On the combustion of heterogeneous AP/HTPB composite propellants: A review

A new micromechanical formulation based on a unit cell model is developed to predict the effective thermal conductivities of carbon nanotube (CNT)-shape memory polymer (SMP) nanocomposites. Model predictions considering interfacial thermal resistance between the CNT and SMP, agglomerated state of CNTs into the SMP matrix and CNT non-straight shape are in reasonable agreement with the experiment reported in the literature. It is found that the CNT agglomeration must be removed to obtain a maximum level of thermal conductivities of SMP nanocomposites. The effects of volume fraction, diameter, cross-section shape, arrangement type and waviness factors of CNTs as well as interfacial thermal resistance on the axial and transverse thermal conductivities of aligned CNT-reinforced SMP nanocomposites are extensively investigated. The results show that the alignment of CNTs into the SMP nanocomposites along the thermal loading can be an efficient way to dissipate the heat. When the CNT waviness increases, a nonlinear decrease in the axial thermal conductivity is occurred, however, the nanocomposite thermal conductivity along the transverse direction quickly rises. It is observed that the interfacial thermal resistance, cross-section shape and arrangement type of CNTs do not affect the axial thermal conductivity of CNT-SMP nanocomposites. But, the interfacial thermal resistance can play a key role in the transverse nanocomposite thermal conductivity. The present fundamental study is very important for understanding the thermal conducting behavior of CNT-SMP nanocomposites which may have a wide range of applications in temperature sensing elements and biological micro-electro-mechanical systems.

Thermal conductivity of shape memory polymer nanocomposites containing carbon nanotubes: A micromechanical approach

The effects of packing structure on the effective thermal conductivity of granular media: A grain scale investigation

Al2O3/graphene reinforced bio-inspired interlocking polyurethane composites with superior mechanical and thermal properties for solid propulsion fuel

Structural characteristics are considered to be the dominant factors in determining the effective properties of granular media, particularly in the scope of transport phenomena Towards improved heat management, thermal transport in granular media requires an improved fundamental understanding In this study, the effects of packing structure on heat transfer in granular media are evaluated at macro- and grain-scales At the grain-scale, a gas-solid coupling heat transfer model is adapted into a discrete-element-method to simulate this transport phenomenon The numerical framework is validated by experimental data obtained using a plane source technique, and the Smoluschowski effect of the gas phase is found to be captured by this extension By considering packings of spherical SiO2 grains with an interstitial helium phase, vibration induced ordering in granular media is studied, using the simulation methods developed here, to investigate how disorder-to-order transitions of packing structure enhance effective thermal conductivity Grain-scale thermal transport is shown to be influenced by the local neighbourhood configuration of individual grains The formation of an ordered packing structure enhances both global and local thermal transport This study provides a structure approach to explain transport phenomena, which can be applied in properties modification for granular media

Gaurav Rajoriya

Papers

Thermal conductivity estimation of high solid loading particulate composites: A numerical approach

Numerical Method to Estimate Thermal Conductivity of a Model Composite Propellant