Design and Fabrication of Tray-Type Semi-Continuous Tunnel Dryer
Omame Onyebuchy Bernard; Ugwu Hyginus Sunday; OnyiaThankGod & Nebo Fidelis
Scientific Equipment Development Institute, Enugu
Email: buchydifference@yahoo.comhygiugwu@gmail.com, onyiato@gmail.comfidenebo@yahoo.com
Corresponding Author: Omame Onyebuchy Bernard
ABSTRACT
A tray type semi-continuous tunnel dryer for Agro-product was designed and fabricated to enhance proper and efficient drying of agricultural products (e.g. cassava chips) in large scale for preservation and export. The overriding considerations in the design were the nature and concentration of the feed, temperature range, air flow rate, discharge as well as the cost of materials. Design calculations assumed steady state considerations and most properties of the system were the values at standard temperature and pressure. Hot air is used as the heating and mass transfer medium in the tunnel. The hot-air generated by a heat exchanger is pumped to the tunnel by an electrically driven blower. Experimental results show that the optimum conditions for drying of cassava (used as a case study) require an inlet hot air temperature of 55-60oC and a residence time of 200-420minutes A reduction of the average moisture content to 6-5% at an equilibrium relative humidity of below 60% was considered as dryness and readiness for storage. This dryer is basically a group of truck-and-tray batch dryers, operated in a programmed series so as to be quasi-continuous. This machine is made up of a tunnel of 12m x 1m x1.2m in size with rails, 98 loading tray of 0.84m x 0.82m x 0.02m in size, heat exchanger, transmission duct, hot air blower, 4kw geared electric motor 38-178 output rpm, temperature gauge(three in number). The capacity of the machine is 300kg per full load (3kg per tray) in 3hrs 50min (relative).Keywords: cassava chips, Heat transfer, Moisture content, equilibrium relative
