Economical analysis of combined fuel cell generators and absorption chillers

AbstractThis paper presents a co-generation system based on combined heat and power for commercial units. For installation of a co-generation system, certain estimates for this site should be performed through making assessments of electrical loads, domestic water, and thermal demand. This includes domestic hot water, selection of the type of power generator, fuel cell, and the type of air conditioning system, and absorption chillers. As a matter of fact, the co-generation system has demonstrated good results for both major aspects, economic and environmental. From the environmental point of view, this can be considered as an ideal solution for problems concerned with the usage of Chlorofluoro carbons. On the other hand, from the economic point of view, the cost analysis has revealed that the proposed system saves 4% of total cost through using the co-generation system

Computer based selection and performance analysis of marine diesel engine

AbstractThe major steps in two-stroke diesel technology have been surprisingly few over the past century, now we have another major step – electronically controlled marine diesel engines. This paper will discuss how the use of computer helps to select diesel engines, compare between different types, increase the performance of the conventional diesel engines and generate the different performance curves for such engines

Flame speed and particle image velocimetry measurements of laminar burning velocities and Markstein numbers of some hydrocarbons

Particle image velocimetry, PIV, is described for measuring laminar burning velocities during flame propagation in spherical explosions, by the measurement of the flame speed and gas velocity just ahead of the flame. Measurements made in this way are compared with those obtained from the flame speed method, which is based on the flame front propagation speed and the ratio of unburned to burned gas densities. Different values arise between the two methods, and the principal reason is the common assumption in the flame speed method that the burned gas density is at the equilibrium, burned gas, adiabatic temperature. When allowance is made for the effects of flame stretch rate and Lewis number on this density, the differences in burning velocities are significantly decreased. The PIV methodology enables mass rate of burning velocities to be expressed in terms of the burning velocity at zero stretch rate and the Markstein numbers for strain rate and flame curvature. Burning velocities and Markstein numbers are presented for methane, i-octane, ethanol, and n-butanol over a range of equivalence ratios at atmospheric pressure and, in the case of n-butanol, also over a range of pressures. Account is taken of the low stretch rate at which a laminar flame becomes unstable, and, below which, the burn rate increases due to the enhanced flame surface area. The critical stretch rates for the transition are identified. In measuring Markstein numbers, there is a dependency upon the isotherm employed for the measurement of the stretch rate. This aspect is studied by comparing measurements with two different isotherms. It is concluded that the measured PIV flame measurements might under-estimate the Markstein numbers by about 12%

Measurement of turbulence characteristics in a large scale fan-stirred spherical vessel

Particle Image Velocimetry, PIV, is employed to characterise the near-homogeneous, isotropic, turbulence generated inside a large spherical vessel by four rotating fans. Spatial and temporal distributions of mean and root mean square, rms, velocity fluctuations are investigated, as well as integral length scales, L, Taylor microscales, λ, and Kolmogorov length scales, η, in the fan speed range, 1000–6000 rpm. Mean velocities are about 10% of the turbulence velocity, u' and turbulence is close to homogeneous and isotropic in the central volume. This volume decreases with increasing fan speed, and its radius and other characteristics are expressed in terms of the fan speed. At each speed, the mean gas velocity scarcely varies with time. Relationships are presented for the variations of u' and L with fan speed, temperature and pressure. A new relationship between the autocorrelation function and integral length scale is obtained, for when Taylor's hypothesis is invalid

PROTECTIVE AND CURATIVE EFFECTS OF FRESH ORANGE JUICE (CITRUS SINENSIS L.) SUPPLEMENTATION AGAINST LIVER INJURIES, HEPATIC LIPID, PROTEIN, AND DNAOXIDATIVE DAMAGE INDUCED CYCLOOXYGENASE-2/PROSTAGLANDIN E2 INFLAMMATORY PATHWAY IN FEMALE IRRADIATED RATS

Objective: Our study aimed to examine the protective and curative ability of fresh orange juice (OJ) (Citrus sinensis L.) to counteract the adverse side effects of ionizing radiation (IR) on hepatic tissues of female irradiated rats and that has not been studied in advance. Methods: Forty-nine adult female Sprague-Dawley albino rats (170±5 g) were divided into four sets of 12 animals, except the healthy control group contained 10 rats only and the irradiated control group contained 15 rats and was divided as follow Group I: Healthy control; Group II: Irradiated control, rats receiving a single dose (20 gray absorbed dose [Gy]) of whole-body γ-rays; Group III: Protective group, rats received (5 ml OJ/kg body weight) once daily for 14 days and after 24 h exposed to irradiation; and Group IV: Curative group, then rats were submitted to irradiation than after 24 h, treated with (5 ml OJ/kg body weight) once every day for 14 successive days. Results: Our results explored that fresh OJ contains significant amounts of antioxidants as flavonoids and polyphenols and consequently pre- or post-fresh OJ supplementation to female irradiated rats attenuated significantly (p≤0.05) hepatic lipid, protein, and DNA-oxidative damage, hepatic inflammation, and activated inflammatory cyclooxygenase-2/prostaglandin E2 pathway, liver fibrosis, impaired liver functions, and hepatic lipid metabolism when compared with irradiated control rats. Furthermore, fresh OJ improved significantly (p≤0.05) the hepatic antioxidant capacity in protective and curative groups in comparison with the irradiated control group. Conclusion: The current research illustrated that fresh OJ may improve and normalize the various hepatic biochemical abnormalities resulted from irradiation due to its high content of active constituents of flavonoids and polyphenols. It is advised for people who exposed to IR, especially females, to consume about (5 ml OJ/kg body weight) before exposure as the most significant improvements were recorded in the protective group that supplemented with OJ before irradiation

