单项选择题
A.Water is heated into vapor on heating surfaces
B.Water is vaporized by pressure difference
C.There are no heating-transfer surfaces
D.There are more heating-transfer surfaces
单项选择题 Which one of the followings might not be employed to create vacuum for flash type evaporator? （）
单项选择题 The design of for a flash type evaporator is of critical importance because it must provide an optimum feedwater spray pattern that facilitates the flashing process, and it must also maintain a pressure differential between successive stages（）
单项选择题 A flash-type evaporator discharges heated seawater into a chamber that is maintained at a pressure than the vapor pressure of the entering heated seawater, and subsequently the flashed water vapor thereby produced（）