- Author
-
Saito, K.
|
Inamura, T.
|
Ito, A.
|
Ling, S.
|
Tagavi, K.
- Title
- Study of Crude Oil Combustion Supported on Water. Part 1. Study of Boilover in Liquid Pool Fires Supported on Water: Effects of In-Depth Absorption. Part 2. Holographic Interferometry Temperature Measurements in Liquids for Pool Fires. Final Report.
- Coporate
- Kentucky Univ., Lexington
National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
-
Final Report,
62 p.
- Contract
- NIST-GRANT-60NANB8D0960
- Keywords
-
crude oil
|
combustion
|
water
|
pool fires
|
liquid fires
|
holographic interferometry
|
boilover
|
boiling point
|
temperature measurements
- Abstract
- Part 1. This study is the continuation of previos study (Part 1) on boilover of liquid fuels supported on water. Previously we designed a small scale pool fire apparatus and tested seventeen different (single and multicomponent) liquid fuels on water. Based on those established data, in this paper we have described a one-dimensional model to predict the time required for the water sublayer to start to boil (TWSB). The model includes unsteady term of thermal energy equation, condution and in-depth radiation absorption. To fully implement the model, radiation absorption was measured for toluene and Alberta Sweet crude oil as a function of fuel layer thickness. The model calculation predicts formation of the inverse temperature profiles in the liquid due to the effect of in-depth absorption. Occurrence of the predicted Rayleigh convection in fuel layer is confirmed using a holographic interferometry technique, and it's effect on TWSB is estimated by comparing the model calculations to the experimental results. It is found that significant amount of heat is transferred from the fuel open surface to fuel-water interface by Rayleigh convection, while the heat loss to the wall is found to be at moderate levels. Part 2. This study provides detailed temperature and physical structure measurements within both the n-decane fuel layer and the supporting water sublayer at the onset of the boiling of water sublayer (WSB). Understanding the mechanims of WSB is important to predict the so-called "boilover phenomenon" which is associated with an intense spattering of water and fuel droplets. The in-depth physical structure and temperature profiles were obtained using a holographic interferometry technique with Pyrex rectangular containers with large aspect ratios to provide two-dimensional conditions. The experiments demonstrated that: (1) Maximum temperature was achieved 0.1-0.15 cm below the fuel sur5face possibly due to in-depth radiation absorption which caused Rayleigh convection in the fuel layer near the surface, and (2) The fuel surface remained at a saturation temperature approximately 20K below the boiling point, while the water at the fuel-water interface was superheated. The superheated water layer is dynamically unstable, so that sporadic spatterings of water and fuel droplets (boilover) were observed. To check the applicability of these results to a larger pool fire system a Pyrex pan of 6 cm diameter was used; and occurrence of Rayleigh convection was confirmed using a streak shadow graph technique.