Research Papers

Pressure-Retarded Osmosis Thermosyphon

[+] Author and Article Information
Francisco J. Arias

Department of Fluid Mechanics,
University of Catalonia,
ESEIAAT C/Colom 11,
Barcelona 08222, Spain
e-mail: francisco.javier.arias@upc.edu

Salvador de las Heras

Department of Fluid Mechanics,
University of Catalonia,
ESEIAAT C/Colom 11,
Barcelona 08222, Spain

1Corresponding author.

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received March 29, 2017; final manuscript received April 1, 2018; published online May 29, 2018. Assoc. Editor: Wojciech Lipinski.

J. Sol. Energy Eng 140(5), 051006 (May 29, 2018) (4 pages) Paper No: SOL-17-1113; doi: 10.1115/1.4039893 History: Received March 29, 2017; Revised April 01, 2018

The basis of a novel method for passive solar water heating homologous to the traditional thermosyphon but driven by salinity gradient induced by changes of salinity gradient induced by evaporation at the collector is outlined. Its purpose, likewise than a thermosyphon, is to simplify the transfer of liquid while avoiding the cost and complexity of a conventional pump. However, in this concept, the fluid motion is not obtained from the tendency of a less dense fluid to rise above a denser fluid (natural convection) but rather by taking advantage of the energy released during the spontaneous mixing of the low-concentration (evaporated fraction) solution and the high-concentration (no-evaporated fraction) solution, which have been previously separated into two streams in the evaporator module. Finally, the possibility of driving the thermal osmosis by the strong thermal dependence of the solubility featured by many solutions rather than evaporation is envisaged. One important point in favor of the proposed thermosyphon driven by thermo-osmosis is that makes possible downward heat and mass transfer, i.e., heat and mass transport from the top roofs (where solar collectors are generally placed) to the bottom (inside the homes), and then the use of expensive and voluminous tanks so characteristic of current thermosyphons driven by natural convection is no longer needed.

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Lin, S. , Straub, A. P. , Deshmukh, A. , and Elimelech, M. , 2014, “ Thermodynamic Limits of Extractable Energy by Pressure-Retarded Osmosis,” J. Energy Environ. Sci., 7(8), pp. 2706–2714. [CrossRef]
Straub, A. P. , Deshmukh, A. , and Elimelech, M. , 2016, “ Pressure-Retarded Osmosis for Power Generation From Salinity Gradients: Is It Viable?,” J. Energy Environ. Sci., 9(1), pp. 31–48. [CrossRef]
Wang, Z. , Hou, D. , and Lin, S. , 2016, “ Gross Vs. Net Energy: Towards a Rational Framework for Assessing the Practical Viability of Pressure Retarded Osmosis,” J. Membr. Sci., 503, pp. 132–147. [CrossRef]
Shuttleworth, W. J. , 2007, “ Putting the ‘Vap’ Into Evaporation,” Hydrol. Earth Syst. Sci., 11(1), pp. 210–244. [CrossRef]
Merva, G. E. , 1975, Physio-Engineering Principles, AVI Publishing Company, Westport, CT.


Grahic Jump Location
Fig. 1

Physical model for analysis of the osmotic thermosyphon

Grahic Jump Location
Fig. 2

The required dedicated area of evaporation as function of the power with a reference osmosis pressure Πo = 106Pa, and some mechanical efficiencies in the conversion

Grahic Jump Location
Fig. 3

The strong dependence of some aqueous solutions with temperature could be harnessed for driving the thermosyphon without promoting evaporation




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