Question

Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R).

Assertion (A): LSU dryer is considered as a continuous flow-mixing type of grain dryer.

Reason (R): In LSU dryer, inverted V-shaped air channels are arranged in such a way that air is forced through the descending grain while moving from feed end to discharge end.

In light of the above statements, choose the correct answer from the options given below.

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

Ask what specific design feature of the LSU dryer's ducts actually causes grain mixing, and check if the reason statement mentions that feature.

Answer 1

The Correct Option is B

Compare the LSU dryer with a plain crossflow column dryer to see clearly what mixing requires.

In a plain crossflow column, air enters one side of a grain bed and leaves the other side. Grain touching the air inlet side dries fast and can even overdry, while grain on the exhaust side dries slowly and stays wetter. Because grain columns never swap positions as they fall, this unevenness carries through to the final product, this is the non-mixing design.

The LSU dryer fixes exactly this problem by offsetting each layer of inverted V-ducts from the layer above it. A portion of grain that was near an inlet duct gets pushed around it and ends up near an outlet duct one layer down, and the pattern keeps alternating as grain falls through many layers. That repeated side shift is the mixing action, and it is why LSU is called a mixing type dryer. This confirms Assertion (A) is true.

Reason (R), on the other hand, just states that air moves through the grain from the feed end to the discharge end via the ducts, a description that applies equally to dryers that do not mix grain at all. Since it skips the offset-duct detail that actually creates mixing, it cannot be called the correct explanation of (A), even though it is a true statement on its own.

\[\boxed{\text{Both (A) and (R) true, (R) is not the correct explanation of (A)}}\]