A parametric study and a guide chart to avoid condensation-induced water hammer in a horizontal pipe

An experimental and analytical studies on the condensation-induced water ha mmer (CIWH) for steam-water countercurrent flow in a nearly horizontal circ ular pipe have been performed. A total of 17 experimental data for the onse t of slugging, which is assumed to be the precursor of the CIWH, have been obtained for various flow rates of water. Incorporating the most recent cor relations of interfacial heat transfer and friction factor developed for a circular geometry and using an improved criterion of transition from strati fied to a slug flow, two existing analytical models to predict lower and up per bounds for CIWH have been upgraded. Applicability of the present as wel l as existing CIWH models has been tested by comparison with two sets of CI WH data. The result of this comparison shows that the applicability of the present as well as existing models is reasonably goad. Based on the present models for CIWH, a computer code entitled as 'KAIST-CIWH' has been develop ed and sample guide charts to find CIWH free regions for a given combinatio n of major flow parameters in a long horizontal pipe have been presented al ong with the results of parametric studies of major parameters (D, P, T-f,T -in, and L/D) on the critical inlet water flow rate (W-f,W-in)(crit) for bo th lower and upper bounds. In addition, two simple formulas for lower and u pper bounds that can be used in an emergency for quick results have been pr esented. (C) 2000 Elsevier Science S.A. All rights reserved.