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Zhu W.,Shanghai University | Hu G.,Shanghai University | Hu X.,Shanghai University | Hongbo L.,Shanghai Solar Energy Research Center | Zhang W.,Shanghai Solar Energy Research Center
Simulation Modelling Practice and Theory | Year: 2010

Metal organic chemical vapor deposition (MOCVD) technology is a very efficient way to uniformly grow multi-chip, multilayer and a big area thin film. Kinetic Monte Carlo (KMC) method is one of the important research tools that carry out dynamic simulation of atomic thin films growth. Based on the method of KMC, this paper proposes an algorithm of the process of GaInP thin film grown by MOCVD. KMC simulation and the visualization emulation of GaInP thin film growth in MOCVD reactor are realized. The results of simulation and visualization truly and intuitively displayed process of GaInP thin film growth in MOCVD reactor. The simulation results with this paper's algorithm well coincide with experimental results. This visualization results provide the optimizations of processing parameters which grow GaInP thin film by MOCVD with theoretical basis. © 2009 Elsevier B.V. All rights reserved.

Tian L.,Harbin Institute of Technology | Mao Z.,Harbin Institute of Technology | Wu M.,Shanghai Solar Energy Research Center | Wang W.,Harbin Institute of Technology
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2016

In this paper, a set of dimension parameters of the sub-wavelength structural anti-reflection film are designed to improve the photoelectric conversion efficiency of flexible substrate solar cell and reduce the surface reflection losses. The designed parameters are simulated in TracePro optical simulation software. The simulation results show that the flux enhancement effect is optimum when the Nano-column height is 72 nm, the duty ratio is 0.5 and the grating period at 300-440 nm for the sub-wavelength structural film. Using Nano-imprinting technology, a polyimide membrane anti-reflection is fabricated based on the template of a vesicular structural anodic aluminum oxide (AAO). The influence of the technological parameters, which is of the fabricated AAO template and its Nano-imprinting technology, on the polyimide (PI) transmittance of the films is tested by scanning electron microscope and ultraviolet-visible light detector. In experiments, we fabricate the AAO template in 0.3 mol/L oxalic acid solution consecutively reacting for 1 h in 70 V constant voltage mode. The PI film is obtained with the insulation being 10 min at 280 ℃ and 800 kg pressure. The test results show that when the transmission spectrum is from 440 nm to 1 000 nm in air mass 1.5 (AM1.5) atmosphere, the transmittance of the film is increased by 2%~5% than the primitive PI film. © 2016, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.

Zhang X.,De Montfort University | Zhao X.,De Montfort University | Xu J.,Shanghai Pacific Energy Center | Yu X.,Shanghai Solar Energy Research Center
International Journal of Low-Carbon Technologies | Year: 2013

This article presented a theoretical analysis of the heat transfer limits associated with a gravitational loop heat pipe (LHP), which involves the utilization of an innovative liquid feeding/distributing and vapour/liquid-separating structure. The mathematical equations governing the heat transport capacity were applied to simulate several commonly known heat transfer limits of the pipe, namely, viscous, sonic, entrainment, capillary, boiling and liquid filling mass limits. This will allow the determination of the actual figure of the limitation and analyses of the factors effecting the limits, including the loop operational temperature, wick type, evaporator diameter/length, evaporator inclination angle, vapour column diameter in the three-way fitting, liquid filling mass and evaporator-to-condenser height difference. During the study, the heat-transfer limits associated with the three-way fitting for liquid feeding/distribution and vapour/liquid separation were given particular attention. The results derived from the analytical model indicated that the compound screen mesh wick can achieve better thermal performance over the sintered powder and open rectangular groove wicks. It was also found that the heat transport capacity of such LHP operation is positively proportional to the operational temperature, evaporator diameter, evaporator inclination angle, vapour column diameter within the three-way fitting, liquid filling mass and evaporator-to-condenser height difference, and in a reciprocal order to the evaporator length. With the specified loop configuration and operational conditions, the LHP can achieve a high heat transport capacity of around 900 W. Overall, the work presented in this article provided an approach to determine the heat transfer limitations for such a specific LHP operation that will be of practical use for the associated system design and performance evaluation. © The Author 2012. Published by Oxford University Press. All rights reserved.

Zhang X.,University of Hull | Zhao X.,University of Hull | Shen J.,University of Hull | Xu J.,Shanghai Pacific Energy Center | Yu X.,Shanghai Solar Energy Research Center
Applied Energy | Year: 2014

