Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

液压系统常见的故障诊断及处理

任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法，这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。     

Economie d'énergie en trigénération

Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.     

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia,northwest Greece)

The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.     

Innovative methodologies in renewable energy: A review

This paper is concerned with innovative approaches to renewable energy sources computation methodologies, which provide more refined results than the classical alternatives. Such refinements provide additional improvements especially for replacement of fossil energy usages that emit greenhouse gas (GHG) into the atmosphere leading to climate change impact. Current knowledge gap among each renewable energy source calculation is rather missing fundamentals of plausible, rational, and logical explanations for the interpretation of results. In the literature, there are rather complicated and mechanically applicable methodologies, which require input and output measurement data match with missing physical explanations. The view taken in this review paper is to concentrate on quite plausible, logical, rational, and effectively applicable innovative energy calculation methodologies with simplistic fundamentals. For this purpose, a set of renewable energy methodological approaches is revisited with their innovative structures concerning solar, wind, hydro, current, and geothermal energy resources. With the increase in the renewable energy utilizations to combat the undesirable impacts of global warming and climate change, there is a need for better models that will include physical environmental conditions and data properties in the probabilistic, statistical, stochastic, logical, and rational senses leading to refined and more reliable estimations with application examples in the text. Finally, new research directions are also recommended for more refined innovative energy system calculations.     

Constrained Optimization of Heat Transfer from an Extended Surface

Two different zero‐order optimization techniques are used to maximize the rates of heat transfer from a fin assembly of a specified cost and in the shape of several annular fins that are mounted on a central stem. The problem is formulated to account for two‐dimensional steady‐state heat transfer that is limited by several inequality constraints. The dimensionless governing equations are used to identify the relevant decision variables. The number of fins making up the assembly is treated as an input parameter. A digital computer is used to determine the required temperature distributions and to implement the optimization search algorithms. Three different fin materials are assessed—aluminum, copper and carbon steel. Design optimizations of the extended surface assembly were made over a range of operating conditions, encompassing several different convection heat transfer coefficients that are representative of free and forced convection in air, and several different overall temperature differences between the substrate surface and air. A few recommendations based on trends in the predicted results are given. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 504–521, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21093     

CY6D78Ti型柴油机的开发研制

本文介绍了CY6D78Ti型柴油机的开发研制过程及现状,CY6D78Ti型柴油机能满足国内中、重型卡车和豪华客车市场对柴油机动力性、经济性、可靠性的需求。由于该机型的高档配置,保证了其排放达到欧Ⅱ标准,同时为进一步提高性能、降低排放,采用电控及高压共轨等技术手段搭建了平台。     

我国车用柴油机的技术现状及发展趋势

本文根据国内外信息和资料，分析了我国目前车用柴油机制造技术方面与国际水平所存在的差距，预测今后若千年内车用柴油机要向节能降耗、应用增压技术、提高可靠性、降低排放、采用电控技术方面发展，以尽快接近和赶上国际先进水平．     

Synthesis and electrochemical properties of Li1−xFe0.8Ni0.2O2–LixMnO2 (Mn/(Fe + Ni + Mn) = 0.8) material

A new type of Li_1−xFe_0.8Ni_0.2O₂–Li_xMnO₂ (Mn/(Fe + Ni + Mn) = 0.8) material was synthesized at 350 °C in air atmosphere using a solid-state reaction. The material had an XRD pattern that closely resembled that of the original Li_1−xFeO₂–Li_xMnO₂ (Mn/(Fe + Mn) = 0.8) with much reduced impurity peaks. The Li/Li_1−xFe_0.8Ni_0.2O₂–Li_xMnO₂ cell showed a high initial discharge capacity above 192 mAh g⁻¹, which was higher than that of the parent Li/Li_1−xFeO₂–Li_xMnO₂ (186 mAh g⁻¹). We expected that the increase of initial discharge capacity and the change of shape of discharge curve for the Li/Li_1−xFe_0.8Ni_0.2O₂–Li_xMnO₂ cell is the result from the redox reaction from Ni²⁺ to Ni³⁺ during charge/discharge process. This cell exhibited not only a typical voltage plateau in the 2.8 V region, but also an excellent cycle retention rate (96%) up to 45 cycles.     

