CATALYTIC CRACKING OF QAIYARAH ASPHALTENES USING 5áMOLECULAR SIEVES

Qaiyarah crude oil is one of the heaviest crude oils in the middle east and contains a large proportion of asphattenes (15-17% wt.). Catalytic cracking of hexane-asphaltenes was performed employing 5A molecular sieves. Fractionation of the cracking products was conducted using solvent extraction and column chromatography. 6A molecular sieves in the zeolite form showed a superior cracking behavior, and do not reveal any poisoning by sulphur. Pmr results may indicate production of liquid hydrocarbons from asphaltenes.     

Performance of Evaporative Condensers

Experimental investigation is conducted to study the performance of evaporative condensers/coolers. The analysis includes development of correlations for the external heat transfer coefficient and the system efficiency. The evaporative condenser includes two finned-tube heat exchangers. The system is designed to allow for operation of a single condenser, two condensers in parallel, and two condensers in series. The analysis is performed as a function of the water-to-air mass flow rate ratio (L/G) and the steam temperature. Also, comparison is made between the performance of the evaporative condenser and same device as an air-cooled condenser. Analysis of the collected data shows that the system efficiency increases at lower L/G ratios and higher steam temperatures. The system efficiency for various configurations for the evaporative condenser varies between 97% and 99%. Lower efficiencies are obtained for the air-cooled condenser, with values between 88% and 92%. The highest efficiency is found for the two condensers in series, followed by two condensers in parallel and then the single condenser. The parallel condenser configuration can handle a larger amount of inlet steam and can provide the required system efficiency and degree of subcooling. The correlation for the system efficiency gives a simple tool for preliminary system design. The correlation developed for the external heat transfer coefficient is found to be consistent with the available literature data.     

Multifunctional imaging probe based on gadofulleride nanoplatform

A FAR over-expressed tumor targeting multifunctional imaging probe has been fabricated based on gadofulleride nanoplatform. The combination of highly efficient MRI contrast enhancement and sensitive fluorescence imaging along with the preferential uptake toward FAR tumor cells suggest that the obtained multifunctional imaging probe possesses complementary capabilities for anatomical resolution and detection sensitivity.     

Bio-hydrogen production from thin stillage using conventional and acclimatized anaerobic digester sludge

To assess the viability of biohydrogen production from thin stillage, a comparative evaluation of anaerobic digester sludge (ADS) and acclimatized anaerobic digester sludge (AADS) for biohydrogen production over a wide range of S⁰/X⁰ ratio (0.5-8 gCOD/gVSS) was performed. A maximum hydrogen yield of 19.5 L H₂/L thin stillage was achieved for the AADS while tests with ADS achieved a maximum yield of only 7.5 L H₂/L thin stillage. The optimum range of S⁰/X⁰ ratio for hydrogen production was found to be 1 to 2 gCOD/gVSS using conventional ADS and 3 to 6 gCOD/gVSS using AADS. The biomass specific hydrogen production rate for the AADS was 3.5 times higher than rate for the ADS throughout the range of S⁰/X⁰ ratio examined in this study. The DGGE profiles of the 16S rDNA gene fragments confirmed the superior performance of the AADS over the ADS, showing that the widely known hydrogen producers Clostridium acetobutyricum, Klebsiella pneumonia, Clostridium butyricum and Clostridium pasteurianum were the predominant species.     

Steady-state and dynamic modeling of biohydrogen production in an integrated biohydrogen reactor clarifier system

Steady-state operational data from the integrated biohydrogen reactor clarifier system (IBRCS) during anaerobic treatment of glucose-based synthetic wastewater at HRT of 8 h and SRT ranging from 26 to 50 h and organic loading rates of 6.5–206 gCOD/L-d were used to calibrate and verify a process model of the system developed using BioWin. The model accurately predicted biomass concentrations in both the bioreactor and the clarifier supernatant with average percentage errors (APEs) of 4.6% and 10%, respectively. Hydrogen production rates and hydrogen yields predicted by the model were in close agreement with the observed experimental results as reflected by an APE of less than 4%, while the hydrogen content was well correlated with an APE of 10%. The successful modeling culminated in the accurate prediction of soluble metabolites, i.e. volatile fatty acids in the reactor with an APE of 14%. The calibrated model confirmed the advantages of decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) in biohydrogen production, with the average hydrogen yield decreasing from 3.0 mol H₂/mol glucose to 0.8 mol H₂/mol glucose upon elimination of the clarifier. Dynamic modeling showed that the system responds favorably to short-term hydraulic and organic surges, recovering back to the original condition. Furthermore, the dynamic simulation revealed that with a prolonged startup periods of 10 and 30 days, the IBRCS can be operated at an HRT of 4 h and OLR as high as 206 gCOD/L-d without inhibition and/or marked performance deterioration.     

