The mathematical control model for dynamic start-up process of the VTE-MED seawater desalination system was establishedemploying the previous developed non-linear differential equations for system design and performance analysis. The influences on thestart-up process of the operating parameters, such as the initial feed brine flow rate and the top brine temperature were analyzed.The relationships among the feed brine flow rate, the gained output ratio (GOR) and the start-up time were also investigated, whichcan be evidence to determine the optimal initial feed brine flow rate. The results also indicate that the system can consume the total heatrating generated by the low temperature nuclear heating reactor (LT-NHR) even at the most initial start-up stage, implying the presentdesalination system has excellent coupling characteristics with the LT-NHR. With necessary experiments verifications, the start-up controlmodel developed in this paper can be the theoretical base for the analysis of dynamic performances of the seawater desalinationsystem.

In order to understand the performance of a large-capacity VTE-MED nuclear seawater desalination systemthoroughly, the responding characteristics of the system to the off-design operating conditions were studied. Theinfluence of scale deposit in tubes on the heat transfer areas needed and on the heat transfer coefficients with high topboiling temperature (TBT) was illustrated. The decrease of GOR, and also the damage to the normal operation of thesystem caused by temperature drop of feed brine because of seasonal variation, were explored, based on which acorresponding approach for adjusting feed brine flow rate was proposed. An optimal brine feed flow rate was alsoproposed to obtain the highest GOR under different heat loadings. The work could be helpful for the efficient and safeoperation of nuclear VTE-MED desalination plants.

A physical and mathematical model for the multi-effect distillation process with vertical tube evaporators(VTE-MED) coupled with a nuclear heating reactor (NHR) was described. Results of analysis on thermal hydraulicperformances of the NHR-VTE-MED system are provided. Two types of temperature difference distribution schemes(equal temperature difference and in-section equal heat transfer area) were adopted for the thermal hydraulic performanceanalysis. Heat transfer coefficient, heat transfer area, and production of potable water in every effect were analyzed. Theanalysis shows that the GOR in the NHR-V1T.-MED system for the two types of temperature difference dislributionschemes studied can reach 20.

An analytical model, simultaneously accounting for gravity, vapor shear along axial direction and surface tension e.ects on the condensate ®lm layer, is proposed for fow condensation process in horizontal annulus with small/mini diameter inner tube and traditional industrial-used outer adiabatic tube. The analysis shows that, the e.ect of surface tension can not be neglected for small/mini tube of diameter less than 3 mm o.d., especially in low vapor quality zone. The shear stress and surface tension infuence the fow condensation mainly by means of distributing condensate ®lm uniformly along tube circumference in horizontal annulus. Experiments were conducted to examine the analysis. # 2000 Elsevier Science Ltd. All rights reserved.

The correlating factors for-ow condensation in small/mini-diameter tubes are analyzed by energy consideration. Based on the in-situ interface con®guration, an analytical model is proposed for predicting the heat transfer characteristics. Both analytical and experimental results show that gravity has a decreasing e.ect on-ow condensation in small/mini tubes. The inclination angle a.ects condensation heat transfer mainly by distributing gravity in stratifying the-uids and thinning the liquid ®lm. In larger tubes, the former may become the main reason for heat transfer enhancement, especially in high vapor quality zone and at low inlet vapor Reynolds number. Comparison with the experimental data indicates that the proposed analytical model has a good capability for predicting-ow condensation heat transfer in small/mini-diameter tubes. # 2000 Elsevier Science Ltd. All rights reserved.