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Towards latent heat storage in the low-to-medium temperature range (70–250 °C), screening of sugar alcohols and their binary eutectic mixtures as potential phase change materials was carried out by focusing on the non-isothermal melting and crystallization behaviors. A preliminary screening shortened the long list of isomers from common four-carbon to six-carbon sugar alcohols to only six affordable...
The effect of gas purging at the cathode on the degradation characteristics of dead-ended proton exchange membrane fuel cells (PEMFCs) is investigated herein using different electrolytes. Electrochemical techniques, including the measurement of polarization curves, cyclic voltammetry (CV) and surface and cross-sectional scanning electron microscopy (SEM) of tested the membrane electrode assemblies...
Return volatility plays a key role in quantifying risk, optimizing the portfolio and pricing modelling of financial market. The study focusing on the return volatility of energy market can help greatly understand the energy fluctuating behaviors. In this paper, we introduce a concept of volatility duration into the analysis of the New York Mercantile Exchange (NYMEX) energy market, where the daily...
A modern wind farm on a large scale can be partitioned into several areas and built up in multiple phases because of the limited initial budget, geographic availability, local policy and other factors. Wind farm micro-siting ignoring the wake effects caused by wind turbines built in a later phase is bound to lose the potential profit of the whole project. This paper proposes a micro-siting strategy...
Gas purging is an effective method to remove the accumulated nitrogen and liquid water during the dead-end operation of polymer electrode membrane fuel cell (PEMFC). The effect of the operation pressure on the degradation characteristic of single cell is investigated under continuous gas purging cycles. Various diagnostic techniques including electrochemical characterization, physicochemical properties,...
This paper presents a novel way of simulating the effect of velocity decay and turbulence of wind turbine's wake flow. By decoupling the solving of wake flow from that of the velocity field, the proposed model treats the wake flow intensity as a kind of convective and diffusive virtual matter. The particle random walk method is utilized to simulate the motion of the virtual matter. Comparing to the...
This paper presents the work on a PEMFC (proton exchange membrane fuel cell) with DEAC (dead-ended anode and cathode) to achieve high hydrogen and oxygen utilization. Gas purging is an effective way to remove the excess water and maintain normal operation of fuel cell while the voltage drops to the set value chosen arbitrarily due to accumulation of generated water. However, serious carbon corrosion...
In an attempt to improve the forecasting accuracy of crude oil price fluctuations, a new neural network architecture is established in this work which combines Multilayer perception and ERNN (Elman recurrent neural networks) with stochastic time effective function. ERNN is a time-varying predictive control system and is developed with the ability to keep memory of recent events in order to predict...
Thermodynamic analyses of regenerative ORC (organic Rankine cycle) driven by low-temperature flue gas waste heat are performed. The heat transfer and flow analyses of a regenerator are also analyzed. A simplified optimal design method to optimize main thermodynamic parameters is proposed for the regenerative ORC driven by flue gas waste heat under different temperature conditions. Results reveal the...
In this work, a high effective up-conversion luminescence agent (from infrared and visible light to ultraviolet light), Er3+:YAlO3, was synthesized by sol–gel method. And then, the CuO, MoS2 and Pt were adopted as co-catalysts and the NaTaO3 was used as bulk catalyst, and then the three corresponding visible-light photocatalysts, Er3+:YAlO3/CuO–NaTaO3, Er3+:YAlO3/MoS2–NaTaO3 and Er3+:YAlO3/Pt–NaTaO...
This paper was aimed to prepare, characterize and determine the comprehensive evaluation of promising composite macrocapsules containing microencapsulated PCMs (phase change materials) with calcium alginate gels as the matrix material. Macrocapsules containing microcapsules were fabricated by piercing-solidifying incuber method. Two kinds of microcapsules with n-tetradecane as core material, UF (urea-formaldehyde)...
PEMFC (Proton exchange membrane fuel cell) operated under dead-ended anode mode is an effective and simple device for high hydrogen utilization. Herein, the operation characteristics of PEMFC with dead-ended anode are systematically investigated under various operating temperature, anode inlet pressure, and cathode stoichiometry. In each operating parameter, the solenoid valve located at the anode...
Precise prediction of thermal processes is one of the major concerns in the field of heat transfer and within energy research communities. It has been proven that using LTE (local thermal equilibrium) conditions within a porous medium may give researchers erroneous data. From another point of view, the entropy generation which is directly related to the loss of available work within a system, is in...
In this paper, a high effective up-conversion luminescence agent (Er 3+ :Y 3 Al 5 O 12 ) is synthesized by sol–gel method, and then its corresponding visible-light photocatalysts (Er 3+ :Y 3 Al 5 O 12 /Pt-KNbO 3 ) are successfully prepared by hydrothermal and direct mixing methods. For comparison, Er 3+ :Y 3 Al...
Entropy generation, which is available exergy destruction, is an important subject in fields of energy management and thermal engineering. With the fast-growing rate of composite media applications in both industries and academic researches, it is necessary to study these media from the second law of thermodynamics point of view. In this work, three fundamental composite media, i.e., composite walls,...
Hydrothermal carbonization of water hyacinth was experimentally conducted in the range of 30 min to 24 h at 240 °C, chemical and structural properties of hydrochar products were investigated. Oxygen/carbon ratio, and hydrogen/carbon ratio in all hydrochar products were 0.19–0.45, and 0.94 to 1.51. Higher heating value of hydrochar products was 16.83 MJ/kg to 20.63 MJ/kg. Residence time had little...
Landscape constraints inevitably cause the irregularity of the shape or boundary of a wind farm, which was not fully considered in previous literature. In this paper, a single-boundary constraint model and a novel multi-boundary constraint model incorporated with ray intersection method are developed to quantify the irregular boundary constraint for wind farm micro-siting optimization. In order to...
Graphite nanoplatelets (GnPs), obtained by sonicating the expanded graphite, were employed to simultaneously enhance the thermal (k) and electrical (σ) conductivity of organic form-stable phase change materials (FSPCMs). Using the method of in situ polymerization upon ultrasonic irradiation, GnPs serving as the conductive fillers and polyethylene glycol (PEG) acting as the phase change material (PCM)...
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