Sunday, August 26, 2007
This question has been raised by many engineers and debated in many discussion.
Careful review on the relief valve structure, process fluid passing through a nozzle instead of an orifice. Those many researchers such as Dr. Ron Darby for multiphase flow in Direct Integration method (HDI), Dr Fauske & Dr Henry for two phase relief in Homogeneous Non-equilibrium model (HNE), Dr. Joseph Leung for two phase flow in Omega method, etc have modelled a relief valve as a nozzle.
Classical and conventional studies informed us that vena contracta (VC) will only occur in sharp edge orifice. However, the flow restricting area in a relief valve as decribed by many well knowed specialists is not an orifice, but is actually a nozzle. Thus there is NO vena contracta downstream of the nozzle.
Phenomenon of flow through a nozzle in relief valve is extremely fast. Choked flow is possible occur in some location "A" in the nozzle instead of outside the nozzle (may be closed to the exit end), from the inlet to "A" will be a REVERSIBLE process which generally accepted by most of the specialists. Thus, it is ISENTROPIC process. From location "A" to PSV outlet, the system is expanded and change in state. It will be slow down. There will be transformation energy loss however the enthalpy is maintain constant (ISENTHALPIC). This process is IRREVERSIBLE. "A" is viewed as vena contracta in the relief valve's nozzle. Those in sizing a relief valve, we ignore the frictional loss in the nozzle and consider ISENTROPIC process. However, from expansion process via safety valve (Vena contracta to relief outlet), the process will be ISENTHALPIC.
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Labels: Modelling, Pressure Relief Device, PSV, Thermodynamic
Wednesday, June 13, 2007
Wolverine Tube, Inc. copper and copper alloy tube, fabricated products, brazing alloys, fluxes and lead-free solder, as well as copper and copper alloy rod, bar and other products manufacturer...
Wolverine offer (FREE) two good Heat Transfer Databook...
Wolverine Heat Transfer Data book
A data book discusses on basic heat transfer, sensible heat transfer, Trufin tubes in condensing heat transfer, Trufin tubes in air-cool heat exchanger, Trufin tubes in boiling heat transfer, etc
K.J. Bell, A.C. Mueller, Wolverien Tube Inc.
Wolverine Heat Transfer Engineering Data book
A data book discusses on design considerations for Enhanced heat exchangers, single-phase shell-side flows & heat transfer, heat transfer to air-cooled heat exchangers, condensation on external surfaces, condensation inside tubes, boiling heat transfer on external surfaces, two phase flow pattern, falling film evaporation, thermodynamics of refrigerant mixtures and refrigerant-oil, void fraction in two-phase flows, post dryout heat transfer...
John R. Thome, Wolverien Tube Inc.
Wolverine Heat Transfer Data book
A data book discusses on basic heat transfer, sensible heat transfer, Trufin tubes in condensing heat transfer, Trufin tubes in air-cool heat exchanger, Trufin tubes in boiling heat transfer, etc
K.J. Bell, A.C. Mueller, Wolverien Tube Inc.
Wolverine Heat Transfer Engineering Data book
A data book discusses on design considerations for Enhanced heat exchangers, single-phase shell-side flows & heat transfer, heat transfer to air-cooled heat exchangers, condensation on external surfaces, condensation inside tubes, boiling heat transfer on external surfaces, two phase flow pattern, falling film evaporation, thermodynamics of refrigerant mixtures and refrigerant-oil, void fraction in two-phase flows, post dryout heat transfer...
John R. Thome, Wolverien Tube Inc.
If you benefits from this post...buy me some sweets...
Labels: Ebook, Heat Exchanger, Heat Transfer, Thermodynamic
Friday, April 27, 2007
Today found an interesting website for Process & Chemical Engineer, especially those involve in Design and Engineering...VMG
Virtual Materials Group (VMG), a process simulation and material behavior prediction software...client from oil, chemical and refinery technology companies.
VMGSim™ - VMG product...process simulation system integrates flowsheeting kernel with Visio™ for ease-of-use and graphics interface and Excel™ for seamless bidirectional spreadsheet calculations. (Download)
FREE Articles available in this site...
CAPE-OPEN Specialty Property Packages - New Thermodynamic Models and Software Integration Paradigm A. Satyro, Yau-Kun Li, Rajeev K. Agarwal and Oscar J. Santollani,
"Modeling Urea Processes: A New Thermodynamic Model and Software Integration Paradigm", Presented at the 2000 Clearwater Convention on Phosphate Fertilizer & Sulfuric Acid Technology Sheraton Sand Key Resort, Clearwater Beach, Florida -- June 16-18, 2000
Others FREE articles may request using this LINK
TZValve 3.0.2, a distillation software developed by The Distillation Group is marketed by VMG...I found The Distillation Group website, will expedite this site and share my findings in post...
WebWorm
Labels: Distillation, Modelling, Process simulation, Thermodynamic
