A Study of the Critical Heat Flux in an Accelerating Pool Boiling System
A Study of the Critical Heat Flux in an Accelerating Pool Boiling System. Jim Mills Adams
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Author: Jim Mills AdamsDate: 05 May 2012
Publisher: Literary Licensing, LLC
Language: English
Format: Paperback::160 pages
ISBN10: 125832475X
ISBN13: 9781258324759
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Pool boiling heat transfer and critical heat flux enhancement of copper nanoparticles dispersed in distilled water. 12 Pages INTRODUCTION and also trying to enhance the CHF of the boiling system. Boiling heat transfer is used in a variety of indus- Such achievements, is believed to improve process effi- trial processes and applications, such as refrigeration, ciency and reduce operational costs. This On the Mechanism of Pool Boiling Critical Heat Flux Enhancement in Nanofluids Article (PDF Available) in Journal of Heat Transfer 132(6) June 2010 with 2,043 Reads How we measure 'reads' If liquid in a pool boiling system is maintained at a temperature that is less than the saturation temperature, the liquid is said to be subcooled. To what extent is the boiling heat flux influenced the magnitude of the gravitational field. The influence is evident from the appearance of the gravitational acceleration g in q"_min=Cρ_v h_fg [gσ(ρ_l - ρ_v )/(ρ_(l )+ρ_v )^2 ]^(1/4). Dependence for the maximum Pool boiling of distilled and degassed water in an accelerating system was studied means of high speed motion pictures, up to 20,000 frames per sec. The acceleration was produced the centrifuge principle with the heating surface oriented normal to the vectorial sum of the centrifugal acceleration and the gravitational acceleration. The range of experimental variables include: heat flux between 16,000 During the pool boiling heat transfer, the critical heat flux (CHF) of Pt/Alumina in de-ionized water was found to have a two-fold enhancement compared to that of the same Pt bare wire. The CHF Kamel et al. Outlined the latest studies regarding boiling critical heat flux using nanofluids for two types of boiling processes, pool boiling and flow boiling heat transfer of nanofluids. Their review was concise and focused on collecting the latest works related to the experimental investigations of the CHF of nanofluids. Authors outlined and discussed the improvement that PDF | In the present study, reduced graphene oxide (rGO) is synthesized from graphite using modified Hummer and chemical reduction methods. Various characterizations techniques are carried out to Kim HD, Kim MH. Critical heat flux behavior in pool boiling of water-TiO2 nano-fluids. Fourth Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety; November 28 - December 1, 2004; Sapporo, Japan. 2004. Kim S, Bang I, Buongiorno J, Hu L. Surface wettability change during pool boiling of nanofluids and its effect on critical heat flux. investigation on Pool boiling heat transfer over finned tubes was of critical heat flux (CHF) for saturated water boiling on a horizontal were connected with data acquisition system. The Acceleration due to Gravity (ms-2) h. Heat transfer Effect of Rolling Motion on Pool Boiling Critical Heat Flux (CHF) Elvira F. Tanjung, Samah A Albdour, Faraz Aziz, This study is directed at how the rolling motion affected the boiling phenomena and CHF. 2. Experimental Facility and Method A rolling platform system was designed to simulate the ship motion in the ocean. Fig. 1 show the image of the experimental facility. It consists of a rolling platform system, systems for cryogenic propellants and life support fluids, and future power systems. Also imply changes in direction) of the acceleration of gravity around its mean study of fluid behavior and heat transfer will be placed in it. E.g. The Fluid boiling performance nor of critical heat flux in their parabolic flight experiment The extent to which the acceleration of the boiling system is important as a parameter in determining the critical heat flux was ascertained experimentally. A simple centrifugal apparatus is described which was used for determining the critical heat flux in pool boiling to water at atmospheric pressure and accelerations in the range 1 < (a/g boiling heat fluxes are studied with the aid of a centrifuge facility. Several geometries of the transition from film to nucleate boiling provide the basis for acceptance fraction of critical temperature. Fig. Direction of acceleration of the system. 123-131. Kovalev, S.A., "An Investigation of M.inimum Heat Fluxes in. Today's trends for enhancing boiling heat transfer in terrestrial and space Miniaturization of electronic and photonic systems is challenged a dramatic increase Extensive studies of nucleate boiling on small heaters were As the aircraft was accelerating, these tiny bubbles rose to the water surface EXPERIMENTAL STUDY ON CRITICAL HEAT FLUX UNDER ROLLING CONDITION Hwang J.S.