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College of Engineering and Computing


Our Research

1.Single-phase and two-phase microchannel cooling using synthetic jets

The objective of this project is to develop innovative high heat flux removal cooling solutions that will dissipate over 300 W/cm2 from the die of high power electronics package while keeping the maximum die temperature < 120 oC.
Thermal management of electronics is posing significant challenges with advancements in micro-processors and high-density power electronics. The heat flux from the power devices has risen significantly for future all-electric ships, which will rely on increasing amount of power electronic components. The power consumption trend shows that the relentless increase in heat density will keep on rising with advancement of technology. Novel cooling solutions are in demand for thermal management.
Of those advanced cooling solutions, micro thermo-fluidic technology, which puts liquid phase-change properties to work in microscale structures, is considered one of the most effective solutions for those devices demanding very high-flux heat removal. Liquid microchannel has a dense package with higher heat transfer coefficient. Depending on the application, the liquid flow inside the microchannels can be single-phase or two-phase. Due to the small flow passage, the flow through the channel is dominantly laminar flow in most applications. By combining microchannel flow with micro-impingement jets, the microchannel heat transfer performance is greatly enhanced through either introducing turbulence into single-phase flow, or stabilizing the flow instability of two-phase flow.
We obtained around 40~50% heat transfer enhancement under specified jet operating conditions with a single jet imposing onto single-phase microchannel flow. The effects of multi-jets on the single phase microchannel flow are under investigating experimentally. It’s expected that the synthetic jet would have more promising enhancements. For microchannel flow boiling heat transfer, the synthetic-jets show some suppression on the flow instability which is caused by the rapid bubble generation and explosion. Ongoing research is trying to quantify the effects and explore the mechanism in detail.

See Fig1

Related Publications:

>> Ruixian Fang, Wei Jiang, Jamil Khan and Roger Dougal, ”Experimental Study on the Effect of Synthetic Jet on Flow Boiling Instability in a Microchannel”, 9th International Conference on Nanochannels, Microchannels, and Minichannels (ICNMM2011). June 19-22, 2011. Edmonton, Canada, accepted.
>> Ruixian Fang, Wei Jiang, Jamil Khan and Roger Dougal,”The Effects of a Cross-Flow Synthetic Jet on Single-Phase Microchannel Heat Transfer”, Int. J. Heat and Mass Transfer. (Submitted November 2010).
Ruixian Fang, Wei Jiang, Jamil Khan, Roger A. Dougal, “Experimental Heat Transfer Enhancement in Single-phase Liquid Microchannel Cooling with Cross-flow Synthetic Jet”, 14th  International Heat Transfer Conference (IHTC). Aug. 7-13, 2010.  Washington D.C., USA.
>> Ruixian Fang, Wei Jiang, Jamil Khan, Roger A. Dougal “Experimental Heat Transfer Enhancement for Single Phase Liquid Micro-Channel Cooling Using A Micro-Synthetic Jet Actuator”, Proceedings of MNHMT2009. Dec. 18-21, Shanghai, China.
for more information: fangr@email.sc.edu 
Funded by: ESRDC

