An experimental and analytical studies on the condensation-induced water hammer (CIWH) for steam-water countercurrent flow in a nearly horizontal circular pipe have been performed. A total of 17 experimental data for the onset 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 correlations of interfacial heat transfer and friction factor developed for a circular geometry and using an improved criterion of transition from stratified to a slug flow, two existing analytical models to predict lower and upper bounds for CIWH have been upgraded. Applicability of the present as well as existing CIWH models has been tested by comparison with two sets of CIWH data. The result of this comparison shows that the applicability of the present as well as existing models is reasonably good. Based on the present models for CIWH, a computer code entitled as ‘KAIST-CIWH' has been developed and sample guide charts to find CIWH free regions for a given combination of major flow parameters in a long horizontal pipe have been presented along with the results of parametric studies of major parameters (D, P, T_f,in, and L/D) on the critical inlet water flow rate (W_f,in)_crit for both lower and upper bounds. In addition, two simple formulas for lower and upper bounds that can be used in an emergency for quick results have been presented.
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