1. University of South Carolina Thermal Modeling and Simulation in VTB Supporting ESRDC J. Khan, R. Fang, W. Jiang, M. Antonello, R. Dougal University of South Carolina G. Anderson, M. Zerby, P. Bernatos NSWC, Philadelphia

2. University of South Carolina Outline  Thermal system simulation review  Coupled Multi-scale problem  A control subsystem for a typical zone  Vapor compression chiller model  Waste Heat Utilization: Cogeneration, Regeneration  Solid Oxide Fuel Cell: Hybrid Power Plant  Viscous flow in pipes  VTB Pro  Future work

3. University of South Carolina Incorporate a 3-D Cabinet model into VTB Thermal system simulation review One of the 2 fans SSIM Module (3.02 kW) SV9000 Module (2.2 kW) Cold air supply (Front) @ 59 o C Hot air return (Back) @ 74 o C 5 Liquid-to-air heat exchangers (12.08 kW) Type-1 SS316 Frame (24” W x 48” D x 78” H) 3D Cabinet Model: PCM-2 Cabinet From Georgia Institute of Technology

4. University of South Carolina Chilled Water System Simulation Thermal system simulation review Hot water loop Chilled water loop Temperature loop

5. University of South Carolina Thermal-Electrical Coupled Freshwater-Seawater cooling subsystem for typical zone 2 System Description  VTB will distributes the mass flow rate automatically into each of the 4 cabinets  Thermal simulation coupled with the electronic component simulation  A simple feedback control approach Thermal system simulation review

6. University of South Carolina System Description  This project is accomplished in cooperation with NSWC, Philadelphia.  The connectivity network is used to distribute loads among the PCMs.  The task is to build this network onto VTB platform and connect it with the present ship cooling system.  The connectivity network shown in the Figure includes 5 zones of the ship power distribution. A typical zone is cooled by the freshwater –seawater loop for demonstration purpose, while other zones are not connected as shown in the figure. Thermal system simulation review Load Connectivity Network Simulation

7. University of South Carolina Load Connectivity Network Simulation Thermal system simulation review

8. University of South Carolina Thermal system simulation review System Description  This project is done in collaboration with Georgia Institute of Technology. The objective is to integrate a 3-D shipboard power-electronics cabinet’s model into VTB.  The compact models (PCM-1 and PCM-2) were coded in c++. They encapsulate all the calculations inside their models.  Corresponding VTB models were developed directly by invoking its dynamic-link library file. Link is validated by comparing with the four benchmark ASCII files for PCM-1 and PCM-2.  The cabinet models were inserted into VTB simulation directly by replacing the above LHS-PCM model as described in the freshwater cooling subsystem.  It shows the ability of implementation of alternative cooling technologies into VTB system-level simulation. Incorporate a 3-D Cabinet model into VTB

9. University of South Carolina Incorporate a 3-D Cabinet model into VTB Thermal system simulation review One of the 2 fans SSIM Module (3.02 kW) SV9000 Module (2.2 kW) Cold air supply (Front) @ 59 o C Hot air return (Back) @ 74 o C 5 Liquid-to-air heat exchangers (12.08 kW) Type-1 SS316 Frame (24” W x 48” D x 78” H) 3D Cabinet Model: PCM-2 Cabinet From Georgia Institute of Technology

10. University of South Carolina A Control Subsystem for A Typical Zone ---control system schematic ---control method ---example dynamic simulation Ongoing Thermal system simulation

11. University of South Carolina The goal of this control system is to maintain the heatsink temperature at a desired value. First level of control: control the opening of the each branch signal valve, which will change the mass flow rate through each branch. 2nd level of control: control the opening of the signal valve of the cooling water, which will change the mass flow rate through the Freshwater_Seawater_HEX. 3rd level of control: control the two pumps by increasing its driving Voltage, hence increasing the mass flow rate for both fresh and cooled water through out the system. Control Method

