Which of the following options has effects on convection heat transfer: A: The surface condition for heat transfer. B: Whether chemical reactions occur during the mixed flow of multiple fluids. C: The type of fluid. D: Whether the fluid flow is driven by external power.

The energy is transferred from one region to another by three modes of heat transfer：（），（），and radiation .

Both bombs produce the same three effects: heat, blast, and radiation, ________ the most fatalities. A: the first of them usually causes B: the first of which usually causes C: and the first of which usually causes D: the first of which usually causing

Radiation heat transfer of smoke tube boiler mainly occurs in , convection heat transfer mainly occurs in . A: Furnace and smoke pipe B: Smoke pipe and furnace C: Needle tube, smoke box D: Smoke box and smoke pipe

The temperature of the two gray body increases 50 ℃<br/>respectively, then the heat flow by radiation should be ( ) A: Reduced B: Increased C: Unchanged D: Uncertainty