Song Pan

A Review of the Piston Effect in Subway Stations

In recent years the piston effect in subways has become a topic of interest for researchers and engineers. Many publications have appeared on this topic, but reliable information is scattered and poorly organized. This review paper covers the latest publications on the piston effect in subways. We compile information about the mechanism of the piston effect, evaluate its influence, and describe how it can be effectively utilized.

Comments on Thermal Physical Properties Testing Methods of Phase Change Materials

There is no standard testing method of the thermal physical properties of phase change materials (PCM). This paper has shown advancements in this field. Developments and achievements in thermal physical properties testing methods of PCM were commented, including differential scanning calorimetry, T-history measurement, the water bath method, and differential thermal analysis. Testing principles, advantages and disadvantages, and important points for attention of each method were discussed. A foundation for standardized testing methods for PCM was made.

Experimental Study of the Performance of Air Source Heat Pump Systems Assisted by Low-Temperature Solar-Heated Water

Due to the low temperatures, the heating efficiency of air source heat pump systems during the winter is very low. To address this problem, a low-temperature solar hot water system was added to a basic air source heat pump system. Several parameters were tested and analyzed. The heat collection efficiency of the solar collector was analyzed under low-temperature conditions. The factors that affect the performance of the heat pumps, such as the fluid temperature, pressure, and energy savings, were analyzed for cases where the solar energy auxiliary heat pump and the air source heat pump are used independently. The optimal heating temperature and the changes in the fluid temperature were determined. The influence of the compression ratio and the coefficient of performance (COP) were investigated theoretically. The results revealed the parameters that are important to the performance of the system. Several measures for improving the COP of the heat pump units are provided for other applications and future research.

“Cross-Ventilation” Effect of Piston Wind and Energy-Saving Evaluation for the Ventilation and Air Condition in Subway Station

This study takes a subway station of line 2 in Beijing as study object, based on the piston wind flow characteristics of a field test and a 1:8 scale model experiment combining the theoretical research and the numerical simulation, specially analyzed the influence on the piston wind flow characteristic of the different setting heights of the Semi-enclosed platform doors (SPDs), and based on the test results of air temperature and humidity in and out of the subway station analyzed the “cross-ventilation” effect of piston wind and evaluated its contribution to the energy consumption of the ventilation and air condition in subway station. Results show that little difference in the piston wind volume exists when height of the SPDs changes [Enclosed platform doors (EPDs) or Semi-enclosed platform doors (SPDs)]; according to the summer weather condition of the large day–night temperature difference and the lower enthalpy in Beijing, a SPD can improve the indoor air quality and reduce the energy consumption of ventilation and air condition in subway stations in Beijing.

The Effective Use of the Piston Effect, Natural Cold Sources, and Energy Saving in Beijing Subways

With the development of the subway, the energy consumption of subway ventilation and air-conditioning systems is increasing rapidly. To solve this problem, this paper describes the environment of a subway station in Beijing subway line no. 2 from July to September, 2011, and uses numerical methods to quantitatively analyze and evaluate the contributions of the subway piston effect and natural outdoor cold sources to energy saving in the air-conditioning system and improvement of the subway environment. The results show that the piston effect can be used for ventilation in each area of the subway station. During summer, part of the subway air-conditioning season, a natural cold source can introduce a cold capacity of 5,100 GJ to the subway station.

The Researches on the Current Energy Consumption and Energy-Saving Potential of Beijing Subway

Energy conservation is a long-term strategic approach of economic development. Subway is a most important way of urban mass transit, the energy consumption of subway accounted for a large part in mass transit. Therefore, retrofitting the subway for energy saving is close to the current policy, it can relieve the energy pressure, so it plays an important role on the sustainable development of economy. This paper conducted a survey of Beijing subway energy consumption, and summed up annual energy consumption data of the Beijing subway lines. Based on this research, this paper shows the energy-saving potential of the Beijing subway. Also it lays the foundation of energy saving transformation for subway.

Building Energy Audit and Energy-Saving Analysis for a Five-Star Hotel in Beijing

Building energy audit and equipment energy-saving assessment are an important part of the building energy monitoring system in the construction. This paper takes a five-star hotel in Beijing as an example and audits the building energy consumption of the hotel. By testing air conditioning chillers, chilled water pumps, cooling water pumps and other equipments analyses energy-saving potentiality of the conditioning system and lighting equipments. The results would help us put forward some sound energy-saving measures, regulatory frameworks and reduce energy equipment consumption.

Energy Saving Analysis on Solar Capillary Radiation Heating System

Radiation capillary used as air conditioning terminal lower the demand of heating water temperature. In additional, solar collectors could also supply amount of low grade energy for heating. Meanwhile, solar is a kind of renewable, sustainable and environment friendly energy. It will save a massive of conventional energy if make full use of solar for heating. In this paper, an experimental system made of solar collector, capillary network and pump was built up and tested. According to thermal load of experimental room, both solar collector area and capillary network area are calculated, and circulating water temperature was analyzed in detail. A summary is given about characteristics of heat storage and release of solar collector, indoor air temperature varying and amount of energy saving. The key factors affect efficiency of collector includes water volume, water temperature in tanker and indoor air temperature. The results show that the solar system can well meet the heating demand and the effect of energy saving is very significant compared to common heating system.

The Current Researches on the Piston Effect in Subway Station

More and more scholars have attached importance to the piston effect, which seriously impact the metro environment. In this paper, after referring the present researches on the piston effect domestically and oversea, the author studied their methods and results and then summed up the disadvantages, for the further exploration.