N2 - An approach – relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx) has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3solution were used as working fluids. Nanoparticles were tested at the concentration of 0.01% and 0.1% by weight. A modified Peclet equation and Wilson method were used to estimate the overall heat transfer coefficient of the tested TPTHEx. The obtained results indicate better performance of the TPTHEx with nanofluids as working fluid compared to distilled water, independent of nanoparticle concentration tested. However, increase in nanoparticle concentration results in overall heat transfer coefficient decrease of the TPTHEx examined. It has been observed that, independent of nanoparticle concentration tested, decrease in operating pressure results in evaporation heat transfer coefficient increase. L1 - http://www.journals.pan.pl/Content/105675/PDF/02_paper.pdf L2 - http://www.journals.pan.pl/Content/105675 PY - 2016 IS - No 2 EP - 44 DO - 10.1515/aoter-2016-0011 KW - two-phase thermosyphon KW - heat exchanger KW - nanofluid KW - Wilson method A1 - Cieśliński, Janusz T. PB - The Committee of Thermodynamics and Combustion of the Polish Academy of Sciences and The Institute of Fluid-Flow Machinery Polish Academy of Sciences DA - 2016 T1 - Effect of nanofluid concentration on two-phase thermosyphon heat exchanger performance SP - 23 UR - http://www.journals.pan.pl/dlibra/publication/edition/105675 T2 - Archives of Thermodynamics