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91.
This study was performed to investigate and scale-up the hot-melt coating process in fluidized beds. A series of well-designed experiments was carried out in a pilot scale unit with 20 kg product capacity to investigate the effects of process variables on the efficiency of the coating of Cefuroxime Axetil with stearic acid. Results showed that the efficiency is at the highest when the fluidization air flow rate is adjusted by considering the changes in the amount of materials present in the unit as well as the changes in the terminal velocities of particles during the process.With the objective to scale-up the hot-melt coating process from pilot to production scale, a dynamic thermodynamic model based on conservation equations of mass and energy was developed. Predictive accuracy of the model was assessed by applying it to the pilot scale unit and comparing its predictions with the online measurements taken on the same unit. Results showed that the predictions of the model agree well with the measurements. Utilizing this model and taking several experiments performed in the pilot scale unit as a basis, scaling up of the hot-melt coating process was carried out. Comparisons of the model predictions with the measurements taken on the production scale unit (200 kg product capacity) revealed that the model is able to reproduce the product attributes and the outlet air temperatures across scales. Therefore, it proves to be a promising tool that can be used in the scale-up of the hot-melt coating processes in fluidized beds. 相似文献
92.
Omer Said Toker Mahmut Dogan Erdal Canıyılmaz Nevruz Berna Ersöz Yahya Kaya 《Food and Bioprocess Technology》2013,6(4):896-908
In this study, the steady and dynamic rheological properties of the dairy dessert samples (puddings) containing carrageenan, alginate, guar and xanthan gums and their combinations were investigated in a model system, and mixture design was utilized to observe the effects of the gums and their interactions. The flow behaviour of the pudding samples fitted to the Ostwald de Waele model (R 2?>?0.98). All the samples exhibited a gel structure with their higher G′ (storage modulus) values than the G″ (loss modulus) values. Carrageenan was the most effective hydrocolloid on both the steady and dynamic rheological parameters of the dairy dessert samples. On the other hand, alginate had relatively smaller effect. Furthermore, 30 pudding samples containing different gum or gum combinations were classified into two groups (A and B) by using principal component analysis (PCA). Samples containing more than 33% carrageenan in their formulations made up the group A which positively correlated to K (consistency index), η 50 (apparent viscosity at shear rate 50 s?1), G′, G″, G* (complex modulus) and η* (complex viscosity) values. 相似文献
93.
Mahmut Dogan Tuğba Aktar Omer Said Toker Nevruz Berna Tatlisu 《International Journal of Food Properties》2013,16(8):1677-1692
Physicochemical (pH, brix, and color), sensory (color, taste, odor, mouthfeeling, consistency, bitter flavor, and general acceptability), and rheological properties of the hot chocolate beverages including different cocoa combinations were investigated in the present study. Cocoa type significantly affected all of the properties. Simple additive weighting approach was applied to obtain one score from seven different sensory parameters and simple additive weighting score was used in mixture design to determine optimum cocoa type or cocoa combination. Ostwald de Waele model described the flow behavior of the hot chocolate beverage samples with R2 values ranged between 0.818 and 0.999. The consistency coefficient (K) and apparent viscosity at shear rate 50 s?1 (η50) were significantly affected by cocoa type found in the formulation of the beverage. The mixture design approach was performed in order to determine variation of the responses (physicochemical, sensory, and rheological parameters) as a function of cocoa concentration. Simple additive weighting scores were satisfactorily described by established equation as a function of cocoa concentration to be used in the formulation of the hot chocolate beverage (R2 = 0.8645). 相似文献
94.
Ji Zou Shui‐Gen Huang Kim Vanmeensel Guo‐Jun Zhang Jef Vleugels Omer Van der Biest 《Journal of the American Ceramic Society》2013,96(4):1055-1059
A carbide boronizing method was first developed to produce dense boron carbide‐ zirconium diboride (“B4C”–ZrB2) composites from zirconium carbide (ZrC) and amorphous boron powders (B) by Spark Plasma Sintering at 1800°C–2000°C. The stoichiometry of “B4C” could be tailored by changing initial boron content, which also has an influence on the processing. The self‐propagating high‐temperature synthesis could be ignited by 1 mol ZrC and 6 mol B at around 1240°C, whereas it was suppressed at a level of 10 mol B. B8C–ZrB2 ceramics sintered at 1800°C with 1 mole ZrC and 10 mole B exhibited super high hardness (40.36 GPa at 2.94 N and 33.4 GPa at 9.8 N). The primary reason for the unusual high hardness of B8C–ZrB2 ceramics was considered to be the formation of nano‐sized ZrB2 grains. 相似文献
95.
96.
The paper presents the results of an experimental investigation of a novel steam jet refrigerator suitable for solar energy applications. The primary flow of the ejector is controlled using a spindle in order to provide fine tuning and for ejector operation as well as optimum coefficient of performance. The influence of the spindle position, and the boiler temperature, as well as that of evaporating temperature which denotes the cooling load temperature, on the performance of the ejector is assessed. 相似文献
97.
98.
In present study the exergy and economical analysis of a cogeneration plant system in Turkey (Esenyurt Thermic Power Plant) was performed based on the measured data during the operation time of the system. First and second laws of thermodynamics are adapted to the measured data. Furthermore, fuel-utilization efficiency, rate of power heat and rate of process heat are determined. The system is considered as a steady-state open thermodynamic system. 相似文献
99.
Abdeen Mustafa Omer 《Renewable Energy》2001,24(2)
The Republic of Sudan in Eastern Africa has one of the fastest growing economies in Africa. However, its remotely isolated rural areas pose problems to rural energy management and development because of poor road links with the urban centres, and remoteness from the national electrical transmission grid. Development of renewable energy sources, therefore, has a vast potential in Sudan. Solar energy, with excellent sunshine of over 3000 h per year, is of paramount importance, the applications of which are already quite siginficant and are growing at steady rate. Solar energy is suitable for small-scale water pumping in remote areas where the demand is regular, such as for drinking water, but it may also be used for irrigation. Most areas in Sudan have climates suitable for solar pumping. A review is given of the use of solar energy for water pumping to improve the living conditions of the population in rural areas and to develop techniques for utilization of solar energy in a tropical environment condition. Results, suggests that, solar powered water pumping must be encouraged, promoted, invested, implemented, and demonstrated by full scale in Sudan. 相似文献
100.
A novel thermoelectric refrigeration system employing heat pipes and a phase change material: an experimental investigation 总被引:2,自引:0,他引:2
This paper presents results of tests carried out to investigate the potential application of heat pipes and phase change materials for thermoelectric refrigeration. The work involved the design and construction of a thermoelectric refrigeration prototype. The performance of the thermoelectric refrigeration system was investigated for two different configurations. The first configuration employed a conventional heat sink system (bonded fin heat sink) on the cold side of the thermoelectric cells. The other configuration used an encapsulated phase change material in place of the conventional heat sink unit. Both configurations used heat pipe embedded fins as the heat sink on the hot side. Replacement of the conventional heat sink system with an encapsulated phase change material was found to improve the performance of the thermoelectric refrigeration system. In addition, it provided a storage capability that would be particularly useful for handling peak loads and overcoming losses during door openings and power-off periods. Results showed that the heat sink units employing heat pipe embedded fins were well suited to this application. Results also showed the importance of using a heat pipe system between the cold junction of the thermoelectric cells and the cold heat sink in order to prevent reverse heat flow in the event of power failure. 相似文献