Cost-optimal design of a household batch electrodialysis desalination device

This thesis investigates the pareto-optimal design of a household point-of-use batch electrodialysis (ED) system to provide a cost-effective replacement for existing reverse osmosis (RO) devices, for brackish water desalination of Indian groundwater, at lower energy consumption and higher recovery: 80-90% vs 25-40%. Target specifications derived from user-interviews, and RO products, guided the selection of a batch architecture, for which a coupled flow-mass transport model to predict desalination rate was developed, and validated using a lab-scale ED stack. The effects of varying the production rate (9-15 L/hr) and product concentration (100-300 mg/L) requirements on optimal selection of geometry, flow-rates, and applied voltage for total cost minimization were then explored using a multi-objective genetic algorithm. Given the low utilization of the system and the current cost of materials, the energetic cost was dominated by the capital-cost of the system. At a fixed feedwater concentration of 2000 mg/L, which is representative of the upper bound on groundwater salinity underlying much of India, and a recovery ratio of 90%, the capital cost sharply increased for systems targeted at 100 mg/L vs 200 mg/L and 300 mg/L: $141, $93, and $79, respectively averaged for systems that produced between 11.5 and 12.5 L/hr of desalinated water. Promising directions for additional cost reduction include voltage-regulation during the batch process and the development of inexpensive pumps. In addition, a candidate cost-optimal design was prototyped and tested to verify that the measured desalination performance agreed with the modeled expectations.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Mechanical Engineering

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2017

Author dc:creator

• Shah, Sahil R. (Sahil Rajesh)

Advisor dc:contributor.advisor

• Amos G. Winter, V.

• Mechanical Engineering.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/111935

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/111935