Quantitative measurement method of cold and hot air penetration based on infrared thermal imaging technology

Abstract

The invention discloses a quantitative measurement method of hot and cold air penetration based on infrared imaging technology, which belongs to the technical field of building detection, and aims to quickly detect the penetration air volume of building envelope structures (doors, windows), and the data can be used for heating energy. Research on energy consumption and indoor air quality. It includes the following steps: select the doors and windows to be measured; use an infrared thermal imager to take infrared thermal imaging images of the gaps in the doors and windows; measure the pressure difference inside and outside the doors and windows, and combine the thermal imaging images at the gaps to select two points with large gradients to measure the gaps The wind speed at the location; the thermal imaging image is processed, the gap is automatically identified and the temperature gradient of each micro-element of the gap is obtained; the measured two-point wind speed and temperature gradient are combined with the Fourier formula to obtain the temperature gradient and penetration wind speed at the gap between doors and windows The relational expression; read the temperature gradient of the micro-element section, and calculate the infiltration wind speed of each micro-element section by combining the above relational formula; calculate the gap width of the door and window according to the Bernoulli equation; Multiplying the width can calculate the hot and cold air penetration of doors and windows. Compared with the traditional pressure difference method, the present invention improves the calculation speed, has small measurement error, and is a new method that can be generally applicable to measure the penetration of cold and hot air in a room.

Description

[0001] (1) Technical field [0002] The invention belongs to the technical field of building detection, and specifically relates to a method for quantitatively measuring hot and cold air infiltration based on infrared imaging technology, which is used to conveniently detect the infiltration air volume of building enclosure structures. [0003] (2) Background technology [0004] Air leakage in buildings is critical to quantitatively assess building energy consumption due to air infiltration and exposure of indoor occupants to outdoor particulate matter. In order to obtain the amount of air leakage, it is necessary to measure the airtightness of the building. At present, the conventional method for measuring the airtightness of the building is the differential pressure method. The principle of the pressure difference method is to artificially create a pressure difference between the room to be tested and the outdoor environment, and then measure the air supply or exhaust air volu...

AI Technical Summary

Problems solved by technology

Dufour[3] used IR technology to measure the length and height of a simple two-dimensional gap in the experiment, but due to the edge effect of thermal imaging and light diffraction, the measurement results were inaccurate

Liu [4] The air volume passing through the gap is calculated by thermal imaging technology combined with heat balance and convective heat transfer equation, but the method needs to assume many unknown parameters, and it is difficult to apply in practice

[0005] To sum up, there are three problems in the existing building air leakage measurement methods: (1) not universal; (2) large error; (3) low measurement efficiency.

In order to overcome the defects of the above air leakage measurement method, the present invention proposes a quantitative measurement method of cold and hot air penetration based on infrared imaging technology, combining infrared thermal imaging technology on the basis of traditional pressure difference method, with the help of mathematical software such as MATLAB. The process of image recognition and temperature gradient calculation is optimized, so that it can quickly calculate the air leakage of doors and windows in different regions and under different window conditions, which better makes up for the defects of existing air volume measurement

Images