2.Ship System-Level Thermal Models and Simulations

The objective of the project is to develope thermal models, thermal subsystems and incorporate them into dynamic simulation of ship electrical power systems for system-level ship thermal management. For the Navy’s future all-electric ships, thermal issues become more important due to the fact that the increasing amount of advanced power electronics, high power sensors, etc, will result in large amount of additional heat load. To evaluate the impact of the transient load expected to be experienced on both the ship’s electrical systems and thermal systems, it will be necessary to better co-design the electrical and thermal systems, in particular to account for transient responses during dynamic events due to thermo-electrical system interactions. Such a simulation approach will permit ship designers to address thermal issues earlier in the design process to produce more efficient, less costly ship power systems.
Many thermal models for dynamic simulation have been developed for this project. Major components, such asVTB several types of heat exchangers, heat sinks, condenser, evaporator, radiators, expansion valve, temperature controller, pressure regulators, mixing chamber, etc, were added into the VTB component library. Most of them are based on the principals of heat transfer, thermodynamics and fluid mechanisms. By integrating those components, dynamic simulations for several most essential cooling schemes of ship’s cooling system were implemented successfully. Those demo simulations include the fresh water cooling subsystem and the chilled water cooling subsystem on board of the notional DDG-51 class destroyer.
We also have demonstrated the capability of thermo-electrical coupled co-simulation between a power generation subsystem and a zonal thermal subsystem. This is implemented by integrate the fresh water cooling model with the existing Solid Oxide Fuel Cell / Gas Turbine hybrid power generation model. By using the co-simulation methodology, the impacts of the ship’s load change on the dynamic performance of the each subsystem, i.e., Solid Oxide Fuel Cell, Gas Turbine, propulsion plant and thermal plant were evaluated. Right now, a more detailed gas turbine model is under developing which will employ the whole performance maps of the compressors and power turbines.

See Fig2

Related Publications

>> Ruixian Fang, Wei Jiang, Jamil Khan, Roger Dougal, “Thermal Modeling and Simulation of the Chilled Water System for Future All Electric Ship”, IEEE Electric Ship Technologies Symposium, Alexandria, VA, April 10-13, 2011.
>> Ruixian Fang, Wei Jiang, Jamil Khan, Roger Dougal, “Thermal System Modeling and Co-Simulation with All-Electric Ship Hybrid Power System”. Journal of Energy Resources Technology, under review, Aug. 2010.
>> Ruixian Fang, Wei Jiang, Jamil Khan, Roger Dougal, “System-Level Thermo Modeling and Co-simulation with Hybrid Power System for Future All Electric Ship”, 2009 IEEE Electric Ship Technologies Symposium, pp.547-553, Baltimore, April 2009.
>> Ruixian Fang, Wei Jiang, Jamil Khan, “System-Level Dynamic Thermal Modeling and Simulation for an All-Electric Ship Cooling System in VTB”. 2007 IEEE Electric Ship Technologies Symposium, pp462-469, Arlington, VA, May 2007.
>> Wei Jiang, Jamil Khan, Roger A. Dougal “Dynamic Centrifugal Compressor Model for System Simulation”. Journal of Power Sources , Volume 158, Issue 2 , 25 August 2006, Pages 1333- 1343.
>> Wei Jiang, Ruixian Fang, Roger A. Dougal, Jamil Khan, “Dynamic Electro-thermal Simulation of a Tubular Solid Oxide Fuel (SOFC)”. 2006 ASME International Mechanical Engineering Congress & Exposition (IMECE), IMECE2006-16279 , Nov., 2006.
>> Wei Jiang, Ruixian Fang, Roger A. Dougal, Jamil Khan, “Parameter Setting and Analysis of a Dynamic Tubular SOFC Model”. Journal of Power Sources, Volume 162, Issue 1 , 8 November 2006, Pages 316-326.
Wei Jiang, Ruixian Fang, Roger A. Dougal, Jamil Khan, “Thermo-electric Model of a Tubular SOFC for Dynamic simulation”. ASME, Journal of Energy Resources Technology, accepted in Jan. 2007.
For more information: fangr@email.sc.edu    
Funded by: ESRDC

3.Enhanced Flow Boiling in Copper Nanowires Coated Microchannel

Removing high heat flux from a limited space is quite a big challenge for the thermal engineers and a major obstruction for further miniaturization and performance enhancement of electronics devices. Thermal engineers are searching different avenues for removing ultra high heat flux from a limited space keeping the heat sink small and investing less power. Micro-channel based two phase heat sink is a highly efficient way for that purpose, which already has attracted thermal researcher’s attention. Two phase flow in micro-channel is greatly influenced by the solid liquid interface characteristics. In this project, solid liquid interface has been modified by developing Cu nanowire on the solid surface to enhance the performance of the two phase heat sink. Experiments have been carried out in bottom-surface heated single micro-channel using DI water as coolant. From our preliminary investigation results, nanowire coating has been found effective in lowering the boiling incipience temperature, surface superheat temperature and in enhancing the boiling heat transfer rate.
The overall focus of this project is to reduce the heat sink size and surface super heat temperature by increasing the flow boiling heat transfer rate and reducing the boiling incipience temperature. This project is intended to have application in high heat flux electronics components.
See Fig3a, Fig3b, Fig3c, Fig3d 

