Analysis and design of a multi-effect desalination system with thermal vapor compression and harvested heat addition

The design and optimization of a concentrated solar power-desalination of seawater (CSP-DSW) plant is based on the accurate characterization and better integration of sub-components, such as the multiple effect distillation (MED). We set out to design and fabricate two pilot MED systems that consist of high performing components and involve a high degree of thermal integration with the rest of the system. An MED system with a series of thermal vapor compressors (TVCs) driven by heat harvested from the thermal storage subsystem of the CSP-DSW is proposed. An algorithm is presented which optimizes the gain output ratio (GOR) by varying of the number and entrainment ratio of TVCs. The use of modular parallel plate falling film heat exchangers and overall process thermal management increase the flexibility and overall efficiency of MED. Experience with the design and fabrication of a transparent single-effect experimental MED aimed to quantify the performance of the parallel plate falling film heat exchanger and to allow visualization of permeate vapor is discussed. A 10 kWt four-effect MED design is also described for use in a proof-of-principle CSP-DSW study to be performed at the Cyprus Institute.