Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Heat transfer to impinging isothermal gas and flame jets

https://seniordesign.engr.uidaho.edu/2006_2007/am2/experimental%20_and_numerical_study_of_pressure_drop_and_heat_transfer_in_a_single-phase_micro-channel_heat_sink.pdf

Experimental and numerical study of pressure drop and heat transfer in a single-phase micro-channel heat sink

Advanced models of fuel droplet heating and evaporation

Publisher Summary This chapter presents a discussion on jet impingement heat transfer. The chapter describes the applications and physics of the flow and heat transfer phenomena, available empirical correlations and values they predict, and numerical simulation techniques and results of impinging jet devices for heat transfer. The relative strengths and drawbacks of the Reynolds stress model, algebraic stress models, shear stress transport, and v 2 f turbulence models for impinging jet flow and heat transfer are compared in the chapter. The chapter provides select model equations as well as quantitative assessments of model errors and judgments of model suitability. The review of recent impinging jet research publications identified a series of engineering research tasks that are important for improving the design and resulting performance of impinging jets: (1) clearly resolve the physical mechanisms by which multiple peaks occur in the transfer coefficient profiles, and clarify which mechanism(s) dominate in various geometries and Reynolds number regimes, (2) develop a turbulence model, and associated wall treatment if necessary, that reliably and efficiently provides time-averaged transfer coefficients, (3) develop alternate nozzle and installation geometries that provide higher efficiency, meaning improved Nu profiles at either a set flow or set blower power, and (4) further explore the effects of jet interference in jet array geometries, both experimentally and numerically. This includes improved design of exit pathways for spent flow in array installations.

/pdf/jet-impingement-heat-transfer-physics-correlations-and-3h1zkpep1u.pdf

Jet Impingement Heat Transfer: Physics, Correlations, and Numerical Modeling

Radiation transfer is relevant to a number of key technical issues related to nuclear reactor safety studies. To gain understanding of thermal radiation transfer under hypothetical reactor accident conditions, analysis of radiation transfer in a finite length cylindrical vessel containing high-temperature aerosols that absorb, emit, and scatter thermal radiation has been performed. The fine particles are assumed to be produced by the dispersion of the reactor core debris under high pressure. The model parameters used in the calculations correspond to those proposed in the High-Pressure Melt Streaming experimental program. Results of calculations show that the extinction coefficient and the single scattering albedo of the aerosol and the emissivity of the vessel are important model parameters. The sensitivity studies have identified the radiative property data base needed to make realistic radiative transfer calculations relevant to hypothetical reactor accidents in which fine aerosol particles are generated from the core debris.

Radiation Transfer in a Cylindrical Vessel Containing High-Temperature Corium Aerosols

Similarity solution for laminar film boiling over a moving isothermal surface

Direct flame impingement (DFI) furnaces consist of large arrays of high velocity combusting jets with temperatures up to 1700 K and impinging on complex configuration surfaces of the work pieces. This results in serious convergence problems DFI modeling and computational efforts. A new method of modeling convective-diffusion transfer (CDT) and zone radiation transfer (RT) employing different calculation schemes with a multi-scale grid is presented. Relatively coarse grid calculation domain allows use of conservative and accurate zone radiation transfer method with only modest computational efforts. A fine grid calculation domain is used to predict convective -diffusion transfer for a representative furnace section, containing a small number of jets that allows to significantly decrease the computer time. The main difficulty of coupling between convective-diffusion transfer (CDT) and radiation heat transfer numerical computations is successfully overcome using a relatively simple algorithm. The method allows one to model the physicochemical process taking place in the DFI and reveals as well as explains many features that are difficult to evaluate from experiments. The results were obtained for high velocities (up to 400 m/s) and high firing rates. Maximum (available for natural gas-air firing) total heat fluxes up to 500 kW/m2 and convective heat fluxes of up to 300 kW/m2 were obtained with relatively 'cold' refractory wall temperatures not exceeding 1300 K. The combustion gas temperature range was 1400-1700 K. A simplified analysis for NOx emissions has been developed as post-processing and shows extremely low NOx emissions (under 15 ppm volume) in DFI systems. Good agreement between measurements and calculations has been obtained. The model developed may be regarded as an efficient tool to compute and optimize industrial furnaces designs in limited time.Copyright © 2006 by ASME

Mathematical Modeling of Direct Flame Impingement Heat Transfer

The effect of radiation heat transfer on the transient combustion of a single fuel droplet with a finite rate of chemical reaction and variable physical properties has been clarified under the assumptions of spherical symmetry. Evaporation curves, transient variation of flame location, temperature profiles, and the ratio of flame to droplet radius were compared to the previous results without radiation effect. It was shown that the radiation has at least a 25-percent effect to lower the maximum flame temperature. Further, the present results were compared to the experimental results obtained by several researchers.

Effect of thermal radiation on transient combustion of a fuel droplet with finite rate of chemical reaction.

A layer of radiating gas is analyzed to determine its effectiveness in shielding a surface from incident radiation The radiation falling on the “free boundary” of the layer is made up of a diffuse and a collimated component It is assumed that the gas is gray and capable of absorbing, emitting and isotropically scattering radiation; and the surface is a gray, diffuse emitter and reflector of radiation Heat transfer by conduction and convection is neglected compared to radiation, the problem is formulated exactly in terms of integral equations, and an approximate solution is obtained by the collocation method A comparison of the heat transfer results with those of the unshielded case shows that for a highly absorbing surface there is considerable reduction in heat transfer if the optical thickness of the layer is large enough On the other hand, there is very little reduction in heat transfer for a highly reflecting surface regardless of the magnitude of the optical thickness

Raymond Viskanta

Papers

Radiation Transfer in a Cylindrical Vessel Containing High-Temperature Corium Aerosols

Similarity solution for laminar film boiling over a moving isothermal surface

Mathematical Modeling of Direct Flame Impingement Heat Transfer

Effect of thermal radiation on transient combustion of a fuel droplet with finite rate of chemical reaction.

Effectiveness of a layer of an absorbing-scattering gas in shielding a surface from incident thermal radiation