thermal comfort

Study on leakage localization of direct-buried heating pipeline based on reconstructing VMD components by energy analysis

In order to improve the accuracy of acoustic wave method for leakage localization of directly buried heating pipelines in complex noise environment, this paper proposes a method of heating pipeline leakage localization based on energy analysis and reconstruction of effective modal components, i.e., the detection signal is adaptively decomposed into a set of Intrinsic Modal Functions (IMFs) using Variable Divided Modal Decomposition (VDD), effective modal components with leakage characteristics are identified and extracted, and signal weighted reconstruction is accomplished through the analysis of the energy occupation ratio (EOR). The signal weighting reconstruction is completed. Leakage experiments and engineering measurements show that: the average localization deviation of the conventional VMD leakage localization method and this paper's method is 1.57, 0.51 m, and the relative localization deviation is 8.42%, 2.75%, respectively, and the localization accuracy of this paper's method is improved by 67.34%; in the engineering measurements, the conventional VMD method fails to discover the leakage location of the pipeline, and the localization deviation of the leakage location determined by this paper's method is 1.78 m; this paper's method can be used to identify leaks in the pipeline. 1.78 m; the method in this paper can suppress the residual noise in the effective modal components, reduce the influence of noise components on leakage localization, and improve the leakage localization accuracy of heating pipelines in complex noise environments.

Analysis and calculation of diffused oxygen supply in indoor spaces in highland areas

The indoor oxygen concentration change equation was derived and analyzed based on the air volume balance equation and the oxygen volume balance equation, and case calculations were made for this equation. The results show that when the target indoor oxygen concentration is determined, the rate of change of indoor oxygen concentration is mainly determined by the fresh air volume, and the required steady-state oxygen supply decreases when the fresh air volume is small, but the time required to reach the target indoor oxygen concentration from the initial oxygen supply concentration increases, which makes it difficult to meet the requirements for room use. Therefore, it is proposed to correct the steady state calculated oxygen supply quantity at the early stage of oxygen supply, and increase the oxygen supply quantity appropriately to achieve the set target indoor oxygen concentration within the specified time, and to obtain the required correction coefficients of the oxygen supply quantity through the calculation of scientific computing software, which can be used for the design and calculation of the diffuse oxygen supply quantity of indoor space in plateau areas.

Effect of natural ventilation and pollutant concentration distribution in rooms of buildings with deep concave façade

A deep concave façade building room in Xi'an with lateral wind direction was used as the research object, and multi-scale CFD simulation of outdoor to indoor fields was carried out through the transition field model to study the indoor air quality under different window opening methods. The results show that: full-opening windows have a better effect on discharging indoor pollutants, but their resistance to outdoor pollutants is not as good as that of single-opening flat façade windows; when indoor pollutants are concentrated in a single room, the convective ventilation formed by the open windows will cause the pollutant concentration in other rooms with no pollutant sources to increase; when the pollutants are scattered in each room, the convective ventilation can reduce the pollutant concentration in each room, and the reduction is about 50%; single-opening windows can reduce the pollutant concentration in each room, and the reduction is about 50%. Reduce the magnitude of about 50%; single flat window can effectively eliminate outdoor pollutants into the room, and increase the air outlet is the best way to discharge indoor pollutants.

Research on design parameters of thermal insulation of building facades based on thermal comfort

Thermal adaptation models and thermally acceptable temperature intervals for four typical cities in hot summer and cold winter regions and cold regions are given. The common enclosure structures in the four cities were investigated, and the time-by-time change values of the internal surface temperatures of different enclosure structures were obtained based on the dynamic change of outdoor air temperature on a typical design day in summer. Based on the thermal adaptation model, the human acceptable maximum internal surface temperatures of common enclosure structures in typical cities of different climate zones were determined and compared and analyzed with the current relevant codes. The results show that the maximum internal surface temperatures of enclosure structures in natural ventilation environments stipulated in the codes of Shanghai and Xi'an cannot meet the thermal comfort requirements of personnel, and the limit values stipulated in the codes should be adjusted downward appropriately.