Thermal-Hydraulic Component Design Library
Contents
1. BOREL L Thermodynamique et nerg tique Vol 1 troisi me dition Editions Presses polytechniques romandes 1991 MILLER D S Internal Flow systems 2 Edition Amazon Technology 1989 FAISANDIER J M canismes ol o hydrauliques Editions Dunod 1987 IMAGINE S A Hydraulic Component Design user manual 2000 IMAGINE S A Thermal Hydraulic Library user manual 2000 Using the Thermal Hydraulic Component Design library 28 28 Reporting Bugs and using the Hotline Service AMESim is a large piece of software containing many hundreds of thousands of lines of code With software of this size it is inevitable that it contains some bugs Naturally we hope you do not encounter any of these but if you use AMESim extensively at some stage sooner or later you may find a problem Bugs may occur in the pre and post processing facilities of AMESim AMESet or in one of the interfaces with other software Usually it is quite clear when you have encountered a bug of this type Bugs can also occur when running a simulation of a model Unfortunately it is not possible to say that for any model it is always possible to run a simulation The integrators used in AMESim are robust but no integrator can claim to be perfectly reliable From the view point of an integrator models vary enormously in their difficulty Usually when there is a problem it is because the equations being solved are badly conditioned This means that the sol2. Resistive components CT oe STE These submodels are used to compute the mass flow rate using Bernoulli s equation 2 A dm p c A 220P q p Cq is the flow coefficient null A is the flow area calculated from the geometry of the component m Ap is the pressure drop in the component PaA pis the density computed at a working temperature and pressure kg m The enthalpy flow rate in the component is computed as follows dmh dmx h where dm is the mass flow rate through the resistive component and is the specific enthalpy of the fluid The mass and enthalpy flow rates are computed at port 2 and are duplicated at port 1 with reversed sign Every THCD valve is an adiabatic component meaning that the energy dissipated in it is completely transferred to the liquid Nothing is exchanged with its surroundings C n Eam E The submodel shown above is used for the calculation of hydraulic leakage and corresponding viscous friction forces It is also a resistive component in which the flow path is assumed to be in the annular area between the cylindrical spool or piston and a cylindrical sleeve The length of this clearance flow path is assumed constant The leakage is directly proportional to the differential pressure the diameter and the cube of the clearance and inversely proportional to absolute viscosity and contact length September 2004 Using the Thermal Hydraulic Component Design library 23 28 5 3 Capacitive
3. What we want to highlight in this example is the difference observed on the injected volume results whether the cross coupling effects between pressure and temperature are accounted for or not The model of such a system is represented in Figure 15 below Figure 15 Model of a high pressure fuel injector This model represents a basic electronic unit injector Its aim is to inject fuel at very high pressure up to 2000 bar for heavy duty applications This system is composed of three main parts that are described in what follows September 2004 Using the Thermal Hydraulic Component Design library 13 28 Part A The control valve Part B The plunger ED a ae Part C the needle The operating principle of such a system is the following a cam controlled plunger part B compresses a small volume chamber 11 filled with fuel When the control valve is open all the fuel flows to the low pressure circuit tank 6 When the control valve closes the pressure rises very quickly and reaches the needle cracking pressure modeled with components 13 14 15 The injection starts When the control valve opens again the pressure decrease is very fast and the injection is stopped The complete model comprises twenty components from the Thermal Thermal Hydraulic Signal and THCD libraries Each is referenced in Figure 15 by a number Fill in the parameters of these components as described in the table below leaving the ot
4. components The two icons indicated as Ch on the figure are capacitive components that is to say that they compute pressure and temperature from their derivatives with respect to time Similar to the resistive components six variables are exchanged at each port with the difference that thermal hydraulic chambers receive mass flow rate enthalpy flow rate volume and its derivative and provide pressure and temperature The mass of liquid in the volume is given by m pxV 1 The continuity equation for the one dimensional flow gives dm gt mM i represents the number of inputs of the control volume 2 It is possible from equation 1 and 2 to formulate the continuity equation in terms of the density derivative as follows ME pe dp _ dt Pat 3 dt V a The density being a thermodynamic property of the liquid it is a function of pressure and temperature p p p T 4 By differentiating with respect to temperature and pressure equation 4 leads to dp 2 apa2 dT 5 Op J OT From this equation it 1s possible to write the continuity equation in terms of the pressure derivative as follows dp dp 2 dT 6 oT September 2004 Using the Thermal Hydraulic Component Design library 24 28 Using the definition of the liquid properties and more particularly the isothermal Bulk modulus Pr and the volumetric expansion coefficient the pressure derivative with respect to time is given b