Wood feedstock qualities for energy conversion and the potential for their biological improvement

The accomplishments of the Wood Feedstock Quality activity of Task V of the International Energy Agency's Bioenergy Agreement are described. Areas investigated included energy products and co-products from woody biomass; effects of harvesting, processing and storage on feedstock quality; the effect of feedstock quality on the efficiency of biomass conversion; the potential for biological improvement; the need for standardization of feedstock qualities; and the need for clonal characterization.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Deuterium storage of Ti40Zr40Ni20 icosahedral quasicrystal

Ti₄₀Zr₄₀Ni₂₀ icosashedral quasicrystal was observed to load hydrogen in a much lower capacity than similar Ti–Zr–Ni alloys. To verify the result, the alloy is further studied by using deuterium instead of hydrogen in this work. With a home-made gas–solid reaction system, XRD and XPS techniques, the investigation was conducted on deuterium absorption and desorption properties of Ti₄₀Zr₄₀Ni₂₀ alloy and its phase stability during the deuteration course. It is shown that the quasicrystal can load deuterium rapidly in an elevated volume of 11.5 mmol·D₂/g·M (D₂ denotes deuterium molecular and M the metal). After the full storage of deuterium, the quasicrystal phase remained, however the quasilattice expanded at a rate of 6.28%, revealing the occurrence of severe quasilattice stress. The solution of deuterium in the alloy caused the increase of binding energy of the metal elements, as much as 0.4 eV for Ti, 0.6 eV for Zr and 0.1 eV for Ni, which reflects the location of deuterium near Ti and Zr. The deuterium release was very slow at low temperature and could be complete at least above 610 °C. Based on the gained results, the quasilattice shrink would be more reasonable to explain the big difficulty of the desorption.     

Minerals and iron-making reactions in blast furnaces

Coke is central to blast furnace operation, but because it is the most expensive raw material used, there is continuing pressure to minimize its use. Consequently, it has become increasingly pertinent to measure and predict the factors affecting coke performance more accurately. Coke performance is affected both by its properties and blast furnace operation. Recently, the importance of the minerals in coke in determining its performance in the blast furnace has been recognized. Minerals in coke influence its reaction with gas, metal and slag phases. This paper reviews coke behavior in an operating blast furnace with the main emphasis being on the role of its inherent mineral matter. Various techniques including advanced approaches such as scanning electron microscopy (SEM) and quantitative X-ray diffraction (XRD) have been used to identify and quantify coke minerals. Fundamental studies based on bench-scale reactors have highlighted the role of various mineral phases on the kinetics of gasification, hot-metal carburization and slag reactions. Because coke reaction rates are influenced by the constituent mineral phases differently, conventional ash analysis is not sufficient to determine the true impact of coke minerals on coke reactivity. The dominant catalytic phases of coke minerals can be identified and related to coke gasification with CO₂ at low temperatures. The kinetics of hot-metal carburization by coke and its temperature dependence is influenced by the melting behavior of minerals. Coke–slag reaction rates are largely influenced by total mineral matter content as well as composition. Coke changes its properties during descent through an experimental blast furnace (EBF) and some of these changes are presented. The increase in the ordering of the carbon in the coke as it descends the EBF can be related to increases in coke ordering in a bench-scale reactor, indicating that order in a particular coke may serve as a thermometer of its maximum exposure temperature. Moreover, coke fines emissions are influenced by the extent of graphitization in industrial blast furnaces. In contrast, coke reactivity in an operating blast furnace is influenced by recirculating alkalis as well as inherent mineral matter. Mineral phases of industrial cokes were found to be changed after CO₂ gasification with increasing reaction temperatures. Coke quality needs in current and emerging blast furnace process innovations are discussed to highlight that existing tests are not sufficient. A comprehensive coke quality index is required, particularly one that incorporates the heterogeneity of coke minerals, in order to make a reliable assessment of the impact of cokes on iron-making reactions.     

