Development of Unified Physical Model for Flow Boiling inside an Internally, Spirally, Grooved Tube, which is Applicable for Fluids with Much Different Thermophysical Properties

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The flow pattern and heat transfer of evaporating ammonia inside a horizontal spirally grooved tube were experimentally investigated. Test fluids used were HCFC123 and ammonia, those physical properties are much different from each other. The characteristics of experimentally obtained flow pattern information and heat transfer coefficients were investigated.At first the limit of currently available model and method to treat this problem were shown through this discussion. The measured flow pattern transition qualities were compared with some available correlations both for a smooth tube and a grooved tube. The new correlations for the transition quality between separated and annular flow regimes, for the transition quality between annular/separated to mist flow regimes, and for the heat transfer coefficients in annular flow regime were proposed for both HCFC123 and ammonia by one equation. Also physical model to treat fluids with much different physical properties were proposed.