Date of Award

3-2002

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

Gharib S. Aly

Second Advisor

Dr. Ali M. EI-Nashar

Abstract

A mathematical model has been developed to predict the performance of any multi-effect desalination with thermal vapor compression (MED-TVC). The model consists of mass and energy balances, rate equations, correlations for film heat transfer coefficients for horizontal falling film evaporators, and correlations for physical and thermodynamic properties for saline water. The mathematical model has been coded using visual Basic and assigned the name MEDUAE.

Computer simulations were executed, using the in-house developed program (MEDUAE) and the commercial software package Evapolund using design and plant operating data of 3 different MED-TVC desalination plants in UAE. The main objectives have been to calibrate and verify the general nature of the developed computer program, and to check some critical plant design values. The process variables that were used in all simulations include the saturation temperature of vapor streams leaving each effect, the flow rate of water produced (plant capacity), the concentration of brine rejected, the heat transfer area of evaporators at both clean and fouled conditions, and the overall heat transfer coefficients.

The simulation results obtained from both MEDUAE and Evapolund are very similar, suggesting the reliability of the mathematical model and the in-house developed program. The results also revealed that, in designing this type of desalination plants, the process designers and plant contractors add a safety margin of about 10% to the heat transfer area of all evaporators to maintain the plant capacity at fouled conditions.

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