نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشیار پژوهشکده باغبانی

2 دانشجوی کارشناسی ارشد بخش مهندسی ماشینهای کشاورزی

3 عضو هیئت علمی پژوهشکده باغبانی دانشگاه شهید باهنر کرمان

چکیده

در فرایند تهیه خوراک دام یا روغن از هسته خرما ابتدا آن را می­خیسانند تا هسته نرم شود و انرژی کمتری صرف آسیاب کردن آن گردد.  در این پژوهش به بررسی اثر دمای آب در چهار سطح 25، 35، 55، و 65 درجه سلسیوس در میزان جذب آب و قطر ذرات آسیاب شدة هسته خرما پرداخته شده است.  بررسی روند جذب آب توسط هسته خرما نشان می­دهد که با افزایش دمای آب، سرعت و میزان جذب آب و همچنین میزان رطوبت نهایی هسته خرما افزایش می­یابد.  حداکثر میزان جذب آب در دماهای ذکر شده به ترتیب 59، 62، 71، و 73 درصد بر پایه وزن خشک بود.  بررسی فرایند جذب آب توسط سه مدل تحلیلی، پیج و نمایی نشان داد که هر سه مدل به­خوبی در داده­های آزمایشگاهی برازش شده ولی مدل پیج با ضریب تبیین بیشتر (99/0=R2) بهتر داده­ها را توجیه کرد.  بررسی تأثیر دما و مدت آب دادن بر روی هسته­های خرما نشان داد که با افزایش دما و مدت خیساندن، اندازه ذرات آسیاب شده با نرخ بیشتری کاهش یافت.  مناسب­ترین دمای آب 35 درجه سلسیوس بود که با خیساندن هسته­ها در این دما به مدت 72 ساعت و آسیاب کردن آنها به مدت 30 ثانیه، قطر متوسط ذرات به کمتر از 2/1 میلی­متر کاهش یافت در حالی­که این کاهش اندازه برای دمای 25 درجه سلسیوس پس از گذشت حدود 175 ساعت به­دست آمد.  مدل لگاریتمی ارائه شده برای بیان قطر ذرات آسیاب شده به صورت تابعی از زمان خیساندن به خوبی با داده­های آزمایشگاهی مطابقت کرد (98/0>R2).

کلیدواژه‌ها

عنوان مقاله [English]

Investigating and Modeling Water Absorption at Different Temperatures and its Effect on Grinding Date Pits

چکیده [English]

Part of the process of feed preparation or oil extraction for date pits is to soak the pits in water. Soaking softens the pits and reduces the required milling energy. In this research, the effects of water temperature at 25°, 35°, 55° and 65°C on water absorption and grinding of the date pits was investigated. The water absorption curves indicated that the rate of absorption and the final moisture content of the pits increased as the water temperature increased. The final moisture content of the pits for these temperatures were 59%, 62%, 71% and 73% w.b., respectively. Modeling water absorption using analytical, Page and exponential models indicated that the three models showed good fit with the experimental data (R2>0.95). The best results were obtained using the Page model with R2 = 0.99. The results of grinding the pits indicted that the average diameter of the ground particles decreased as soaking time and temperature of the water increased. A logarithmic model was defined to express the diameter of the particles as a function of grinding time. The presented model fit well with the experimental data (R2>0.98).

کلیدواژه‌ها [English]

  • Date pit
  • Grinding
  • modeling
  • water absorption
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