• Energy Research
• Closed Access close
• PL close
• AT close
• EU close

Abstract ETFE (ethylene tetrafluoroethylene) cushion integrated flexible photovoltaics (PV) is an extension of building integrated photovoltaics into membrane structures, which could be near zero-energy, sustainable and environmental-friendly buildings. This paper focused on a two-layer ETFE cushion integrated flexible photovoltaics with experimental study and theoretical analysis. Field experiments on a prototype were carried out to investigate temperature distribution and characteristics. It is found that temperature distribution was the result of solar irradiance, incident angle and surface curvature of ETFE cushion and that solar irradiance had an essential effect on temperature distribution. The theoretical thermal model was developed based on energy balance equation and the corresponding differential equation was solved by the Runge-Kutta method. Maximum temperature difference of 3.3 K between experimental and numerical results demonstrated that this thermal model could predict PV temperature appropriately. Furthermore, a modified equation to determine heat transfer coefficients was proposed and average heat transfer coefficients of PV and ETFE foil were 4.89 W/(m 2 K) and 4.39 W/(m 2 K). In general, this study could provide basic values and observations for investigating thermal performance of ETFE cushion integrated flexible photovoltaics.

Abstract In dispersed power generation, low power devices are used for local combined generating of heat end electric power. There are developing concepts of micropower plants with electric generators driven by steam or gas microturbines. The paper presents the results of an experimental investigations of the microturbine set consists of the turbine with partial admission, permanent magnet generator and three phase AC-to-DC rectifier. The microturbine was designed for steam of HFE7100 as a working medium. The dynamic behavior of the microturbine unit was experimentally examined. Microturbine unit was tested during changes of the parameters of the working medium or the electrical load. Experiments were performed with compressed nitrogen as a working medium. The dynamic model of microturbine unit was developed. The examples of the comparison between experiment results and simulations are shown and discussed in the paper.

Abstract The reliability of nuclear structures relates directly to the reliability of mechanical and electronic systems. Nuclear structures may be viewed as part of operational system as well as part of standby safety system. Except for proof loading, most of the load types, seen by nuclear structures, such as containments, primary piping, etc. during their design life, are random in time and space. Structural resistances, governed mainly by the respective material properties show also random characteristics. Methods of structural reliability, as discussed here, provide the means to process rationally the available information. Hence, they are an indispensable tool within the frame work of probabilistic risk analyses (PRA's). The probabilistic analysis is exemplified by determining the reliability of a containment structure sited in an area with strong seismicity.

AbstractDespite the rapid increase in the performance of perovskite solar cells (PSC), they still suffer from low lab‐to‐lab or people‐to‐people reproducibility. Aiming for a universal condition to high‐performance devices, we investigated the morphology evolution of a composite perovskite by tuning annealing temperature and precursor concentration of the perovskite film. Here, we introduce thermal annealing as a powerful tool to generate a well‐controlled excess of PbI2 in the perovskite formulation and show that this benefits the photovoltaic performance. We demonstrated the correlation between the film microstructure and electronic property and device performance. An optimized average grain size/thickness aspect ratio of the perovskite crystallite is identified, which brings about a highly reproducible power conversion efficiency (PCE) of 19.5 %, with a certified value of 19.08 %. Negligible hysteresis and outstanding morphology stability are observed with these devices. These findings lay the foundation for further boosting the PCE of PSC and can be very instructive for fabrication of high‐quality perovskite films for a variety of applications, such as light‐emitting diodes, field‐effect transistors, and photodetectors.

Information about decadal to millennial variability of El Nino Southern Oscillation (ENSO) is fundamental for the assessment of ENSO responses to natural and anthropogenic forcings. Despite a growing number of ENSO reconstructions, the overall picture of Holocene ENSO variability is inconsistent. Here, we revisit the iconic Holocene ENSO sediment record of Lake Pallcacocha, Ecuador (Rodbell et al., 1999). We asked: (i) How coherent are the records of clastic layers (flood layers) in the sediments of Lake Pallcacocha and adjacent Lake Fondococha? (ii) What are the synoptic-scale atmospheric conditions that lead to intense precipitation and, potentially, to alluvial activity promoting the deposition of clastic layers in these lakes? (iii) Is intense precipitation in this area associated with El Nino, or not? We analyzed clastic layers in Late-Holocene sediments from multiple cores in Lakes Pallcacocha and Fondococha from Cajas National Park, southern Ecuadorian Andes. Additionally, we investigated precipitation data from 13 nearby meteorological stations to test if intense precipitation (percentiles P0.95, P0.99, P0.995) is predominantly related to El Nino conditions or not (based on 15 different ENSO indices). Our results show that the absolute flood frequencies (clastic layers per 100 years) differ substantially from lake to lake. This indicates that the frequency of clastic layers reflects different sensitivities (thresholds of precipitation) of the catchments to alluvial activity. 210Pb ages suggest that neither the 1982/83 nor the 1997/98 very strong El Ninos produced clastic layers comparable to those found in the late Holocene. Daily precipitation records from meteorological stations close to Lake Pallcacocha including a high-altitude station from the western slope of the Andes did not show unusually high precipitation during the super El Nino 2015/16. We further find that intense precipitation in this area occurs at roughly equal probability under El Nino, La Nina and neutral conditions. Although the spectral properties of the late Holocene clastic layers in Lake Pallcacocha fall into the typical ENSO frequency band, we do not find evidence in the recent sediments and the meteorological data that would support a diagnostic link between alluvial activity in Lake Pallcacocha and strong El Nino events. Our data do not support the idea that the (late) Holocene flood record of Lake Pallcacocha is a conclusive paleo-El Nino record

ABSTRACT This study aims to investigate the hydrothermal co-liquefaction of rice straw (RS) and waste cooking-oil model compound (WCOM) under sub-critical conditions for the optimum bio-crude yield and conversion. Effects of temperature, catalyst (K2CO3), residence time and mass ratios of RS to WCOM on products’ distribution were examined and the reaction mechanism for co-liquefaction of RS and WCOM was also explored. The highest bio-crude yield (88.77%) was obtained when mass ratio of RS to WCOM was 1:3 at 300 ℃, 10 min and in absence of K2CO3. When the mass ratio was 3:1, 1:1 and 1:3, the synergistic effect approached 14.38%, 11.38% and 12.84%, respectively. WCOM could improve the overall conversion rate of RS during co-liquefaction. GC-MS analysis suggested that the bio-crude contained large amounts of fatty acids and smaller amounts of phenols and ketone aldehydes. Co-liquefaction was found effective to improve the qualitative and quantitate features of products from biomass.