Publications
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Heatsimulation During the Development of a Bus E-Drive
Abstract
The present article describes how to support a development project by heat and fluid simulation in all project stages in the example of the development of an electric wheel hub drive unit. The project starts at a low know-how level in the planning stage, which is then enhanced continually by simulation. A detailed and adapted simulation model will then be available with the finished product. The process chain - simple calculation, design, testing, detailed model, design, testing, is repeatedly carried out during the project. Finally, a design proposal for the cooling system of a city bus is shown.
Publication: Heatsimulation During the Development of a Bus E-Drive, Altvater and Boch, 2003.pdf
Source: Verein Deutscher Ingenieure (VDI) Berichte
Author: Dipl.-Ing. (FH) R. Altvater, Dipl-Ing. (FH) P. Boch, ZF Friedrichshafen AG, Friedrichshafen
Year: 2003
Content Tags:
Tank Sizing Analysis for Reduced Gravity Cryogenic Transfer Receiver Tank
Understanding fluid behavior in microgravity is essential to further development of cryogenic storage in space environments. The Reduced Gravity Cryogenic Transfer project is designed to investigate tank chilldown in a microgravity environment onboard a parabolic flight. This work focused on examining the feasibility of chilling down different tank sizes using liquid nitrogen within the time constraints of the flight. Thermal models of four different tank geometries were made using Thermal Desktop and SINDA/FLUINT. The tank wall was modeled as a series of solid finite elements while the fluid inside the tank was represented by twinned liquid and vapor lumps. Fluid was injected into the bottom of the tank to simulate a dip tube and vented out of the top of the tank. The tank wall temperature as well as the state of the fluid inside the tank was tracked throughout the simulation. Several different cases were run with different chilldown operations for each tank model using a combination of charge, hold, and vent cycles. The average wall temperature, propellant mass savings and thermal efficiency of each of the four tanks were compared under seven different chilldown operations. A recommendation was made for the receiver tank size based on these parameters.
Publication: TFAWS2021-CT-01.pdf
Source: TFAWS 2021
Author: Erin M. Tesny, Daniel M. Hauser, Jason W. Hartwig
Year: 2021
Content Tags: two-phase, twinned tanks, chilldown, solid finite elements, finite elements, finite element, parametric analysis, parametric, material properties
JWST Testing Issues – Thermal & Structural
This study explores JWST thermal and structural testing issues and possible solutions, as presented to NASA in June 2004
Publication: bell_telescope.pps
Source: Aerospace Thermal Control Workshop 2005
Author: William Bell, Frank Kudirka, & Paul-W. Young
Year: 2005
Content Tags: chilldown, refrigeration cycle, convection heat transfer, insulation, radiation, flow regime mapping, radiation analysis groups
Optimization and Automated Data Correlation in the NASA Standard Thermal/Fluid System Analyzer
SINDA/FLUINT (Ref 1-7) is the NASA-standard heat transfer and fluid flow analyzer for thermal control systems. Because of its general formulation, it is also used in other aerospace specialties such as environmental control (ECLSS) and liquid propulsion, and in terrestrial industries such as electronics packaging, refrigeration, power generation, and transportation industries.
SINDA/FLUINT is used to design and simulate thermal/fluid systems that can be represented in networks corresponding to finite difference, finite element, and/or lumped parameter equations. In addition to conduction, convection, and radiation heat transfer, the program can model steady or unsteady single- and two-phase flow networks.
C&R’s SinapsPlus® is a complete graphical user interface (preand postprocessor) and interactive model debugging environment for SINDA/FLUINT (Ref 8, 9). SinapsPlus also supports the C language in addition to the traditional choice of Fortran for concurrently executed user logic.
This paper describes revolutionary advances in SINDA/FLUINT, the NASA-standard heat transfer and fluid flow analyzer, changing it from a traditional point-design simulator into a tool that can help shape preliminary designs, rapidly perform parametrics and sensitivity studies, and even correlate modeling uncertainties using available test data.
Innovations include the incorporation of a complete spreadsheet-like module that allows users to centralize and automate model changes, even while thermal/fluid solutions are in progress. This feature reduces training time by eliminating many archaic options, and encourages the performance of parametrics and other what-if analyses that help engineers develop an intuitive understanding of their designs and how they are modeled.
The more revolutionary enhancement, though, is the complete integration of a nonlinear programming module that enables users to perform formal design optimization tasks such as weight minimization or performance maximization. The user can select any number of design variables and may apply any number of arbitrarily complex constraints to the optimization. This capability also can be used to find the best fit to available test data, automating a laborious but important task: the correlation of modeling uncertainties such as optical properties, contact conductances, as-built insulation performance, natural convection coefficients, etc.
