Trong cách nói thông thường, năng lượng tái tạo được hiểu là những nguồn năng lượng hay những phương pháp khai thác năng lượng mà nếu đo bằng các chuẩn mực của con người thì là vô hạn. | 7 Advanced Mechanical Vapor-Compression Desalination System Jorge R. Lara Omorinsola Osunsan and Mark T. Holtzapple Texas A M University United States 1. Introduction Vapor compression is a reliable and robust desalination technology that is attractive because of its capacity to treat large volumes of water with a wide range of salt concentrations. However compared to other major desalination technologies such as reverse osmosis mechanical vapor compression has had relatively high operating and capital costs. New innovative developments in compressor and evaporator designs make it possible to reduce energy consumption so it is a more competitive alternative. Texas A M University has developed an advanced vapor-compression desalination system that operates at high temperatures. Advanced sheet-shell latent heat exchangers promote dropwise condensation allowing small temperature and pressure differentials between the saturated boiling liquid and the condensing steam hence reducing the energy requirements. This newer system consists of a train of non-scaling evaporators arranged so feed water flows countercurrently recovering heat from both the condensate stream and the concentrated discharge brine. A high-efficiency gerotor compressor provides the compression work required to return saturated steam to the initial stage of the evaporator train. An experimental investigation of hydrophobic copper plates described below shows that extraordinarily high heat transfer coefficients can be attained. The gerotor compressor is particularly advantageous for applications where either electricity or mechanical energy is available. Extensive studies in dropwise condensation show that for low temperature differentials across the hydrophobic plate heat transfer coefficients will increase with elevated steam pressures. According to the data described in this study dropwise condensation of saturated steam and forced-convection boiling of saturated water separated by a thin hydrophobic