5. filename to be used thermal hydraulic Thermal Hydraulic SAME libthh data diesel data properties polynomials CONSO constant signal Signal control and constant value 50 observers UDO00 stage Signal control and output at start of stage 1 700 piecewise linear signal observers output at end of stage 1 00 duration of stage 1 50s TFQTO signal into volumetric Thermal Hydraulic default parameters flow rate L min TFPC1 temperature at port 1 50 degC thermal hydraulic Thermal Hydraulic internal diameter 7 2 mm adiabatic pipe length 0 4 m TFNDO1 Thermal Hydraulic no parameters thermal hydraulic node September 2004 Using the Thermal Hydraulic Component Design library 4 28 TF223 thermal hydraulic Thermal Hydraulic cross sectional area 0 018 mm restriction TFTKO default parameters thermal hydraulic tank Thermal Hydraulic F000 zero force source Mechanical no parameters THBAP026 thermal hydraulic Thermal Hydraulic diameter of poppet 5 mm poppet with conical Component Design diameter of hole 3 5 mm seat diameter of rod 0 mm THBAI21 mass with friction and Thermal Hydraulic mass 0 01 kg ideal end stops Component Design viscous friction 40 N m s lower disp limit 0 m higher disp limit 0 001 m piston diameter 5 mm THBAP16 Thermal Hydraulic rod diameter 0 mm thermal hydraulic Component Design spring stiffness 1000 N mm piston with spring spring force at zero displacement p
6. fluid thermal hydraulic properties was plotted September 2004 Using the Thermal Hydraulic Component Design library 21 28 5 Formulation of equations and underlying assumptions The Thermal Hydraulic Component Design library comprises four kinds of elements that are mass submodels inertial components piston submodels transformer components valve submodels resistive components chamber submodels capacitive components Fil Thermal Hydraulic Component Design The first two rows of components are used for absolute motion The three last components are purely ydraulic components with thermal effects The other components are used for relative motion With the relative motion models both the internal and external elements of the submodels are capable of motion With the absolute motion models the body is considered fixed in space We will concentrate on the absolute motion icons September 2004 Using the Thermal Hydraulic Component Design library 22 28 5 1 Piston submodels 1 The active area on which pressure acts is very important in hydraulic systems The one hydraulic port submodels have their mass and enthalpy flow rate equal to 0 These components have to be connected to a thermal hydraulic chamber to exchange the volume variation and its derivative information which is now used to compute pressure and temperature In the one hydraulic port submodels we will find only pistons with or without springs 5 2
7. industrial applications where both pressure and temperature variations are important we recommend that you use TFFD2 submodel This submodel uses polynomial functions to evaluate the thermal hydraulic properties of the liquid used for the simulation The fluid properties concerned are the density the viscosity the specific heat at constant pressure the thermal conductivity the bulk modulus the volumetric expansion coefficient and the specific enthalpy In this submodel the order of the polynomial forms has been increased so that it enables to reproduce very accurately the evolution of the fluid properties as a function of pressure and temperature In addition this submodel accounts for cavitation phenomena If you need more information about the way these thermal hydraulic properties are dealt with in the THCD library refer to the Thermal Hydraulic Library user s guide in section Advanced Thermal hydraulic properties To test this advanced properties submodel build the system shown in Figure 10 It comprises 5 elements from the Thermal Hydraulic and the Signal libraries Each element is referenced in Figure 10 by a number Fill in the parameters of these components as described in the table below leaving the other parameters at their default values TFFD2 thermal hydraulic advanced properties with cavitation Piecewise linear signal UD00 piecewise linear signal TFPTO conversion of a signal into a temperature and a pr
8. mm chamber length at zero displ 17 mm pressure at port 1 Z barA temperature at port 1 40 degC dead volume 1 5 cm thermal contact conductance 1e10 W m degC contact surface Je10 mm temperature at port 1 40 degC no parameters If you look carefully at the model shown in Figure 16 you can notice that the fluid in the hydraulic chamber can exchange heat with the outside At this stage an explanation is necessary First consider Figure 16 below September 2004 Figure 16 Thermal hydraulic chamber with heat exchanged Using the Thermal Hydraulic Component Design library 16 28 The thermal hydraulic chamber component 17 comprises 3 thermal hydraulic ports and 1 thermal port The thermal port is used to model a heat exchange between the liquid in the chamber and the outside The hydraulic chamber supplies the temperature of the fluid at the thermal port the temperature source component number 19 constitutes the ambient air temperature and component 18 1s used to calculate the heat exchange between the chamber and the outside In component 18 if the parameters supplied imply a heat exchange between the fluid and the outside which is very high the temperature of the liquid in the chamber will be kept to 40 degC As aresult all the transformation in the hydraulic chamber will be isothermal Conversely if the parameters supplied in component 18 imply a heat exchange between the fluid and the outside which
