When fluid currents are produced by external sources , the solid-to-fluid heat transfer is termed . A: free convection B: natural convection C: forced convection

The mechanisms by which the heat may flow are three: conduction, convection, and radiation.

传热的基本方式有（ ）（Conduction）、热对流（Convection）和热辐射（radiation）

‍传热的基本方式有（ ）（Conduction）、热对流（Convection）和热辐射（radiation）‏‍‏

Birds orient themselves carefully with regard to the sun and gently ________ their wings to increase convection (气流对流) cooling.

万能蒸烤炉的基本功能有 。 A: steaming B: roasting C: convection D: frying

Which of the following is not the way of heat loss? () A: Shivering B: Radiation C: Conduction D: Convection E: Evaporation

Lifting actions may be provided by several factors except _____. A: rising terrain B: fronts C: convection D: crosswind

What’s the most popular heating system according to the engineer A: Every room has a heater. B: The Central room has a heater. C: A heat chamber heats air and passes the warm air through ducts and openings into rooms. D: The rooms are installed with blowers or convection.

The thermal conductivity of the insulation material outside the tube is 0.08W/m.K. The convection heat transfer coefficient outside the tube is 8W/m2.K. What is the critical insulation diameter of the tube? A: 20m B: 2m C: 0.2m D: 0.02m