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Abstract Price volatility analysis has been reported in the literature for most competitive electricity markets around the world. However, no studies have been published yet that quantify price volatility in the Ontario electricity market, which is the focus of the present paper. In this paper, a comparative volatility analysis is conducted for the Ontario market and its neighboring electricity markets. Volatility indices are developed based on historical volatility and price velocity concepts, previously applied to other electricity market prices, and employed in the present work. The analysis is carried out in two scenarios: in the first scenario, the volatility indices are determined for the entire price time series. In the second scenario, the price time series are broken up into 24 time series for each of the 24 h and volatility indices are calculated for each specific hour separately. The volatility indices are also applied to the locational marginal prices of several pricing points in the New England, New York, and PJM electricity markets. The outcomes reveal that price volatility is significantly higher in Ontario than the three studied neighboring electricity markets. Furthermore, comparison of the results of this study with similar findings previously published for 15 other electricity markets demonstrates that the Ontario electricity market is one of the most volatile electricity markets world-wide. This high volatility is argued to be associated with the fact that Ontario is a single-settlement, real-time market.

Abstract The accurate prediction of heat transfer deterioration (HTD) is important to ensure the safe operation of scCO2 cycles driven by various heat sources. Here, the scCO2 heat transfer experiment is performed in a 10 mm diameter vertical tube, covering the ranges of pressures 7.51–21.1 MPa, mass fluxes 488–1500 kg/m2s and heat fluxes 43.7–488 kW/m2. Both uniform heating and non-uniform heating cases are dealt with, but more attention is paid on non-uniform heating. We show that non-uniform heating displays strong circumference angles dependent heat transfer characteristic. Normal heat transfer (NHT) displays gentle rise of wall temperatures along flow length, but for HTD, wall temperature peak is detected ahead of pseudo-critical point. Pseudo-boiling is introduced to deal with scCO2 heat transfer. Heat added to scCO2 is decoupled into a temperature rise part and a phase change part. Flow structure includes a vapor-like fluid near tube wall and a liquid-like fluid in tube core. The analogy between subcritical boiling and supercritical heat transfer results in a supercritical-boiling-number SBO to govern the vapor layer thickness. Sudden change from NHT to HTD is found when crossing a critical SBOcr, which is 5.126 × 10−4 for uniform heating based on our experimental data and other data in the literature, but becomes 8.908 × 10−4 for non-uniform heating using our experimental data. Compared to uniform heating, non-uniform heating is found to delay the occurrence of HTD. The criterion presented here is useful to avoid the occurrence of HTD in the design and operation of scCO2 cycles.

Abstract Numerical studies were conducted for different inlet particle concentrations of a cyclone. The simplified Eulerian model—Algebraic Slip Mixture Model (ASMM) was used for different inlet particle concentrations. With the increase of the inlet particle concentration, particle–particle interaction becomes important. ASMM can take into account this effect in this condition. The present work considered the particle of different size as different phase, and obtained a collision coefficient by experiment when considering the interaction between particles. The advantage of the ASMM is that this model can save a lot of calculating time comparing with the full Eulerian model. However, higher inlet particle concentration will result in the agglomeration between particles deduced by some mechanisms. In point of this fact, the calculated results based on ASMM have some differences comparing with the practical ones. Therefore, this model still has some discrepancies which plead for further improvement. In spite of this fact, this model can be used to analyze the effect of the inlet particle concentration on the separation characteristics of the cyclone qualitatively in practical applications.

Abstract Micro combustor acts as the most important component of the micro thermo photovoltaic (TPV) system. It is crucial that the design and performance of a micro combustor are optimized for its application in a micro TPV system. A micro combustor with front-cavity is proposed in this study, and comparisons of flame stability and thermal performance of the micro combustor with and without front-cavity are made. In addition, the effects of front-cavity size and front-cavity shape on OH mass fraction, flame location and thermal performance of micro combustor are also discussed. The front-cavity in the micro combustor helps to improve the flame stability, increase outer wall temperature value and total energy conversion efficiency for the micro TPV system. It is found that the micro combustor with arc front-cavity (inner diameter ratio of front-cavity and combustion chamber is β = 0.9) is more suitable for the application in the micro TPV system.

The power battery was manufactured with the commercial LiMn2O4 and graphite, and its storage performances with different charged state were studied. Structure, morphology and surface state change of the LiMn2O4 before and after storage were observed by XRD, XPS and AC technique, respectively. The result shows that the capacity recovery of LiMn2O4 stored at discharge state is best (99.2%). While that of full-charged state is worst (93.6%). The cyclic performance of LiMn2O4 stored at full-charged state is best (capacity retention ratio of 89.8% after 200 cycles), while that of before storage is 83.0%. The crystal of the spinel was destroyed after storage, and the intensity of breakage is increased with charged state increasing. The amount of soluble Mn and Li-ion migration resistance (Rf) are increased with chare state increasing, and the oxygen loss is detected.

Abstract Solar energy has an enormous potential to solve society energy needs in a sustainable way. Notably, photovoltaic systems (PV) permit to obtain electricity based on solar energy. However, some issues must be addressed to establish PV as a reliable source of electrical power, for example, its low energy density. One of the approaches to improve the performance of PV systems is to utilize the solar spectrum in solar cells efficiently. Downconversion (DC) is a process where a high energy photon is converted into two or more photons with lower energy. Trough downconversion is possible to use a wider portion of the solar spectrum raising the efficiency in different kinds of solar cells. The present paper reviews the state of the art of materials and methods used to take advantage of downconversion processes in solar cells. Here we discuss some of the pros and cons of different designs in solar cells as well as the main characteristics of the materials utilized.

Anaerobic digestion of high solids chicken manure was conducted in a batch screening assay. Different mixtures of the fresh manure and anaerobically digested sludge or pit manure, resulting in different total solids levels, were incubated at 35°C. The efficiency of organic matter conversion to methane was found to decrease with increasing organic loads to the digesters. The highest solids at which the digestion was still feasible was around 10% total solids. Methanogenesis took place at free ammonia (NH3) concentrations of up to 250 mg/l. The efficiency of organic nitrogen conversion to ammonia (NH3+NH+4) ranging from 62·6% to as high as 80·3% was achieved in most digestions.

Hot flue gas evaporation technology is an effective strategy for zero liquid discharge of desulfurization wastewater. However, there is a potential risk that heavy metals such as Hg may be released from the wastewater during evaporation, disrupting the original balance of the power plant or even exceeding the Hg emission standard. Wastewater evaporation and Hg release behavior were obtained using a single droplet drying system. At an evaporation temperature of 300 °C, approximately 18.5% of Hg was released in the constant wet-bulb temperature period, and the remaining was released in the following evaporation periods. Furthermore, a fixed-bed experiment, in combination with density functional theory calculations, was used to investigate the possible migration mechanisms of released Hg. The results revealed that high HCl concentration, introduced fly ash, and precipitated evaporation products play a crucial role in the fate of Hg, and 85.3% of Hg finally turned into less harmful particulate-bound Hg. This study provides a new and effective strategy for evaluating the migration process of pollutants in wastewater treatment. Moreover, it will serve as an essential reference for advanced wastewater treatment and heavy metals control technologies in the future.