For a dual-purpose power plant with low temperature multi-effect distillation (LT-MED) desalination plant, the heating steam is normally extracted from steam turbine with pressure much higher than needed. In order to use the steam energy more efficiently, the thermal vapor compressor (TVC) is normally adopted to form the vapor recirculation utilization. A mathematical model for a multieffect desalination with thermal vapor compression (MED-TVC) desalination plant was developed and the model validity was examined by comparing with a commercial MED-TVC plant which showed good results in this paper. It also presents the performance calculation of the MED-TVC desalination system with different steam pressures and temperatures. With higher steam pressure, the gained output ratio (GOR) of the desalination plant could get higher values. The recirculation position of vapor in a multi-effect distillation system has a great effect on the GOR as well.

A B S T R A C TThe horizontal-tube falling film evaporation is a widely adopted technique in multiple-effect distillation desalination plant. It has a high heat transfer coefficient under quite small temperature difference. In this paper, an experimental equipment for horizontal-tube falling film evaporation was set up. Experiments were carried out to show how the heat transfer coefficient is affected by different parameters including heat flux, circumference direction of tubes, spray density, evaporation temperature, and experimental fluid. Results indicate that the heat transfer coefficient decreases after a little increase with growth of spray density. The heat transfer coefficient decreases along the tube circumference, but at the bottom of the tube, it shows increasing trend. In addition, a simple comparison between seawater and fresh water in heat transfer coefficient is also provided.

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A B S T R A C TAn experimental platform for horizontal-tube falling-film evaporation was set up to measure heat transfer characteristics. Experiments were carried out to show how the heat transfer coefficient (HTC) was affected by different parameters including spray Reynolds number (Re), saturation temperature, salinity, and tube arrangement. The results revealed that the HTC increased first and then decreased with growth of Re, and the HTC of seawater decreased with increasing saturation temperature. The results also showed that the HTC of rotated square pitch was higher than triangular pitch, rotated triangular pitch, and square pitch, but the heat transfer capacity per unit volume of triangular pitch was the highest. Meanwhile, the HTC decreased during the increase of salinity.

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