实现重力式热管换热器设计计算功能，简单按照设计任务书，给出所需热管的结构尺寸，涉及的热管蒸发段和冷凝段长度分别为1m，绝热段长度30cm，内径20cm，外径25cm，热管工质为水。-C language for thermosyphon s design.Realize the gravity heat pipe heat exchanger design and calculation functions , simple design in accordance with the mission statement , given the size of the required structure of the heat pipe , heat pipe evaporator and condenser section lengths were involved 1m, adiabatic length 30cm, inner diameter 20cm, 25cm outside diameter heat pipe working fluid is water.