Sustainable Energy

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Authors: Bo Zhao, Shan Rang Yang, Ya Cai Hu
Abstract: The geographical contradictions between plenty of water and high solar radiation constitute are hindering the development of concentrated solar power (CSP) plants, dry cooling systems are compelled to adopt to solve the contradictions for the CSP plants. This paper analysis the feasibility of a novel indirect air cooling with compound refrigerating cycle (CRC-IAC) system used in CSP plants. The solar field and power block in the analysis are modeled using NREL’s Solar Advisor Model (SAM), excluding heat rejection system. Thermodynamic simulations and optimizations for operation exhaust pressure with the changes of ambient dry-bulb temperature are presented. The ideal cycle performance for CRC-IAC system is evaluated and quantified. Moreover, the system was compared with circulating wet cooling (CWC) and air cooling condenser (ACC) in terms of electricity generation and levelized electricity cost (LEC). The results show that the LEC of CRC-IAC is increased by 6.44% and reduced by 5.38%.
Authors: Ling Ling Wang, Shu Ju Hu, Yan Feng Meng, Rui Ma
Abstract: The performance of grid-connected Photovoltaic (PV) power generation system operating in the field is inevitably affected by environmental parameters (solar irradiance, temperature, humidity, wind speed, spectrum, cloud cover, dust, etc.), of which the main factors are solar irradiance and temperature. Based on the data of 100kW PV system of ShangYi PV Plant captured form June 1, 2012 to May 31, 2013 (1 min resolution) and the data of Qinghai Delingha 20MW PV Plant in China captured in 2012., the influence of solar irradiance and temperature on PV system is analyzed. The results show hourly PV array DC power has highly significant positive correlation with hourly total solar radiation, also PV system AC power output and solar irradiance have good consistency. Both of them show irradiance is the main environment factor to the PV system. Then using the captured data, the relationship between maximum load and PV panels surface temperature is also analyzed, the surface temperature is higher, the maximum load is lower.
Authors: Qin Bo He
Abstract: Optical and photothermal properties of MWCNT-H2O nanofluids were investigated in the present work. The transmittance of nanofluids over solar spectrum (250 to 2500nm) was measured by the UV-Vis-NIR spectrophotometer based on integrating sphere principle. The photothermal properties of nanofluids were studied expose to the solar radiation. The experimental results show that the transmittance of MWCNT-H2O nanofluids is much less than that of deionized water, and decreases with increasing nanoparticle mass fraction. The highest temperature and heat gain of MWCNT-H2O nanofluids (0.02wt%) can increased up to 31.87% and 54.14% compared with deionized water, respectively. From the results it can be concluded that MWCNT-H2O nanofluids is suitable for direct absorption solar thermal energy systems.
Authors: Jun Ming Liang, Jian Feng Lu, Jing Ding, Jian Ping Yang
Abstract: The heat loss and thermal performance of solar parabolic trough vacuum receiver were experimentally measured and analyzed by heat transfer model. According to the present experiments, the heat loss of solar parabolic trough vacuum receiver has good agreement with the heat loss of vacuum receiver from Solel company. As the wall temperature increase from 108°C to 158°C, the heat loss of solar parabolic trough vacuum receiver remarkably increases from 35 Wm-2 to 57 Wm-2. The heat transfer model of parabolic trough solar receiver is then theoretically investigated due to the energy balances between the heat transfer fluid, absorber tube, glass envelope and surroundings. When solar radiation flux is constant, the heat efficiency of solar parabolic trough system decreases with the wall temperature and oil temperature. When solar radiation flux or solar concentration ratio increases, the heat efficiency of solar parabolic trough system increases.
Authors: Mi Xu, Hong Wei Han
Abstract: Carbon counter electrode based solid-state dye sensitized solar cells (ss-DSCs) have been investigated with the influence of scattering ZrO2 layer. Compared with the traditional noble metal based ss-DSCs, the scattering layer, which lies between the titania working electrode and counter electrode, plays the roles of both insulator to isolate the carbon electrode from the TiO2 working electrode and reflector to enhance the light harvesting efficiency. The particle size of the ZrO2 presents the remarkable effect on the performance of the ss-DSC.
Authors: Chun Rong Xue, Yu Qin Gu, Ming Liang Deng
Abstract: Thin-film anti-reflecting coatings can greatly reduce the optical loss by making use of phase changes, and the reflectivity depends on the refractive index of materials. TiO2ZnS and Si3N4 coatings are suitable for using as single layer anti-reflecting coating on bare silicon surface, while the MgF2/ZnS and SiO2/TiO2 double-layer anti-reflecting coating result in a minimum reflectance lower than 0.5% over broad spectral regions, with an average reflectance of approximately 2.25% between 400 and 1100 nm on the non-textured Si substrate. The short circuit current of silicon solar cells has significant improvement after depositing anti-reflecting coatings, and it increases the efficiency of the Si solar cells.
Authors: Miroslav Rimár, Štefan Kuna, Marcel Fedák
Abstract: The contribution deals with the climatic conditions in which a solar rotatable structure with flat solar panels was placed on the roof of the building in which the Department of Process Technique is located. There was designed a control system of the structure in order to achieve an increase in efficiency of solar panels. Presented are three ways of the rotatable structure positioning. During the first measurements, the data were obtained and recorded with a fixed position of the solar panels, the second measurements were carried out while the solar panels were rotating along the ecliptic without being dependent on the actual value of the solar radiation intensity, while with the third measurements the rotation was initiated depending on the intensity of the incident solar radiation on the collectors surface. The archived data obtained from individual measurements are presented in the graphs which show the advantage of solar panels rotation in terms of achieving higher temperatures of a solar fluid and a heat transfer medium of an accumulation tank.
Authors: Gang Li, Huan Wang, Run Ping Niu, Qi Zhen Chen, Zhen Li
Abstract: In this paper, the author use solar energy with capillary network systems as the added heating measure of kang . The influence of the system on the surface temperature of Kang and the indoor temperature was researched by experiment. The tested data shows that the average temperature of the head、medium and tail of traditional Kang in a normal room are 65.7°C、43.28°C and 39.82°C. The difference of temperature on Kang surface is higher than 20°C. The average temperatures of the head、middle and tail of the Kang using this system are 51.34°C、38.26°C and 33.79°C. Comparing the two groups of data, we can get the conclusion that the distribution of temperature in the new system Kang is more balance than traditional Kang, which improves the surface comfort of Kang. The average indoor temperature with solar energy auxiliary Kang is 18.5 °C, which is 6.3°C higher than ordinary room. Due to the small thermal inertia of capillary network, the indoor temperature rises quickly when the system is running. It can make quality improvement of indoor thermal environment realtime at will, which greatly improves the thermal comfort of the Kang surface and indoor temperature.
Authors: Sun Jian
Abstract: Liquid desiccant air-conditioning system is one kind of thermally driven open-cycle absorption air-conditioning systems which have been widely researched and applied because of its unique advantages in recent years.In this paper, an experimental equipment of liquid desiccant air-conditioning system was set up based on the mechanism of liquid desiccant dehumidification and regeneration. The dehumidifier and regenerator were all counter-flow towers and body of the tower were made of stainless steel to withstand the corrosive effect of the liquid desiccant. In experiments, mixture desiccant of calcium chloride and lithium chloride was applied.The performance of regeneration of the system was studied under different system operating condition. The effects of the inlet parameters on the efficiency of regeneration are discussed. The results show that the mass flow rate,humidity of the air,temperature and mass flow rate of the diluted solution can all affect the performance of regeneration of the system.

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