9. outlet and at the flow junction as shown in Figure 7 components 13 and 20 There is a huge pressure drop in the pressure relief valve which induces a dissipation of energy by friction This energy is transformed into heat that is transferred to the liquid This results in an increase in temperature at the relief valve outlet The liquid flows through the relief valve with an initial temperature of Ti 50 degC The increase in temperature in the relief valve is approximately 56 degC In Figure 7 we can see the evolution of the mixing temperature At this location in the circuit is a mixture of a 700 L hr volumetric flow rate which temperature is 50 degC and a 75 L hr volumetric flow rate which temperature is 106 degC This results in a 775 L hr volumetric flow rate in the tank with a temperature of 74 degC The transient and steady state behaviors of the system are strongly related to the thermal properties of the liquid used for the simulation To observe this display the pressure at the check valve inlet see Figure 8 a component number 13 and the temperature at the same component outlet as shown in Figure 8 b You will notice in this figure that these simulation results are compared to the simulation results obtained with the simple pressure relief valve model shown in Figure 4 September 2004 Using the Thermal Hydraulic Component Design library 7 28 1 4 110 1 ay eee e 2 i 100 H es a a0 1 Temp rature at simple relief val
10. start of stage 2 0 output at end of stage 2 0 duration of stage 2 2e 3 sec stage 3 output at start of stage 3 7 output at end of stage 3 duration of stage 3 e6 sec value of gain e6 60 No parameters filename AME libthh data advanced diesel80 rme20 data cross sectional area 4 pi mm tank pressure 7 barA tank temperature 40 degC default parameters default parameters 15 28 ae 7 15 ae F000 zero force source THBAP026 thermal hydraulic poppet with conical seat THBAI21 mass with friction and ideal end stops THBAP16 thermal hydraulic piston with spring THBAP12 THBHC12 thermal hydraulic chamber with heat transfer THCDCO contact conductive exchange THTS1 constant temperature source TEN221 thermal hydraulic node Mechanical Thermal Hydraulic Component Design Thermal Hydraulic Component Design Thermal Hydraulic Component Design Thermal Hydraulic Component Design Thermal Hydraulic Component Design Thermal hydraulic no parameters diameter of poppet 5 mm diameter of hole 3 mm diameter of rod 0 mm mass 0 01 kg viscous friction 40 N m s lower disp limit 0 m higher disp limit 5e 5 m piston diameter 5 mm rod diameter 0 mm spring stiffness 1000 N mm spring force at zero displacement pi 3e 3 2 300e5 4N chamber length at zero displacement 7 mm piston diameter 1 0 mm rod diameter 0
11. tends to zero minimum values for the thermal contact conductance and the contact surface it will be possible to study the temperature evolution of the fluid in the hydraulic chamber Therefore setting the parameters of component 18 at very high values will be used to mask the cross coupling effects between pressure and temperature whereas setting these parameters at their minimum values will be used to study the influence of the cross coupling effect between temperature and pressure on the results Doing this will highlight the result differences on the injected volume Display the velocity of the piston component 0 the pressure in the chamber component 17 the input signal on the control valve component 1 and the poppet lift component 13 as shown in Figure 17 below Piston velocity m s Control valve duty cycle null 2 5 1 1 1 2 0 8 1 5 0 6 1 0 4 0 5 0 2 0 0 0 00C 0 0025 0 0050 00075 00100 0 0125 0 0150 0 000 0 0025 0 0050 00075 00100 00125 00150 time s time s 3 10 Pressure in the chamber bar4 Poppet lift mm 2 1 0 050 1 0 040 1 5 0 030 1 0 020 0 5 0 010 0 0 000 0 00C 0 0025 0 0050 0 0075 00100 00125 0 0150 0 000 0 0025 0 0050 0 0075 00100 00125 00150 time s time s Figure 17 Control variables and behaviour of the system September 2004 Using the Thermal Hydraulic Component Design library 17 28 In this system the velocity of the piston is imposed as shown in Figure 17 As the piston starts to move
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13. 5 1 75 1 5 B0 1 25 FAA J 0 75 AO 0 5 45 0 25 0 40 O00 0 0025 0 0050 0 0075 0 0100 0 0125 0 0150 O00 0 0025 0 00S0 0 0075 0 0100 0 0125 0 0150 time 3 time 2 Figure 20 Evolution of the pressure and temperature in the adiabatic chamber September 2004 Using the Thermal Hydraulic Component Design library 19 28 On the graph of Figure 20 it is possible to notice that the increase in temperature is strongly related to the increase in pressure Indeed the temperature evolution follows the pressure evolution During the compression of the hydraulic chamber the temperature which was originally equal to 40 degC reaches 67 degC when the pressure in the chamber is at its maximum This illustrates clearly the cross coupling effect between temperature and pressure In addition you can compare the results obtained for the pressure with infinite heat exchange and with zero heat exchange as shown in Figure 21 10 i 1 Pressure in the chamber isothermal conditions bard 2 Pressure in the chamber adiabatic conditions bar 2 25 1 75 1 25 0 75 0 5 0 25 U U O000 0 0025 0 0050 0 0075 0 0100 0 0125 0 0750 time Figure 21 Comparison of pressure results Figure 21 shows that the level of pressure reached in the case of an adiabatic chamber is equal to 2212 barA whereas the level of pressure reached in the case of an infinite heat exchange between the chamber and the outside is equal to 1975 barA There is a difference o
