Natural convection inside a horizontal cylinder

Martini, W. R.

doi:10.1002/aic.690060217

Cited by 52 publications

(12 citation statements)

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“…It seems that mass transfer takes place at the surface of the tube mainly through the formation of a laminar boundary layer and a diffusion layer adjacent to the tube wall, the thickness of the hydrodynamic boundary layer and the diffusion layer increases in the upward direction with a consequent decrease in the mass transfer coefficient. The presence of a moving layer at the tube surface agrees with the finding of Martini and Churchill (1960). However when the boundary layer of the right hemicylinder meets with the boundary layer of the left hemicylinder at the top of the tube surface' a downward flow of the two boundary layers takes place into the core of the solution.…”

supporting

confidence: 84%

“…the vorticity would be uniform. Martini and Churchill (1960) presented experimentally determined velocity and temperature profiles for the case of natural convection of air within a horizontal cylinder with the Rayleigh number varied between 2 x lOs and 8 x 10 6 • The authors concluded that (a) most of the flow took place in a narrow ring adjacent to the cylinder wall while the central core of air was essentially stagnant, and (b) within the Rayleigh number range studied, the Nusselt number was found to have a constant value of? Weinbaum (1964) study of temperature and velocity distribution inside horizontal cylinders and found a qualitative agreement with the work of Martini and Churchill.…”

Section: Introductionmentioning

confidence: 97%

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Natural Convection Mass Transfer in Horizontal Tubes

Sedahmed

Shemilt

1983

Chemical Engineering Communications

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supporting

confidence: 84%

Section: Introductionmentioning

confidence: 97%

Natural Convection Mass Transfer in Horizontal Tubes

Sedahmed

Shemilt

1983

Chemical Engineering Communications

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“…He succeeded in solving the energy balance using his own experimental values for the velocity field, but was unable to obtain stable solutions of the mass and momentum balances simultaneously with the energy balance, or even separately using his own experimental values for the temperature field Ž . Martini and Churchill, 1960 . In retrospect that latter failures were a consequence of the choice of inappropriate numerical algorithms, as well as of the limitations of the computer, an IBM650 with magnetic-drum storage that required programming in machine language and input on punched cards.…”

Section: A Chroniclementioning

confidence: 95%

Progress in the thermal sciences: AIChE Institute Lecture

Churchill

2000

AIChE Journal

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Rather than merely sur®eying progress in the prediction of heat transfer o®er the past half century, attention is focused on the factors that ha®e led to significant ad®ances in understanding and practice. An almost one-to-one correspondence is demonstrated between ad®ances in heat transfer and those in computer hardware and software. Howe®er, the de®elopment of specialized algorithms for flow and heat transfer by indi®idual in®estigators appears in most cases to be an essential ingredient. Direct contributions of experimentation are relati®ely minor, but the synergy of combined experimentation and numerical analysis is most often the key to disco®ery and inno®ation. A quiet re®olution has occurred in the form of correlati®e equations, and the primary and almost sole contribution of closed-form analysis has been the deri®ation of asymptotes for that purpose. Finally, progress in heat transfer has occurred primarily in discrete steps, and most often as a consequence of exploratory research andror the obser®ation and pursuit of the explanation for an anomaly. IntroductionThe first Institute Lecture was given at the Annual Meeting in Pittsburgh in 1949 by William H. McAdams and was on the subject of Heat Transfer. I was present at his talk, and the intervening period of 49 years corresponds closely to that of my own career in research and teaching in this very field. In that half of a century, the experimental and analytical advances in heat transfer, per se, have been rather modest but those associated with machine computation have been overwhelming, particularly in heat-exchanger design and the numerical solution of differential and integral models. The net result is a total change in the character of the thermal sciences and their role in our profession. Heat transfer has virtually disappeared as a distinct field of industrial practice and academic research in chemical engineering, but remains a subject of critical importance in traditional chemical and materials processing, as well as in every current new endeavor of chemical engineers from biomedical technology to the manufacture of computer chips. As an example of a traditional application, an endothermic homogeneous reactor may be considered to be essentially a pure heat exchanger in that the rate of reaction is proportional to the rate of heat transfer and nearly independent of the chemical kinetic mechanism.As an example at the modern end of this spectrum of applications, the speed and mechanical design of the largest computers are now limited by the rate of heat removal. For these reasons, heat transfer has rightfully retained a prominent place in the curriculum of chemical engineering.This article describes a few important advances in the past half century that have led to the present state of the thermal sciences, but it is not intended to be a review in the conventional sense. The future is of greater interest than the past, and, as a guideline for the achievement of future advances, I will try to identify what prompted some of those of the recent past....

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“…For example, Refs. [12, 13, 14] consider a horizontal cylinder that is uniformly heated on one horizontal band of the circumference and cooled on the diametrically opposite band; however, the warmer band is either beneath, or opposite to, the cooler band. In contrast, Refs.…”

Section: Sunshine-driven Temperature Gradients and Flowsmentioning

confidence: 99%

Detecting leaks in gas-filled pressure vessels using acoustic resonances

Gillis

Moldover

Mehl³

2016

Review of Scientific Instruments

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We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f2 than by measuring the ratio p/T. Here f is the resonance frequency of an acoustic mode of the gas inside the pressure vessel; p is the pressure of the gas, and T is the kelvin temperature measured at one point in the gas. In general, the resonance frequencies are determined by a mode-dependent, weighted average of the square of the speed-of-sound throughout the volume of the gas. However, the weighting usually has a weak dependence on likely temperature gradients in the gas inside a large pressure vessel. Using the ratio p/f2, we measured a gas leak (dM/dt)/M ≈ −1.3×10−5 h−1= 0.11 year−1 from a 300-liter pressure vessel filled with argon at 450 kPa that was exposed to sunshine-driven temperature and pressure fluctuations as large as (dT/dt)/T ≈ (dp/dt)/p ≈ 5×10−2 h−1 using a 24-hour data record. This leak could not be detected in a 72-hour record of p/T. (Here M is the mass of the gas in the vessel and t is time.)

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Natural convection inside a horizontal cylinder

Cited by 52 publications

References 1 publication

Natural Convection Mass Transfer in Horizontal Tubes

Natural Convection Mass Transfer in Horizontal Tubes

Progress in the thermal sciences: AIChE Institute Lecture

Detecting leaks in gas-filled pressure vessels using acoustic resonances

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