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Coupled Thermo-electric VTB Simulation Model of Cooling Loop of a Ship System

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Coupled Thermo-electric VTB Simulation Model of Cooling Loop of a Ship System

ESRDC Modeling and Simulation WorkshopTallahassee, FL14 February, 2006

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

University of South Carolina

Greg Anderson, Mark Zerby, Phil Bernatos

NSWC, Philadelphia

- Problem Statement
- Models
- Thermal
- Electrical

- Simulation Results
- Conclusions

Problem Statement

FreshWater Heatsink HeatExchanger

Temperature

mass flow

Level 4

2nd layer of Fw_HEX

Level 3

PCM board

Level 2

Valve

Pipe

Mixing model

HeatSink

Level 1

Pump

FreshWater SeaWater HeatExchanger

SeaWater

Schematic for zone 2

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

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

L

Fresh water

Where ----Fresh water temperature at time t

----Sea water temperature at time t

Sea water

Tin

L/120

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.

Sea_Water Element #i

Heat Sink

- Assume no temperature gradient along the length direction;
- Governing Eqns :

T2,Q2

Qa

Where ----Inlet heat flow from heat source

---- Outlet heat flow from heatsink

---- heat absorbed by heatsink

T1,Q1

Where ----Mass of heatsink

---- Heatsink heat capacity

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

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

m ,p

m ,p

Tout

Tin

Q,T

Where ----heatsink temperature at time t

---- heatsink temperature at time t-h

m1,p1

m2,p2

#1

#2

#3

T1,final

Tin

Tav

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.

Q1

Q2

Q3

Q,T from heat sink

Element model

Other models

T1

m1

- Water Mixing Chamber Model
- Valid for 2 entering streams with different mass flow rate and temperature;
- Governing Eqns :

m2

T2

Which can be written as

T_out

m_out

- Pipe Model
- Mainly account for the pressure change caused by height elevation;

- Linear Valve Model
- Assume pressure drop linearly depends on the throttle opening.

- 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

- 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

Three-phase electrical terminal

Thermal port

- 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

Induction machine

Control system

PEBB’s with

Thermal port

Controlled rectifier

Example simulation results for PCM and Heatsink Model

4 PCM Heat Source

4 Heatsink Temperature

Example simulation results for the freshwater-Seawater HeatExchanger

Fresh water inlet Temp.

Sea water outlet Temp.

Fresh water outlet Temp.

Example simulation results for the freshwater-Seawater HeatExchanger

Fresh water Temperature Field

#10 Element

Length direction

#120 Element

#110 Element

#100 Element

#20 Element

Example simulation results for the freshwater-Seawater HeatExchanger

#10 Fresh water Temperature

#20 Fresh water Temperature

#100 Fresh water Temperature

#110 Fresh water Temperature

#120 Fresh water Temperature

- 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