Heat Transfer Characteristics Of Materials Research Articles

Heat transfer behavior of as-processed and cleaned picosecond pulse laser processed copper

Improving the heat transfer characteristics of materials can be accomplished by increasing the surface area. This surface roughening can be accomplished efficiently and directly using pulsed-laser processing. Here, laser processing of copper using a picosecond laser pulse technique produced mound-like structures, with surface morphologies and subsurface microstructures dependent on laser pulse count, with higher pulse counts producing a unique layering of Cu and Cu2O in the mounds. Processing in ambient air resulted in the formation of surface oxides. The presence of oxides deleteriously influenced the heat transfer characteristics, with a lower heat transfer coefficient compared to unprocessed Cu. To remove the oxidation, the laser-processed copper was subjected to different acid treatments. It was found that treatment using citric acid resulted in efficient and effective removal of oxides both surface and subsurface. For low pulse count samples, an improvement in the heat transfer characteristics was observed after oxide removal, and outperformed the polished reference sample at heat fluxes above approximately 90 W/cm2. However, the removal of oxides using citric acid was found to actually decrease heat transfer characteristics for high pulse count samples with the onion-like subsurface layers, as oxide removal left behind voids in the structure which were detrimental to heat transfer. Thus, optimized laser surface processing which avoids subsurface onion-like layer formation enhances heat transfer performance.

Impact of the carbon nanotube reinforcement in glass/epoxy polymeric nanocomposite on the quality of fiber laser drilling

In this work, the influence of multi-walled carbon nanotube is presented on laser drilling of multi-walled carbon nanotube–doped glass/epoxy polymeric nanocomposite. Multi-walled carbon nanotubes were dispersed in polymer matrix to improve the thermal conductivity and heat transfer characteristics of materials, which also reduces the divergence in decomposition temperature of matrix and glass fiber. Effect of carbon nanotube on laser drilling–induced damages was assessed by considering heat-affected zone, taper angle, and surface roughness as output parameters. Scanning acoustic microscopy showed the useful technique to examine the laser drilling damage around the hole by providing ply-by-ply damage analysis. In addition, scanning electron microscope provided more details to better analyze the machining quality of laser-drilled hole. Energy dispersive X-ray analysis provided the elemental analysis of charred material which is deposited on the hole wall. Obtained results indicate that the quality of hole was improved significantly due to addition of multi-walled carbon nanotube in polymer matrix.

Review of Materials for Energy Saving Technology

During the last 20 years, interest in the closed adsorption heat pump and refrigeration systems has increased steadily. In this paper, consideration is given to aspects of adsorption refrigeration in terms of existing materials used in adsorption refrigeration, heat transfer characteristics of materials, and cost of materials and manufacturing. The heat and mass transfer play very important roles in improving the cycle performances and their optimization is one of the technological challenges in developing adsorptionrefrigeration systems. In order to optimize an adsorber it is essential to control unconsolidated adsorbers; coated adsorbers and consolidated adsorbers. The paper is a general review of adsorption refrigeration technology and provides information of value to those involved with heat pump and refrigeration systems technology.

Review of materials for adsorption refrigeration technology

PurposeDuring the last 20 years, interest in the closed adsorption heat pump and refrigeration systems has increased steadily. In this paper, consideration is given to aspects of adsorption refrigeration in terms of existing materials used in adsorption refrigeration, heat transfer characteristics of materials, and cost of materials and manufacturing.Design/methodology/approachThe paper is a general review of adsorption refrigeration technology.FindingsIn recent years several papers have been published in this area and many aspects of the system have been addressed. Much effort has been devoted to enhance materials properties.Originality/valueThe paper provides information of value to those involved with heat pump and refrigeration systems technology.