14. 5 0 0150 O00 0 0025 0 00S0 0 0075 0 0100 0 0125 0 0150 time 3 time 3 Figure 18 Evolution of the pressure and the temperature in the chamber infinite heat exchange with the outside In this case the pressure in the chamber increases up to 1975 barA and the temperature in the chamber remains constant and is equal to 40 degC Display now the results for the injected volume as shown in Figure 19 below This information is given by the output of component number 2 September 2004 Using the Thermal Hydraulic Component Design library 18 28 Injected volume isothermal conditions ram 200 150 100 50 0 O 000f 0 0025 0 0050 0 0075 0 0700 0 0725 0 0750 time Figure 19 Injected volume infinite heat exchange with the outside In isothermal conditions the total injected volume is equal to 223 mm 3 At this stage we want to compare the previous results pressure temperature and injected volume with the results obtained when the heat exchange between the fluid and the chamber tends to zero that is to say when the chamber is adiabatic To model this change the values of the parameters of component 18 to their minimum values for the thermal conductance and the contact surface Perform a new simulation with the same simulation parameters as before and display the temperature and the pressure in the chamber as shown in Figure 20 below 3 d Pressure in the chamber bar Temperature in the chamber degC 2 25 ro L 1 2 6
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16. Thermal Hydraulic Component Design Library Version 4 2 September 2004 rp CH IMAGINE Copyright IMAGINE S A 1995 2004 AMESim is the registered trademark of IMAGINE S A AMESet is the registered trademark of IMAGINE S A ADAMS is a registered United States trademark of Mechanical Dynamics Incorporated ADAMS Solver and ADAMS View are trademarks of Mechanical Dynamics Incorporated MATLAB and SIMULINK are registered trademarks of the Math Works Inc Netscape and Netscape Navigator are registered trademarks of Netscape Communications Corporation in the United States and other countries Netscape s logos and Netscape product and service names are also trademarks of Netscape Communications Corporation which may be registered in other countries PostScript is a trademark of Adobe Systems Inc UNIX is a registered trademark in the United States and other countries exclusively licensed by X Open Company Ltd Windows Windows NT Windows 2000 and Windows XP are registered trademarks of the Microsoft Corporation X windows is a trademark of the Massachusetts Institute of Technology All other product names are trademarks or registered trademarks of their respective companies TABLE OF CONTENTS De TMU O QU CONS circes nn tn Di et nsc sde 1 2 Getting started with the Thermal Hydraulic Component Design Library 2 3 A new Thermal Hydraulic properties submodel ssssssssssssscccccccssssseeeeeee
17. ary 2 28 Fi Thermal Hydraulic Component Design Figure 3 Components of the Thermal Hydraulic Component Design Library First look at the components available in this library Display the title for each component by moving the pointer over the icons When this is done build the model of the check valve system as shown in Figure 5 In the first tutorial example of the Thermal Hydraulic user s guide a simple pressure relief valve is modelled see Figure 4 It consists of a variable restriction The upstream pressure is used to control the opening of this restriction It starts to open when the upstream pressure reaches 000 bar In this section we will study the same system but this time we will model very accurately the pressure relief valve using technological basic elements from the THCD library maxi LOQQ x 0 Figure 4 Simple model of a pressure relief valve September 2004 Using the Thermal Hydraulic Component Design library 3 28 Temperature 6 hoe PEE oi 20 19 18 LJ 22 Figure 5 Injection system including a THCD built pressure relief valve This model comprises 23 elements from the Thermal hydraulic Signal and THCD libraries Each is referenced in Figure 5 by a number Fill in the parameters of these components as described in the table below leaving the other parameters at their default values Finally perform a simulation over 50 seconds with a communication interval equal to 0 1 second TFFD1
18. e dmh is the outgoing enthalpy flow rate O 1S the heat flow rate exchanged with the outside V is the volume dm is the mass flow rate through the volume a is the volumetric expansion coefficient p is the fluid density and A is the specific enthalpy Finally the temperature derivative with respect to time is given by dT _ dmh dmh dmxh Q Ta dp dt me Pl dt Equation 14 is the complete energy equation represented by the temperature derivative with respect to time The pressure derivative term in this equation shows the cross coupling effect with the continuity equation 8 represented by the pressure derivative with respect to time 5 4 Further assumptions Concerning the thermal aspects in the components of the thermal hydraulic library the following assumptions are made e the flow is one dimensional e the properties of the liquid are homogeneous in the volumes e aeration and cavitation phenomena are taken into account when using submodel TFFD2 e inthe liquids heat transfers by radiation or conduction are neglected e the displayed temperatures are total temperatures e components of the THCD library enable you to model multi fluid systems 5 5 Other important rules e The THCD library deals with liquids only e It is better if the user builds the system slowly and run a simulation after each portion of circuit is added This normally leads to a better understanding of the system and the results It i
