# Temperature Dependence of Density and Viscosity of Biobutanol-Gasoline Blends
## 4 Conclusions  
It must be stated that the obtained results, especially the coefficients of the mathematical models, are usable for the advanced numerical modelling of flow properties of biobutanol-gasoline blends; for example, the modelling of the pressure drop, shear stress, maximum and mean flow velocity, volume and mass flow, two-dimensional and three-dimensional velocity profiles, friction factor, laminar and turbulent flow (Reynolds number), etc. The results are certainly applicable in industrial practice. For instance, the models with the coefficients could be used to set a car control unit, which would be able to evaluate the exact amount of fuel needed for injection into the combustion chamber according to the current concentration of the biobutanol in the gasoline (RON 95 and RON 98) and current temperature of the fuel, because, as this paper stated, these can affect the fuel volumetric mass density and the dynamic/kinematic viscosity. It is appropriate to emphasise these research findings:  
* The RON 98 gasoline reaches higher values in the volumetric mass density than the RON 95 gasoline. * The volumetric mass density of the biobutanol-gasoline blends almost linearly (coefficient of exponential model \(b\to 0\)) decreases with an increasing temperature for all concentrations. * The RON 98 gasoline reaches lower values in the dynamic and kinematic viscosity than the RON 95 gasoline. * The dynamic and kinematic viscosity of the biobutanol-gasoline blends nonlinear decreases with an increasing temperature for all concentrations. * The biobutanol-gasoline blends with a higher biobutanol content have higher dynamic and kinematic viscosity values. * The dynamic and kinematic viscosity of the biobutanol-gasoline blends with a content up to 10 vol.% of biobutanol is almost the same as the dynamic and kinematic viscosity of the RON 95 and RON 98 gasolines without a biocomponent (\(p<0.05\)). * The dynamic and kinematic viscosity of the biobutanol-gasoline blends with a content up to 85 vol.% of biobutanol is similar to the dynamic and kinematic viscosity of the pure biobutanol (\(p<0.05\)). Figure 11: Three-dimensional graph created using multivariate polynomial model for kinematic viscosity of biobutanol-gasoline (RON 98) blends. Experimental data are presented as the mean (\(N=20\)) for selected temperatures and concentrations. **Author Contributions:** Conceptualization, D.T. and V.K. ; methodology, D.T., A.P., and V.K. ; software, A.P. ; validation, D.B.N., A.W. ; formal analysis, D.T. ; investigation, D.T. ; resources, V.K. ; data curation, D.B. ; writing--original draft preparation, D.T. ; writing--review and editing, D.B., D.B.N., and A.W. ; supervision, V.K. ; project administration, V.K. ; funding acquisition, D.T. and V.K. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the Internal Grant Agency of the Faculty of AgriSciences no. AF-IGA-2020-IP060. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Data is contained within the article. **Acknowledgments:** Authors would like to acknowledge the LSU AgCenter for the proofreading and scientific collaboration on this manuscript. **Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. **Appendix A**  
**Table A1. Values of volumetric mass density of biobutanol-gasoline (RON 95) blends (mean \(\pm\) Scheme 5). **