Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : thermal conductivity


Thermal Investigations of Double Pass Solar Air Heater with Two Types of Porous Media of Different Thermal Conductivity

Jalal M. Jalil; Shrooq J. Ali

Engineering and Technology Journal, 2021, Volume 39, Issue 1A, Pages 79-88
DOI: 10.30684/etj.v39i1A.1704

This study describes an experimental investigation of the thermal efficiency of stainless steel mesh and steel wool as a porous medium in the lower channel of a double pass solar air heater. An experimental setup was planned and developed. Various types of porous media with high thermal conductivity and with different porosities have been tested. The effects of the porosity of wire mesh, the thermal conductivity of porous media, mass flow rate, and the intensity of radiation have been studied. Experimental results show that thermal efficiency with using porous media is greater than without using porous media. When used steel wool as a porous medium, the thermal efficiency reached 79.82 percent while it can be achieved 76. The percent by using stainless mesh as porous material. The reduction in porosity increasing thermal efficiency. The thermal efficiency of multi-pass solar air collector when used steel wool as porous media is 6, 12.6 and31.7percent higher than without porous media at porosity 98.75, 97.5, and 96.25percent. While it can increase 8.1 and 28.5 percent at porosity 97.875 and 95.75 percent when using stainless steel as porous media.

Manufacturing of Thermal and Acoustic Insulation From (Polymer Blend/Recycled Natural Fibers)

Huda. M. khdier; Ahmed Hussein; Wafaa M. Salih

Engineering and Technology Journal, 2020, Volume 38, Issue 12, Pages 1801-1807
DOI: 10.30684/etj.v38i12A.1509

These works study the characterization of thermal and acoustic insulation behavior of Polymer Blend/Recycled Natural Fibers. Acoustic insulation is an important property in design criterion in buildings and used to avoid the damage caused by the sounds of the explosion of rockets and bombs. This work is done through reinforcing 80% epoxy resin EP with 20% polycarbonate PC with two different recycled natural fiber RNF (hemp fiber H.F., cornhusk fiber C.H.F) at various weight fractions of (2,4,6) %, the samples, were formed by hand lay-up then the acoustic and thermal insulation tests carried out. The results show that altering both kinds of RNF can improve acoustic insulation. Also, it could be noticed that sound insulation efficiency can improve with increasing RNF weight fraction. Finally, the optimum results got at 6% hemp composite that shows better acoustic insulation than cornhusk composites. The thermal conductivity improved by increasing the fiber weight fraction. The maximum value of thermal conductivity for composite samples with (H.F., C.H.F) fibers at (6% wt) equal to (0.71609W/m. Kº) and (0.73686W/m. Kº), respectively. The composite samples with C.H.F. fibers have slightly higher thermal conductivity value than composite samples with H.F.

A Study of Some Mechanical and Physical Properties for Palm Fiber/Polyester Composite

Samah M. Hussein

Engineering and Technology Journal, 2020, Volume 38, Issue 3B, Pages 104-114
DOI: 10.30684/etj.v38i3B.598

This research has been done by reinforcing the matrix (unsaturated polyester) resin with natural material (date palm fiber (DPF)). The fibers were exposure to alkali treatment before reinforcement. The samples have been prepared by using hand lay-up technique with fiber volume fraction of (10%, 20% and 30%). After preparation of the mechanical and physical properties have been studied such as, compression, flexural, impact strength, thermal conductivity, Dielectric constant and dielectric strength. The polyester composite reinforced with date palm fiber at volume fraction (10% and 20%) has good mechanical properties rather than pure unsaturated polyester material, while the composite reinforced with 30% Vf present poor mechanical properties. Thermal conductivity results indicated insulator composite behavior. The effect of present fiber polar group induces of decreasing in dielectric strength, and increasing dielectric constant. The reinforcement composite 20% Vf showed the best results in mechanical, thermal and electrical properties.

Recycling of Waste Paraffin Wax by the Addition of SiO2 Nano-Powders to Improve Thermal Conductivity

Aseel B. Al-Zubaidi

Engineering and Technology Journal, 2019, Volume 37, Issue 9A, Pages 369-373
DOI: 10.30684/etj.37.9A.4

Paraffin wax is an important material used in thermal energy storage (TES) systems. The thermal conductivity of the material is an important parameter that decides the degree of exploitation of the paraffin wax in TES systems. The thermal conductivity is improved by the addition of silicon oxide nanoparticles (1%, 2%, 4%, and 6%) to the paraffin wax. The average size of the SiO2 particles is equal to 38 nm. The addition of SiO2 nano-particles at very small ratios was found to enhance the thermal conductivity of the paraffin wax considerably. SiO2 nanoparticles, add to paraffin wax, have a significant effect in enhancing the thermal storage characteristics of paraffin
Paraffin wax is an important material used in thermal energy storage
(TES) systems. The thermal conductivity of the material is an important
parameter
that
decides the degree of exploitation of the paraffin wax in TES
systems. The thermal conductivity is improved by the addition of silicon oxide
nanoparticles (1%, 2%, 4
%,
and 6%) to the paraffin wax. The average size of the
SiO
2
particles is equal to 38 nm. The a
ddition
of SiO
2
nano
-particles at very
small ratios was found to enhance the thermal conductivi
ty of the paraffin wax
considerably. SiO
2
nanoparticles, add to paraffin wax, have
a significant effect
in enhancing the thermal storage characteristics of paraffin

Improvement of The Mechanical and Thermal Properties of Clay Bricks by Using Local Materials in Iraq

Haqi Ismael Qatta

Engineering and Technology Journal, 2012, Volume 30, Issue 19, Pages 3308-3327

This research studies the effect of adding industrial wastes materials with
different percentages on the thermal and mechanical properties of clay
bricks . Different types of admixtures were used in this work, including
rubber cuttings, wood saw dust and barley reeds ash with ( 5%,10% 15%
,20% ) by weight of each one respectively. Thermal conductivity, specific heat
capacity, compressive strength, flexural tensile strength, porosity and variation
of density have been examined for each samples at all percent of addition
and comparing with the reference clay bricks samples . Test results show that
the admixtures effect on the properties of clay bricks, when used barley reeds
ash which the best additives because take good properties, the density of clay
bricks is reduced 33%,thermal conductivity reduced 46% and the compressive
strength increased 20% comparing with the standard bricks. The experimental
work carried in the industrial factory of clay bricks in the Nahrawon city in
Baghdad.