Shell and tube heat exchangers are widely being used in many of industrial and power engineering applications. Different techniques have been employed in order to enhance the performance of the heat exchanger. Air bubble injection is one method to increase the turbulence of the flowing fluids which in turn enhance the heat transfer performance. Injecting air bubbles is one of the promising tech...

In the design of heat exchangers, it is necessary to determine the heat transfer rate between hot and cold fluids in order to calculate the overall heat transfer coefficient and the heat exchanger efficiency. Heat transfer rate can be determined by inverse methods. In this study, the unknown space-time dependent heat flux imposed on the wall of a heat exchanger internal tube is estimated by app...

mixed convection fluid flow and heat transfer of water-al2o3 nanofluid inside a lid-driven square cavity has been examined numerically in order to find the optimal distribution of discrete heat sources on the wall of a cavity. the effects of different heat source length, richardson number and grashof number on optimal heat source location has been investigated. moreover, the average nusselt num...

In this study, for the first time, the heat transfer and the pressure drop of zinc oxide nanoparticles in alternating elliptical axis (AEA) tube have been investigated experimentally. The zinc oxide nanoparticles were at volumetric concentrations 1% and 2%. The base fluid was heat transfer oil and the experiments were conducted at constant wall temperature. Also, the study was done in Reynolds ...

helical coil heat exchangers are widely used in industrial applications ranging fromcryogenic processes, air-conditioning, and nuclear reactors to waste heat recovery due totheir compact size and high heat transfer coefficient. in this kind of heat exchangers, flowand heat transfer are complicated. this paper reports a numerical investigation of theinfluence of different parameters such as coil...

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...

In this paper the heat transfer characteristics of a two-phase closed thermosyphon over a wide range of heat transfer rates, system pressure, aspect ratios and filling ratios were studied. The experiments focused on the boiling and condensation heat transfer characteristics of a thermosyphon with a copper tube having 25 and 32 mm inside and outside diameters. Distilled water was used as the wor...

In this paper the heat transfer characteristics of a two-phase closed thermosyphon over a wide range of heat transfer rates, system pressure, aspect ratios and filling ratios were studied. The experiments focused on the boiling and condensation heat transfer characteristics of the thermosyphon. The experimental boiling and condensation heat transfer coefficients inside the thermosyphon were com...

sometimes the need for non-circular ducts arises in many heat transfer applications because of lower pressure drop of non-circular cross section such as square duct compared to circular tube, particularly in compact heat. but square cross section has poor heat transfer performance and it is expected that using a nanofluid as a new heat transfer media may improve the heat transfer performance of...

the performance of a γ-al 2 o 3 /n-decane nanofluid shell-and-tube heat exchanger in a biomass heating plant is analyzed to specify the optimum condition based on the maximum heat transfer rate and performance index for wide range of nanoparticle volume fraction (0–7%). compared with pure          n-decane, the obtained results in this research show that by using γ-al 2 o 3 /n-decane nanofluid ...