19. e submodel TFFD2 takes into account cavitation phenomena To show this change the parameters of component number 2 so as to vary the pressure from 0 to 1 barA Run the simulation using the same final time and communication interval as previously and display the density and the bulk modulus of the fluid as a function of pressure for the four temperatures defined above as shown in Figure 13 3 Fluid density kg m 3 x10 Fluid bulk modulus bar 900 1 1 25 1 20 degC PRE 37 degC 2 20 degC Vi 800 4 fi 3 80 degC 37 degC VE F 700 120 degC 1 80 degC z 7 120 degC Ly ae 600 500 400 300 200 100 0 0 0 2 0 4 0 6 0 8 1 0 0 2 0 4 0 6 0 8 1 Pressure barA Pressure barA Figure 13 Density and bulk modulus evolution in aeration and cavitation conditions September 2004 Using the Thermal Hydraulic Component Design library 11 28 To interpret these results it is important to know that the saturation pressure is equal to 2000 barA This means that below this pressure dissolved air and gas are coexisting in the fluid Before pressure decreases to 0 5 barA the dissolved air turns into gas into the liquid Therefore the fluid density and the bulk modulus are decreasing When the liquid begins to vaporize there is a sudden decrease of the bulk modulus and the density the air dissolved is totally transformed into gas At this stage 1t is necessary to do a zoom on the interesting region of the graphs which is lying be
20. essure TFFPR calculation of thermal liquid properties September 2004 Thermal hydraulic Signal control and observers Signal control and observers Thermal hydraulic Thermal hydraulic filename SAME ibthh data_advanced dieselS0 rme20 data stagel output at start of stage 1 20 output at end of stage 1 20 duration of stage 1 J sec stagel output at start of stage 1 output at end of stage 1 2000 duration of stage 1 J sec no parameters default parameters Using the Thermal Hydraulic Component Design library 9 28 Use the batch facility in Tools menu Batch setup option to define four temperature values at which the fluid properties will be calculated 20 37 80 and 120 degC and perform a simulation over 1 second with a communication interval equal to 0 01 second When this is done plot the density and the bulk modulus of the fluid versus pressure for these four temperatures as shown in Figure 11 x10 925 Fluid density kg m 3 Fluid bulk modulus bar4 1 20 degC 2 37 degC 3 80 degC 4 120 degC 0 0 5 Pressure bar 1 5 2 10 0 0 5 Pr ssure bar 1 5 Figure 11 Thermal properties of the liquid From these results it is easy to understand that variations in pressure and in temperature in a thermal hydraulic system have a great importance on the thermal hydraulic properties of a fluid Indeed if we consider a temperature variation from 20 to 120 degC at constan
21. essure and to take into account both on the calculation of the fluid thermal hydraulic properties This is why special fluid properties are used in this library note that these properties are already used in the Thermal Hydraulic Library For this reason the THCD Library is fully compatible with the Thermal and Thermal Hydraulic Libraries In addition it contains the equivalent of all the submodels found in the HCD Library These submodels have been modified so as to account for thermal phenomena In this manual several tutorial examples are presented to illustrate the use of this library and finally a brief review of the theory and the assumptions used in this library is given We recommend you read and do the tutorial examples of the Thermal Thermal Hydraulic and Hydraulic Component Design manuals before attempting the examples below September 2004 Using the Thermal Hydraulic Component Design library 1 28 2 Getting started with the Thermal Hydraulic Component Design Library The Thermal Hydraulic Component Design library comprises a set of basic components from which it is easy to model and observe the evolution of temperatures pressures mass and enthalpy flow rates in hydraulic systems Hence we recommend you do the following example as a first contact with the Thermal Hydraulic Component Design library If you did the tutorial examples of the Thermal Hydraulic library user s guide you will certainly recognize the system shown
22. f 12 between these two values We can wonder if this will have an impact on the results obtained for the injected volume Display on the same graph as shown in Figure 22 the evolution of the injected volume in the case of an adiabatic chamber and in the case of an infinite heat exchange between the fluid in the chamber and the outside September 2004 Using the Thermal Hydraulic Component Design library 20 28 1 Injected volume isothermal conditions mm3 2 Injected volume adiabatic conditions mm3 eeu 200 175 150 125 100 fo 50 25 0 0000 0 0025 0 0050 0 0075 0 0100 0 0125 0 0150 time Figure 22 Comparison on the injected volume adiabatic chamber and infinite heat exchange In the adiabatic case the total injected volume is higher than in the case of an infinite heat exchange the temperature in the chamber remains constant Indeed the total injected volume is equal to 240 5 mm in the adiabatic case and it is equal to 223 mm when the temperature remains constant in the chamber This means that neglecting the evolution of the temperature due to the compression of the volume can imply errors on the injected volume calculated that are close to 8 This is easily conceivable because the evolution of the pressure and the temperature in the chamber has a strong influence on the thermal hydraulic properties of the injected fluid this is what was highlighted in a previous section when the evolution of the
23. her parameters at their default values When this is done run a simulation for 0 0 5 seconds with a communication interval of 0 0001 seconds September 2004 Using the Thermal Hydraulic Component Design library 14 28 Submodel name and type Belongs to Principal simulation parameters category piecewise linear signal piecewise linear signal INTO submodel of integrator SSINK submodel for plugging a signal port TFFD2 thermal hydraulic advanced properties with cavitation TFVRO thermal hydraulic variable restriction dm f cqmax lamc TFTKO thermal hydraulic tank TFVFO0 thermal hydraulic volumetric flow rate sensor VELC02 conversion of a signal to a velocity in m s and a displacement in m September 2004 Signal control and observers Signal control and observers Control Control Thermal hydraulic Thermal hydraulic Thermal hydraulic Thermal hydraulic Mechanical Using the Thermal Hydraulic Component Design library time at which duty cycle starts 5e 3 sec stagel output at start of stage 1 0 output at end of stage 1 2 5 duration of stage 1 3e 3 sec stage2 output at start of stage 2 2 5 output at end of stage 2 2 5 duration of stage 2 4e 3 sec stage3 output at start of stage 3 2 5 output at end of stage 3 0 duration of stage 3 3e 3 sec stagel output at start of stage 1 7 output at end of stage 1 duration of stage 1 9 e 3 sec stage 2 output at
