Numerical balancing in a humidification dehumidification desalination system

This thesis details research on the thermal and concentration balancing of a humidification dehumidification desalination system. The system operates similarly to the natural rain cycle. Seawater is heated, sprayed into an airstream to increase the air's humidity, then pure water is condensed out of the same stream in a separate unit. These systems are typically inefficient due to entropy generation caused by mismatch between the temperature and humidity profiles in both the humidifier and dehumidifier components. Numerical models are developed for several different systems, and it is shown that for a given system with fixed inputs, entropy generation is minimized by way of balancing; i.e., the extraction and reinjection of the water or air streams within the humidifier and dehumidifier to equalize the capacity rates of the streams. Several modifications to existing baseline cycles are made to reach cases of minimum entropy generation. In these cases, the performance of the system is dramatically improved and the amount of energy needed to drive the system is reduced. For both on and off-design models, the addition of multiple extractions markedly improves the performance as compared to a baseline case with no extractions.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2011

Author dc:creator

• Miller, Jacob A., S.M. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• John H. Lienhard, V.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about 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/1721.1/68692

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/68692