Aḥanṣal

Le nom d’Aḥanṣal s’attache à un influent lignage d’arbitres tribaux à prétention chérifienne, implanté sur le versant nord de l’Atlas, entre le Jbel Azourki et le Jbel Izlaguen. Il marque la région avec la présence de la tribu « laïcisée » des Iḥanṣalen, une rivère – l’asif Aḥanṣal – qui offre une vallée d’accès à la plaine atlantique par Bin el-Ouidan, et diverses zaouïat – ces complexes socio-religieux, siège arbitral et parfois, mais pas toujours, loge de confrérie. Le lignage saint des Iḥ..

Teas: Direct test on quality and antioxidant activity using electron paramagnetic resonance spectroscopy

Abstract. The manufactured teas may conveniently be divided into three classes: Green teas, Oolongs (delicate black teas), and Black Teas. Several indirect methods are employed to measure the antioxidant activity of tea extracts that is basically takes place by monitoring the inhibition of oxidation of a suitable substrate using the extracts of antioxidant materials from the studies systems. This study is concerned with the results of electron paramagnetic resonance (EPR) spectroscopy that is utilized to investigate several categories of green and black teas: Twining Green Tea (TGT) of London, Rabea Green Tea (RGT) of Saudia, Chinese Green Tea (CGT) of China, English Breakfast Tea (EBT) of Ahmed Tea-London, and Rabea Black Tea (RBT) of Saudia. Three EPR signals from all the studied samples are observed. The assignment of these signals will discussed and correlated with the quality of leaves. Mainly, two paramagnetic species are considered to be responsible for the observed EPR signals; manganese(II)-protein system of the leaves and a stable free radical of aromatic origin. The study will provide facts on the dependency of radical signal on the oxidative degradation procedures of the studied samples. The intensity and feature of Mn(II)-EPR-signal is found to be related to the disintegration of tea leaves

Behaviour of 4-(4-acetoaminophenyl)-4-oxobut-2-enoic acid towards carbon and nitrogen nucleophiles and use of these products in the synthesis of some interesting heterocycles

The present work is devoted to study the interaction of-aroylacrylic acid derivative (1) with some containing active methylene compounds under Michael reaction conditions and afforded the Michael adducts (2a-e). When compound 1 was allowed to react with cyclohexanone in the presence of ammonium acetate as catalyst, it afforded hydroquinoline derivative (3). Interaction of the acid 1 with highly and moderately reactive hydrocarbons e.g. p-xylene and acetanilide in the presence of anhydrous aluminumchloride under Friedel-Crafts reaction conditions afforded (4a-b). On the other hand, when the acid 1 was allowed to react with benzyl amine in dry benzene yielded 2-benzylamino-4-(4-acetaminophenyl)-4-oxobutanoic acid (5). This later compound was used to synthesize some heterocyclic compounds (7-11). Also, aza Michael adduct (6) used asthe key starting material for the synthesis of some interesting heterocyclic compounds e.g. pyridazinone, oxazinoneand furanone derivatives (13-16)

Evaluation of the results of arthroscopic repair of rotator cuff tears

Rotatorenmanschettenruprturen gehören zu den häufigsten Beschwerdebildern der Schulter. Seit kurzem werden nun arthroskopische Rekonstruktionsmethoden angewandt, die viel versprechende Ergebnisse zeigen. Ziel dieser Studie war die Ergebnisse der arthroskopischen Rotatorenmanschettenrekonstruktion zu bewerten und ihre Einflußfaktoren zu ermitteln. Die Studiengruppe besteht aus 40 Patienten( 19m, 21f) zwischen 37-78Jr. ( Median 61,15 Jr.). Spezielle Ein- und Ausschlusskriterien wurden angewandt. Die Symptome bestanden im Median seit 0,83Jr. ( 0,25-5Jr.). Arthoskopische Rotatorenmanschettenrekonstruktion wurde mittels Knochenankertechnik in Kombination mit einer subacromialen Dekompression durchgeführt. Arthroskopische Rekonstruktionen haben somit ein gutes Ergebnis und ermöglichen die Rekonstruktion der Rotatorenmanschette ähnlich der offenen Operationstechniken mit Vermeidung deren Komplikationen