24. i 3 5e 3 2 1000e5 4N chamber length at zero displacement 1 mm TFPC3 Thermal Hydraulic temperature at port 1 50 degC thermal hydraulic adiabatic pipe TFPC2 Thermal Hydraulic temperature at port 2 50 degC thermal hydraulic adiabatic pipe TENDO3 Thermal Hydraulic no parameters Thermal hydraulic node The Thermal Hydraulic Component Design library can be classified as shown below Thermal Hydraulic Component Design Library Resistive Components Transformer components Capacitive Components Mass flow rate Enthalpy flow Convert a Pressure Temperature dm kg s rates pressure into a p barA T degC dmh W force Figure 6 Components classification in the THCD library The resistive submodels can be described as steady state submodels A more accurate description is they are instantaneous submodels By this we mean that they are assumed to react instantaneously to the temperatures and pressures applied to them so that they are always in an equilibrium state September 2004 Using the Thermal Hydraulic Component Design library 5 28 The capacitive submodels have two state variables the temperature and the pressure that are passed at ports This means that each of these variables is defined by a differential equation These are very commonly used in Thermal Hydraulic Component Design library systems and we will describe them as transient submodels Six variables are exchanged at Thermal Hydraulic ports Temperature T degC P
25. in Erreur Source du renvoi introuvable In the Thermal Hydraulic manual example the pressure relief valve was modeled using components from the Thermal hydraulic library and the Signal library This is a simple way of modeling this pressure relief valve we did not go into the details of the technology That is what we will do now using the components of the THCD library The system shown in Erreur Source du renvoi introuvable is part of a simplified injection system It consists of a pump that is feeding the injectors a pressure relief valve and a tank in which the flow rates coming from the pressure relief valve and the upstream part of the pump are mixed The distribution of mass flow rates is imposed as shown on the sketch 200 L hr pump injector 50 degC 100 L hr 100 L hr pressure relief valve 75 L hr Figure 1 Simplified part of an injection system In this example the unit chosen for the volumetric flow rates is L hr because it is one of the commonly used units in injection systems To model this system select the Thermal Hydraulic and the Thermal Hydraulic Component Design libraries category icon shown in Figure 2 O Figure 2 THCD and Thermal Hydraulic libraries category icons To produce the popup shown in Figure 3 select the Thermal Hydraulic Component Design library category icon shown in Figure 2 on the left September 2004 Using the Thermal Hydraulic Component Design libr
26. ity If this is the case we would like to know about it By reporting problems you can help us make the product better On the next page is a form When you wish to report a bug please photocopy this form and fill the copy Even if you telephone us having the filled form in front of you means you have the information we need To report the bug you have three options fax the form reproduce the same information as an email telephone the details Use the fax number telephone number or email address of your local distributor HOTLINE REPORT Creation date Created by Company Contact Keywords at least one Problem type O Bug O Improvement O Other Summary Description Involved operating system s C All C Unix all C PC all O HP Windows 2000 O IBM C Windows NT LI SGI L Windows XP L SUN LJ Linux L Other L Other Involved software version s O All O AMESim all O AMERun all 1 AMESet all 1 AMECustom all LI AMESim 4 0 CL AMERun 40 I AMESet 4 0 L1 AMECustom 4 0 L AMESim 4 0 1 LJ AMERun 4 0 1 1 AMESet 4 0 1 1 AMECustom 4 0 1 L AMESim 4 0 2 LJ AMERun 4 0 2 LI AMESet 4 0 2 I AMECustom 4 02 1 AMESim 4 0 3 LJ AMERun 4 0 3 LJ AMESet 4 0 3 1 AMECustom 4 0 3 L AMESim 4 1 LI AMERun 4 1 LJ AMESet 4 1 L1 AMECustom 4 1 Web Site http www amesim com FRANCE ITALY SPAIN PORTUGAL BENELUX SCANDINAVIA IMAGINE s a 5 rue Brison 42300 ROANNE FRANCE Tel 04 77 23 60 30 Tel 33
27. ressure p barA Mass flow rate dm kg s Enthalpy flow rate dmh W Volume vol cm Derivative of the volume dvol L min Two variables are exchanged at thermal ports Temperature T degC Heat flow rate dh W In order to reproduce the results obtained in the Thermal Hydraulic manual tutorial example we design this pressure relief valve for 1000 bar Thus the spring force at zero displacement corresponds to this pressure multiplied by the poppet seat section The seat diameter is 3 5 mm which implies a section of D soal 7 x 3 5e E 3 The spring force Fo is P 1000e5 Pa F Panl gt ff Pxs seat F 962 1N seat In order to avoid instabilities we have to include an important viscous friction Use Vf 40 N im s The viscous friction coefficient is computed considering the relation below Vf 2xExVKxM where K is the spring stiffness in N m M is the mass of the moving conical part of the poppet is the damping ratio In this example we chose E 20 M 0 01kg V 40N m s September 2004 Using the Thermal Hydraulic Component Design library 6 28 From this the spring stiffness can be deduced K 1000 N mm 110 Temperature at relef valve outlet deg Mixing temperature degC D 10 20 Time s 30 40 50 Figure 7 Evolution of the temperature in the injection circuit The main point of interest in this example is the evolution of the liquid temperature at the pressure relief valve