12. University of South Carolina Control Subsystem Schematic

13. University of South Carolina Example simulation basic parameters Control the heat sink temperature at 55 degree Celsius Heatexchanger (HEX) ----heat source power 52kw System startup temperature at 35 Celsius degree Each pump capacity 6.3Kg/s Dynamic test after reaching steady state Reduce the heat source #1 from 52kw  42kw (1 st level control) Increase the heat source #2 from 52kw  62kw (1 st level control) Increase the heat source #2 from 52kw  72kw (all 3 level level control) Example Simulation

14. University of South Carolina Chill water after AC freshwater seawater HEX Hot water after AC Chill water before AC Hot water before AC Example Simulation Step changes of the heat power Each Heatsink Temperature variation

15. University of South Carolina Each Heat Sink Temperature Example Simulation Step changes of the heat power Each branch mass flow rate variation

16. University of South Carolina 18 Heat Sink Temperature 4 AC_PLANT HEAT DISSIPATION HEAT EXCHANGERS HEAT ABSORPTIONAND HEAT SOURCE VARIATION Example Simulation Step changes of the heat power Pumps mass flow rate variation

17. University of South Carolina 18 Heat Sink Temperature 4 AC_PLANT HEAT DISSIPATION 18 HEXS HEAT ABSORPTION HEXS MASS FLOW RATE ANDAC_PLANT MASS FLOW RATE AC_PLANT MASS FLOW RATE HEX MASS FLOW RATE Example Simulation HEAT DISSIPATED BY THE SYSTEM

18. University of South Carolina 18 Heat Sink Temperature 4 AC_PLANT HEAT DISSIPATION 18 HEXS HEAT ABSORPTION HEXS MASS FLOW RATE ANDAC_PLANT MASS FLOW RATE AC_PLANT MASS FLOW RATE AC HEAT DISSIPATION Example Simulation Step changes of the heat power Freshwater & Seawater temp. variations at the HEX

19. University of South Carolina Ongoing Thermal system simulation System Description  This ongoing project is a collaboration with Florida State University.  The goal of the ongoing project is to study the transient interactions between the electrical and the thermal sub-systems.  The approach utilizes the existing large scale real-time simulation capabilities of electrical systems at Florida State University on the RTDS platform in conjunction with real-time simulation models of thermal systems implemented on the VTB platform.  Current thermal modeling consideration for VTB-RT at USC --- Update the hydraulic/thermal models to be more robust for test purposes, which includes the friction pipe modeling, controllable valve modeling and link the thermal/physical properties with thermal models, etc. Real-time co-simulation between the RTDS and VTB/Pro

20. University of South Carolina Real-time co-simulation between the RTDS and VTB/Pro VTB/Pro schematic for RTDS testing at FSU Ongoing Thermal system simulation

21. University of South Carolina Microchannel Water Reservoir Water Reservoir Heater Micro Synthetic Jet Top Plate Single phase microchannel flow: Disrupt laminar flow in forced convectional microchannel flow to improve heat transfer. Two phase microchannel flow boiling control: Suppress reverse flow boiling by introducing momentum into the main flow field and stabilize the two phase flow, thus enhance the CHF. Experimental Investigation of Micro-channel Cooling Using a Synthetic Jet Actuator

22. University of South Carolina (1) Front View (2) 3D View (4) Bottom View (3) Top View without cover plate Cover Plate Base Plate Heater Silicon Substrate Inlet Water reservoir Outlet Water reservoir Microchannel Base Plate Synthetic Jet housing and membrane Synthetic Jet Heater Jet Opening Microchannel: 4cm long (heating length: 2cm), 1000 μm wide, 200 μm deep Test Section Design

23. University of South Carolina Thermal Loop at USC to Study Heat Transfer with Nano-Fluid

24. University of South Carolina Heat Transfer Coefficient for Various Nanoparticle Concentration

25. University of South Carolina Conclusion and future work  Conclusion The work presented here provides the first step for using VTB/Pro as a potential system-level dynamic simulation platform for an all-electric ship thermal management.  Future work More Robust thermal management dynamic simulation will include the following areas: Address issues of multi-scale (temporal and spatial) related to all electric ship system Run coupled electrical and thermal models on multiple time scale, which is fundamental for the large scale ship system simulation. Parallel Computing

26. University of South Carolina Future Work Implement control system and Demonstrate the effectiveness of the control system Study the system response at various levels of uncertainty associated with the components Update the chiller models to make them more robust and easy to apply multi-objective control objective. Enrich the thermal/hydraulic models library in VTB Pro to include all kinds of valves, pipes, bends etc.