*, Lee Y.G., Park I.W. And Park G.C. *Author for correspondence Department of Nuclear Engineering, Seoul National University, Seoul, 151-744, Korea, E-mail: ABSTRACT This paper presents defining characteristics of the critical heat flux (CHF) for the boiling of R-134a in vertical tube operation under Saturated pool boiling heat transfer coefficients and critical heat flux were measured along three downward facing pin fin surfaces in deionized water to study the effects of inclination angle and pin fin structure on the wall superheat and critical heat flux. The key conclusions are as follows: A number of aspects of pool boiling heat transfer and critical heat flux (CHF) characteristics have been studied such as the effect of surface orientation Pumping System. Thermocouples for. Pool gravitational acceleration. [m/sec2] hfg. This paper is the second part of a two-part study on pool boiling critical heat flux (CHF) from flat surfaces. While the first part reviewed different CHF models and associated mechanisms and Study of pool boiling and critical heat flux enhancement in nanofluids Key words: nanofluids, nanoparticle deposition, critical heat flux, pool boiling, wettability, contact angle. 1. Introduction Addition of solid nanoparticles to common fluids such as water is an effective way to increase the Critical Heat Flux (CHF). The resulting colloidal suspensions are known in the literature as nanofluids. Materials phase flow, boiling heat transfer, and the critical heat flux (CHF) of ethanol water mixtures are of critical interest. McGillis et al. [2] explored the experiments using binary mixtures of water with methanol or 2-propanol to determine the CHF in saturated pool boiling. They found that the CHF of the Many theories predicting the critical (or burnout) heat flux in saturation pool boiling have been First Published June 1, 1963 Research Article The extent to which the acceleration of the boiling system is important as a parameter in ABSTRACTIt is traditionally accepted that the critical heat flux (CHF) decreases with increasing nucleation site density (NSD). However, such a CHF-NSD relation was no longer observed in the BETA-B experiment performed on nano-film heaters; instead the increase of NSD resulted in a gain in CHF. To address this seeming contradiction in the relation between critical heat flux and nucleation The long-term goal of WRL is to aid and accelerate the development The finned surfaces extended the base area critical heat flux (CHF) beyond the critical heat Figure 1: Test section and system used in low pressure pool boiling experiments. A much later study investigated saturated nucleate pool boiling of water at. further research is required especially in the area of subcooled departure from nucleate boiling and the related heat transfer mechanisms. Acceleration of gravity proportional critical pressure pressure at T max,r reduced pressure PIP 't cr1 heat flux viii. Units Changes in the system's parameters can effect the classical An experimental study of nanostructure modified nucleation site density and contact angle that significantly enhances the Heat Transfer Coefficient (HTC) and the Critical Heat Flux (CHF) in pool boiling heat transfer of water on copper surfaces has been conducted. Critical heat flux (CHF) in an internally heated annulus. B. CHF Due to Flooding In a pool-boiling system, burnout occurs due to vapor-. A pgD. (8) blanketing Boiling is an important phase change phenomena as it plays a crucial role in the design of high heat flux system like boilers, heat exchangers, microscopic heat transfer devices. However boiling phenomenon is limited critical heat flux. At In this study experiments were carried out uniformly heating a test section (stainless The effects of various parameters of interest (like heat flux, mass flux, system pressure, vapor is termed in the literature as critical heat flux (CHF), dryout or departure from nucleate boiling point. Gravitational acceleration [m/s2]. In the present experimental study, the critical heat flux (CHF) of an oxidized Nucleate pool boiling is known to be a very effective mechanism of phase heat transfer surface is frequently observed in most thermal energy systems. Density, surface tension, and acceleration due to gravity, respectively. Method 2K-Method 3K-Method Flow through Elbow Fluid Acceleration In this chapter, we will study flow boiling in a vertical heated channel. Also on the system parameters such as the pressure and coolant flow rate, In both designs, the nucleate boiling heat flux cannot be increased indefinitely. An analytical model for near-saturated pool boiling critical heat flux on vertical surfaces Article (PDF Available) in International Journal of Heat and Mass Transfer 40(10):2327-2339 July 1997
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