Lee et al. Nanoscale Research Letters 2011, 6:258 NANO EXPRESS Open Access Round-robin test on thermal conductivity measurement of ZnO nanofluids and comparison of experimental results with theoretical bounds Wook-Hyun Lee1, Chang-Kyu Rhee2, Junemo Koo3, Jaekeun Lee4, Seok Pil Jang5, Stephen US Choi6*, Ki-Woong Lee1, Hwa-Young Bae1, Gyoung-Ja Lee2, Chang-Kyu Kim2, Sung Wook Hong3, Younghwan Kwon4, Doohyun Kim4, Soo Hyung Kim4, Kyo Sik Hwang5, Hyun Jin Kim5, Hyo Jun Ha5, Seung-Hyun Lee5, Chul Jin Choi6 and Ji-Hwan Lee6 Abstract Ethylene glycol (EG)-based zinc oxide (ZnO) nanofluids containing no surfactant have been manufactured by onestep pulsed wire evaporation (PWE) method. Round-robin tests on thermal conductivity. | Lee et al. Nanoscale Research Letters 2011 6 258 http content 6 1 258 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Round-robin test on thermal conductivity measurement of ZnO nanofluids and comparison of experimental results with theoretical bounds Wook-Hyun Lee1 Chang-Kyu Rhee2 Junemo Koo3 Jaekeun Lee4 Seok Pil Jang5 Stephen US Choi6 112 2 3 4 Ki-Woong Lee Hwa-Young Bae Gyoung-Ja Lee Chang-Kyu Kim Sung Wook Hong Younghwan Kwon Doohyun Kim4 Soo Hyung Kim4 Kyo Sik Hwang5 Hyun Jin Kim5 Hyo Jun Ha5 Seung-Hyun Lee5 Chul Jin Choi6 and Ji-Hwan Lee6 Abstract Ethylene glycol EG -based zinc oxide ZnO nanofluids containing no surfactant have been manufactured by one-step pulsed wire evaporation PWE method. Round-robin tests on thermal conductivity measurements of three samples of EG-based ZnO nanofluids have been conducted by five participating labs four using accurate measurement apparatuses developed in house and one using a commercial device. The results have been compared with several theoretical bounds on the effective thermal conductivity of heterogeneous systems. This study convincingly demonstrates that the large enhancements in the thermal conductivities of EG-based ZnO nanofluids tested are beyond the lower and upper bounds calculated using the models of the Maxwell and Nan et al. with and without the interfacial thermal resistance. Introduction Nanofluids a new class of fluids engineered by uniformly dispersing nanostructures such as nanoparticles nanotubes nanorods and nanofibers in base fluids have heat and mass transport properties that are far superior to those of the base fluids. For example a number of research groups presented surprising experimental findings that nanofluids significantly enhance thermal conductivities 1-8 convective heat transfer coefficient 9-13 and heat absorption rate 14 . Therefore these novel nanofluids have the potential to become next-generation coolants and working fluids for
