Coupled Thermo-electric VTB Simulation Model of Cooling Loop of a Ship System Jamil Khan, Ruixian Fang, A. Monti, Wei Jiang, University of South Carolina

Coupled Thermo-electric VTB Simulation Model of Cooling Loop of

a Ship System

Jamil Khan, Ruixian Fang, A. Monti, Wei Jiang,

University of South Carolina

Greg Anderson, Mark Zerby, Phil Bernatos

NSWC, Philadelphia

ESRDC Modeling and Simulation Workshop Tallahassee, FL

14 February, 2006

Outline

• Problem Statement

• Models– Thermal– Electrical

• Simulation Results

• Conclusions

Problem Statement

Schematic for zone 2

Level 4

Level 3

Level 2

Level 1

FreshWater SeaWater HeatExchanger

FreshWater Heatsink HeatExchanger

Pipe

Pump

Valve

SeaWater

HeatSink

Temperature

mass flow

PCM board

Mixing model

2nd layer of Fw_HEX

Fresh Water- Sea Water Heat Exchanger

• Number of elements can be changed• Governing Eqns for each element:

L

L/120

Sea_Water Element #i

Tin

Conditions: m*h<=M where M is the mass of fluid of each element, as a special case, e.g., m*h=M , for each time step water in one element totally move into the next element.

22,_,_,_,_ tswhtavswtfwhtavfw

i

TTTTUAQ

htavfwfw

htfwfw

infw TM

hmT

M

hmT

_,__,, )1()(

Where ----Fresh water inlet temperature

----Fresh water temperature at time (t-h)

----Average fresh water mixing temperature at time (t-h)

----Mass flow rate

----time step

----Mass in control volume of each element

infwT ,

htfwT _,

htavfwT _,_

fwm

hfwM

htavswsw

swhtsw

sw

swinsw T

M

hmT

M

hmT

_,__,, )1()(

Where ----Fresh water temperature at time t

----Sea water temperature at time t

tfwT ,

tswT ,

htavfwtfwfwfw

i TTh

CMQ _,_,

htavswtswswsw

i TTh

CMQ _,_,

i

iQQ

fw

fw

M

hm

fw

fw

M

hm1

infwT ,htfwT _,

sw

sw

M

hm

infwT ,

sw

sw

M

hm1

htswT _,

Fresh water

Sea waterswm

inswT ,

iQ

Heat Sink

• Assume no temperature gradient along the length direction;

• Governing Eqns :

T1,Q1

T2,Q2

Qa

Q M CdT

d ta

We can also build this modal for several parts if necessary, that will take consider of the temperature difference along the length direction.

Where ----Inlet heat flow from heat source

---- Outlet heat flow from heatsink

---- heat absorbed by heatsink

21 QQQa

1Q

2Q

aQ

Where ----Mass of heatsink

---- Heatsink heat capacity

M

C

FreshWater- HeatSink Heat Exchanger

• Each model includes 12 elements;

• Governing Eqns for each element: The same logic used in this model as shown in Fresh water- Sea water

HeatExchanger

Conditions: m*h<=M where M is the mass of each element, as a special case, e.g., m*h=M , for each time step water in one element totally move into the next element.

m ,p m ,p

Tin Tout

Q,T

Element model

m1,p1 m2,p2

Tin T1,finalTav

#1 #2

Q1 Q2 Q3

#3

Q,T from heat sink

12

1iiQQ

22,_,_,, tfwhtavfwthshths

i

TTTTUAQ

htavfwtfwfwfw

i TTCh

MQ _,_,

htavfwfw

htfwfw

infw TM

hmT

M

hmT _,__,, )1()(

Where ----heatsink temperature at time t

---- heatsink temperature at time t-h

thsT ,

hthsT _,

Other models

Water Mixing Chamber Model

• Valid for 2 entering streams with different mass flow rate and temperature;

• Governing Eqns :

m1T1

m2

T2

m_outT_out

Pipe Model

• Mainly account for the pressure change caused by height elevation;

outouthmhmhm 2211

outoutTmTmTm 2211Which can be written as

Linear Valve Model

• Assume pressure drop linearly depends on the throttle opening.

Electrical System Model

• models can be seamlessly substitute to perform analysis Two different levels of details have been developed for the Electro-thermal model

• Those two with more or less focus on electrical system waveform

Model 1

• The electrical system is represented as a constant power load (the user can specify active and reactive power)

• The interaction with the thermal system is given by the efficient coefficient

• Any loss resulting from the efficiency calculation is supposed to be a forcing function for the thermal system

Model 1

Three-phase electrical terminal

Thermal port

Model 2

• The model includes the power electronics, the control and the electrical machine

• The power electronics is modeled through an averaged model

• Switching and conduction losses are estimated from the averaged model

Model 2

PEBB’s withThermal port

Control system

Induction machine

Controlled rectifier

4 PCM Heat Source

4 Heatsink Temperature

Example simulation results for PCM and Heatsink Model

Example simulation results for the freshwater-Seawater HeatExchanger

Fresh water inlet Temp.

Sea water outlet Temp.

Fresh water outlet Temp.


Fresh water Temperature

Field

#120 Element

#110 Element

#100 Element

#10 Element

#20 Element

Length direction


#120 Fresh water Temperature





Conclusions

• A real time coupled thermo-electrical simulation for slice 2 of DDG-51 has been successfully developed in VTB

• The simulation couples electrical and thermal models• Results have been validated with experimental data• The simulations can be extended to include chillers• Transient responses to changing loads can be

studied – Simulation is available for demonstration

Documents

Coupled Thermo-electric VTB Simulation Model of Cooling Loop of a Ship System Jamil Khan, Ruixian Fang, A. Monti, Wei Jiang, University of South Carolina