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A framework for the reliability evaluation of grid-connected PV (photovoltaic) systems with intermittent faults is proposed using DBNs (dynamic Bayesian networks). A three-state Markov model is constructed to represent the state transition relationship of no faults, intermittent faults, and permanent faults for PV components. The model is subsequently fused into the DBNs. The reliability and availability...
Nanoencapsulation of n-octadecane phase change material with silica shell was performed through interfacial hydrolysis and polycondensation of tetraethyl orthosilicate in miniemulsion. The chemical composition and crystallinity of the synthesized n-octadecane@SiO2 nanocapsules were characterized by FT-IR spectroscopy and XRD analysis. DSC (differential scanning calorimetry) and TG results demonstrated...
The process of energy conservation and emission reduction in China requires the specific and accurate evaluation of the energy efficiency of the industry sector because this sector accounts for 70 percent of China's total energy consumption. Previous studies have used a “black box” DEA (data envelopment analysis) model to obtain the energy efficiency without considering the inner structure of the...
Studies on RPSC (road pavement solar collectors) have shown the potential of reducing the UHI (urban heat island) effects by dissipating the heat from the pavement for energy harness. Several works have shown that the generated heat could be utilised for sustainable urban energy system. However, none of the previous literatures have assessed the effect of building geometry on the performance of the...
The use of SEHRAC (storage-enhanced heat recovery room air-conditioner) for space cooling and free water heating has been confirmed effective but its overall performance will unavoidably be affected by the associated increase in water temperature in the heat recovery water tank. Measures to enhance the heat storage capacity of the water tank will thus be beneficial to the overall performance of SEHRAC...
Distillation columns with adiabatic stages inherently entail high entropy production because heat is only supplied to the reboiler and removed from the condenser. DDC (Diabatic distillation columns) can reduce the entropy production and they can be realized through the installation of heat exchangers in series at the stages in the column by circulating a cooling fluid in the rectifying section from...
Direct optimal control methods are used. The pin fin's volume is minimized for given heat flux value. Schmidt's criterion is not adopted. The optimal pin fin profile is neither parabolic nor circular. It consists of two regions. In the first region, close to the basis, the pin thickness decreases linearly. In the second region the pin thickness is constant or may decrease, depending on thermal loads...
This paper presents a straightforward method for assessing the uniformity and mixing time of bubbles based on uniform design in a direct contact heat exchanger. The evolution of bubbles movement is experimentally tracked using an imaging technique that is processed in the Matlab software to obtain the local bubble concentration. The local discrepancy of a set of bubbles seems to be a useful concept...
Manufacturers lack the economic tools to properly perform maintenance procedures to increase manufacturing reliability while reducing system energy consumption. A return on investment strategy is developed to provide plant managers with a quantitative method to optimize the maintenance actions that lead to the largest return on investment. Over the long term, this energy economic analysis results...
A detailed understanding of the hydrodynamics of a tidal current turbine is paramount to the further development and adaptation of tidal current energy. Hydrodynamic modelling of such systems assists with reducing the cost of energy through accurate performance prediction enabling design refinement. Blade element momentum theory offers an efficient modelling technique to compute the hydrodynamic performance...
This paper suggests a chaotic optimizing method, based on the GBABC (global best artificial bee colony algorithm), where the random sequences used in updating the solutions of this algorithm are replaced with chaotic sequences generated by chaotic maps. The new algorithm, called chaotic CGBABC (global best artificial bee colony algorithm), is used to solving the multi-area economic/emission dispatch...
The present work provides an international comparison of the energy intensity and the carbon dioxide intensity in road transport for a group of 90 countries over the period 1980–2012. This paper attempts to perform a comparative analysis to find the most appropriate mapping of the energy performance in road transport taking into account the three dimensions of sustainable energy development, namely...
This paper presents a comprehensive SA (sensitivity analysis) of the typical PRH (public rental housing) development in Hong Kong based on a combined building energy, daylight and AFN (airflow network) simulation. A generic building model is constructed with a proposed MM (mixed-mode) ventilation control strategy to fulfill the thermal comfort requirement in the local green building guidance. The...
Owing to the poor performance of the previous CO2 two-rolling piston expander prototype, improvements were made to increase its efficiency. The improvement measures included increasing the expansion ratio by minimizing the size of the intermediate channel and adopting some sealing methods to block the leakages, such as integrating the intermediate plate and filling O-rings in the seal grooves of the...
A detailed parametric and optimization studies of reheat and regenerative Braysson cycle has been carried out. The effect of compressor and turbine inlet temperatures, temperature rise in a stage of multi-stage compression, individual component efficiencies and exit pressure of reheat turbine on the performance has been studied. The effect of perfect cooling after regeneration leads to a gain of 7...
DED (Dynamic economic dispatch) considering valve-point effects is a complicated non-convex optimization problem in power system. For large-scale DED problem with hundreds of generators, how to avoid the curse of dimensionality remains a big challenge due to the exponential growth of search space. In allusion to this problem, this paper presents a promising heuristic approach named CSO (crisscross...
The present study focuses on the predictions and verification of these predictions of solar energy using ground-based solar measurements from the Hellenic Network for Solar Energy and the National Observatory of Athens network, as well as solar radiation operational forecasts provided by the MM5 mesoscale model. The evaluation was carried out independently for the different networks, for two forecast...
An efficient solid-base catalyst with low leaching K2MgSiO4 component on industrial silica gel was synthesized by a simple sol–gel method. The Jatropha biodiesel with high yield of 96.8% was produced by adopting in-situ esterification and transesterification reactions using the solid-base catalyst. The facile methanolysis process with excellent catalytic reactivity depends on the low leaching active...
Short-term wind speed forecasting plays a major role in wind energy plant operations and the integration of wind power into traditional grid systems. This paper proposes a hybrid model, which is composed of the EWT (empirical wavelet transform), PACE (partial auto-correlation function) and GPR (Gaussian process regression) method, for short-term wind speed prediction. In this proposed approach, the...
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