ptc system simulations - gamma technologies · 2015-08-20 · mercedes-benz research and...

Mercedes-Benz Research and Development India


PTC System Simulations

GT India User conference 2014, Bangalore.

Gangumalla Venkat Rao.


Contents

PTC system simulations | G.Venkat Rao| RDI/CE | 13.10.2014 2

Organization Overview

Significance of System Simulations

Simulation Approach

Project Case studies

Questions & Answers


Mercedes Benz


A brand of Daimler AG which has an innovation history of 125 years

Innovator of the first automobile.

A Daimler Global R&D center

Founded in 1996.

CAD/CAE/EE/IT CAE: Structural CAE/3D CFD/1D CFD CFD: 3D CFD/1D CFD

1D CFD: Power train, Powertrain cooling, HVAC, Vehicle thermal management.

Mercedes Benz R&D India


Significance of system simulations


Design verification Design optimization

Selection of cooling

concept

Selection of air cooled or

water cooled heat

exchangers.

Positioning of components

in a circuit.

Selection of components.

Concepts trade off and

selection.

Design verification

Simulations for the

Design in progress.

Simulations for all load

cases.

Model calibrations

Detailed analyses

Design modifications

Optimize operating

conditions (Fan/pump

speeds/Valve

positions).

Parametric studies.

Study/verify of design

modifications for

continuous

improvement.

Conceptual evaluation


Simulations


Hydraulic simulations

Prediction of coolant flow for various

components.

Prediction of coolant flow through

vent lines.

Checks on back flow scenarios.

Predictions of operating pressures.

Studies on piping diameters.

Prediction of coolant flow for Turbo

after-cooling scenarios.

Thermal simulations

Prediction of coolant, lube oil,

transmission oil, charge air

temperatures.

Prediction of under hood cooling air

flow for heat exchangers, air side

temperatures.

Fig 1. Cooling system piping layout


Approach


A. Pipe modeling - GEM 3D

C. Underhood air flow : CFD/COOL3D

B. Heat rejection : Measurements/

GT Power

D. Transmission losses

Source: http://www.greencarcongress.com/2011/08/skyactiv-20110804.html

Source: http://www.sussexautos.co.uk/mercedes-tronic-plus.php


Approach


COOLANT heat

rejection @

Reference point

Corrected COOLANT

heat rejection

Reference COOLANT

temperature

Reference CHARGE

AIR temperature

Reference LUBE

OIL temperature

Dynamic heat rejection model


Approach


OIL heat

rejection @

Reference point

Corrected OIL heat

rejection

Reference COOLANT

temperature

Reference CHARGE

AIR temperature

Reference LUBE

OIL temperature

Dynamic heat rejection model


Hydraulic simulations

At constant coolant temperature.

At various pump speeds and Thermostat position combinations.


1. Coolant flow prediction for components 2. Coolant flow distribution predictions


Thermal simulations


Pre requisite: Hydraulic model.

Load case specification: Vehicle speed/Gear/Gradient/

Transmission losses/Ambient

temperature.

Predictions: Coolant, lube oil, transmission oil,

Charge air temperatures for various

vehicle operating conditions.

New engine technologies offers additional requirements for PTC system which brings challenges for

PTC system design to meet various functional requirements.

Fig 2. PTC system applications



Project Case study 1


Charge air cooling


Objective: To evaluate charge air cooling performance of the two design

concepts.

Concept A (Single Radiator) Concept B (Dual Radiator)


GT models


Concept A (Single Radiator) Concept B (Dual Radiator)

Note: All the components (Heat exchangers, reservoir) modelled as external sub assemblies.


Performance evaluation


Concept A

Concept B

Concept B (Dual Radiators) meets the specifications.

The predictions in good agreement with the

measurements.

Load case (TCA-Tamb)/Requirement

Concept A Concept B

V35kmph 0.93 0.90

VMAX_1 1.10 0.87

VMAX_2 1.23 1.03

TCA : Charge air temperature at Charge air cooler exit location

Tamb: Ambient temperature.


Battery cooling system


Key functions: Cooling and heating for Battery and

Charger.

Features: Flow control valves to switch flow direction

according to the requirement.

Chiller and Radiators to dissipate heat from

the system to ambient.

Schematic

Scenarios: Charging ON, Radiator active mode

Charging ON, Chiller active mode

Charging OFF, Radiator active mode

Charging OFF, Chiller active mode




Fig 3. Coolant flow distribution (Normalized values wrt pump flow)

The valve position (angle) is determined which

maintains the desired flow distribution between

Battery and Charger.

Coolant flow predictions

1.00 0.39 0.61

0.95

0.05


Charge air cooling


Objective: To improve charge air temperatures

New design concepts

1. Single orifice into CAC vent line 2. Dual orifice into CAC vent line 3. Position filling line at Radiator

upstream

Baseline design

Design features: High temperature circuit and low temperature

circuit have a common reservoir.

High temperature coolant flows from the common

reservoir to NT circuit.

Common

reservoir

High temp

circuit




Observations: The design (Position filling line at Radiator upstream ) offers significant improvement over the

other two design modifications however it drives significant design changes and offers low

pressure coolant for CAC.

The dual orifice design offers improved performance with minor design changes.

Table 3. Charge air temperature difference from the Baseline design

Improvement in Charge air temperature

Load case Single

orifice

Dual

orifice

Filling line

relocation

VMAX_1 -1.1 -1.7 -6.2

VMAX_2 -1.0 -1.7 -6.4

VLOW_1 -1.0 -1.7 -6.3

VLOW_2 -0.8 -1.4 -5.7



Questions & Answers



Thank you

ptc system simulations - gamma technologies · 2015-08-20 · mercedes-benz research and...

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