Thermotec Engineering Services GmbH

Air Conditioning and Cooling System

Simulation /

Approaches to Handle Data and Huge

Number of Variations

Robert Tauscher

Overview

■ Introduction

■ Our daily business

■ System complexity and number of variants

■ Approaches to handle complexity and variants

■ Examples

■ Component Level: Subassembly Evaporator, Condenser, HX

■ System Level: Universal System Template

■ Modeling and Calibration Level: System Identification

■ Calibration Level: Hydraulic, Thermal

■ Verification Level

■ Conclusion

Who is Thermotec?

■an engineering company - 15 engineers and physicists -

specialized on thermodynamics and .fluid mechanics

■automotive, aerospace and defense industries

■simulation: thermal/hydraulic systems, thermal

management and cooling .systems

(1D and 3D-CFD)

■ test benches: wind tunnel for radiator and heat exchanger

performance tests

■sensor development / measurement techniques

■cooperations with universities / research projects

■our partners:

www.thermotec-es.com

Technische

Universität

München

Our Daily Business - General

■ Analysis of AC and Cooling Systems

■ Evaluation of concepts, variants, …

■ Dimensioning of components / complete systems

■Control Strategies:

■ Development and Proof of Concept

■ Failure Scenarios and Backup Strategies

■What if … analysis

■ Dimensioning / Scaling

■ Pumps, fans (size, operating points, …)

■ Radiators (scaling)

■ Piping (pressure drop diameter, etc.)

■ Comparison of concepts / components …

Our Daily Business - Simulation

■ Modeling

■ Physical or

■ System Identification

■ Verification: compare model with experimental data

■ Experiment

■ Data collection and pre-processing

■ Steady state and transient

■ Model Calibration (experiment, 3D-CFD, …)

■ Component level

■ System level

■Post-processing / Analysis

■Presentation / Documentation …

■2ph-/AC-System integration in vehicle cooling system model

■vehicle model system generation / data handling / huge number of variantssystem

Q

QQ

Qair

Q

Q

Q

Q

Q

Q

Q

Challenge: Cooling System & Control Strategy for a System with

Battery & Power Electronics + AC-System

DT: +5K DT: +5K DT: +50KT.ambient DT: +2…5K

■cabin modeling / system identification

■cabin calibration

■HX, condenser… sub-model generation

■piping/hydraulics calibration

component

direction of heat flow / heat transfer

loss of thermodynamik potenzial / „thermal resistance“

Approaches

Multiple Coupled AC and Cooling System Simulation / Automated

Handling of Data and Variations: Challenges and Approaches

Challenges

large

number of

concepts to

be

evaluated

large

number of

subsystems

within a

model

huge

number of

variants and

derivatives

of a model

frequent

changes of

data during

design

process

very complex

calibration of

model and

subsystems

to experiment

coupled

simulation &

harware in the

loop (HiL),

controls

simulation

time

convergence

evaluation

documentation

robustness

reproducibility

.

Universal System Model Template

steady-state / transient

calibration

fast running / real-time

.n

e

.. .

.

.

.

.

..

.

.

.

.

.

.

.. ..

...

system identification

major sub-systemsthermal / hydraulic

simulation model

universal

system

model

template

database for

models,

components

and data

physical

modelling,

system

identification

automated

start & check

of

simulations

semi-

automatic

model and

subsystem

calibration

automated

standard

and custom

made

evaluation

scripted

generation

of models,

components

and variants

modular

simulation

set,

defined

interfaces

Vehicle AC and Cooling System –

From a Simple Model to Complex Systems

and a Huge Number of Variants

The Challenge:

■ 1

■ 10

■ 40 … 55

■ 5.000 … 11.000

■ 25.000 … 110.000

■ 1 … 700 x 10 … 100

■ 26.000

Gamma‘s example of a simple air-

conditioning circuit with battery

cooling

(„System_Battery_Cooling“)

Facts & model data of a

state of the art vehicle air-

conditoning circuit & coupled

cooling system model

?

what is necessary and

how will the model look like,

that we can meet

the challenges?

Vehicle Cooling System – Model Complexity and Variants 2016

1

10

40 … 53 (*50)

5.000 … 11.000 (*10.000)

25.000 … 110.000 (*100.000)

1 … 700 (*400) x 10 … 100

26.000 (*15.000)

(* GT-User Confernce 2015!)

■ Universal modular GT-System-Model-Template

■ Fluid Circuits: coolant (ht, lt,…), oil, air, refrigerant …

■ External subassemblies - main modules of vehicle

■ Total number of GT-parts in 1 model

■ Code lines in a „ready-to-simulate“ model file (*.dat-file)

■ Simulations/1 night (variants x use cases)

■ Result files (700 variants with 10 use cases)

up to:

Automation in Each Level of Simulation Workflow

■ Component Level - Automatic Component-model creation

■ Evaporator, Condenser, Radiator, Heat exchanger

■ System Level – Automatic Multiple/Cascades Coupled AC-Cooling-System creation

■ Universal System Model Template

■ Modelling & Calibration Level - System Identification

■ Calibration Level - Model Calibration (steady state, transient…)

■ hydraulic

■ hydraulic & thermal, …. Maximum Likelihood Optimization

■ Analysis Level / Presentation Level – Custom Made Offline Evaluation Tool

■ Verification Level – Development of Sensors and Measurement Techniques

Automation – Component Level:

Component Generation*/Heat Exchanger: Evaporator, Condenser, ..