28. s also less likely that the setting of parameters will be forgotten The user will have to be very careful when running multi liquid simulations the indices of thermal hydraulic fluid must be adjusted in the corresponding submodels e Files of thermal liquid properties are available in the AME libthh data for use with submodel TFFD1 and the AME libthh data_advanced for use with submodel TFFD2 directories September 2004 Using the Thermal Hydraulic Component Design library 26 28 e This version of the THCD library includes about 100 submodels Full documentation of these submodel is available in HTML format or more briefly directly in AMESim in the description of each submodel e The AMESim thermal hydraulic library can be coupled with the thermal library to study thermal interactions between liquids and solids Really in the THCD library thermal ports have been added to hydraulic components Figure 23 13 18 it 0 T THCD component 17 Figure 23 coupling Thermal and THCD components Thermal component Thermal ports September 2004 Using the Thermal Hydraulic Component Design library 27 28 References Ref 1 Ref 2 Ref 3 Ref 4 Ref 5 Ref 6 Ref 7 September 2004 INCROPERA F P DEWITT D P Fundamentals of Heat and Mass Transfer Fourth Edition John Wiley amp Sons 1996 EYGLUNENT B Thermique th orique et pratique l usage de l ing nieur Editions Herm s 1994
29. ss 9 4 Another application example high pressure fuel injector cccccccccsssssssees 13 5 Formulation of equations and underlying assumptions see 22 5 PISTON SUBMODEUS Annee dent aes 25 5 2 RESISTIVE COMPONENTS Sn munie memes 23 33 HCAPACITIVE COMPONENTS ns a di Aude 24 Set FUR THEKASSUMIP TIONS ne en eee et Nes 26 5 OTHER IMPORTANT RULES au datent 26 R FCFONCES sinistre stenacsenenies den ic ddeeter aa a etes tes 28 September 2004 Table of Contents 1 1 Using the Thermal Hydraulic Component Design Library 1 Introduction The Thermal Hydraulic Component Design Library THCD is used to construct a model of a component from a collection of very basic blocks This methodology is very efficient because it enables you to go very deeply into the details of the components technology For instance all types of hydraulic jacks servo valves check valves can be modeled easily using this library It differs from the Hydraulic Component Design Library in that it allows you to study not only the pressure levels and the flow rates distribution in the system but also the temperatures and the enthalpy flow rates evolution in the system In special application cases for which pressure and temperature variations are wide typically injection systems this is of great importance In this case it is no more realistic to work in isothermal conditions and it becomes essential to consider the cross coupling effects between temperature and pr
30. t pressure say 1000 barA the density variation is almost equal to 60 kg m that is to say a 7 decrease of the value of the density Similarly if we consider a pressure variation from to 2000 barA at constant temperature say 20 degC the density variation is almost equal to 70 kg m that is to say an increase of 8 of the value of the density It follows that the cross coupling effects between temperature and pressure have a strong impact on the properties of the fluid To observe this display the evolution of all the properties available for plotting in submodel TFFPR as shown in Figure 12 To do this use the batch facility to define five pressure values at which the fluid properties will be calculated 1 500 1000 1500 and 2000 barA and for each run vary the temperature from 0 to 120 degC September 2004 Using the Thermal Hydraulic Component Design library 10 28 Fluid density kg m 3 Fluid absolute viscosity cP 1 I0 1 barA 1 ie 900 barA AA J p 1000 barA 4 a a 1500 barA oe 2000 barA 5 750 20 40 60 80 100 120 120 Temperature degC Temperature degC 3 Fluid specific heat at constant pressure J kg K Fluid thermal conductivity W m K x10 T 1 3 2 4 3 4 4 D aa 29 2 2 2 1 1 9 20 40 60 80 100 120 20 40 60 80 100 120 Temperature degC Temperature degC Figure 12 Thermal hydraulic properties of a special diesel fuel with respect to pressure and temperature In addition th
31. the fluid is compressed in the chamber due to chamber length variations At the beginning of the simulation the control valve is fully opened As a result the flow coming from the chamber and resulting from the displacement of the piston passes totally through the control valve low pressure circuit At time 0 009 seconds the control valve is closed instantaneously look at the curve in Figure 17 describing the input signal which is used to control the opening and the closing of the control valve and as a result the pressure in the hydraulic chamber suddenly increases When this pressure reaches and overcomes the needle cracking pressure the injection starts When the control valve opens again the pressure in the chamber suddenly decreases and becomes smaller than the needle cracking pressure At this stage the injection 1s interrupted and the fuel flows to the low pressure circuit By setting very high values for the parameters of component 18 we model a chamber with a heat exchange with the outside which is infinite As a result the temperature in the chamber remains constant and equal to 40 degC Display the evolution of the pressure and the temperature in the chamber with the high values for the parameters of component 8 as specified in the previous table as shown in Figure 18 below 3 a Pressure in the chamber bar Temperature in the chamber degC 2 4 1 1 1 5 40 5 1 40 0 5 39 5 0 39 OC 0 0025 0 0050 0 0075 0 0100 0 012
