Answer: The rate of heat transfer decreases.
Explanation:
Fin effectiveness is defined as the ratio of heat transfer rate from a finned surface to the heat transfer rate from the same surface if there were no fins. Its value is expected to be greater than 1.
Having effectiveness value of 0.9 which is less than 1 indicates that the heat transfer rate will decrease since a fin effectiveness smaller than 1 shows that the fin acts as insulation (thermal insulation).
