مدلسازی فرآیند اتمیزاسیون التراسونیک شیر و تولید پودر شیر به روش خشک کردن پاششی

استفاده از سیستم های التراسونیک در بسیاری از مسائل کاربردی اثبات شده است. از جمله آنها اتمیزاسیون التراسونیک بوده که در صنایع مختلف از جمله صنایع غذایی و پوشش‌دهی کاربرد فراوانی دارد. در پژوهش پیش رو، ابتدا به مرور کارهای انجام شده در این زمینه پرداخته شده و پس از آن با استفاده از روابط ارائه شده برای اتمیزاسیون سیالات مختلف در مقالات بررسی شده، به بررسی تاثیر ارتعاشات التراسونیک بر اتمیزاسیون و تبخیر شیر به عنوان یک ماده غذایی پرداخته و فرآیند خشک شدن آن به روش خشک کن پاششی پیش بینی گردید. سپس به بررسی اثر پارامترهای مختلف نوسان از جمله فرکانس، دامنه و همچنین دمای سیال بر نرخ اتمیزه شدن سیال پرداخته شد. نتایج مدلسازی نشان داد که با افزایش دامنه ارتعاشات، زمان لازم برای خشک شدن قطرات تبخیر شده به روش التراسونیک کاهش یافته و همچنین قطر پودر تولید شده، قطر ذرات تبخیر شده و نرخ تبخیر به روش التراسونیک افزایش یافت. بطوری‌که 4 برابر شدن دامنه ارتعاشات باعث کاهش 14.4 درصدی زمان لازم برای خشک شدن قطرات و افزایش 62.6 درصدی نرخ تبخیر شد. همچنین با مدلسازی فرآیند مشخص شد که با افزایش فرکانس ارتعاشات، زمان لازم برای خشک شدن قطرات تبخیر شده به روش التراسونیک افزایش یافت. بطوری‌که در یک دمای ثابت گاز خشک کن و دمای ثابت شیر تغییر فرکانس از 10 به 40 کیلو هرتز منجر به افزایش 21.4 درصدی زمان لازم برای خشک شدن قطرات شد. همچنین با افزایش دمای شیر از 15 تا 30 درجه سانتی گراد، در یک فرکانس و دامنه ارتعاشات ثابت، زمان لازم برای خشک شدن قطرات تبخیر شده 12.4 درصد کاهش و قطر ذرات تولید شده .11.3 درصد افزایش داشت.

modeling the ultrasonic atomization process of milk and powder production using spray drying method

introduction the beneficial use of ultrasonic systems has been proven in many applications. among them, ultrasonic atomization is widely used in various industries, including food and coating industries. ultrasonic vibrations of liquids can produce fine droplets called atomized fluid. during the fluid atomization process, droplet size and distribution can be precisely controlled so that the droplets become very small and high-level particle distribution is achieved which can be easily evaporated. this method is widely used in various industries, including food industry (for the production of driedpowder products) and coating industry. the key factor that affects droplet size is the frequency and amplitude of the ultrasonic vibrations and the properties of the fluid, including the fluid viscosity and surface tension. materials and methods based on a review of literature, it is clear that the modeling of the ultrasonic method for spray dryers and the production of milk powder has not been done so far. in the present work, first, the research background is reviewed and then, using the relationships provided for the ultrasonic atomization of different fluids in the reviewed articles, the effect of ultrasonic vibrations on the atomization and evaporation of milk as a food and the powder production was studied using spray drying process. then the effects of various oscillation parameters such as frequency, amplitude and also the temperature of the fluid, which affects its viscosity, density and surface tension, on the rate of atomization of the fluid was investigated. in the present work, we first examine the fluid whose range of properties is true in relations. one of the most widely used liquids in the food industry is milk. by examining the viscosity, surface tension and density of the milk and obtaining the dimensionless numbers we, in and oh, it is determined that the provided relations can also be used for milk. after calculating the diameter of the evaporated particles of milk due to ultrasonic vibrations as well as the evaporation rate, the independent variables of the research can be changed. first, in the constant physical properties of a fluid, we change the frequency and amplitude of ultrasonic oscillations and studied their effect on the produced particle diameter and evaporation rate. in the next step, with the constant frequency and amplitude of ultrasonic oscillations, the effect of changes in fluid properties (temperature change) on the produced particle diameter and evaporation rate was investigated. in the next stepthe effect of frequency and amplitude of ultrasonic fluctuations as well as changes in fluid properties (temperature change) on the powder diameter produced and the time required for the drying process was investigated. the analysis of all data obtained from the above steps was performed using mathlab software.results and discussionthe main and summary results obtained from the present study are as follows:as the amplitude of the vibrations and the temperature of the milk increased, the drying time required for the evaporation of droplets decreased, but the powder diameter and the evaporation rate increased.as the frequency of vibrations increased, the drying time required for the evaporation of droplets increased, but the powder diameter and the evaporation rate decreased. the results showed that quadrupling the amplitude of the vibrations reduces the time required for the droplets to dry by 14.4% and increases the evaporation rate by 62.6%. at a constant temperature of the gas dryer and the milk, changing the frequency from 10 to 40 khz results in 21.4% increase in the time required for the droplets to dry. also, with increasing the temperature of the milk from 15 to 30°c, at a constant frequency and amplitude of vibrations, the time required for drying the droplets decreases by 12.4% and the diameter of the particles produced increases by 11.3%.