The flow and heat transfer characteristics of TiO2-water nanofluids with different nanoparticle mass fractions in a spirally fluted tube and a smooth tube are experimentally investigated at different Reynolds numbers. The effects of pH values and doses of dispersant agent on the stability of TiO2-water nanofluids are discussed. The effects of nanoparticle mass fractions and Reynolds numbers on ...

In the present study, the effect of various nanofluids on mass transfer coefficients in an irregular packed liquid-liquid extraction column was investigated. The chemical system of toluene–acetic acid–water was used. 10 nm SiO2, TiO2 and ZrO2 nanoparticles with various concentrations were dispersed in toluene-acid acetic to provide nanofluids. The influence of concentration and hydrophobicity/h...

thermal resistance of the external walls of buildings is highly important for reducing and optimizing the energy consumption needed for heating and cooling the buildings. identifying and evaluation of the thermal performance of common external wall systems can be very effective in improving the heat resistance. the hollow clay- block system extremely are in use in the iran construction system, ...

In order to improve the efficiency and rate of heat transfer in heat exchangers, various techniques such as increasing the heat transfer coefficient are proposed. This study is devoted to the investigation of heat transfer coefficient variations due to the addition of CuO, TiO2 and CuO/TiO2 nanoparticles into a shell and tube heat exchanger. CuO/TiO2 nanocomposite was synthesized using mechanic...

Using the analogy between heat and mass transfer processes, the recently developed entransy theory is extended in this paper to tackle the coupled heat and mass transfer processes so as to analyze and optimize the performance of evaporative cooling systems. We first introduce a few new concepts including the moisture entransy, moisture entransy dissipation, and the thermal resistance in terms o...

ethylene was polymerized in slurry phase over a ticl4/mg(oc2h5)2 catalyst activated by al(c2h5)3. it was shown experimentally that mass transfer resistance has no effect on polymerization kinetics. after estimation ofthe active site concentration by inhibition method with carbon monoxide, the effects of polymerization temperature, monomer and cocatalyst  oncentrations and hydrogen were investig...

Variability in the cultivated germplasm for economic traits such as resistance to rice tungro virus, sheathblight, yellow stem borer, drought and salt tolerance is limited. This necessitated search for the genes in secondary and tertiary gene pool of genus Oryza. Fortunately, wild species are an important reservoir ofuseful genes for resistance to major disease, pest and tolerance t...

In this research, the thermodynamics and mass transfer of CO2 absorption has been studied in a mixture of MDEA-MEA amines. A relation is presented for mass transfer flux in the reactive-absorption process. For this purpose, the effective parameters on the mass transfer flux were investigated in both liquid and gas phases. Then, using dimensional analysis with the Pi-Buckingham theorem, the effe...

an investigation on the thermal performance of the soil as geothermal heat energy storage medium has been conducted. the thermal characteristics of the soil storage and the heat transfer from a heat exchanger in the soil, surrounding and bottom surface will be discussed. this investigation forms a contribution to a project to realize such storage to be charged from a solar heating system. this ...

liquid membrane processes have attracted many interests in recent years for removal of heavy metals such as cadmium from industrial wastewaters. in this study, a modified hybrid liquid membrane system is introduced. the setup is worked by applying the water-insoluble dioctyl phthalate as the organic solvent. n-octanol and tetra butyl ammonium bromide are added to the organic phase to increase t...