Taking into account the random scatterings due to random eigenfrequencies and random hopping matrices, we obtain the correlation functions for phonon and sound density fluctuations, which yield three and one entropy fluctuation modes at high frequencies, and three and one thermal conductivity at...

A new improved way for the inclusion of the vibrational degrees of freedom into the calculation of the thermal conductivity of dilute gases of diatomic molecules is proposed and has been tested for nitrogen and carbon monoxide. The effective cross-sections needed have been obtained using...

The commercial purity dibromobenzene (DBB) and succinonitrile (SCN) were purified using a columnar distillation system. Thin walled rectangular specimen cells (60–80 μm thick) were fabricated and filled with the purified materials under the vacuum. The specimen cell was placed in a horizontal...

Exfoliated graphite nanoplatelets (xGnP) were applied to enhance the thermal conductivity of polyaniline (PANI) based form-stable phase change materials (PCMs). The xGnP was first dispersed in palmitic acid (PA) uniformly under the assistance of ultra-sonication. The xGnP/PA mixture was then...

For the purposes of enhancing the heat-transfer utility of the heat pipe in a solar collector, the present work attempted to improve nanoparticle dispersion stability by means of a chemical reformation process wherein nanofluid is formulated with hydroxyl radicals combined with oxidized...

The effective thermal conductivity of six vertical closed-loop ground heat exchangers (GHEXs), which were installed in a test bed located in Wonju, South Korea, has been experimentally evaluated by performing in-situ thermal response tests (TRTs). To compare the thermal efficiency of the GHEXs...

The Kelvin line-source equation, used to analyze thermal response tests, describes conductive heat transfer in a homogeneous medium with a constant temperature at infinite boundaries. The equation is based on assumptions that are valid for most ground-coupled heat pump environments with the...

Convection is shown in earlier studies to improve the thermal contact between heat exchanger and borehole wall in water-filled boreholes. This study investigates the effect of convection on the required borehole length for a ground-coupled heat pump installation. Artificial convection was...

In the present study, the performance of a heat pump unit is measured by varying the secondary fluid flow rate and compressor speed. Test results are applied to design the GCHP system, and then the effects of the flow rate and the thermal conductivity on the performance of the system and the...