27. University of South Carolina Supplemental Material Additional Models

28. University of South Carolina Vapor Compression Chiller --- update the AC models to make them more robust and easy to incorporate into this chilled water system --- Example model description Chiller System Update

29. University of South Carolina System Description  Shell and tube condenser (water-cooled flood type)  Shell and tube evaporator (direct in-tube expansion type)  Centrifugal compressor (First principal model)  Thermostatic expansion valve  R134a working fluid  Control degree of superheat at the exit of evaporator  Vary compressor RPM to adjust heat load Chiller system layout on VTB

30. University of South Carolina Chiller Model Model descriptions  Evaporator and Condenser are the two major transient components The transients in the heat exchangers are usually the slowest and have the largest impact on the chiller transient performance. A distribution model for the Evaporator and Condenser by employing finite volumes method.  Compressor and Expansion valve model The dynamics of compressor and valve are considered to be fast relative to the heat exchangers, therefore they can be built from quasi-steady-state relationships. Centrifugal compressor (First principal model, validated in VTB) Reciprocal compressor (simple and better for control, developed in VTB )  Two-phase flow assumptions : homogeneous equilibrium flow (Often adequate for VC cycles)

31. University of South Carolina Example evaporator model

32. University of South Carolina Example evaporator model

33. University of South Carolina Example evaporator model Solution Method  Writing conservation equations for all N elements in the Evaporator, a complete system of 4N equations are obtained with 4N unknowns: Pref --- refrigerant pressure N nodal enthalpy, href N tube temperature, Tt N water temperature, Tw N-1 intermediate refrigerant mass flow rate, m  Coupled with external boundary conditions, this system of equations can be solved uniquely by the VTB solver.

34. University of South Carolina 6.63 o C 10.39 o C 5.56 o C 36.11 o C 31.11 o C Mass_rate_sw 40.34kg/s Mass_rate_R134a 4.55kg/s Mass_rate_fw 44.4kg/s Chiller Dynamic Simulation

35. University of South Carolina Chiller Dynamic Simulation Chiller response to a step change of 75% heat load

36. University of South Carolina System Description  This project is also a collaborative work with NSWC, Philadelphia.  Combination the freshwater cooling subsystem and chiller subsystem into the ship’s chilled water system and evaluate the system performance. It laid the ground work for big system simulation.  Simulation based on the DDG-51 class chilled water system consisted of 4 A/C plants and 18 compartments. using the chiller subsystem to model each A/C plant and the freshwater cooling subsystem to model each compartment.  The chilled water system thermal management issues for many type of configurations can be evaluated by this simulation. The loop configuration can be changed by controlling the valves Thermal system simulation review Chilled Water System Simulation

37. University of South Carolina Chilled Water System Simulation Thermal system simulation review Hot water loop Chilled water loop Temperature loop

38. University of South Carolina Flow in pipes models --- Hydraulic pump modeling --- Pipe lines modeling Ongoing Thermal system simulation

39. University of South Carolina Flow in pipes update modeling System Description  Water Pump – based on the characteristic curve of specific pump, which will give more accurate results than the theoretical one in case of the pump is specified.  Pipe - Update the pipe model by including the friction losses for the laminar/fully turbulent fluid flow.  Valve - Update the valve model by adding actual cross section feedback feature to the RT-version.

40. University of South Carolina Pump Characteristic Model

41. University of South Carolina Flow in pipes update modeling

42. University of South Carolina Conclusion and future work  Conclusion The work presented here provides the first step for using VTB/Pro as a potential system-level dynamic simulation platform for an all-electric ship thermal management.  Future work More Robust thermal management dynamic simulation. It includes the following areas: Run coupled electrical and thermal models on multiple time scale, which is fundamental for the large scale ship system simulation. Update the chiller models to make them more robust and easy to apply multi- objective control objective. Build and update the thermal/hydraulic models include all kinds of valves, pipes, bends etc.