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Research on Integral Calibration Techniques for Heat Flow Meter by Hot-Box Method

Author: WanQing
Tutor: DongHua；ZhouEnZe
School: Qingdao Technological University
Course: Heating,Gas Supply, Ventilation and Air Conditioning Engineering
Keywords: Energy detection Hollow block Hot box Heat flow meter Wind velocity Temperature fluctuations Solar radiation
CLC: TU111.2
Type: Master's thesis
Year: 2010
Downloads: 57
Quote: 0
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Abstract

In order to improve the efficiency of energy use in the buildings, the state increase investment in emerging energy-saving products, has made significant progress, hollow blocks and insulation technology developed in this context. Homogeneous material, the need for new building envelope the energy detection technology with adaptation. This paper analyzes the characteristics and problems of the building envelope energy-saving detection of a variety of techniques proposed using heat flow meter calibration by hot box method to detect hollow block wall. On the basis of physical and mathematical models of the hollow block wall and the insulation condition, combined with DO radiation model, the model of solar radiation, fluid-structure interaction model, using numerical analysis the temperature and heat flux. Hollow block, the outer surface temperature and heat flux thermal bridges around the values ??are not the same. Only a particular value as the basis for calculating the heat transfer coefficient will inevitably lead to results quite different. Therefore, the use of heat flow meter hollow block wall detection, further calibration is required through the hot box test of numerical accuracy and correction factors. The hollow blocks steady-state heat transfer experiments show that the average heat flux hot box on power meter as the basis to calculate the heat transfer coefficient, the result is more accurate, can be used as the basis of the calibration of the heat flow meter calculations. The calibration results show that the specimen of the same hollow block, insulation correction factor is less than the insulation. The heat flow meter due to the production process and different placement, the correction factor is not the same. Field unsteady detection process, the test results influenced by many conditions. The heat flow meter is tightly affixed on the items to be tested, in order to ensure the thermal contact resistance is minimized, and to increase the measurement accuracy. Detection hollow block outer wall insulation, given typical daily meteorological parameters, Outdoor other things being equal, as calculated on the basis of inner wall heat flux and combined with arithmetic average calculation results show that the wind speed does not affect the result of the heat transfer coefficient . Solar radiation analysis showed that the south-facing wall and north to the wall during the day when the results of the difference is very large, there is little difference of night. According to the arithmetic mean of the results of the full-time, the south wall of error is 28%, while the north wall of the margin of error of 18%, the test should be chosen by the solar radiation the smaller North to the wall, and in the characterization of the characteristic values ??of the wall should be without a sun radiation data. This article assumes that the outdoor temperature harmonic wave, the investigated temperature fluctuation amplitude detection. The conclusions show that when the outdoor temperature fluctuations, and the results will be more deviation from the steady-state value. Area ratio to calculate the thermal resistance resulting in engineering thermal resistance in the range of allowable error of all time according to the inspection, when the fluctuations were 73.3%, 9% and 4%, respectively, so try to avoid excessive fluctuations in weather conditions at a temperature under the wall heat transfer coefficient detected.

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