Two-phase heat transfer coefficients for internal flows play a critical role in the design and analysis of evaporators and condensers. Previous studies propose empirical relations that combine the effects of nucleate and convective boiling onto the overall heat transfer coefficient. Although these relatively simple empirical relations offer physical insight on the nucleation, boiling and flow p...

This paper examines the forced convection flow of incompressible, electrically conducting viscous fluid past a sharp wedge in the presence of heat generation or absorption with an applied magnetic field. The system of partial differential equations governing Falkner Skan wedge flow and heat transfer is first transformed into a system of ordinary differential equations using similarity transform...

This work experimentally studied the convective flow and heat transfer characteristics of a novel nanostructured heat transfer fluid: "ethanol/polyalphaolefin nanoemulsion" flowing through 12 circular minichannels of 1-mm diameter each. Ethanol/polyalphaolefin nanoemulsion is a thermodynamically stable system formed by dispersing ethanol into a mixture of "polyalphaolefin (PAO)" and surfactants...

This paper presents simulations of the integral coefficients of performance of a heat pump system coupled with a vertical ground heat exchanger (GHE). The GHE is simulated using different assumptions concerning the heat transfer in the ground, heat exchange between the ground and the brine and vertical variation of the brine temperature. The differences in the predicted performance coefficients...

The enhancement of boiling heat transfer, the most powerful energy-transferring technology, will lead to milestones in the development of high-efficiency, next-generation energy systems. Perceiving nano-inspired interface functionalities from their rough morphologies, we demonstrate interface-induced liquid refreshing is essential to improve heat transfer by intrinsically avoiding Leidenfrost p...

A two-phase flow experiment using air and water-based γ-Al2O3 nanofluid was conducted to observe the basic hydraulic phenomenon of nanofluids. The local two-phase flow parameters were measured with a conductivity double-sensor two-phase void meter. The void fraction, interfacial velocity, interfacial area concentration, and mean bubble diameter were evaluated, and all of those results using the...

This second part of a two-part study concerns heat transfer characteristics for FC-72 condensing along parallel, square micro-channels with a hydraulic diameter of 1 mm, which were formed in the top surface of a solid copper plate. Heat from the condensing flow was rejected to a counter flow of water through channels brazed to the underside of the copper plate. The FC-72 condensation heat trans...

Nucleate pool boiling heat transfer coefficients of Al2O3-water and TiO2-water nanofluids have been experimentally measured on three horizontal tubes with different materials and similar roughness under atmospheric pressure. Results revealed that the presence of nanoparticles in the base fluid leads to an increase in pool boiling heat transfer coefficients on stainless steel and brass tubes in ...

the forced convection heat transfer of turbulent al2o3-water nanofluid flow inside the grooved tubeswith the different aspect ratio of the rectangular grooves is numerically investigated. the governingequations have been solved using finite volume method (fvm) coupled with simple algorithm. it isassumed the heat flux is constant on the grooved walls. the single-phase approach is applied for the...