Objective of the paper is to present an investigation into the dynamic performance of a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for potential use in space heating or hot water generation. The methods used include theoretical computer simulation, experimental verification, analysis and comparison. The fundamental equations governing the transient processes of solar transmission, heat transfer, fluid flow and photovoltaic (PV) power generation were appropriately integrated to address the energy balances occurring in different parts of the system, e.g., glazing cover, PV cells, fin sheet, loop heat pipe, heat pump cycle and water tank. A dedicated computer model was developed to resolve the above grouping equations and consequently predict the system's dynamic performance. An experimental rig was constructed and operated under the real weather conditions for over one week in Shanghai to evaluate the system living performance, which was undertaken by measurement of various operational parameters, e.g., solar radiation, photovoltaic power generation, temperatures and heat pump compressor consumption. On the basis of the first- (energetic) and second- (exergetic) thermodynamic laws, an overall evaluation approach was proposed and applied to conduct both quantitative and qualitative analysis of the PV/LHP module's efficiency, which involved use of the basic thermal performance coefficient (COPth) and the advanced performance coefficient (COPPV/T) of such a system. Moreover, a simple comparison between the PV/LHP heat-pump system and conventional solar/air energy systems was conducted. The research results indicated that under the testing outdoor conditions, the mean daily electrical, thermal and overall energetic and exergetic efficiencies of the PV/LHP module were 9.13%, 39.25%, 48.37% and 15.02% respectively, and the average values of COPth and COPPV/T were 5.51 and 8.71. The PV/LHP module was found to achieve 3-5% higher solar exergetic efficiency than standard PV systems and about 7% higher overall solar energetic efficiency than the independent solar collector. Compared to the conventional solar/air heat pump systems, the PV/LHP heat pump system could achieve a COP figure that is around 1.5-4 times that for the conventional systems. It is concluded that the computer model is able to achieve a reasonable accuracy in predicting the system's dynamic performance. The PV/LHP heat pump system is able to harvest significant amount of solar heat and electricity, thus enabling achieving enhanced solar thermal and electrical efficiencies. All these indicate a positive implication that the proposed system has potential to be developed into a high performance PV/T technology that can contribute to significant fossil fuel energy saving and carbon emission. © 2013 Elsevier Ltd.

Zhang X.,De Montfort University | Zhao X.,De Montfort University | Smith S.,De Montfort University | Xu J.,Shanghai Pacific Energy Center | Yu X.,Shanghai Solar Energy Research Center
Renewable and Sustainable Energy Reviews | Year: 2012

In this paper, the global market potential of solar thermal, photovoltaic (PV) and combined photovoltaic/thermal (PV/T) technologies in current time and near future was discussed. The concept of the PV/T and the theory behind the PV/T operation were briefly introduced, and standards for evaluating technical, economic and environmental performance of the PV/T systems were addressed. A comprehensive literature review into R&D works and practical application of the PV/T technology was illustrated and the review results were critically analysed in terms of PV/T type and research methodology used. The major features, current status, research focuses and existing difficulties/barriers related to the various types of PV/T were identified. The research methods, including theoretical analyses and computer simulation, experimental and combined experimental/theoretical investigation, demonstration and feasibility study, as well as economic and environmental analyses, applied into the PV/T technology were individually discussed, and the achievement and problems remaining in each research method category were described. Finally, opportunities for further work to carry on PV/T study were identified. The review research indicated that air/water-based PV/T systems are the commonly used technologies but their thermal removal effectiveness is lower. Refrigerant/heat-pipe-based PV/Ts, although still in research/laboratory stage, could achieve much higher solar conversion efficiencies over the air/water-based systems. However, these systems were found a few technical challenges in practice which require further resolutions. The review research suggested that further works could be undertaken to (1) develop new feasible, economic and energy efficient PV/T systems; (2) optimise the structural/geometrical configurations of the existing PV/T systems; (3) study long term dynamic performance of the PV/T systems; (4) demonstrate the PV/T systems in real buildings and conduct the feasibility study; and (5) carry on advanced economic and environmental analyses. This review research helps finding the questions remaining in PV/T technology, identify new research topics/directions to further improve the performance of the PV/T, remove the barriers in PV/T practical application, establish the standards/regulations related to PV/T design and installation, and promote its market penetration throughout the world. © 2011 Elsevier Ltd. All rights reserved.

Zhang X.,De Montfort University | Zhao X.,De Montfort University | Xu J.,Shanghai Pacific Energy Center | Yu X.,Shanghai Solar Energy Research Center
Applied Energy | Year: 2013

This paper introduced the concept, potential application and benefits relating to a novel solar photovoltaic/loop-heat-pipe (PV/LHP) heat pump system for hot water generation. On this basis, the paper reported the process and results of characterizing the performance of such a system, which was undertaken through dedicated thermo-fluid and energy balance analyses, computer model development and operation, and experimental verification and modification. The fundamental heat transfer, fluid flow and photovoltaic governing equations were applied to characterize the energy conversion and transfer processes occurring in each part and whole system layout; while the energy balance approach was utilized to enable inter-connection and resolution of the grouped equations. As a result, a dedicated computer model was developed and used to calculate the operational parameters, optimise the geometrical configurations and sizes, and recommend the appropriate operational condition relating to the system. Further, an experimental rig was constructed and utilized to acquire the relevant measurement data that thus enabled the parallel comparison between the simulation and experiment. It is concluded that the testing and modelling results are in good agreement, indicating that the model has the reasonable accuracy in predicting the system's performance. Under the given experimental conditions, the electrical, thermal and overall efficiency of the PV/LHP module were around 10%, 40% and 50% respectively; whilst the system's overall performance coefficient (COPPV/T) was 8.7. Impact of the operational parameters (i.e. solar radiation, air temperature, air velocity, heat-pump's evaporation temperature, glazing covers, and number of the absorbing heat pipes) to the performance of the system (in terms of efficiencies of the PV/LHP module and the system's overall performance coefficient COPPV/T) was investigated individually. The results indicated that lower solar radiation, lower air temperature, higher air velocity and smaller cover number led to enhanced electrical efficiency but reduced thermal efficiency of the module; whereas lower heat-pump's evaporation temperature and larger number of heat absorbing pipes gave rise to both thermal and electrical efficiencies of the module. The research results would assist in developing a high efficient solar (space or hot water) heating system and thus contribute to realisation of the energy saving and associated carbon emission targets set for buildings globally. © 2012 Elsevier Ltd.