Sequential supercritical water gasification and partial oxidation of hog manure

The catalytic hydrogen production from hog manure using supercritical water gasification and partial oxidation was investigated in a batch reactor at a temperature of 500 °C, and pressure of 28 MPa using several metallic catalysts. Hog manure was characterized by a total and soluble chemical oxygen demand (TCOD, SCOD) of 57,000 and 28,000 mg/L, total and volatile suspended solids (TSS, VSS) of 25,000, 19,000, and ammonia of 2400 mg/L, respectively. The order of H₂ production was the following: Pd/AC > Ru/Al₂O₃ > Ru/AC > AC > NaOH, and the order of COD reduction efficiency was as follows: NaOH > Ru/AC > AC > Ru/Al₂O₃ > Pd/AC. The behavior of the volatile fatty acids (VFAs), ethanol, methanol, ammonia, H₂S, and sulfate was investigated experimentally and discussed. A 35% reduction in the H₂ and CH₄ yields was observed in the sequential gasification partial oxidation (oxidant at an 80% of theoretical requirement) experiments compared to the gasification experiments (catalyst only). Moreover, this reduction in gas yields was coincided with a 45% reduction in the liquid effluent chemical oxygen demand (COD), 60% reduction of the ammonia concentration in the liquid effluent, and 20% reduction in the H₂S concentration in the effluent gas.     

Energy Management in Car Underhood Compartment—Temperature and Heat Flux Analysis of Car Inclination Effects

It has been shown by the authors that car inclination influences the temperatures of different underhood components. Here these effects are analyzed by heat-flux measurements. The results of underhood temperature and heat-flux measurements carried out on a passenger vehicle in wind-tunnel S4 of Saint-Cyr l’Ecole are presented. The underhood compartment of the vehicle is instrumented with 40 surface and air thermocouples and 20 flux meters of normal gradient. Experiments are performed with a specific technique for separate measurement of convective and radiative heat fluxes. Three car position configurations are tested: flat, uphill, and downhill positions. Measurements are made for three different thermal functioning modes. Fluxmetric analysis based on overall heat flux as well as on separate convective and radiative heat fluxes is reported here in order to establish the effects and variation tendencies of car inclination on the temperature–heat flux pair. For most of the tested positions in the underhood top region, the car inclination improves convective heat transfer and penalizes radiative heat transfer. The reduction in radiative heat transfer dominates the convective heat-transfer improvement, resulting in augmentation of the overall heat flux as well as the temperature.     

Water–zeolite adsorption heat pump combined with single effect evaporation desalination process

The single effect evaporation desalination process combined with adsorption heat pump (ADVC) is modeled analyzed as a function of the system design and operating parameters. The analysis gives variations in the thermal performance ratio, the specific heat transfer area, and the specific flow rate of cooling water. The performance evaluation is made as a function of the brine boiling temperature, the difference in the temperature of the compressed vapor and the boiling brine, and the water content in the adsorption bed. Results show that the thermal performance ratio of this configuration is the highest among all single effect evaporation desalination systems. Moreover, the specific flow rate of the cooling water and the specific heat transfer area are similar to those of other single effect configurations. It should be stressed these promising features makes the ADVC system highly attractive to small and remote communities and of special interest in situations where energy cost is high.     

The effect of endoscopic sinus surgery on mucociliary clearance in patients with chronic sinusitis

In a prospective study 20 patients suffering from recurrent, therapy-refractory menorrhagias were pre-treated for endometrial ablation after exclusion of intrauterine abnormalities and histological pathology. Two injections of GnRH-analogues (3.75 mg leuprorelinacetate depot, Enantone Gyn, Takeda Pharma GmbH Aachen, Germany). Two weeks after the last injection a hysteroscopic surgery by roller-ball-techniques was performed in 10 patients and a balloon-thermocoagulation by Cavaterm-technique (Wallsten Medical, Morges, Schweiz) was performed in 10 patients. Both patients groups were comparable according to age and anamnesis. In a follow-up of 9 to 15 months we found about identical results. All 20 patients were satisfied with the treatment. The Cavaterm-coagulation is in comparison to the operative hysteroscopy a simple method for endometrial coagulation, and can also be used by an hysteroscopically inexperienced gynaecologists with simple technical equipment. In strict indication the Cavaterm-coagulation is a simple method of endometrial ablation in many patients.