بررسی خشک کردن پسته در یک خشک‌کن خورشیدی مجهز به سامانه‌ی بازیافت حرارتی هوا به هوا

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه شهید باهنر کرمان، دانشکده کشاورزی، بخش مکانیک بیوسیستم

2 دانشگاه شهید باهنر کرمان

چکیده

پژوهش حاضر به معرفی و بررسی عملکرد یک خشک­کن خورشیدی مجهز به سامانه­ی بازیافت حرارت از هوای گرم خروجی، برای خشک­ کردن پسته پرداخته است. آزمایش­های مربوط به ارزیابی خشک­کن در سه سطح دما  و سه سطح دبی هوای خشک­کننده انجام شدند. نتایج پژوهش نشان داد که با افزایش دما از 55 به 75 درجه­ی سلسیوس، زمان خشک کردن 61/57 درصد، سهم انرژی خورشیدی 32/24 درصد، سهم انرژی بازیافتی 80/6 درصد و بازده جمع کننده 56/2 درصد کاهش یافتند. درحالی­که، انرژی مصرفی گرم­کن الکتریکی 9/1 برابر بیشتر شد. با افزایش دبی از 045/0 به 085/0 کیلوگرم بر ثانیه، سهم انرژی خورشیدی 54/20 درصد کاهش، سهم انرژی بازیافتی 30/18 درصد و بازده جمع کننده 19/5 درصد افزایش داشتند. سامانه­ی بازیافت انرژی به طور متوسط 58/28 درصد از انرژی لازم در طی فرایند خشک کردن را تأمین کرد. همچنین افزایش دما موجب افزایش مقدار خندان شدن پسته و استحکام مکانیکی مغز آن گردید.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

An investigation on pistachio drying in a solar dryer equipped with an air to air waste heat recovery system

چکیده [English]

Only a small percentage of provided thermal energy is used for the drying process in the hot air dryers while, a large fraction is lost via the dryer walls and exhaust air. The present study developed a solar dryer with a simple heat recovery system for pistachio drying. The evaluation tests were conducted at different levels of drying temperature (55, 65 and 75 OC) and air flow rate (0.045, 0.065 and 0.085 kg/s). The results showed that rising the temperature from 55 to 65 OC caused a reduction of 57.61% in drying time, 24.32% in solar fraction, 6.8% in recovery fraction and 2.56% in the collector efficiency. Meanwhile, average electricity consumption at temperature of 75 OC was 1.9 times more than that at 55 OC. Increasing the air flow rate from 0.045 to 0.085 kg/s improved collector efficiency and recovery fraction while it led to a reduction of 20.54% in solar fraction. Totally, it can be said that the waste heat recovery system accounted for about 28.58% of total energy needed for pistachio drying. The results also indicated that both shell splitting number and pistachio kernel strength increased at the higher air temperatures.

کلیدواژه‌ها [English]

  • Solar dryer
  • Waste Heat Recovery System
  • Energy Fraction
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