pressurereg

A PRESSURE REGULATOR OPTION FOR THE GENERALIZED FLUID SYSTEM SIMULATION PROGRAM (GFSSP): 

A PRESSURE REGULATOR OPTION FOR THE GENERALIZED FLUID SYSTEM SIMULATION PROGRAM (GFSSP) Paul Schallhorn Sverdrup Technology, Inc. GFSSP User’s Group Meeting November 16, 2000 Task 560-6100-0500-01

OUTLINE: 

OUTLINE Objective Approach Results Summary

OBJECTIVE: 

OBJECTIVE Objective: To add a pressure regulator capability to the Generalized Fluid System Simulation Program (GFSSP) Version 3.0, via the User Subroutines.

APPROACH: 

APPROACH A pressure regulator is a device that will maintain a set downstream pressure provided that the upstream pressure is larger than the set point. In order to maintain pressure, area will vary as a function of time; therefore, the pressure regulator will be applicable to transient models only. When the upstream pressure is greater than the desired regulated pressure, the area of the regulator will be calculated by means of a derivative of area w.r.t. pressure.

APPROACH (Continued): 

APPROACH (Continued) When the upstream pressure is less than or equal to the desired regulated pressure, the area will be set to the maximum value for the device. The area will be calculated using the following formula:

APPROACH (Continued): 

APPROACH (Continued) The coding for the pressure regulator was performed in the following user subroutines of GFSSP 3.0: FILENUM (file number assignment user subroutine) USRSET (user defined input file user subroutine) BNDUSER (user defined update subroutine called at the end of each time step) PRNUSER (user defined output user subroutine) Pressure regulator branches should be modeled using resistance option -02 (flow through a restriction), with the area specified equal to the maximum allowable area. Additional information regarding the regulator is provided in a later section of the file.

APPROACH (Continued): 

APPROACH (Continued) User Develops Modified GFSSP Input File For Pressure Regulator Model User Initiates a run of a pressure regulator (p.r.) model (GFSSP3PR.EXE ) Subroutine READIN calls USRSET if USETUP=.TRUE. Specialized input file includes logical indicating if p.r. is present, p.r. version & p.r. information ITER=0? At the end of each time step, BNDUSER is called to calculate an update p.r. branch area to maintain downstream pressure no yes Calculate circuit conditions at next time step Supply Ap.r. new Write results to main GFSSP output files; write pressure regulator information to a special file entitled “PRESREG.OUT” Last Time Step? no yes End Flow Chart Running GFSSP3PR

APPROACH (Continued): 

APPROACH (Continued) Modified Input Deck GFSSP VERSION 300 ANALYST PAS INPUT DATA FILE NAME PRTESTA.DAT OUTPUT FILE NAME PRTESTA.OUT TITLE PRESSURE REGULATOR TEST USETUP T PRESSURE REGULATOR VERSION 100 DENCON GRAVITY ENERGY MIXTURE THRUST STEADY TRANSV SAVER F F T F F F T F HEX HCOEF REACTING INERTIA CONDX ADDPROP PRINTI ROTATION F F F F F F F F BUOYANCY HRATE INVAL MSORCE MOVBND TPA VARGEO TVM F T F F F F F F SHEAR PRNTIN PRNTADD LAMINAR TRANSQ PRESSREG F F F F F T PRESS INSUC VARROT F F F NORMAL SIMUL SECONDL F F F NNODES NINT NBR NF 3 2 2 1

APPROACH (Continued): 

APPROACH (Continued) Modified Input Deck - Continued RELAXK RELAXD RELAXH CC NITER 1 0.5 1 0.0001 100 DTAU TIMEF TIMEL NPSTEP 0.1 0 200 1 NFLUID(I), I=1,NF 4 NODE INDEX 1 1 2 1 3 2 . . . BRANCH 23 UPSTREAM ANGLE 12 0.0000 DOWNSTREAM ANGLE NUMBER OF PRESSURE REGULATORS 1 PRESS.REG. BRANCH DESIRED DOWNSTREAM PRESSURE (PSIA) 12 40.0 RESTART NODE INFORMATION FILE FNODE.DAT RESTART BRANCH INFORMATION FILE FBRANCH.DAT

MODEL VALIDATION RESULTS: 

MODEL VALIDATION RESULTS Three test cases were identified to validate that the pressure regulator option works as desired. These cases are: 1. Tank-Pressure Regulator-Tube, with initial tank pressure >> regulated pressure (validates maintaining desired downstream pressure). 2. Tank-Pressure Regulator-Tube, with initial tank pressure ~ regulated pressure (validates maintaining maximum area requirement). 3. Tank-2 Pressure Regulators-2 Tubes, with initial tank pressure > regulated pressures (validates multiple pressure regulators, each maintaining their own desired downstream pressure).

PRESSURE REGULATOR VALIDATION - TEST CASE 1: 

PRESSURE REGULATOR VALIDATION - TEST CASE 1 Physical Situation Model N2 Tank of 10 ft3, initially at 600 psia, 75°F 0.1 inch inner diameter tube, 10 feet long. Pressure Regulator, set for a downstream pressure of 40 psia. 1 3 2 12 23 Pressure Regulator, set for a downstream pressure of 40 psia. 0.1 inch inner diameter tube, 10 feet long. N2 Tank of 10 ft3, initially at 600 psia, 75°F

PRESSURE REGULATOR VALIDATION - TEST CASE 1RESULTS: 

PRESSURE REGULATOR VALIDATION - TEST CASE 1 RESULTS

PRESSURE REGULATOR VALIDATION - TEST CASE 2: 

Physical Situation Model N2 Tank of 10 ft3, initially at 55 psia, 75°F 0.1 inch inner diameter tube, 10 feet long. Pressure Regulator, set for a downstream pressure of 50 psia. 1 3 2 12 23 Pressure Regulator, set for a downstream pressure of 50 psia. 0.1 inch inner diameter tube, 10 feet long. N2 Tank of 10 ft3, initially at 55 psia, 75°F PRESSURE REGULATOR VALIDATION - TEST CASE 2

PRESSURE REGULATOR VALIDATION - TEST CASE 2RESULTS: 

PRESSURE REGULATOR VALIDATION - TEST CASE 2 RESULTS

PRESSURE REGULATOR VALIDATION - TEST CASE 3: 

Physical Situation Model N2 Tank of 10 ft3, initially at 600 psia, 75°F 0.1 inch inner diameter tube, 10 feet long. Pressure Regulator, set for a downstream pressure of 50 psia. 1 4 2 12 24 Pressure Regulator, set for a downstream pressure of 50 psia. 0.1 inch inner diameter tube, 10 feet long. N2 Tank of 10 ft3, initially at 600 psia, 75°F PRESSURE REGULATOR VALIDATION - TEST CASE 3 0.1 inch inner diameter tube, 10 feet long. Pressure Regulator, set for a downstream pressure of 27.5 psia. 3 13 34 0.1 inch inner diameter tube, 10 feet long. Pressure Regulator, set for a downstream pressure of 27.5 psia.

PRESSURE REGULATOR VALIDATION - TEST CASE 3RESULTS: 

PRESSURE REGULATOR VALIDATION - TEST CASE 3 RESULTS

SUMMARY: 

SUMMARY A pressure regulator option has successfully been added to GFSSP 3.0 via User Subroutines. The option uses a modified version of the GFSSP input file. Three test cases were identified to validate the capability. These three test cases have been modeled, and successfully validate the modeling approach. Based upon this validation, a recommendation to proceed with documentation and release of GFSSP3PR is requested.