Modeling HCCI combustion of biofuels: A review

The ever increasing energy demands coupled with the limited availability of fossil fuels and the detrimental environmental effects resulting from their use, has guided research toward seeking alternative fuels to gradually substitute conventional ones. Among these, biofuels have received increasing attention due to their attractive features of being renewable in nature and reducing the net CO₂ emissions. Biofuels have been used in conventional diesel and gasoline engines either as neat fuels or as supplements.Fortunately, a relatively new combustion concept for internal combustion engines, namely homogeneous charge compression ignition (HCCI) combustion, has been evolved in parallel to the biofuel research. HCCI combustion seems to be able to take advantage of the diverse properties of biofuels, since in this combustion mode ignition is not externally instigated, but relies on the compression and subsequent autoignition of a fuel-air mixture. This fact allows the utilization of different fuels or blends thereof, in order to regulate the ignition point and provide adequate operation under diverse operating conditions.This study provides an overview of existing simulation models for the simulation of biofueled HCCI combustion. Simulation models aid and supplement the experimental research conducted on HCCI combustion, providing a fundamental insight into the physicochemical parameters affecting performance and emissions formation. The simulation models include single-zone models, multi-zone models, probability based models, and multi-dimensional models in order of complexity. The vast majority of these models implement chemical kinetics to simulate the combustion process, not only due to the inherent dependence of HCCI combustion on the physicochemical properties of the fuel, but also due to the sometimes complex chemical structure of the biofuels, which include esters, ethers and alcohols. The reaction paths for these homologous series are quite different from the conventional hydrocarbons used to simulate conventional fuels, and provide the ground for current and future research work.     

Phase equilibrium measurements for the I2–H2O and I2–HI–H2O systems of the sulfur–iodine cycle using a continuous-flow apparatus

Liquid–liquid equilibrium (LLE) phase behavior was investigated for the binary iodine–water (I₂–H₂O) and the ternary iodine–hydroiodic acid–water (I₂–HI–H₂O) at the elevated temperatures and pressures of interest for the reactive distillation column of the Sulfur–Iodine Cycle. A continuous-flow apparatus, with wetted parts fabricated from tantalum-tungsten alloys, was designed and constructed for the highly corrosive conditions of this work. A central feature of the apparatus is the equilibrium view cell, which allows for the observation and discernment of vapor-liquid, liquid-liquid, and liquid–liquid–vapor equilibria for HIx systems.     

Simulation of a thermal battery using Phoenics

Thermal batteries are primary disposable systems specially designed to develop a high energy density in a short period. In the present work, the modeling of heat generation and propagation within three Ca/CaCrO₄ thermal batteries has been carried out, using a transient model. The commercial CFD software Phoenics^® has been used and, through a typical finite volume approach, the related 2D transport equations have been solved, giving the time-dependent temperature profiles. To check the quality of the model, the temperature of pseudo-equilibrium state (a typical thermodynamic parameter), has been analyzed. The temperatures related in the literature were close to those calculated. The results also indicate that the fusion of electrolytes is virtually an instantaneous process when compared to the time to reach the pseudo-equilibrium state, which indicates that the generation of electrical current occurs immediately after the thermite burning.     

Experimental study of the vapour–liquid equilibria of HI–I2–H2O ternary mixtures,Part 1: Experimental results around the atmospheric pressure

In the framework of the massive production of hydrogen using the sulfur–iodine thermochemical cycle, the design of the reactive distillation column, chosen by CEA for the HIx section, requires the knowledge of the partial pressures of the gaseous species (HI, I₂, H₂O) in thermodynamic equilibrium with the liquid phase of the HI–I₂–H₂O ternary mixture in a wide range of concentrations up to 270 °C and 50 bar. In the first of these two companion papers, we describe the experimental device which enables the measurement of the total pressure and concentrations of the vapour phase (and thus the knowledge of the partial pressures of the different gaseous species) for the HI–I₂–H₂O mixture in the 20–140 °C range and up to 2 bar. This device is used to carry out a large set of experiments investigating various mixtures with optical on-line diagnostics (FTIR for HI and H₂O, UV–visible for I₂). This leads to the determination of the concentrations in the vapour phase for many experimental conditions, results of which are given in this paper. The companion paper (part 2) describes the experimental device which enables measurements of the total pressure and species concentrations in the vapour phase in the process domain.     

Acid hydrolysis of bagasse for ethanol production

Acid hydrolysis of surplus cellulosic materials, such as bagasse, into fermentation sugars offers enormous opportunity world wide to add incremental value to farming operations and displace expensive, imported, polluting oil fuel products. Arkenol has developed and patented a strong acid hydrolysis process which can economically convert cellulose into ethanol for transportation fuel. Arkenol has begun development of three such sugar cane plantation projects and has a similar rice straw-to-ethanol project fully permitted and in financing.