بررسي و بهينه يابي خشك كردن تمشك و انرژي مصرفي آن در روش خشك كردن تركيبي بسترسيال- مايكروويو با كمك روش سطح پاسخ

Evaluation and optimization drying raspberries and energy consumption in the combined Fluidized bed- Microwaves drying system via response surface methodology

در اين مطالعه، اثر پنج فاكتور شامل توان مايكروويو، دماي هوا، سرعت جريان هوا، زمان شروع مايكروويودهي و مقدار ماده بر روي زمان و انرژي لازم براي خشك كردن تمشك سياه تا محتواي رطوبت 50 درصد بر مبناي خشك در يك خشك‎كن تركيبي بستر سيال- مايكروويو مورد بررسي قرار گرفت. طرح آزمايشي شامل استفاده از روش آماري سطح پاسخ و طرح مركب مركزي بود. براي هر پاسخ از آناليز رگرسيون خطي-چندگانه استفاده گرديد و مدل‌هاي چند جمله‌اي درجه دوم به دست آمد. تجزيه و تحليل واريانس (ANOVA) براي بررسي كفايت و دقت برازش مدل انجام شد. با مدل تجربي بدست آمده ارتباط بين متغيرها و پاسخ‏هاي مورد مطالعه توسط روش سطح پاسخ تشخيص داده شد. ضرايب همبستگي مدل‌هاي رگرسيون براي زمان خشك كردن و انرژي مصرفي به ترتيب 964/0 و 970/0 بود. شرايط بهينه خشك كردن شامل: توان مايكروويو 600 وات، دماي هوا C°85 سرعت جريان هوا 15 متر بر ثانيه، زمان شروع مايكروويودهي از لحظه‎اي كه محتواي رطوبتي 344 درصد كاهش بافته و مقدار ماده 73 گرم تعيين گرديد كه تحت اين شرايط زمان و انرژي مصرفي به ترتيب 66/52 دقيقه و 2/65 كيلوژول توسط مدل پيش‏بيني شد. نتايج نشان داد كه زمان و انرژي مصرفي با افزايش دما، توان و مدت مايكروويودهي و كاهش سرعت جريان هوا كاهش مي‏يابد. در اين رابطه نمودار سينتيك خشك شدن نمونه‌ها تحت شرايط ذكر شده رسم گرديد كه نشان داد با افزايش دما از 55 بهC° 85 زمان خشك كردن 76% مي‎يابد و مايكروويو اين زمان را 30 تا 80% كاهش مي‎دهد

The present research surveyed the effect of five factors including: microwaves power, air temperatures and its flow rates, microwaving time onset and amount of substances on the requested time and energy for combined fluidized bed- microwaves drying of black raspberry into 50% dry base wet content. Response surface methodology and Central composite was used as experimental design. Multiple linear regression was used for obtaining second polynomials models for each analyses followed by ANOVA analysis in order to confirming the adequacy and accuracy of resulted models. Using the empirical resulted model the relationship between variables and responses were determined via response surface method. Correlation coefficients of the regression models were 0.964 and 0.970 respectively for the drying time and energy consumption. The Optimized drying condition were including; 600 watts for microwaves power and microwaving onset from that time as the moisture content was 344% decreased,73 g for amount of substances, and 85?C and 15 m.s-1 for air temperatures and its flow rates respectively. Under mentioned conditions, the fitted model was predicted 52.66 Min and 65.2 Kj respectively for the requested drying time and energy consumption at combined drier. As a conclusion, the results showed that requested drying time and energy consumption were decreased with increasing of temperatures, microwaving time and its power, and decreasing of air flow rates. In this regard, the drying kinetics curve samples were drawn under the conditions listed that showed drying time is reduced to 76% with increasing temperature from 55 to 85 and use the microwave reduced drying time until 30 to 80%.