Yuan L.,CAS Shanghai Institute of Technical Physics | Lin Y.,CAS Shanghai Institute of Technical Physics | He Z.,CAS Shanghai Institute of Technical Physics | Xu W.,CAS Shanghai Institute of Technical Physics | And 3 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2011

In view of the strong background radiation and the low signal noise rate of the long-wave hyperspectral imaging spectrometer, an infrared spectral imaging system which could restrain the background radiation was designed. The background radiation was analyzed by the TacePro software. The analysis include composition of the background radiation (within the whole spectral range), relative background radiation of each channel, background radiation as different mechanism inwall surfaces absorbance, and background radiation at different temperature of machine inwall. The background radiation was mainly suppressed by cooling opto-mechanic system and polishing inwall surface. A ground-based experimental device was established, whose spectral range was from 7.7 to 9.3 μm, spectral resolution was 54 nm, spatial resolution was 0.75 mrad and scanning way was push broom. Measurement of the whole instrument presents that spectral resolution (SRF) of the system reaches the designed value and NETD is less than 300 mK as the inwall surfaces of opto-mechanic is at 150 K.

Li H.,Hebei University of Technology | Zhang H.,Hebei University of Technology | Wang L.,Hebei University of Technology | Wang L.,Shanghai Solar Energy Research Center | And 5 more authors.
Journal of Materials Chemistry | Year: 2012

Herein we demonstrate an alternative route to make Eu 3+- exchanged zeolite L crystals (Eu 3+/ZL) highly luminescent by modification with silylated β-diketone. The modified crystals show strong red emission under UV-light irradiation due to the effective energy transfer from the grafted molecules to the Eu 3+ ions. The obtained materials were characterized with FT-IR, SEM, XRD and elemental analysis. FTIR and elemental analysis confirm that the amount of grafted molecules decreases with increasing size of the ZL crystals. Luminescence spectroscopy was used to study the luminescence properties of the modified Eu 3+/ZL crystals. The formation of europium(iii) diketonate complexes and energy transfer from TTA to Eu 3+ ions have been confirmed by luminescence spectroscopy. The Eu 3+ 5D 0 radiative (k r) probabilities and the 5D 0 quantum efficiency were estimated based on the emission spectra and lifetimes. The studies showed that the luminescence performances of the modified ZL crystals can be significantly affected by the crystal size, e.g., photoluminescence emission intensity, 5D 0 lifetime, 5D 0 radiative (k r) probabilities and the 5D 0 quantum efficiency (q) decreases as the size of the ZL crystals increases. © 2012 The Royal Society of Chemistry.

Li Z.Q.,East China Normal University | Li X.D.,East China Normal University | Liu Q.Q.,East China Normal University | Chen X.H.,East China Normal University | And 4 more authors.
Nanotechnology | Year: 2012

A simple approach for preparing near-infrared (NIR) to visible upconversion (UC) NaYF 4:Yb/Er/Gd nanorods in combination with gold nanostructures has been reported. The grown UC nanomaterials with Au nanostructures have been applied to flexible amorphous silicon solar cells on the steel substrates to investigate their responses to sub-bandgap infrared irradiation. Photocurrentvoltage measurements were performed on the solar cells. It was demonstrated that UC of NIR light led to a 16-fold to 72-fold improvement of the short-circuit current under 980nm illumination compared to a cell without upconverters. A maximum current of 1.16 mA was obtained for the cell using UC nanorods coated with Au nanoparticles under 980nm laser illumination. This result corresponds to an external quantum efficiency of 0.14% of the solar cell. Mechanisms of erbium luminescence in the grown UC nanorods were analyzed and discussed.

Wang R.Z.,Shanghai Solar Energy Research Center | Yu X.,Shanghai Solar Energy Research Center | Ge T.S.,Shanghai Solar Energy Research Center | Li T.X.,Shanghai Solar Energy Research Center
Applied Thermal Engineering | Year: 2012

Based upon the fast development of energy efficiency, energy safety and use of renewable and sustainable energy, various energy systems related to residential refrigeration, power generation and storage have been developing. Some of them are in large scale application, while others are still under development. Current status of residential refrigeration, power generation and energy storage technologies have been briefly summarized in this paper. Also, future residential refrigeration, power generation and energy storage technologies are highlighted, and some roadmaps are discussed. © 2012 Elsevier Ltd. All rights reserved.

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