Finally, this paper presents an overview of related developments that, coupled with the optimization capabilities, further enhance the power of the whole package.
Publication: sfpaper.pdf
Source: IECEC
Author: Brent A. Cullimore
Year: 1998
Content Tags: design optimization, model correlation, parameterize, parametric, two-phase flow, two-phase, optical properties, submodels, registers, expression editor, user logic, concurrent engineering, concurrent design, dynamic mode, dynamic SINDA, specific heat, solver, constraint, slip flow, Phenomena, capillary systems, mixtures, working fluids, nonequilibrium, vapor compression, uncertainty, uncertainty analysis
Optimization, Data Correlation, and Parametric Analysis Features in SINDA/FLUINT Version 4.0
This paper describes revolutionary advances in SINDA/FLUINT, the NASA-standard heat transfer and fluid flow analyzer, changing it from a traditional point-design simulator into a tool that can help shape preliminary designs, rapidly perform parametrics and sensitivity studies, and even correlate modeling uncertainties using available test data.
Innovations include the incorporation of a complete spreadsheet-like module that allows users to centralize and automate model changes, even while thermal/fluid solutions are in progress. This feature reduces training time by eliminating many archaic options, and encourages the performance of parametrics and other what-if analyses that help engineers develop an intuitive understanding of their designs and how they are modeled.
The more revolutionary enhancement, though, is the complete integration of a nonlinear programming module that enables users to perform formal design optimization tasks such as weight minimization or performance maximization. The user can select any number of design variables and may apply any number of arbitrarily complex constraints to the optimization. This capability also can be used to find the best fit to available test data, automating a laborious but important task: the correlation of modeling uncertainties such as optical properties, contact conductances, as-built insulation performance, natural convection coefficients, etc.
Finally, this paper presents an overview of related developments that, coupled with the optimization capabilities, further enhance the power of the whole package.
Publication: sf981574.pdf
Source: ICES 1998
Author: Brent A. Cullimore
Year: 1998
Content Tags: design optimization, model correlation, parameterize, parametric, two-phase flow, two-phase, optical properties, submodels, registers, expression editor, user logic, concurrent engineering, concurrent design, dynamic mode, dynamic SINDA, specific heat, solver, constraint, slip flow, Phenomena, capillary systems, mixtures, working fluids, nonequilibrium, vapor compression, uncertainty, uncertainty analysis
Optimization and Automated Data Correlation
Optimization and Automated Data Correlation in the NASA Standard Thermal/Fluid System Analyzer
SINDA/FLUINT (Ref 1-7) is the NASA-standard heat transfer and fluid flow analyzer for thermal control systems. Because of its general formulation, it is also used in other aerospace specialties such as environmental control (ECLSS) and liquid propulsion, and in terrestrial industries such as electronics packaging, refrigeration, power generation, and transportation industries. SINDA/FLUINT is used to design and simulate thermal/fluid systems that can be represented in networks corresponding to finite difference, finite element, and/or lumped parameter equations. In addition to conduction, convection, and radiation heat transfer, the program can model steady or unsteady single- and two-phase flow networks. CRTech's SinapsPlus® is a complete graphical user interface (preand postprocessor) and interactive model debugging environment for SINDA/FLUINT (Ref 8, 9). SinapsPlus also supports the C language in addition to the traditional choice of Fortran for concurrently executed user logic. This paper describes revolutionary advances in SINDA/FLUINT, the NASA-standard heat transfer and fluid flow analyzer, changing it from a traditional point-design simulator into a tool that can help shape preliminary designs, rapidly perform parametrics and sensitivity studies, and even correlate modeling uncertainties using available test data. Innovations include the incorporation of a complete spreadsheet-like module that allows users to centralize and automate model changes, even while thermal/fluid solutions are in progress. This feature reduces training time by eliminating many archaic options, and encourages the performance of parametrics and other what-if analyses that help engineers develop an intuitive understanding of their designs and how they are modeled. The more revolutionary enhancement, though, is the complete integration of a nonlinear programming module that enables users to perform formal design optimization tasks such as weight minimization or performance maximization. The user can select any number of design variables and may apply any number of arbitrarily complex constraints to the optimization. This capability also can be used to find the best fit to available test data, automating a laborious but important task: the correlation of modeling uncertainties such as optical properties, contact conductances, as-built insulation performance, natural convection coefficients, etc. Finally, this paper presents an overview of related developments that, coupled with the optimization capabilities, further enhance the power of the whole package.
