Comparative Analysis on Semi-empirical Models of Jet Fire for Radiant Heat Estimation

Abstract

Sudden release of combustible/flammable materials at high pressure could result in the occurrence of a jet fire in the processing industry. Understanding the jet fire phenomenon and its mechanism could assist practitioners and researchers to predict the radiant energy transfer caused by the jet fire. Due to the dynamics of jet fire occurrence, the development of a semi-empirical model to predict thermal characteristics in different scenarios might provide huge advantages to the industry and safety practitioners as it is nonexpensive and a reliable prediction. There are four semi-empirical models for jet fire thermal radiation estimation that has been developed to date, namely, solid flame model (SFM), single-point source model (PSM), multipoint source model (MPSM), and line source model (LSM). It is the aim of this paper to explore each model applicability and approach to estimate the radiant heat flux based on the governing factors associated with the models, i.e., atmospheric transmissivity, flame length, lift-off length, flame shape, radiant heat fraction, total heat release, and receiver location. It is found that the applicability of each model and the derived parameters are largely contributed by the flame scale (small, medium, and large), flame orientation, flame length, and flame shape as well as the flame distance to the target receiver. From the discussion made, it can be suggested that for both near- and far-field measurement, the weighted MPSM is a reliable model that can be used for both vertical and horizontal orientations with some modification upon the consideration of buoyancy effect. On another note, LSM is able to provide a better prediction for linear trajectory of jet flame; however, the applicability is still limited for jet flame trajectory with buoyancy effects due to fewer data available and validation in various release conditions and scenarios.