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General introduction

The HFFLASH model is an HF-specific utility program that can be used to calculate post-flash temperature and liquid fraction upon release of anhydrous hydrogen fluoride (HF).
HFFLASH main use is to create a link file to the HEGADAS (-S, -T) dispersion program. This file contains the post-flash temperature and liquid fraction. Together with evaporating pool data from LPOOL this information is needed to give a source term description needed in HEGADAS.

Range of applications and limitations

The HFFLASH/HEGADAS combination should be used for unpressurised (low-momentum) releases where a liquid pool forms on the ground. Pool data can be generated using the LPOOL model.
For pressurised releases the HFPLUME model should be used followed by a HEGADAS or PGPLUME run if required.
The flash calculations assume that ambient pressure is 1 atm.


A description of all the input parameters that can occur in an HFFLASH input file will be given.

The HFFLASH input file has the DOS filename 'casename.HFI' where 'casename' is the user-supplied name of the problem.

In the following, actual keywords are given in capitals and in bold.
All parameters, except TITLE, occur in blocks preceded by a specific block keyword. For HFFLASH these block keywords are: RESERVOIR and PIPE.

The TITLE keyword does not occur in a parameter block.

TITLE The title of the current problem to be run with HFFLASH.
At most 50 alphanumeric characters.
Optional, no default.

The RESERVOIR block contains the parameters which describe the reservoir thermodynamic state of the anhydrous HF.

TRES Temperature of the HF in the reservoir (Degrees C).
-50 <= TRES <= 150.
PRES Absolute pressure within the reservoir (atm).
0.7 <= PRES<= 20.
Note: ambient pressure is assumed to be 1.0 atm.

The PIPE block contains the release pipe/orifice exit-plane conditions.

DMDTHF Mass discharge rate of HF (kg/s).
0.01 <= DMDTHF <= 103
The HFSPILL model might be used to estimate DMDTHF.
DEXIT Effective orifice diameter of the discharge pipe (m).
0.001 <= DEXIT <= 5.

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