| Absorption heat transformer (AHT) has no environmental hazards and saves energy, it is recognized as environmental protection device and has got many researchers'attention. It has been widely used in many areas with the recycled heat energy below 130℃. The high temperature AHT is very prosperous in some industrial area as well, and becoming an important work to raise the operating temperature of AHT. Based on the heat transfer performance for falling film absorption on the exterior wall of a vertical tube, a vertical absorption test platform and a CFD model are established.Specific coating tubes are prepared on the external surface of bare brass tube with the designed surface configuration form. The liquid film velocity is measured by the thermal tracing technique. The effect of solution spray density is studied.The experimental investigation of the vertical falling film absorption outside the bare brass tube and different circumferential coated tubes at high temperature is conducted. The effects of solution spray density and inlet temperature on the heat and mass transfer are investigated. The results show that the heat transfer coefficients and mass transfer coefficients increase with the increase of solution inlet temperature; the heat transfer coefficients on the coated distribution tube are higher than that on the bare brass tube, but the mass transfer coefficients on the coated distribution tube are lower than that on the bare brass tube.A two-dimensional two-phase flow CFD model using the volume of fluid (VOF) method is presented. The effects of solution spray density and inlet temperature on the heat transfer are studied.Finally, the CFD simulation of the vertical falling film flow outside different corrugated tubes at high temperature is conducted. The flow behaviors of liquid on various tubes are investigated. The effects of different ripple height and ripple spacing on flow and heat transfer are investigated.
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