Publication: sfpaper.pdf
Source: IECEC 1998
Author: Brent A. Cullimore
Year: 1998
Content Tags:
Development of Cryogenic Capillary Pumped Loop
A cryogenic capillary pumped loop (CPL) has been developed, designed, fabricated and successfully demonstrated by test. Using no moving parts, the novel device is able to start from a supercritical state and cool a remote dissipation source to 80-90K. Design studies were conducted for integration requirements and component design optimization and prototype units were designed, fabricated and successfully tested with excellent results. The development included the miniaturization of CPL technology to allow heat acquisition from sources with a small footprint and direct integration to a cryocooler cold finger. Applications include the cooling of cryogenic electronics, sensors, and fuels. The technology possesses many advantages over cryogenic heat pipes including ground testability and mechanical isolation. Because of the CPLs ability to transport loads over a distance, cryocoolers can be located remotely from the detector (up to a meter away or across a gimbaled joint). In addition, it passively seeks the coldest rejection environment, allowing a single cryogenic CPL to enable switching between multiple passive cryogenic radiators. This work was performed under funding from NASA Goddard Space Flight Center.
Publication: IECEC98.pdf
Source: IECEC
Author: Jane Baumann, Brent Cullimore
Year: 1998
Content Tags: capillary pumped loop, CPL, CCPL, cryogenic, cooling loop, supercritical, start-up, design optimization, two-phase, heat loads, working fluids, evaporator, condenser, robust design, capillary systems, wicks, heat pipe, heatpipe
Propulsion Applications of the NASA Standard General Purpose Thermohydraulic Analyzer
The NASA standard tool for thermohydraulic analysis, SINDA/FLUINT, includes thermodynamic and hydrodynamic solutions specifically targeted at the growing demand for design and analysis of liquid propulsion systems. Applications in this field have included:
- Helium pressurization system design
- Cryogenic line chill-down transients
- Regenerative nozzle cooling
- Cryogenic turbomachinery chill-down transients
- Hydrazine line filling
- Feedline transients, including pogo suppression
- Feedline anti-geyser design
- Cryogenic tank pressurization and discharge, including thermal stratification, dissolved pressurant, and capillary liquid acquisition devices
Many organizations have previously used separate in-house tools specialized for each of the above applications. However, these organizations typically do not have the resources nor infrastructure to maintain these codes when cognizant engineers are lost, nor to modify and validate them for new vehicles or applications, nor to train new engineers on their use.
The use of a single general-purpose tool to encompass all such analyses offers not only solutions to the above problems, but also enables integrated analyses and the ability to communicate with vendors and customers.
Publication: propulse.pdf
Source: CRTech White Paper
Author: Brent A. Cullimore, Cynthia M. Beer, David A. Johnson
Year: 2000
Content Tags: chilldown, cryogenics, turbomachinery, register, registers, oxidizer tank, two-phase flow, cryogenic storage, nonequilibrium, valves, parametric, model correlation, solver, supercritical, mixtures, pressurant gas, orifices, compressors, user logic, choking, choked, nozzles, slip flow, liquid surface, interface, capillary systems, thermal stratification, stratified tanks, stratification
Design and Transient Simulation of Vehicle Air Conditioning Systems
This paper describes the need for dynamic (transient) simulation of automotive air conditioning systems, the reasons why such simulations are challenging, and the applicability of a general purpose off-the-shelf thermohydraulic analyzer to answer such challenges.
An overview of modeling methods for the basic components are presented, along with relevant approximations and their effect on speed and accuracy of the results.
Publication: vtms2001.pdf
Source: VTMS
Author: Brent A. Cullimore, Terry J. Hendricks
Year: 2001
Content Tags: compressor, evaporator, evaporators, condensers, slip flow, working fluids, registers, vapor compression, throttle, capillary tube, choked
Refrigeration System Design and Analysis
Modeling lessons learned form Ford, Visteon, GM, Delpi, Danfoss, etc.
Publication: VCimaps.pps
Source: ITherm
Author: Brent Cullimore
Year: 2002
Content Tags: vapor compression, compressor, two-phase heat transfer, evaporator, condenser, parametric, slip flow, finite difference
Adding Heat Pipes and Coolant Loop Models to Finite Element and/or Finite difference Thermal/Structural Models
Active cooling technologies such as heat pipes, loop heat pipes (LHPs), thermosyphons, loop thermosyphons (LTSs), and pumped single- or two-phase coolant loops require specialized modeling treatment. However, these 1D ducted systems are largely overlooked in 3D thermal modeling tools. The increasing popularity of CFD and FEM models and generation of analysis data from 3D CAD data are strong trends in the thermal analysis community, but most software answering such demands has not provided linear modeling elements appropriate for the simulation of heat pipes and coolant loops.
