Q1: Pick out the wrong statement.

ANS:D - Overall heat transfer co-efficient in a heat exchanger is controlled by the value of the film co-efficient, which is higher.

This statement refers to the overall heat transfer coefficient (U) in a heat exchanger, which represents the overall efficiency of heat transfer between the two fluids involved. The overall heat transfer coefficient takes into account both the convective heat transfer coefficients on the fluid sides as well as the conductive resistance through the heat exchanger wall. In a typical heat exchanger, heat transfer occurs through multiple resistances, including the convective resistances on the fluid sides and the conductive resistance through the heat exchanger wall. The film coefficient (ℎh) represents the convective heat transfer coefficient on each fluid side. Generally, one fluid side will have a higher film coefficient compared to the other due to differences in fluid properties and flow conditions. The overall heat transfer coefficient (�U) is calculated using a weighted average of the individual film coefficients on each side of the heat exchanger, along with the conductive resistance through the heat exchanger wall. When one side of the heat exchanger has a higher film coefficient (ℎh) than the other, it contributes more significantly to the overall heat transfer coefficient. Therefore, the statement suggests that the overall heat transfer coefficient (�U) in a heat exchanger is primarily influenced by the value of the film coefficient (ℎh) on the side with the higher coefficient. If one side has a significantly higher film coefficient, it will dominate the overall heat transfer coefficient and control the efficiency of heat transfer in the heat exchanger.