Atmospheric Water Extraction

Atmospheric Water Extraction: Fresh Water Production using Ocean Thermal Energy

Noordhoek Hegt, Floris (TU Delft Mechanical, Maritime and Materials Engineering)

Infante Ferreira, C.A. (mentor)
Kleute, B.J. (mentor)
Vlugt, T.J.H. (mentor)
Pourquie, M.J.B.M. (mentor)

Delft University of Technology

Mechanical Engineering | Sustainable Process & Energy Technology

2017-08-24

Many regions in the world depend heavily on expensive desalinated water for fresh water consumption, in particular tropical areas. Current mainstream desalination technologies (Reverse Osmosis and Multi-Stage Flash Evaporation) are quite energy intensive and thus costly. Today’s challenge is to design a desalination system that could run with local available renewable energy and provide affordable fresh water, even in the most arid environments. A potential fresh water production method that differs from mainstream technologies is Ocean Thermal Water Production (OTWP). This method makes use of high temperature and high relative humidity air in the tropics and condenses it against a cooled fresh water loop in a packed bed column. The system is expected to deliver fresh water at a competitive level once built at a larger scale. This master thesis project improves a previously researched OTWP model and validates the model by testing its output values against experiments done using an experimental setup at the TU Delft P&E laboratory. Taking into account the previous work done during the thesis of van der Drift [49] and Lopez [30], the theoretical background for building an OTWP model has been further described and expanded in this thesis. Three different direct contact condensation theories have been thoroughly examined. The first two theories suggest that heat and mass in the DCD are transferred through a constant laminar film on the packing [38] [1] [4]. The third theory is an add on to the laminar film model, and suggests that heat and mass is also transferred through the creation and dynamics of small droplets within packings [34]. The model and its 4 main submodels are fine-tuned to be able to reproduce the thermodynamics occurring in the experimental setup. The model is tested under different steady state conditions using experiments, to provide insight on the model’s robustness and reliability. The final improved simulation model is used to present conclusions on heat transfer, mass transfer and water production rates for the experimental setup. A brief economic analysis of the system is performed to arrive at an energy price of water for the OTWP experimental system. Although the final energy price for the OTWP setup is quite unfavorable, 14 kWh/m3 as opposed to 2-3.5 kWh/m3 for current desalination systems, tips to improve a possible future pilot facility are proposed. Here high yield and low cost are key requirements, and the design of a future pilot facility needs to be optimized using these two pillars.

Atmospheric water extraction
Ocean thermal water production
Direct contact condenser
fresh water production
psychrometrics
experiment
model

http://resolver.tudelft.nl/uuid:86274241-830b-483e-bfab-029bd575c688

2022-08-24

Student theses

master thesis

© 2017 Floris Noordhoek Hegt