Evaporator, HX

Condenser, Radiator

type (cross-flow, …)

geometry, dimensions

hydraulic and thermal

performance

properties of matter

Process Relevant Data

manual step

Data Sheet (GT-Excel-

Template or Custom)

automatic step

*details in GT-User-Conference 2015 presentation

dimensions

properties of matter

hydraulic (Dp)

thermal efficiency

NTU-limits

…

correction if necessary

Check Input Data

dimensions

height

# tubes

width

depth !

fins: spacing /

thickness

tubes: wall thickness

Scaling

(optional)

Visual Check & Last

Modifications

Generation of

GT-Subassembly

and Automatic Pre-

processing

evap./cond/HX-test

bench

Documentation of Nu-

Re-Regression Quality

correction of regression

to meet raw data (option)

add Model to

Component Database

Universal Modular

System Model Template

for each variant:

all relevant model

parameters and data

sheets

list of all relevant

external Subassemblies

for each model variant

Database of Variants /

Variants Parts List

automatic step

Coupled AC and Cooling System Simulation – Automated

Handling of Data and Variations* Check

check consistency of

data:

- parameters

- subassemblies

combination

- boundary

conditions

- …

generate

*.gtm file for each variant

*.dat file for each variant

check: all models

generated?

log file of variants

Model Generation

check workload of

cluster server and

available licenses

send models to

distributed server

Simulation /

Batch / Distributed Run

Check Simulations /

Process Results

check simulations

- all runs finished?

- convergence?

option: re-start

simulation of selected

models (failed,

crashed…)

Process Results

collect and combine

results / first check

Data Reduction &

Evaluation

Excel-Add-In and

template for results:

steady state / transient

0

1

2

3

4

5

6

7

8

0

20

40

60

80

100

120

140

160

0 200 400 600 800 1000 1200

Gan

g

Fahr

zeug

gesc

hwin

digk

eit

[km

/h],

Tem

pera

ture

n [°C

]

F56Ha B48 170kW, Guadix, kinematisch vs gemessen

Fahrzeug_output_Geschw #1_GT_2 WT_KMKHT_output_T_WT_Ein_Inner #1_GT_2

WT_MOEWWT_output_T_WT_Ein_Inner #1_GT_2 WT_GOEWWT_output_T_WT_Ein_Inner #1_GT_2

T_KM_KMKHT_ein Guadix_Messung T_MO_MOEWWT_ein Guadix_Messung

T_GO_GOEWWT_ein Guadix_Messung Fahrer_Gang #1_GT_2

Reporting /

Sharing of Results

- standard report

- interactive evaluation

. tool

Documentation …

archiving

documentation

data proc. for 3rd

party use (3D-CFD…)

clean up

- delete huge

number of files

- free disk space

*details in GT-User-Conference 2015 presentation

System Battery/Power Electronics + AC-System

■Cooling strategy for system HVS (high voltage storage) + Power Electronics (PE)

■Cooling strategy for AC-System + Cabin

■ Integration in Vehicle Cooling System Model

■ multiple cascaded coupling via fluid circuits (chiller / multi-stage) and via

underhood flow

■ modular universal system model

■Simulation Time / Robustness / Convergence …

HVSCabinEvaporator

CondenserSystem

Hydraulics

■ Calibration of Cabin and AC model to Pull-Down measurements

Modelling & Calibration Level: System Identification

air flow

temperature

flow rate

…

Pull-Down Measurement: transient

temperatures at many cabin positions

cabin model template

needs a lot of – often

unknown – input data

calibration to transient

temperatures at many

sensor positions

Ambient: 3

Vehicle: 4

Component Materials: 13

Component Masses: 7

Component Geometry: 13

View Factors: 7

Cabin Initial State: 11

Solar Properties: 7

Miscellaneous: 6

Layer Weighting: 18

Thermal Comfort Pred.: 3

GT-Post-Output:1

Plots: 5

----------------------------

Total: 98 (!) data fields

Cabin Template

System

u (t) : input y (t): output

v (t) : disturbances

exp.ht_target/T_Head_rig

xp.t_target/eT_Head_lef

exp.ht_target/T_Feet_rig

xp.t_target/eT_Feet_lef

y(t)

RT_Louver_C

LT_Louver_Cu(t)

T_Louver

(L+R)T_Feet (L+R)

T_Head(L+R

)

