Regarding the importance of rheological properties of water based drilling fluids, the effects of silica nanospheres, multiwall carbon nanotubes (MWCNTs) and two types of their hybrid, i.e. H1 (80 wt.% silica nanosphere/20 wt.% MWCNT) and H2 (50 wt.% silica nanosphere/50 wt.% MWCNT) on the viscosity and density of distilled water were investigated. According to the results, viscosity and density of the nanofluids increased with the concentration, while they were reduced by increasing the temperature. At high concentrations, the least increase in the viscosity of distilled water by adding the nanomaterials is related to H2 (8.2% increase at 1.0 wt.%). Likewise, the optimum operating temperature at higher concentrations was 20 C. As the results show, increase in the density of distilled water by adding the nanomaterials is insignificant, that in the worst case it did not exceed 0.9%. The least increase in the density of base fluid at high concentrations was for H1. 

In this paper, thermal analysis method (TGA) was adopted to describe the combustion behavior of bituminous coal(GC), anthracite(LC), biomass(PS) and plastic(PVC).The structure characteristics of these samples were carried out using Raman spectroscope followed by peak deconvolution and data analysis. The kinetic parameters and combustion reaction mechanism were obtained by fitting experimental data with the random nucleation nuclei growth model (RNGM) and volume model (VM) in order to find out the kinetics characteristics responsible for the combustion of the samples. The results indicate that significant difference between combustion process of these samples are mainly attributed to their differences structures, the combustion reactivity of PS is better than GC duo to the catalysis of alkali matter in biomass ash. RNGM model is better than VM model for simulating the combustion process, and TRNGM model plays a good performance in depicting the combustion process of PVC with three reaction stages.