This paper describes techniques whereby CAD line-drawing methods can be used to quickly generate 1D fluid models of heat pipes and coolant loops within a 3D thermal model. These arcs and lines can be attached intimately or via linear contact or saddle resistances to plates and other surfaces, whether those surfaces are modeled using thermal finite difference methods (FDM), or finite element methods (FEM), or combinations of both. The fluid lines can also be manifolded and customized as needed to represent complex heat exchangers and plumbing arrangements. Furthermore, the assumption of 1D flow can be combined with 2D/3D models of walls, including advanced methods of extruding a complex 2D cross-section along a curved or mitered centerline.
To demonstrate these concepts, several distinct examples are developed and discussed.
Publication: FloCAD3-ICES.pdf
Source: ICES
Author: B. Cullimore, D. A. Johnson
Year: 2003
Content Tags: finite difference, heat pipe, Loop Heat Pipe, finite element, structural mesh, duct, noncondensible gas, condenser, wall
Multi-Variable Optimization of Electrically-Driven Vehicle Air Conditioning Systems Using Transient Performance Analysis
The National Renewable Energy Laboratory (NREL) and U.S. Department of Energy (DOE) are interested in developing more efficient vehicle air conditioning (A/C) systems to reduce fuel consumption in advanced vehicle designs. Vehicle A/C systems utilizing electrically-driven compressors are one possible system design approach to increasing A/C system performance over various drive cycle conditions. NREL’s transient A/C system model was used to perform multivariable design optimization of electrically-driven compressor A/C systems, in which five to seven system design variables were simultaneously optimized to maximize A/C system performance. Design optimization results demonstrate that significant improvements in system COP are possible, particularly system COP > 3, in a properly optimized system design with dynamically-controlled operation. System optimization analyses investigated dynamic A/C system design strategies employing dual-compressor-speeds in electrically-driven systems to evaluate their effects on system performance. A system optimization methodology was developed which can systematically quantify impacts on A/C system design and performance resulting from varying degrees of design influence being given to widely different design objectives. The technique is based upon formulating optimization objective functions from linear combinations of critical design performance parameters that characterize independent design goals. It was demonstrated here by giving varying degrees of design influence to maximizing system COP and maximizing evaporator cooling capacity over SC03 and US06 drive cycles.
Publication: C599-061.pdf
Source: NREL
Author: T. Hendricks
Year: 2003
Content Tags: design optimization, compressor, condenser, evaporator, expansion, system-level modeling, design variables
e-Thermal: A Vehicle-Level HVAC/PTC Simulation Tool
This paper describes a vehicle-level simulation model for climate control and powertrain cooling developed and currently utilized at GM. The tool was developed in response to GM's need to speed vehicle development for HVAC and powertrain cooling to meet world-class program execution timing (18 to 24 month vehicle development cycles). At the same time the simulation tool had to complement GM's strategy to move additional engineering responsibility to its HVAC suppliers. This simulation tool called "e-Thermal" was quickly developed and currently is in widespread (global) use across GM. This paper describes GM's objectives and requirements for developing e-Thermal. The structure of the tool and the capabilities of the simulation tool modules (refrigeration, front end airflow, passenger compartment, engine, transmission, Interior air handling …) is introduced. Model data requirements and GM's strategy for acquiring component data are also described. The paper includes an example of a typical application of the tool with sample output from the simulation and some comparison to actual test data from a vehicle under the same test scenario.
Publication: 2004-01-1510.pdf
Source: SAE Technical Paper Series
Author: Todd M. Tumas, Balaji Maniam, Milind Mahajan, Gaurav Anand, Nagendra Jain
Year: 2004
Content Tags: Components, heat exchangers, system-level modeling, third-party software, refrigeration cycles, model correlation
e-Thermal: Automobile Air-Conditioning Module
e-Thermal is a vehicle level thermal analysis tool developed by General Motors to simulate the transient performance of the entire vehicle HVAC and Powertrain cooling system. It is currently in widespread (global) use across GM. This paper discusses the details of the airconditioning module of e-Thermal. Most of the literature available on transient modeling of the air conditioning systems is based on finite difference approach that require large simulation times. This has been overcome by appropriately modeling the components using Sinda/Fluint. The basic components of automotive air conditioning system, evaporator, condenser, compressor and expansion valve, are parametrically modeled in Sinda/Fluint. For each component, physical characteristics and performance data is collected in form of component data standards. This performance data is used to curve fit parameters that then reproduce the component performance. These components are then integrated together to form various A/C system configurations including orifice tube systems, txv systems and dual evaporator systems. The A/C subsystem uses airflow rates, temperatures, humidity’s and compressor speed as inputs. The outputs include overall system energy balance, system COP, refrigerant flow rates and system pressures. The A/C simulation runs about three times faster to three times slower than real time. The modeling technique used is also capable of tracking the effect of system charge on the overall system performance. A database of automotive air conditioning components accompanies the simulation tool. This database is then integrated in e-Thermal to provide the component data for modeling. Validation results for component level models are demonstrated. They form the basis of system level models. System level validation is also demonstrated. The simulation times vary from 3 times faster than real time to 5 times slower than real time depending on the nature of the simulation.
