Solidification Blockage of a Circular Pipe in a Piping System

Research Project

Project/Area Number	63550176
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Thermal engineering
Research Institution	Kanagawa University
Principal Investigator	CHIDA Kikuji Kanagawa Univ. Dept. Mech. Eng. Professor, 工学部・機械工学科, 教授 (60078293)
Co-Investigator(Kenkyū-buntansha)	TAJIMA Mamoru Kanagawa Univ. Dept. Mech. Eng. Res. Associate, 工学部機械工学科, 助手 (70078327)
Project Period (FY)	1988 – 1990
Project Status	Completed (Fiscal Year 1990)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1990: ¥400,000 (Direct Cost: ¥400,000) Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywords	Circular Pipe Flow / Solidification / Pressure Drop / Blockage
Research Abstract	The following studies were carried out during past three years under the auspices of this Grant. For straight circular pipe : (1) Measurement of the pressure drop of the cooled pipes with L/D=80, 40, 20 for the range of Re=100-10000, Tw^=0-10 using water. (2) Observation of the solidified ice layers developed in the pipes of L/D=40 under unsteady condition as well as steady state condition. (3) Verification of the quasi-steady state method for blockage criteria. For curved circular pipe (90-degree bend) : (4) Survey for a effective dimensionless parameter for circular pipe flow with developing section. (5) Observation of the ice layers formed in the bend using the split-type bends. (6) Measurement of steady state pressure drops of the bend with R/a=100 for the range of Re=350-7000, Tw=2-7. Conclusions derived are (1) As Reynolds number of the in-flow becomes larger, the steady state pressure drop of the cooled pipe decreases in the laminar region, then experiences sharp decrease in the narrow transient region, and after this region, i.e. in the turbulent region increases along the Blasius curve. Existence of two stable steady states is found in the case of Tw=2. (3) At higher Tw a so-called step is found to be formed, and the step moves down-stream direction not only up-stream direction during the course of cooling. (4) Application of the quasi-steady state method using the derived steady state pressure drops to the present experimental piping system reveals that this method gives somewhat dangerous criterion, possibly due to the overshoot of the pressure drop during cooling.