| 摘要 |
<p>The tunnel has an air heater and a blower which directs heated air to an intermediate compartment of the tunnel. Trollies loaded with fruit advance, counter current to hot air, along a tunnel section leading to the intermediate compartment. From the compartment the trollies leave along a second tunnel section, now moving co-current with the hot air. Air blown into the tunnel is now drawn entirely from outside the tunnel without recycling any air exhausted from the tunnel. The air heater is operated intermittently under control of an adjustable cycle timer. The tunnel is used for a drying process in which air is heated to about 100 degrees for introduction to the intermediate compartment. Air at this temp. would rapidly spoil the prod. but is only used for short spells of about 18-20 mins with intervals of 4-5 mins. during which unheated air is blown through the tunnel. Process parametes are pref. selected so that fruits adjacent the intermediate compartment are retained in a temp. range with upper and lower limits =20 degrees apart.</p> |