Publication: 2004-01-1509.pdf
Source: SAE Technical Paper Series
Author: Gaurav Anand, Milind Mahajan, Nagendra Jain, Balaji Maniam, Todd M. Tumas
Year: 2004
Content Tags: parametric, two-phase flow, two-phase, Components, heat exchangers, compressor, condenser, evaporator, expansion, system-level modeling, third-party software, refrigeration cycles, model correlation
FDM/FEM System-level Analysis of Heat Pipes and LHPs in Modern CAD Environments
Publication: aerospace2005heatpipes.pps
Source: Aerospace Thermal Control Workshop
Author: Brent Cullimore, Jane Baumann
Year: 2005
Content Tags: LHP, Loop Heat Pipe, radiation analysis groups, concurrent engineering, heat pipe, system-level modeling, noncondensable gas, VCHP, CCHP, wall, two-phase heat transfer, two-phase flow, condenser, condensers, evaporator, evaporators
Analysis and Test Verification of Transitional Flow in a Dewar Vent
The pressure of the cryogen within a Dewar determines the operating temperature since the cryogen is typically in a saturated state. Thus, the operating temperature of a Dewar is directly related to the ambient pressure external to the Dewar and the flow losses associated with venting cryogen. Given the low vapor pressures of some cryogens, such as solid hydrogen, the vent flow from Dewars used in space can enter the transitional and molecular flow regimes. In order to accurately predict the operating temperature within such Dewars, the analysis tool used to model the cryostat must account for free molecular and mixed flow losses as well as those for continuum flow.
As part of our analysis of Dewar designs for the James Webb Space Telescope Mid-Infrared Instrument (MIRI), we modified the continuum flow modeling capability of SINDA/FLUINT to accurately predict the pressure drop due to transitional and molecular flow in the MIRI Dewar vent line. This paper describes the modifications made to the flow loss computations within the analyzer and the testing conducted to verify these modifications.
Publication: Schweickart.pdf
Source: Topsfield Engineering Service, Inc.
Author: Russell B. Schweickart and Gary Mills
Year: 2005
Content Tags: pressure drop, capillary tube, nozzle, manifold, valve, slip flow
Upper Stage Tank Thermodynamic Modeling Using SINDA/FLUINT
Modeling to predict the condition of cryogenic propellants in an upper stage of a launch vehicle is necessary for mission planning and successful execution. Traditionally, this effort was performed using custom, in-house proprietary codes, limiting accessibility and application. Phenomena responsible for influencing the thermodynamic state of the propellant have been characterized as distinct events whose sequence defines a mission. These events include thermal stratification, passive thermal control roll (rotation), slosh, and engine firing. This paper demonstrates the use of an off the shelf, commercially available, thermal/fluid-network code to predict the thermodynamic state of propellant during the coast phase between engine firings, i.e. the first three of the above identified events. Results of this effort will also be presented.
Publication: AIAA-2006-50513.pdf
Source: AIAA
Author: P. Schallhorn, D. Michael Campbell, Sukhdeep Chase, Jorge Piquero, Cindy Fortenberry, Xiaoyi Li, Lisa Grob
Year: 2006
Content Tags: Optimization, parametric, radiation, radiation analysis groups, conduction, evaporation, CFD, convergence, structural, heat flux, thermal stratification, register, two-phase, slosh, wall, splash
Upper Stage Tank Thermodynamic Modeling Using SINDA/FLUINT (Presentation)
Publication: TFAWS-08-1009_presentation.pdf
Source: TFAWS Short Course
Author: Paul Schallhorn, D. Michael Campbell, Sukhdeep Chase, Jorge Piquero, Cindy Fortenberry, Xiaoyi Li, Lisa Grob
Year: 2008
Content Tags: CFD, two-phase, slosh, thermal stratification, diffusion, boundary layer, twinned tanks, boiling