Wandong Zheng

Heat transfer performance of a seawater-source heat pump with radiant floor heating system in cold areas of China

The thermal performance of seawater-source heat pump with radiant floor heating system during the whole heating season in cold regions of China is studied. High-density polyethylene helical coil heat exchanger and a new type radiant floor heating system with aluminium layer is adopted to improve the thermal performance of the system. The heat transfer characteristics of the heat exchanger in flowing seawater and the thermal resistance of each component is experimentally studied, which will be much helpful in the optimizing of heat exchangers used for the seawater-source heat pump system. The temperature distribution of the radiant floor heating system with aluminium layer is tested and the system thermal efficiency is studied during the whole heating days. The results indicate that the heating system has a large popularizing and utilizing value.

Investigating the environmental quality deterioration and human health hazard caused by heating emissions

By analyzing the status quo of the district heating energy consumption and air quality in China, it was found that with the environmental quality degradation, the previous assessment method using energy efficiency as the index cannot consider the impact on the environmental quality and human health simultaneously. Hence, to analyze the environmental quality deterioration and human health hazard due to the heating emissions, a novel assessment method was proposed and can be used to guide the improvement strategies. In this study, based on the quantitative influence of the heating emissions, urban population density and pollution duration, heating impact index (HII) as a new comprehensive evaluation index was introduced. It can be used to assess the urgency of the heating improvement in the studied regions. To estimate the air pollution status quo caused by heating emissions, 66 main heating cities in China were selected as the studied objects. The results showed that the calculated average heating emission-contributed air quality index (AQI) was 45% and polluted time percentage was 39%. The industrial emissions in 19 cities were the main reason to deteriorate the environmental quality during the heating season. While in the remaining 47 cities (71.2% of total studied cities), heating emissions dominated the deterioration of environmental quality. Subsequently, the cities with HII larger than 0.1 were divided into six levels to provide a guide for the Chinese government and relevant departments to improve the heating system and reduce human health hazard. This study can also be used as a reference for other polluted cities to investigate the environmental quality deterioration and human health hazard degrees due to the heating emissions.

Experimental and Numerical Investigation of Bypass Tunnel on Piston Effect of Underground Subway Station

With the rapid growth of the infrastructure constructions in China, more and more metro lines have been built in recent years. The piston wind have a significant influence on the air temperature and the flow field of subway stations and tunnels. The bypass wind tunnel located on both side of the platform, which have great effect of shunt piston wind. This study conducted a train-induced experiment in Xia wafang (XWF) station of Tianjin metro line 1, and the air temperature and velocity data were recorded. Meanwhile, a train-induced numerical simulation was carried out for full-scaled model. The experimental data was compared with the CFD results to analyze the influence of bypass tunnel on the indoor environment and the comfort of passengers. The results indicate that the bypass tunnel can significantly reduce the air velocity of the waiting area and improve the comfort of passengers. The bypass tunnel play an important role in reducing the piston airflow entering the stations, and reducing the piston effect of the station environment.