■ transient behavior of components and systems very often cannot be described

sufficiently by simple physical models

■e.q. thermal masses / thermal inertia / thermal resistance of cabin model or

engine

■with transient test data available dynamical models can be obtained by system

identification (transfer function between input and output, regarding

disturbances)

■ these models - generated in MATLAB/SIMULINK - can be utilized in GT-Suite

as SimulinkHarness-Objects replacing the standard cabin model object

System Identification

System Cabin

transfer function

identified

State-Space Model

cabin.dll

T_Louver (L+R)

T_Feet (L+R)

T_Head(L+R)

RT_Louver_C

LT_Louver_Cu(t)

exp.ht_target/T_Head_rig

xp.t_target/eT_Head_lef

exp.ht_target/T_Feet_rig

xp.t_target/eT_Feet_lef

y(t)

Modelling & Calibration Level: System Identification

Implementation in GT-Suite Model

T_Louver (L+R)

T_Feet (L+R)

T_Head(L+R)

test data

test data

test data

test data

■ linear State-Space-Model (blackbox)

■20 state variables

■ fast model generation (5s)

■high accuracy

■ if detailed knowledge of physics is

available greybox models can be used

(parameter identification)

■ test data should catch dynamical

behaviour in a sufficient way

System Identification and Model Calibration: Results

exp.ht_target/T_Head_rig

xp.t_target/eT_Head_lef

exp.ht_target/T_Feet_rig

xp.t_target/eT_Feet_lef

y(t)

exp

exp

exp

exp

Automation – Calibration Level: Model Calibration - Hydraulics

Goal: hydraulic calibrated GT-model for each use case / control strategy @each branch in

coolant circuit, esp. local flow rates and pressure distribution

System

MEADS Radar Unit

many communicating parallel - but

different - flow paths to be calibrated

(100)

piping of refrigerant loop

CAD GEM3D

3D-CFD / experiment

interface GT-hydraulic model

subassembly

hose and piping

system

PID-controlled

orifices for each

sector and branch

automatic calibration

for each use case

hydraulic calibrated

model

Automation – Calibration Level: Model Calibration – Thermal, …

■ Goal: find measurement errors and model calibration factors for

■ heat flow: heat rejection engine, air cond, gear box, …

■ flow rates: refrigerant, coolant, air, oil, atf, …

■ performance maps: heat exchangers, pumps, …

■ that the model can reproduce measured

■ temperatures

■ pressures

■ flow rates, …

■ for all (sensor) positions

■ simultaneously and for all use cases

■ as automatic as possible

■ comply with mass and energy conservation! consistent solution

Calibration Level: Model Calibration and Test Data Validation

based on Maximum Likelihood Optimization

■ Goal: find measurement errors and model calibration factors

■GT-Model based on maps for single components

(Compressor, Condenser,…) and certain boundary

conditions

■component maps usually derived from tests or simulation

GT- Model test bench

pGT, TGT, mdotGT ≠ ptest, Ttest, mdottest

reasons for deviations (simulation vs. experiment):

■component data (maps, …) imprecise?

■system model inaccurate?

■measurement errors (e.g.temperatures)?

■or a combination of both? most likely!

Maximum Likelihood Optimization

■ Wind Tunnel / HX-Test bench

■ HX-Performance

■ Uniformity

■ COOL3D-Benchmark

■ glas fibre sensor: 2-phase-flow, boiling local gas

content measurement

■ high-dynamic pressure sensors

■ ultra-high-dynamic temperature sensor (twin-sensor),

temperatur gradients > 800K/s

hight-transient expansion flows,

zB. airbag-unfolding

Verification Level: Thermotec Wind Tunnel / Sensor Technology

■ capacitive gas content sensor aeration z.B. engine oil

■ wire-mesh sensor / phase and/or component distribution

■ verification simulation filling/degassing

■ verification simulation fording ability

■ Berner Impactor / Particle Image Velocimetry (PIV)

■ verification simulation particel flow

■ contact angle measurement

■ verification fogging and steaming up

Verification Level: Thermotec Sensor Technology

Automation – Evaluation / Presentation Level

■Custom Made & Interactive Evaluation and Presentation Tools for

■ Off-Line Usage (no licenses required)

■ „Non-Experts“

■ Marketing Purposes

Conclusion

■ What is necessary to handle and simulate complex AC and cooling systems and

what is possible with Gamma Technologies GT-Suite?

■ Models / Simulation

■ Short simulation times fast running models (FRM) / fast convergence

■ Robust models

■ Modelling

■ Automation of model generation (VBA)

■ Component and system-model generation / modification

■ Co-simulation with System Identification / Simulink (SimulinkHarness)

■ Model data: administration in external file(s) or database (Excel)

■ Tools to model specified components very detailed

■ Simulation

■ Automation of pre- and post-processing (VBA, Excel)

■ Automation and organisation of simulation-runs 24/7 workload of server and

licenses (VBA, Excel)

■ Automation of model calibration (VBA and GT)

Thank You for Your Attention!

www.thermotec-es.com