Related Publications:

 

>> Muhmmad Yakut Ali, Fanghao Yang, Ruixian Fang, Chen Li, Jamil Khan, “Thermohydraulic Characteristics Of A Single-Phase Microchannel Heat Sink Coated With Copper Nanowires”.Frontier of Heat and Mass Transfer (FHMT), Volume 2, No. 3, 033003, 2011.
>> AKM M. Morshed, Fanghao yong, yakut Ali, Jamil A. Khan, Chen Li, “Enhanced flow boiling in a micro channel with integration of nanowires”, Applied Thermal Engineering, volume 32, January 2012, Pages 68-75.
For more information: fangr@email.sc.edu   
Funded by: ESRDC

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4.Enhanced Convective Microchannel cooling with nanofluids

The objective of this project is to develop efficient high heat flux removal cooling solutions for power electronics package. Thermal management of electronics is posing significant challenges with advancements in micro-processors and high-density power electronics. The power consumption trend shows that the relentless increase in heat density will keep on rising with advancement of technology. Novel cooling solutions are in demand for thermal management.
In this project high thermal conductive nanofluid has been used as a coolant and its thermal performance has been investigated in a microchannel. In addition to experiment, a simplified molecular dynamics model has been employed to undersatand the heat transfer enhancement mechanism.

See Fig4a, Fig4b

For more information: fangr@email.sc.edu   
Funded by: ESRDC

5.Heat Transfer at the Solid Liquid interface: MD investigation

Solid liquid interface phenomena plays a very significant role in heat transfer, specially in micro and nanoscale. Little manipulation in nanoscale phenomena can result in signifianct enhancement in conventioanl scale heat transfer. To design heat removal device more efficiently specially when the dMDevice size in micro or nanoscale range, solid liquid interface phenomena needs to undertand properly.

Molecular dynamics (MD) simulation is a powerful tool to investigate the nanoscale phenomena. In this project MD simulation has been used to investigate the nanoscale curvature and roughness effect on heat transfer and phase change phenomena at the solid liquid interface.

The outcome of the project will be very useful for nanoscale heat removal device design.

See Fig5

For more information: fangr@email.sc.edu   
Funded by: ESRDC

6. Thermally-stable Ionic Liquid Carriers for Nanoparticle-based Advanced Heat Transfer in Concentrating Solar Energy Applications

Heat transfer fluids are commonly used in industry and in solar energy collections as a means to exchange energy from one source (solar energy) to another either to dissipate the energy or convert the energy into power (steam turbine). The properties of the thermal fluid greatly affect the overall efficiency of the system, thus there is always a driving force to design a thermal fluid with better physical properties. High temperature stability and high heat storage capability are the critical factors for those heat transfer liquids. Currently used heat storage medium liquid has the low decomposition temperature and high melting point which results in high operating cost. To meet the above requirements Ionic Liquids (IL) may be the replacement of the heat storage medium of the solar collector.

The present study proposes to enhance the heat transfer and solar thermal energy collection by dispersing small volume percentages of nanoparticles into the ionic liquid carriers, creating Nanoparticle Enhanced Ionic Liquids (referred to as NEILs). This project is a collaborative work with Savannah River National Laboratory and University of Notre Dame. The objective of our task is to determine heat transfer coefficients of NEIL under both forced and natural convection conditions.

