Heat transfer

About: Heat transfer is a research topic. Over the lifetime, 181795 publications have been published within this topic receiving 2923586 citations. The topic is also known as: heat exchange.

Darryl E. Metzger Memorial Session Paper: Experimental Heat Transfer and Friction in Channels Roughened With Angled, V-Shaped, and Discrete Ribs on Two Opposite Walls

Abstract: Experimental investigations have shown that the enhancement in heat transfer coefficients for air flow in a channel roughened with angled ribs is on the average higher than that roughened with 90 deg ribs of the same geometry. Secondary flows generated by the angled ribs are believed to be responsible for these higher heat transfer coefficients. In an effort basically to double the area of high heat transfer coefficients, the angled rib is broken at the center to form a V-shaped rib, and tests are conducted to investigate the resulting heat transfer coefficients and friction factors. Three different square rib geometries, corresponding to blockage ratios of 0.083, 0.125, and 0.167, with a fixed pitch-to-height ratio of 10, mounted on two opposite walls of a square channel in a staggered configuration, are tested in a stationary channel for 5,000 < Re < 30,000. Heat transfer coefficients, friction factors, and thermal performances are compared with those of 90 deg, 45 deg, and discrete angled ribs. The V-shaped ribs are tested for both pointing upstream and downstream of the main flow. Test results show that: (a) 90 deg ribs represent the lowest thermal performance, based on the same pumping power, and is essentially themore » same for the 2:1 change in blockage ratio, (b) low-blockage-ratio (E/D{sub h} = 0.083) V-shaped ribs pointing downstream produced the highest heat transfer enhancement and friction factors. Among all other geometries with blockage ratios of 0.125 and 0.167, 45 deg ribs showed the highest heat transfer enhancements with friction factors less than those of V-shaped ribs, (c) thermal performance of 45 deg ribs and the lowest blockage discrete ribs are among the highest of the geometries tested in this investigation, and (d) discrete angled ribs, although inferior to 45 deg and V-shaped ribs, produce much higher heat transfer coefficients and lower friction factors compared to 90 deg ribs.« less

Enhancement of Heat Transfer by Ultrasound: Review and Recent Advances

Abstract: This paper summarizes some applications of ultrasonic vibrations regarding heat transfer enhancement techniques. Research literature is reviewed, with special attention to examples for which ultrasonic technology was used alongside a conventional heat transfer process in order to enhance it. In several industrial applications, the use of ultrasound is often a way to increase productivity in the process itself, but also to take advantage of various subsequent phenomena. The relevant example brought forward here concerns heat exchangers, where it was found that ultrasound not only increases heat transfer rates, but might also be a solution to fouling reduction.

Engineering Heat Transfer

Abstract: Fundamental Concepts Mechanisms of Heat Transfer Dimensions and Units Fourier's Law of Heat Conduction Thermal Conductivity Convection Heat Transfer Convection Heat-Transfer Coefficient Radiation Heat Transfer Emissivity and Other Radiative Properties Combined Heat-Transfer Mechanisms Steady-State Conduction in One Dimension One-Dimensional Conduction Equation Plane Geometry Systems Polar Cylindrical Geometry Systems Spherical Geometry Systems Thermal Contact Resistance Heat Transfer from Extended Surfaces Steady-State Conduction in Multiple Dimensions General Conduction Equation Analytical Method of Solution Graphical Method of Solution Conduction Shape Factor Solution by Numerical Methods (Finite Differences) Numerical Method of Solution for Two-Dimensional Problems Methods of Solving Simultaneous Equations Unsteady-State Heat Conduction Systems with Negligible Internal Resistance Systems with Finite Internal and Surface Resistances Solutions to Multidimensional Geometry Systems Approximate Methods of Solution to Transient-Conduction Problems Introduction to Convection Fluid Properties Characteristics of Fluid Flow Equations of Fluid Mechanics Thermal-Energy Equation Applications to Laminar Flows Applications to Turbulent Flows Natural-Convection Problem Dimensional Analysis Convection Heat Transfer in a Closed Conduit Heat Transfer to and from Laminar Flow in Circular Conduit Heat Transfer to and from Turbulent Flow in Circular Conduit Heat-Transfer Correlations for Flow in Noncircular Ducts Convection Heat Transfer in Flows Past Immersed Bodies Boundary-Layer Flow Turbulent Flow over Flat Plate Flow Past Various Two-Dimensional Bodies Flow Past a Bank of Tubes Flow Past a Sphere Natural-Convection Systems Natural Convection on a Vertical Surface: Laminar Flow Natural Convection on a Vertical Surface: Transition and Turbulence Natural Convection on an Inclined Flat Plate Natural Convection on a Horizontal Flat Surface Natural Convection on Cylinders Natural Convection around Spheres and Blocks Natural Convection about an Array of Fins Combined Forced- and Natural-Convection Systems Heat Exchangers Double-Pipe Heat Exchangers Shell-and-Tube Heat Exchangers Effectiveness-Number of Transfer Units Method of Analysis Crossflow Heat Exchangers Efficiency of a Heat Exchanger Condensation and Vaporization Heat Transfer Condensation Heat Transfer Boiling Heat Transfer Introduction to Radiation Heat Transfer Electromagnetic Radiation Spectrum Emission and Absorption at the Surface of an Opaque Solid Radiation Intensity Irradiation and Radiosity Radiation Laws Characteristics of Real Surfaces Radiation Heat Transfer between Surfaces View Factor Methods for Evaluating View Factors Radiation Heat Transfer within Enclosure of Black Surfaces Radiation Heat Transfer within an Enclosure of Diff use-Gray Surfaces Bibliography and Selected References Appendices Index