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.

Condensing heat transfer within horizontal tubes

Abstract: The effects of vapor velocity, liquid loading, and physicai properties of the fluid on the condensing coefficient of a vapor in a horizontal tube were investigated. The data, presented in graphs, were obtained in tests in which the aversge condensing coefficient was determined as a function of the mass flow of the vapor in the tube at constant tube wall temperature and constant pressure. (J.R.D.)

On the Dynamics and Energy Transformations in Steady‐State Hurricanes

Abstract: A dynamic model of the inflow layer in a steady mature hurricane is evolved, relating wind speed, pressure gradient, surface shearing stress, mass flow, and convergence. The low-level air trajectories are assumed to be logarithmic spirals. With this hypothesis, properties such as maximum wind and central pressure are determined through choice of a parameter depending on the inflow angle: a moderate hurricane arises with inflow angles of about 20°, while 25° gives an intense or extreme storm. Most of this study treats the moderate storm. In order to maintain its core pressure gradients, an oceanic source of sensible and latent heat is required. As a result, latent heat release in the inner hurricane area occurs at higher heat content (warmer moist adiabats) than mean tropical subcloud air. The heat transfer from the ocean and the release of latent heat in the core determine the pressure gradient along the trajectory, and this prescribes the particular trajectory selected by the air among an infinite number available from the logarithmic spiral family. This selection principle is evolved using recent work on “relative stability” of finite amplitude thermal circulations. Of an infinite number of dynamically possible spirals, the one is realized which maximizes the rate of kinetic energy production under the thermodynamic constraints, here formulated in terms of the relation between heat release and pressure gradient. Finally, rainfall, efficiency of work done by the storm, and kinetic energy budgets are examined in an attempt to understand the difference between the hurricane—a rare phenomenon—and the common sub-hurricane tropical storm. DOI: 10.1111/j.2153-3490.1960.tb01279.x

Fundamentals of heat and mass transfer, 2nd edition

Abstract: This text introduces the physical effects underlying heat and mass transfer phenomena and develops methodologies for solving a variety of real-world problems. It emphasizes the importance of conservation principles, particularly the first law of thermodynamics, in heat transfer analysis, and has been expanded to encompass principles and problems in mass transfer. Includes numerous examples and problems.

Spin-boson thermal rectifier.

Abstract: The heat conduction properties of nanojunctions attract attention for two reasons. First, heating in nanoconductors, a crucial issue for their operation and stability, is determined by both heat release and conduction in such systems. Secondly, as with electronic conduction, the restrictive geometry raises fundamental questions concerning the relationship between transport processes in microscopic systems and their macroscopic counterparts. Indeed thermal transport properties of nanowires can be very different from the corresponding bulk properties as is demonstrated by the recent confirmation [1] of the prediction [2] that the low temperature ballistic phonon conductance in a one-dimensional quantum wire is characterized by a universal quantum unit. Also of considerable interest are studies that confront the macroscopic Fourier law, J � � KrT, that connects the heat current J to the temperature gradient rT and defines the thermal conductance K, with heat transport on the microscopic scale. Harmonic chains were repeatedly discussed theoretically in these contexts and considerable experimental progress was also made [1]. For reviews see Refs. [3,4]. An intriguing mode of behavior of transport devices is current rectification, allowing larger conduction in one direction than in the opposite one when driven far enough from equilibrium. Such phenomena were extensively studied for electronic conduction in molecular junctions, but much less so for thermal nanoconductors. For a harmonic thermal conductor connecting (by linear coupling) two [left (L), right (R)] harmonic thermal reservoirs that are maintained at equilibrium with the temperatures TL and TR, respectively, heat transfer is a ballistic process and the heat current J can be recast into a Landauer-type expression [2] J �