Jinqing Peng

Analysis of Energy Utilization on Digestion Biogas Tri-Generation in Sewage Treatment Works

This paper presents a combined heating, cooling, and power generation (tri-generation)system using sewage treatment digestion biogas according to the principle of energy gradient utilization technology. The tri-generation scheme adopts Lithium Bromide (LiBr) absorption cooling technology for office air conditioning, a biogas power generator, a heating system for digestion tanks. The performance analysis demonstrates that the scheme is practical in Hong Kong. Surplus cooling of the chiller is used to cool the inlet air of the generator for increasing the biogas power generator output. The electricity generation capacity can be increased by around 7 % annually owing to the inlet air cooler. For a case study of a local sewage water treatment work, the cooling capacity is equal to 422.72 MWh. The hot water meets the digester heating load at the same time. It is estimated that the economic payback period will be about 2 years.

Seismic and Power Generation Performance of U-Shaped Steel Connected PV-Shear Wall under Lateral Cyclic Loading

BIPV is now widely used in office and residential buildings, but its seismic performance still remained vague especially when the photovoltaic (PV) modules are installed on high-rise building facades. A new form of reinforced concrete shear wall integrated with photovoltaic module is proposed in this paper, aiming to apply PV module to the facades of high-rise buildings. In this new form, the PV module is integrated with the reinforced concrete wall by U-shaped steel connectors through embedded steel plates. The lateral cyclic loading test is executed to investigate the seismic behavior and the electric and thermal performance with different drift angles. The seismic behavior, including failure pattern, lateral force-top displacement relationship, and deformation capacity, was investigated. The power generation and temperature variation on the back of the PV module and both sides of the shear wall were also tested. Two main results are demonstrated through the experiment: (1) the U-shaped steel connectors provide enough deformation capacity for the compatibility of the PV module to the shear wall during the whole cyclic test; (2) the electricity generation capacity is effective and stable during this seismic simulation test.

Experimentally diagnosing the shading impact on the power performance of a PV system in Hong Kong

This paper presents an experimental diagnosis on the power performance of a PV system in Hong Kong. The annual solar radiation received by the PV modules was simulated based on the recorded horizontal solar radiation. The theoretical annual energy output of this PV system was about 11,702 kWh/yr, which was higher than the actual energy output by 24.5%. In order to find out the reasons of the energy loss, an on-site inspection and testing was conducted. The shading and aging problems were found in the process of visual inspection. The shading problem can be further subdivided into edge-shading, pillar-shading and nameplate shading. To further understand and quantify the impact of different types of shadings on the power output performance, the I-V curves of a PV module were tested under different solar radiation. The testing results showed that the impact of different types of shadings on the power performance varied with the Sun position, solar radiation as well as the time. In general, the edge-shading effect reduced the energy output of PV system by 11%-15% the pillar-shading effect reduced the energy output by 15%-19%, and both effects of edge-shading and pillar-shading reduced the energy output of PV system by 18%-35%. Thus, the main reason that resulted in the energy loss of this PV system was attributed to the shading impact. If the edge-shading and pillar-shading problems are solved, the annual energy output of the PV system could increase about 20%-24%.

Study on the Optimizing Operation of Exhaust Air Heat Recovery and Solar Energy Combined Thermal Compensation System for Ground-Coupled Heat Pump

This study proposed an exhaust air heat recovery and solar energy combined thermal compensation system (ESTC) for ground-coupled heat pumps. Based on the prediction of the next day’s exhaust air temperature and solar irradiance, an optimized thermal compensation (OTC) method was developed in this study as well, in which the exhaust air heat recovery compensator and solar energy compensator in the ESTC system run at high efficiency throughout various times of day. Moreover, a modified solar term similar days group (STSDG) method was proposed to improve the accuracy of solar irradiance prediction in hazy weather. This modified STSDG method was based on air quality forecast and AQI (air quality index) correction factors. Through analyzing the operating parameters and the simulation results of a case study, the ESTC system proved to have good performance and high efficiency in eliminating the heat imbalance by using the OTC method. The thermal compensation quantity per unit energy consumption (TEC) of ESTC under the proposed method was 1.25 times as high as that under the traditional operation method. The modified STSDG method also exhibited high accuracy. For the accumulated solar irradiance of the four highest daily radiation hours, the monthly mean absolute percentage error (MAPE) between the predicted values and the measured values was 6.35%.