空調機における水の凍結による管破壊現象について

抄録

When water is frozen at some parts inside a pipe, the pressure of water blockaded by growing ice increases unusually and the pipe would be deformed to fracture under a certain circumstance. The behavior of pipe fracture cannot be explained by the volume expansion during phase change that the water is frozen and the ice is growing to the radius direction of pipe. In this study, we have investigated experimentally the behavior of pipe fracture for a plate fin coil in air conditioner about the freezing location, the growing direction of ice, and the change of water pressure and the deformation of pipe in the ice growing process. Moreover, we examined the behavior of water pressure in the ice growing process by numerical analysis. The pressure of water blockaded by growing ice increased to 20 MPa or more. This high water pressure deforms the pipe; the thickness and strength of pipe remarkably decrease at a time of freezing. Therefore, after the deformations of the pipe are repeated by freezing, the pipe could be fractured easily under the normal operating condition.