In regenerative air preheater (as practised in heating of coke ovens), the heat is transferred
A
Through a metallic wall
B
By direct contact of hot flue gas with air
C
By heating an intermediate material (like chequor bricks) and then heating the air from this hot material
D
None of these
Correct Answer: By heating an intermediate material (like chequor bricks) and then heating the air from this hot material