 The present study proposes to enhance the heat transfer and solar thermal energy collection by dispersing small volume percentages of nanoparticles into the ionic liquid carriers, creating Nanoparticle Enhanced Ionic Liquids (referred to as NEILs). This project is a collaborative work with Savannah River National Laboratory and University of Notre Dame. The objective of our task is to determine heat transfer coefficients of NEIL under both forced and natural convection conditions.

Natural Convection Study: Natural convection study is performed in rectangular enclosure test sections which are made with clear polycarbonate Lexan sheet. Two ends of the enclosure are made with conductive copper sheets which are made to perform as hot and cold surfaces. Fig6 shows the complete experimental setup of natural convection study.

Related Publications:

>> Titan C. Paul, AKM M. Morshed, Elise B. Fox, Ann Visser, Nicholas Bridges, Jamil A. Khan, “Experimental Investigation of Natural Convection Heat Transfer of an Ionic Liquid in a Rectangular Enclosure Heated from Below”, IMECE2011 November 11-17, 2011, Denver, Colorado, USA.

For more information : paultc@email.sc.edu  
Funded by : US Deparment of Energy

7.Heat Transfer Enhancement in Nuclear Fuel rod bundles

It proposes to investigate the applicability of the roughening technique to enhance heat transfer in nuclear fuel bundles. The investigation involves experimental testing and numerical simulations. The experimental testing consists of Single Heater Element Loop Test (SHELT) constructed at USC. Observations will be made on differential pressure, velocity distribution, and temperatures for different roughness configurations. The numerical simulation involves Computational Fluid Dynamics (CFD) models of single and rod bundles to predict friction and heat transfer coefficients on the surface of the tube. The roughness design optimization will be performed during the CFD analyses, which utilize height, width, and pitch as design parameters. At least for the bi-dimensional parallel rib-type roughness, the CFD results are expected to be comparable to those obtained in previous work for gas-cooled and light-water reactors. The latter is described in the background review.

See Fig7

Related Publications:

>> Leo A. Carrilho, Jamil Khan, Michael E. Conner, Abdel Mandour, Milorad B. Dzodzo, "TWO AND THREE-DIMENSIONAL SIMULATIONS OF ENHANCED HEAT TRANSFER IN NUCLEAR FUEL ROD BUNDLES", 2009 ASME Summer Heat Transfer Conference July 19-23, 2009, San Francisco, California, USA.

For more information : carrilla@westinghouse.com  
Funded by : Westinghouse

8.Heat Transfer Enhancement in Nuclear Fuel rod bundles with Nanofluids

It proposes to investigate the applicability of the roughening technique and nanofluids to enhance heat transfer in nuclear fuel bundles. The investigation involves experimental testing. The experimental testing consists of Single Heater Element Loop Test (SHELT) constructed at USC. Observations will be made on differential pressure, velocity distribution, and temperatures for different volume percentage of nanofluids.

For more information : marco_piccinini@yahoo.com,  najeeb@email.sc.edu    
Funded by : Westinghouse

9.Gas Turbine Modeling for System level Simulations

The current work mainly focuses on developing a new method of predicting the dynamic model of turbine and its performance during its design, off-design conditions and transient conditions with the help of virtual test bed software indigenously developed by University of South Carolina. This model aids in predicting and reducing the cost of development significantly during the preliminary stages and will acts as a base for future development in various applications of turbine. A stage by stage development of the model is done from scratch by constructing appropriate maps with available data’s and literature; as well as validating these measurements.

