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Silicone elastomer (SiR) nanocomposites were prepared using multiwalled carbon nanotubes (MWCNT) and nano-graphite (NG). The morphology of the SiR nanocomposites has been studied using scanning electron microscopy and high-resolution transmission electron microscopy techniques. Detailed analysis of the morphology reveals a uniform distribution of the MWCNT and NG filler particles in the silicone matrix. On increasing the filler loading, a continuous network structure is formed and aggregation takes place. The effect of the MWCNT and NG loadings on the thermal properties of the silicone elastomer has been investigated. The thermal properties of the SiR nanocomposites were measured by a thermal properties analyzer based on the transient hot-wire method. Studies also suggest that incorporation of nanoparticles improves the thermal conductivity of SiR nanocomposites. The thermal conductivity of SiR nanocomposites increased from 0.200 W/(m K) to 0.440 W/(m K) and to 0.310 W/(m K) for 6 wt% MWCNT and NG loadings, respectively. Because of the positive temperature coefficient and the conductive nature of the nanoparticles, the thermal conductivity of the material increased on increasing the temperature. The thermal diffusivity and the volumetric heat capacity of the SiR nanocomposites were measured. The thermal diffusivity of the SiR nanocomposites increased from 0.1194 mm2/s to 0.3209 mm2/s and to 0.2050 mm2/s for 6 wt% MWCNT and NG loadings, respectively. This indicates that the temperature response becomes faster with MWCNT and NG loadings. The volumetric heat capacity of the silicone elastomer nanocomposites decreased from 1.80 MJ/(m3K) to 1.34 MJ/(m3K) and to 1.40 MJ/(m3K) for 6 wt% MWCNT and NG loadings, respectively. Thus, MWCNT particles are more effective in increasing the thermal conductivity and diffusivity of the SiR nanocomposites, when compared to NG fillers at any loading.

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The present work aims at investigating the performanθe of exponential annular fins of θonstant weight made of funθtionally graded materials FGM . The work involves θom-putation of effiθienθy and effeθtiveness of suθh fins and θompares the fin performanθes for different exponential profiles and grading parameters, keeping the weight of the fin θonstant. The funθtional grading of thermal θonduθtivity is assumed to ηe a power funθ-tion of radial θo-ordinate whiθh θonsists of parameters, namely grading parameters, varying whiθh different grading θomηinations θan ηe investigated. Fin material density is assumed to ηe θonstant and temperature gradient exists only along the radial direθtion. The θonveθtive θoeffiθient ηetween the fin surfaθe and the environment is also assumed to ηe θonstant. A general seθond-order governing differential equation has ηeen derived for all the profiles and material grading. The effiθienθy and effeθtiveness of the annular fin of different geometry and grading θomηinations have ηeen θalθulated and plotted and the results reveal the dependenθe of thermal ηehavior on geometry and grading parameter. The effeθt of variation of grading parameters on fin effiθienθy and effeθtiveness is reported. The results are provided in the form of -D graphs, whiθh θan ηe used as design monograms for further use.

Adsorption refrigeration, being a unique and eco-friendly technology, has gained popularity over conventional refrigeration systems. The present study is aimed at developing an annular finned tube adsorber model which serves as a thermal compressor in adsorption refrigeration systems. The mathematical model is addressed numerically using finite difference discretization method and explicit scheme was used for the solution. The generalized model has been simulated for activated carbon–methanol working pair. The system has an optimum cycle time of 1800s. It was found to have a highest refrigeration capacity of 260.66 kJ/kg at a regeneration temperature of 393 K and evaporator temperature of 283 K. The highest COP (Coefficient of Performance) achieved by the system is 0.3706 at a regeneration temperature of 353 K and evaporator temperature of 283 K. A highest SCP (Specific Cooling Power) of 144.8 W/kg was obtained at an evaporator temperature of 283 K and regeneration temperature of 393 K.