Study on photothermal properties of Zn-ZnO/paraffin binary nanofluids as a filler for double glazing unit

Abstract

Binary nanoparticles may effectively improve photothermal properties of the phase change material (PCM) to expand its application in solar energy, especially in energy-saving window. In the present work, various Zn-ZnO/paraffin binary nanofluids with different concentration and Zn:ZnO ratio are prepared for researching the paraffin photothermal properties enhancement by Zn-ZnO binary nanoparticles, and the applicability of Zn-ZnO/paraffin nanofluids as a filler for double glazing unit is discussed. The results show that: under the same ratio of Zn:ZnO(5:5), 0.001% volume fraction Zn-ZnO/paraffin binary nanofluids gives the largest photothermal conversion efficient ηof 18.1%, and the sample with 0.001% volume fraction, 8:2 ratio has superior conversion ability because of its lower solar absorption fraction (Am=35.1%) and higher conversion efficient(η=18.3%). By simulation of photothermal performance of double glazing unit, 0.001% nanoparticles volume fraction, 8:2 ratio Zn-ZnO/paraffin binary nanofluids as a filler for double glazing unit gives more comfortable indoor environment, reduces the utilization of electrical appliances, so as to achieve the purpose of building energy conservation, furthermore the best thickness of filler layer for target city is 6cm.