【Daily Question】Theoretical Foundation 2020.12.06
Thread Content
Multiple-choice question: The question is shown in the image ( ). Answer: B. Hint: Those who can explain the solution process will receive an additional reward; the answer can be submitted there
B When external disturbances are present, even if the hot side is on top, the natural convection between the hot and cold sides cannot be calculated using heat conduction principles; therefore, option A is incorrect. When Grδ > 5000, strong turbulence is formed in the interlayer; heat transfer is uniform, and convection is the dominant mode of heat transfer, so option C is incorrect. For natural convection heat transfer, the heat transfer criterion Nu = C should be used for calculation; option D is incorrect. With the hot side on the bottom, when the gas’s Grδ is less than 1700, convective heat transfer is weak; heat transfer in the interlayer still relies mainly on conduction. Therefore, it can be calculated using pure conduction principles, so option B is correct.