الفهرس 
Chapter One IntroductionOnly 14 pages are availabe for public view
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Abstract
The present study aims to improving the economy of produced potable water using multi-effect desalination with thermal vapor-compression (MED-TVC) with thermal performance enhancements such as feed preheating process using low grade heat and optimizing the distribution of feed flow rate to each effect. Furthermore, the effects of increasing the number of effects with feed preheating on the MED-TVC performance at parallel and parallel cross feed configurations were studied. A mathematical model of the MED-TVC system has been developed. The governing equations based on energy and mass balances of the system components were solved using a computer program to evaluate the MED-TVC system performance. A mathematical model of the steam jet ejector which depends on the mass and energy balances and continuity equations was developed. In addition, an empirical correlation was derived to predict the entrainment ratio of steam jet ejector to simplify the model simulation. This correlation was validated with literature data and it showed good agreement.
Increase the feed water temperature using low grade heat source has crucial impact on improving the system performance with low extra initial cost. The energy sources to preheat feed water can be the waste heat of steam-power plants, cogeneration, the exhaust flue gases from the gas-power plants, and the internal combustion engines exhaust hot gases.
The improved performance of (MED-TVC) system is achieved by properly preheating the feed water. The feed preheating process leads to an increase in the water production capacity and to a decrease in the specific heat consumption. Consequently, performance enhancement decreases the cost of produced pure water that makes the desalination process being adequately economical.
In the present study, optimizing feed water mass flow rate distribution to each effect, which is considered one of main parameters that affect the performance of MED-TV system, was performed. The performance of MED-TVC system with the optimized quantity of feed water to each effect is greater than the fixed equal feed water mass flow rate to each effect.
The effect of feed water preheating process was studied with varying the number of effects on the MED-TVC system performance. Feed preheating with a higher number of effects increases both of pure water productivity and the Gain Output Ratio and decreases specific heat consumption.
The comparisons between parallel feed, PF, and parallel cross feed, PCF, have been performed which show that the parallel cross feed has higher water product and higher rejected salt concentration. Also, the desalination system with parallel cross feed has the lower heat consumption and lower specific total area of effects. the desalination systems with parallel feed with number of effects equals to 2 ,4 and 6 and at feed temperatures range from 40 to 46 oC reach the same performance of parallel cross feed at feed temperature TF=32 oC (without feed preheating). The desalination systems with parallel feed with feed preheating can achieve the objective of increasing the system performance with simpler layout and lower salt concentration.