady factors in field. For heat flow meter itself, ensure adhesive close to the wall because it can be reduce thermal contact resistant so as to improve precision. For hollow block insulation wall, wind speed had no influence on detection result when other conditions were the same as others. When the fluctuation of outdoor temperature were 2℃,4℃,6℃respectively, the area ration were 73.3%, 9% and 4% for results within the error range. Considering the solar radiation, the error of the south wall was 28% and the north wall was 18% according to daily mean value. In field detection, we should avoid meteorological conditions of great fluctuation of outdoor temperature, and use the data from the condition of little solar radiation influence.