in order to examine the laminar convective heat transfer of nanofluid, experiments carried out using silver-oil nanofluid in a concentric annulus with outer constant heat flux as boundary condition. silver-oil nanofluid prepared by electrical explosion of wire technique and observed no nanoparticles agglomeration during nanofluid preparation process and carried out experiments. the average size...

Experimental measurements of local heat tra nsfer coefficients and pressure drop are made for forced conv ection boiling and condensation for R134a-oil mixtures inside a horizontal tube. The results are compared with the experime ntal data of pure Rl34a. Average convection boiling and cond ensation heat transfer coefficients decreased about 20% at a 10\ o il mass fraction, and boiling and conde...

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...

In the present study, the local characteristics of pressure drop and heat transfer are investigated experimentally for the condensation of a pure refrigerant R134a in multi-port extruded tubes of 8 channels in 1.36mm hydraulic diameter and 19 channels in 0.80mm hydraulic diameter. The experimental data of frictional pressure drop (F.P.D.) and condensation heat transfer coefficient (H.T.C.) are ...

abstract: in this study, al 2 o 3 /eg and tio 2 /eg nanofluids as coolants have been used in the double-tube heat exchanger. the hot solvent inlet heat exchanger must be cooled down with a specified amount. we can use nanofluids as coolants in the heat exchanger for optimization of the heat transfer area. therefore, the efficacy of nanofluids as coolants is verified. furthermore, flow rate of c...

bubble columns are gas- liquid contactors that are widely used in chemical and bio- chemical industries. high mixing that result in high heat and mass transfer rates are amongst their advantages. heat transfer in a bubble column having a bundle of heaters investigated and the variation of heat transfer coefficient with variation in heaters pitch to diameter ratios in a bundle of heaters reporte...

This paper presents the heat transfer coefficients and the pressure drop measured during HC-600a (Isobutane) condensation inside a brazed plate heat exchanger: the effects of saturation temperature, refrigerant mass flux and vapour super-heating are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low...

in this paper by the introduction of the basic equipment of a solar cooling system, solar hydrogen ammonia refrigeration system as a solar cooling technique will be discussed. using heat collector and absorption refrigeration allows us to use residual heat, for cooling, heating and producing hot water and boiling water .this research focuses on methods of heat transfer from the sun into the gen...