Search Results
specific energy, J/kg; T is the temperature, K; μ is the dynamic viscosity, kg/(m/s), τ ¯ ij is the averaged Reynolds stress for components, c p is the heat capacity at constant pressure, J/(kg/K), λ is the thermal conductivity, W/(m/K); δ ij is the
, good formability, and high electrical and thermal conductivities [ 2–4 ]. The strength of heat treatable Al-alloys can be improved by precipitation hardening which consists of three basic steps namely: solution heat treating, quenching, and aging. In
Thermal conductivity (W/m −1 ·°C) ρ Density (Kg/m −3
Organic polymers - carbon nanotubes nanocomposites are synthesized either by mechanical mixing of the two components or by covalently linking the nanotubes to the matrix. The various procedures will be overviewed and the determining factors will be identified for the best mechanical properties of the composites. On the other hand, it will be shown that for highest electrical conductivity much smaller amounts of carbon nanotubes are needed if the nanotubes can be aligned. The thermal conductivity of the nanocomposites will also be overviewed. Finally, together with nanoclay particles, nanotubes are inducing remarkable flame retardant properties in the nanocomposites materials.
Recently developed approaches to droplet and spray modeling in computational fluid dynamics (CFD) codes are reviewed. It is emphasized that the modeling of spray primary break-up needs to take into account the transient nature of sprays, while the modeling of droplet heating and evaporation needs to take into account a number of factors, including recirculation and finite thermal conductivity of liquid, semi-transparency of droplets and the kinetic effects. This modeling needs to take place in realistic three-dimensional enclosures, which makes it essential to find a compromise between the accuracy of the models and their CPU efficiency.
This article concerning natural cellulose fibers as reinforcement in composite materials in civil engineering. In this paper, the attention is given to industrial hemp specifically to the woody part of hemp plant called hemp hurds. The properties of natural fibers are mainly determined by the chemical and physical composition, such as structure of fibers.
The objective of presented research is to characterize raw and physically treated hemp fibers using Fourier transform infrared spectroscopy method. These natural fibers were used as filler into biocomposites and MgO-cement was used as alternative binder. Physico — mechanical properties (compressive strength, thermal conductivity, absorbability) of prepared composites were determined.
Samples of surimi were prepared under laboratory conditions from Adriatic pilchard ( Sardina pilchardus). Water content in surimi was 81.5% before mixing with NaCl and &-carrageenan, which were added in the range of mass fraction from 0 to 10%. Relative apparent specific enthalpy ( H -), initial freezing point T i, density p and thermal conductivity k of surimi in the temperature range from -25 °C to 10 °C were determined by differential thermal analysis (DTA), gravimetric method and line-heat source technique, respectively. For determination of relative apparent specific enthalpy ( H -) the mathematical model of enthalpy based on orthogonal collocation approximation of DTA was applied. Redistributions of apparent enthalpy in the freezing range as functions of mass fractions of added substances were determined. Increase of mass fraction of added substances resulted in the increase of mass fraction of bound (unfreezable) water and lowered initial freezing point T i, which has effects on the decrease of thermal conductivity k and increase of apparent specific enthalpy ( H -) in the temperature range from -25 °C to T i . This effect was more pronounced for samples where surimi was mixed with NaCl.
, http://wpif.org.uk/uploads/PanelGuide/PanelGuide_2014_Annex2B.pdf, (last visited 20 December 2017). [12] Thermal conductivity of common materials and gases, The Engineering ToolBox, 2017, https://www.engineeringtoolbox.com/thermal-conductivity
In this paper, the effect of mean particle length of hemp hurds on compressive strength and other parameters of fibrous-composites is studied. Hemp hurds of various origin (Hungarohemp LTd, Nagylak, Hungary; Hempflax, Netherlands) with a wide particle size distribution were used in the experiments. Six samples of hemp hurds with various mean particle length (from 7.3 mm to 39.9 mm) were used for the preparation of fibrous composites based on MgO-cement as a binder. Bulk density, compressive strength, thermal conductivity and water absorbability of fibrous composites after 28 days of hardening were tested. The impact of men particle length of hemp hurds slices on values of bulk density, compressive strength and water absorbability of hardened composites was confirmed.
measuring the thermal conductivity of nano-fluids , A Review, Renewable and Sustainable Energy Reviews , Vol. 14 , No. 7 , 2010 , pp. 1913 - 1924 . [18] Koniorczyk
