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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Particle Science & Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Mathematical modelling,Shrinkage,Drying rate,Vibro-Fluidized Bed Dryer,Hawthorn Drying
- چکیده:
- چکیده انگلیسی: The drying kinetics of hawthorn in a pilot-scale experimental fluidized bed dryer with and without vibration was investigated. The effect of operating parameters, such as vibration intensity, drying air flow rate, and temperature, on the drying rate and shrinkage of hawthorn was studied. The hawthorn fruit was dried at various drying air temperatures ranging from 40-70oC and drying air volume flow rates ranging from 22-30 m3/h with the vibration intensity ranging from 6.8 to 8.2 Hz. The entire drying process occurred in the falling rate period and no constant rate period was observed in the drying of hawthorn. Four mathematical drying models investigating the drying behavior of hawthorn were evaluated and then the experimental moisture data were fitted in these models. The quality of the models fitting was assessed using the coefficient of determination, chi-square and root mean square error. The logarithmic and Page models for drying rate and the Ratti and Vazquez models for shrinkage were found to be the most suitable for describing the drying and shrinkage curves of hawthorn. The results showed that the vibration intensity, drying air temperature and flow rate has no significant effect on the shrinkage of hawthorn. All mentioned parameters had a significant effect on the drying rate of hawthorn, but the effect of drying air temperature was considerably more compared to the other parameters. It was observed that shrinkage varies linearly with respect to moisture content, and the reduction in radial dimension of hawthorn samples was around 40% at the end of the drying process.
- انتشار مقاله: 27-10-1395
- نویسندگان: Elham Farzan,Mahmood Reza Rahimi,Vahid Madadi
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Particle Science & Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Alumina nanoparticles,Nanofluid,Thermal efficiency,Exergy efficiency,Receiver
- چکیده:
- چکیده انگلیسی: An experimental and theoretical energy and exergy analysis was conducted for a cylindrical cavity receiver employed in a parabolic dish collector. Based on simultaneous energy and exergy analysis, the receiver average wall temperature and overall heat transfer coefficient were determined. A simplified Nusselt number for Heat Transfer Fluid (HTF) through the receiver as a function of Reynolds and Prandtl numbers was proposed. Based on correlated Nusselt number, the effects of two Nanofluids of alumina nanoparticles in water and ethylene glycol as base fluid on the performance of system were investigated. When Nanofluids are employed as HTF through the receiver, the energy and exergy efficiency are greater compare to pure water. The minimum enhancement in receiver thermal efficiency is 25% and enhancement greater than 60% is attainable. The results indicate that, by increasing only 5% volume in nanoparticle concentration in water, the receiver thermal efficiency is increased greater than 20%. The effect of nanoparticle volume fraction on exergy efficiency for small HTF mass flow rates is greater than larger mass flow rates. By selecting only 5% volume of alumina nanoparticle in water, for small HTF mass flow rates, enhancement in exergy efficiency greater than 10% is attainable.
- انتشار مقاله: 22-09-1393
- نویسندگان: Vahid Madadi Avargani,Amir Rahimi,Touraj Tavakoli Gheinani
- مشاهده