For more information: thirunav@email.sc.edu    
Funded by: ESRDC

10. Spray Cooling Compound with a Refrigeration System

With the continues development in the manufacturing processes of electrical and electronic devices such as computers, leasers, electrical cars and other applications that produce high heat flux such as steel manufacturing, the amount of heat released becomes higher due to the reduction in size, the huge amount of data analysis, such as computers, or the requiring of high temperature for manufacturing such as steel casting. Therefore, the need of effective heat removal technology that able to remove high heat flux becomes urgent in order to provide the suitable
working or manufacturing conditions. There are many thermal management technologies that developed to remove high heat from heating objects, such as microchannel, heat pipes, forced convection, spray cooling and many others depending on the application. The most
efficient technique of removing high heat flux is spray cooling due to the involving of several heat removing mechanisms in this process such as forced convection, evaporation, nucleate boiling that includes nucleation over the heated surface and secondary nucleation within the accumulated liquid film. Therefore, spray cooling becomes one of the promising solutions that gets the most attention from researchers in the recent years among other techniques. In this project, experimental study of spray cooling compound with a refrigeration system will be implemented. Fig10a shows a schematic diagram of the spray cooling compound with a refrigeration system. Fig10b shows the experimental setup that will be used in this project.

11. Heat Transfer Enhancement of Spray Cooling System by Surface Modifications.

The main objective of this project is to enhance the heat transfer characteristics in spray cooling system working with deionized water as a coolant. Spray cooling is a very efficient technique to remove the heat from high heat flux surfaces. It can be used in many engineering applications like metal processes, aerospace, nuclear, laser diode arrays, and high power electronics. The fig11 is a schematic diagram for the experimental setup.

The setup mainly consists of a stainless steel water tank, a strainer, a moderate low positive displacement bypass diaphragm pump, a positive displacement flow meter, control valves, a full cone nozzle, a stainless steel chamber, a copper block, a cartridge heater, power supply, and data acquisition system. In this study the heat transfer characteristics will be investigated in the single phase and two phase regions for plain and modified surfaces.  The surfaces will be modified by improving the thermal properties chemically, also, the surfaces will be modified geometrically.

For more information: asalman@email.sc.edu 

12. Experimental and Numerical investigation of Heat Transfer enhancement in Nuclear Fuel rod Bundles.

Surface roughness is used to enhance heat transfer from nuclear fuel rods used in Pressurized Water Reactors (PWRs). The heat transfer enhancement in due to the increase in turbulence of the water flowing around the roughened nuclear fuel rods. However, the enhancement in heat transfer comes at the expense of an increase in pressure drop (i.e. Higher pumping power requirement). Therefore, it is necessary to experimentally quantify the heat transfer enhancement and the associated pressure drop obtained from the new roughness designs on nuclear fuel rod samples, and to make sure that it will be economical to be implemented in the PWR rod bundles.

In order to test the heat transfer and pressure drop in single nuclear fuel rod samples, a Single Heater Element Loop Tester (SHELT) was constructed at USC, See Fig12a .  The loop consists of all the required instrumentations needed for thermal hydraulic testing of single nuclear fuel rod samples.

A numerical analysis is performed using ANSYS Fluent to validate the experimental results. Usually a 2D analysis is conducted by using the k-w shear stress transport model to validate the pressure drop and heat transfer results obtained from the experimental testing. The numerical analysis also provides a glimpse at the underlying physics associated with the increase in heat transfer and the pressure drop.

See Fig12a, Fig12b 

Related Publications:

>> Leo A. Carrilho, Jamil Khan, Michael E. Conner, Abdel Mandour, Milorad B. Dzodzo, "Two and Three Dimensional simulation of enhanced heat transfer in nuclear fuel rod bundles”, 2009 ASME Summer Heat Transfer Conference July 19-23, 2009, San Francisco, California, USA.
>> Umair Najeeb, Leo A. Carrilho, Jamil A. Khan, "Heat Transfer Characteristics of Three-Dimensional Surface Roughness in Nuclear Fuel Rod Bundles." 2013 ASME International Mechanical Engineering Congress and Exposition.
>> Ahmed M. Abir, Titan C. Paul, Leo A. Carrilho, Jamil A. Khan, “Experimental and Numerical Investigation of pressure drop in Silicon Carbide (SiC) fuel rod for Pressurized Water Reactor”, 4th International Workshop on Heat Transfer, 2017 Las Vegas, Nevada. (submitted)

For More information: aabir@email.sc.edu , atikadar@email.sc.edu 
Funded by: Westinghouse