HTRI培训教程2

,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Heat Transfer Research,Inc.All rights reserved.Confidential:For HTRI member use only.,Performance Specifications,Module 2,Module 2,Performance Specifications,Objectives,Define HTRI measures of performance,Introduce options to review performance data,Understand process specification rules,Practice troubleshooting,X,phe,case with deficient performance,Output Summary Data,Process data,Temperatures,Pressure drop,Equivalent shear stress,Maldistribution parameter,Performance data,Duty,overdesign,Actual U,EMTD,Geometry data,Calculated Temperatures,Same as specified temperatures,If specified temperature/pressure is different from heat release data,Reported output temperature based on heat release,Asterisk*shows specified value has been changed,HTRI Guideline:Do not overspecify process conditions,Pressure Drop,Thermodynamic pressure used,Same pressure as measured by gage with wall tap,Nozzle-to-nozzle change in pressure,Frictional losses,Momentum losses or gains,momentum recovery in condensers,momentum losses in reboilers,Channel pressure drop,Port losses,Pressure Drop,Static Head,Static head(or elevation head)handled differently,Not included for single phase,Included in boiling cases,Not included for condensation,Equivalent Shear Stress,Shear stress is one measure of fouling tendency,High shear stress:low fouling tendency,Performance Data,Definitions of Selected Entries,Duty:calculated duty,Calculated duty is averageof hot fluid duty and cold,fluid duty,Actual,U,:incremental average,EMTD,:Duty weighted average,Overdesign,where,Process Specifications,Required Conditions,Rating,or,Design,(duty not specified),Five of six process conditions,Rating,or,Design,(duty specified),Two of three process conditions for each fluid,Simulation,(duty not specified),Two of three process conditions for each fluid,Process Conditions,Definitions,Hot/cold flow rates,Hot/cold temperatures,inlet/outlet,Weight fraction vapor for two-phase(required for isothermal cases),Inlet pressure(required for two-phase),Temperature/weight fraction vapor/pressure constitute a single process condition for two-phase,Process Specification Rules,General,If exchanger duty not specified,fluid duties need not match,Warning if mismatch more than 10%,Overdesign based on average,Flow rates respected,Process Specification Rules,General,Specified temperatures always respected,Exchanger duty always respected for overdesign calculation,Process Specification Rules,Two-Phase,Specified temperatures always respected;weight fraction vapor calculated,If temperature not specified,weight fraction vapor respected;temperature calculated,Process Specification,Rules of Thumb,For ratings,specify duty(if known),Avoid specifying duty mismatch,Do not specify temperatures if vapor fraction must be used,Ensure process conditions are realistic,Tips for Evaluating Performance,Review Data Check and Runtime messages,Review overall results in Output Summary and Final Results,Use Monitors to review averaged incremental data,Use Graphs to review more data at a glance,Message Reports,Outline on message reports,Green,Highest message severity=informative,Yellow,Highest message severity=warning,Red,Highest message severity=fatal,Final Results Page 1,More extensive process conditions,Port pressure drops and velocities,fouling layer thickness,etc.,Final Results Page 2,More extensive plate geometry,Additional heat transfer parameters,Channel Monitor,Monitor starts at channel closest to hot inlet,Variables averaged over 10 increments in each channel,Plate Monitor,Monitor starts at plate closest to hot inlet,Values averaged over entire plate,Hotside Monitor,Monitor starts with first hot pass,Monitor follows hot fluid flow path down each increment,Values are averaged across all hot channels in pass,Coldside Monitor,Monitor starts with first cold pass,Output Profiles,2D plots with averaged data,Same data as in monitors,Multiple parameters viewed,Note that temperature data,are average for each channel,Output 3D Profiles,3D plots with all incremental data displayed,Same data as in calculation,Single parameter viewed,Note that temperature variation,along plate length can be viewed,Example 2,Proposed New Marine Diesel Cooler,Open Example2.htri:Proposed diesel cooler design for ballast water heat treatment,What is maximum seawater skin temperature?,Example 2,Redesign with Lower Surface Temperature,Crystallization fouling can be severe with skin temperature greater than 140,F(60,C),What is minimum flow rate needed to keep skin temperature less than 140,F,Develop alternative design limiting skin temperature less than 140,F,Module 2,Lessons Learned,Performance data can help debug cases,Process specifications must be OK to get right results,With good design and specifications,good results can be expected,Runtime messages do not identify all mistakes,