Ấn phẩm khoa học

STUDY ON THE REVERSAL TIMING FOR THE SRA REVERSIBLE DRYER

--------------------------------------------------------------------------------------------------------------------------------------

STUDY ON THE REVERSAL TIMING  FOR THE SRA REVERSIBLE DRYER #

Phan Hieu Hien, Nguyen Hung Tam, Nguyen Van Xuan # #

#     Paper for presentation at the Seminar on “Agricultural Engineering and Agro-products Processing towards  Mechanization  and  Modernization  in  Rural  Areas“  at  Nong-Lam  University,  HoChiMinh City, 11-12 December 2003.

#  #    Lecturers, Faculty of Agricultural Engineering and Technology, Nong-Lam University HoChiMinh City, Vietnam.  E-mail  phhien@hcm.vnn.vn

Full-Text PDFDownload 

-----------------------------------------------------------------------------------------------------------------------------------------

INTRODUCTION

 

In  Vietnam,  over  the  past  20  years,  the  simple  flat-bed  dryer  has  been  accepted  and developed into the foremost dryer for reducing post-harvest paddy losses due to adverse rainy  weather,  with  about  3000  units  of  capacities  from  4  to  8  tons  per  batch. Good features of these dryers are: fairly high capacity, good grain quality, low drying cost, easy to  install  and  operate.   Nevertheless,  as  simplest  dryers  with  a  major  drawback  of  non- uniformity in final grain moisture content, they have to be changed to meet the needs for more-mechanized dryers at rice milling centers.

The   series   of   SRA   dryers   (RA   is   abbreviation   for   Reversible-Air,   S   is   drying   in Vietnamese) have been designed to serve the above change.  The research began in 1999 at  Nong-Lam  University  (NLU,  formerly  University  of  Agriculture  and  Forestry)  with  a laboratory model for basic information about drying characteristics of various crops with reversible airflow. Next, a pilot 1.5-ton/batch SRA dryer was designed and tested with paddy and coffee.  Finally, the dryer was scaled up to different models, of 2; 4; 6; 8; 10; and 12 tons per batch.   Twenty five SRA units have been applied successfully in various Provinces of Vietnam; of which 8 units have each dried 500- 1500 tons in the past 3 years. Features drawn from testing and using these dryers are:   a) Saving of land space; b) More mechanized, meaning less use of manual labor;  c) Multi-crop use, including high-moisture products such as coffee, sliced cassava, longan…  , and d) The investment and drying cost are not higher compared to a flat-bed dryer of similar capacity.  Successful applications of these  SRA  have  been  reported  elsewhere  (Nguyen  Hung  Tam  et.al.,  2002;   Phan  Hieu Hien, 2003). 

The unique feature of these dryers, is that the drying is reversed only once, which makes the process different from other dryers reported in the literature with periodic air reversal, say, every 2 hours.   Less air reversal means less intervention by manual labor, which in turn  contributes  to  lower  drying  cost.  But  this  once-only  air  reversal  should  ensure moisture uniformity for users’ acceptance.

Chia sẻ:
Về đầu trang