Viscosity measurements on colloidal dispersions (nanofluids) for heat transfer applications

This article reports viscosity data on a series of colloidal dispersions collected as part of the International Nanofluid Property Benchmark Exercise (INPBE). Data are reported for seven different fluids that include dispersions of metal-oxide nanoparticles in water, and in synthetic oil. These fluids, which are also referred to as ‘nanofluids,’ are currently being researched for their potential to function as heat transfer fluids. In a recently published paper from the INPBE study, thermal conductivity data from more than 30 laboratories around the world were reported and analyzed. Here, we examine the influence of particle shape and concentration on the viscosity of these same nanofluids and compare data to predictions from classical theories on suspension rheology

Very high ethanol productivity in an innovative continuous two-stage bioreactor with cell recycle

International audienceThe performance of an innovative two-stage continuous bioreactor with cell recycle—potentially capable of giving very high ethanol productivity—was investigated. The first stage was dedicated to cell growth, whereas the second stage was dedicated to ethanol production. A high cell density was obtained by an ultrafiltration module coupled to the outlet of the second reactor. A recycle loop from the second stage to the first one was tested to improve cell viability and activity. Cultivations of Saccharomyces cerevisiae in mineral medium on glucose were performed at 30°C and pH 4. At steady state, total biomass concentrations of 59 and 157 gDCW l−1 and ethanol concentrations of 31 and 65 g l−1 were obtained in the first and second stage, respectively. The residual glucose concentration was 73 g l−1 in the first stage and close to zero in the second stage. The present study shows that a very high ethanol productivity (up to 41 g l−1 h−1) can indeed be obtained with complete conversion of the glucose and with a high ethanol titre (8.3°GL) in the two-stage system