ME 475/675 Introduction to Combustion Lecture 31 Laminar flame speed and thickness dependence on unburned temperature, pressure, fuel and dilution, Ex. 8.2,

Announcements HW 13 Due Monday, November 9, 2015 Midterm 2 Review Monday, Nov. 9, 2015 Tutorial: Thursday, November 12, 2015, 5-7 pm, SEM 257 Exam: Friday, November 13, 2015 PE 104, 8 to 9:30 (or 9:45?) AM Project In groups of two, construct a backpacking stove Materials will be supplied in lab Determine how long it takes and how much fuel is required to boil water Form your group by Monday, November 9 Inform TA: Hasibul Alam

Pressure and temperature dependence of S L and

Dependence on Fuel Type

Flame Speed Correlations for Selected Fuels

Example 8.3, p. 286

Graduate Research topic using combustion Large Fire Heat transfer Dependence of Fire Time of Concern on Package Location for a 1 PWR Transport Package Paper

Dependence of Fire Time of Concern on Package Location for a 1 PWR Transport Package Ketan Mittal Research Assistant University of Nevada, Reno Miles Greiner Professor of Mechanical Engineering University of Nevada, Reno Funded by the US Nuclear Regulatory Commission, Contract NRC-HQ- 12 -P Packaging and Transportation of Radioactive Materials August 20, 2013 –San Francisco, California Ahti Suo-Anttila Computational Engineering Analysis LLC Albuquerque, New Mexico

Motivation Consider a package designed to transport one used nuclear fuel assembly in proximity to a long-lasting, 12-m diameter jet fuel fire If the package is centered over the pool, how long will it take before the fuel’s cladding reaches its possible burst temperature, 750°C? How far must the package be from the pool’s center so that its cladding will not reach this temperature, even for an infinitely-long-lasting fire? (Safe distance)

Package Response Finite Element Model  Models fuel block, steel-lead-steel construction surrounded by water tank  Inside package, heat generation within the fuel, conduction and surface-to-surface radiation heat transfer

Normal Conditions of Transport Temperatures  Fuel heat generation, Solar heat flux  Natural convection and radiation heat transfer to 38 ° C environment  External surface temperature, hottest at center

Internal Temperature

Comparison to Previous studies

Container Analysis Fire Environment Simulations

Max Cladding Temperature vs time for package Centered over 12-m Pool Simulations were performed for a range of modeling parameters Calculated fire time of concern for the cladding t c (when the cladding reaches 750°C) is between 11.8 and 13.3 hours

Dependence on Package Location The fire time of concern for the cladding increases as the distance between the package and fuel centers increases For S x > 6.4 m (package over the pool edge) the cladding temperature never reaches its burst condition. This work helps risk analysts determine which actual fires have the potential to affect safety and require further study

Time of Concern versus Package Position

Flame Quenching, Mixture Flammability, Ignition

Cold Wall Quenching Quenching distance d Smallest dimension d that allows flame to pass Experimentally determined by shutting off flow of a premixed stabilized flame d tube = (1.2 to 1.5) d tube Could we design and build an experiment to observe this using different sized screens? d d

Simplified Quenching Analysis for a slot b=2 b>2

Quenching will take place when b=2 b>2

Example 8.4, page 290