32. tween 0 and 0 5 barA as shown in Figure 14 Fluid density kg m 3 Fluid bulk modulus bar 20 degC 37 degt 80 degC 120 degC 20 degl 37 degC 80 degC 120 degC pvaph 0 0 05 0 1 0 15 0 2 0 25 0 3 0 35 0 4 0 45 0 0 1 0 2 0 3 0 4 0 5 0 6 Pressure bar Pressure bar Figure 14 Influence of liquid vaporization on the fluid density and bulk modulus When the pressure reaches pvaph 0 5 barA the liquid starts to vaporize and it is totally vaporized when the pressure has reached pvapl 0 4 barA These two pressures correspond respectively to the high saturated vapor pressure and the low saturated vapor pressure of the liquid These two pressures are parameters of submodel TFFD2 and can be changed Finally when the pressure value is in the range 0 to 0 4 barA it is considered that almost all the liquid has turned into vapor and as a result a polytropic law is used to describe the properties of the gas Please refer to Technical Bulletin N 117 AMESim Standard Fluid Properties for full details on the cavitation model used in submodel TFFD2 September 2004 Using the Thermal Hydraulic Component Design library 12 28 4 Another application example high pressure fuel injector The aim of this second tutorial example is to model very simply a high pressure fuel injector using components from the THCD library In this special case the level of operating pressure and the fast transient behaviour are of great importance
33. ution is ill defined It is possible to write down sets of equations that have no solution It such circumstances it is not surprising that the integrator 1s unsuccessful Other sets of equations have very clearly defined solutions Between these extremes there is a whole spectrum of problems Some of these will be the marginal problems for the integrator If computers were able to do exact arithmetic with real numbers these marginal problems would not create any difficulties Unfortunately computers do real arithmetic to a limited accuracy and hence there will be times when the integrator will be forced to give up Simulation is a skill which has to be learnt slowly An experienced person will be aware that certain situations can create difficulties Thus very small hydraulic volumes and very small masses subject to large forces can cause problems The State count facility can be useful in identifying the cause of a slow simulation An eigenvalue analysis can also be useful The author remembers spending many hours trying to understand why a simulation failed Eventually he discovered that he had mistyped a parameter A hydraulic motor size had been entered making the unit about as big as an ocean liner When this parameter was corrected the simulation ran fine In follows that you must spend some time investigating why a simulation runs slowly or fails completely However it is possible that you have discovered a bug in an AMESim submodel or util
34. ve outlet bard has dde da 2 Temp rature at THCD relief valve outlet band 2 Pressure at THOD relief valve inlet bard a0 r0 60 BO 10 eo 30 40 50 0 10 20 30 40 50 time z a simple pressure relief valve b THCD relief valve Figure 8 Results comparison We can notice small differences in the results Figure 8 due to the fact that the pressure relief valve modeled with the THCD library is much more complex and includes more physical and technological aspects in the system which in this case is more representative of a real relief valve Poppet lift mm Pressure drop in the relief valve bar4 0 020 1 2 TE 0 010 0 6 O 4 0 005 0 2 0 000 0 0 10 20 30 40 A 0 10 20 a30 40 Al time 3 time 5 a b Figure 9 Dynamic behavior of the relief valve In order to observe the dynamic behavior of the relief valve set the parameters of the piecewise linear signal component 5 at 0 for the output at start of stage 1 and 200 for the output at end of stage I with a duration of stage of 50 s Perform a simulation and display the poppet lift see Figure 9 a and the pressure drop in the relief valve versus time as shown in Figure 9 b above We can observe the cracking pressure at 000 barA and the linear increase of the pressure drop which is more representative of a real relief valve September 2004 Using the Thermal Hydraulic Component Design library 8 28 3 A new Thermal Hydraulic properties submodel For most
35. y dp 1 dp aT B a 7 dt using equation 3 6 leads to where Pr p T nn is the isothermal fluid bulk modulus PaA 2 OP Jr 1 Op a DT St is the volumetric expansion coefficient 1 K PAOLI The temperature is a state variable and is computed from the energy conservation assumption The first equation describes the relationship between the specific internal energy and the specific enthalpy of the liquid u h 9 p where u is the specific internal energy W is the specific enthalpy W p is the pressure PaA and pis the density of the liquid kg m The energy in the control volume is given by 2 m u MQZz 10 The three terms in equation 10 represent respectively the internal energy the kinetic energy and the potential energy We modify equation 10 introducing the second assumption the kinetic and potential energies in the control volume are neglected This leads to E mu 11 The derivative of the specific enthalpy can be written as follows dh__ dT 7 dp on eer 12 dt dt p dt om September 2004 Using the Thermal Hydraulic Component Design library 25 28 Differentiating and combining equations 9 11 and 12 leads to the following relation mat mc dmh dmh O OP ty 13 dt dt where m is the mass of liquid in the volume c is the specific heat of the liquid at constant pressure dmh is the incoming enthalpy flow rat
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