scholarly journals The development of a liquid cooling test system for the analysis of porous surfaces

2021 ◽  
Author(s):  
◽  
Benjamin Sherson
Keyword(s):  
Heat Transfer ◽  
Closed Loop ◽  
Cooling System ◽  
Pressure Sensors ◽  
Test System ◽  
Design Development ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Porous Microstructures ◽  
Silver Surfaces

<p>Closed-loop liquid cooling systems are used in a wide variety of high temperature environments, as liquids tend a higher thermal conductivity than air. Microchannels and porous microstructures have proved to be useful in improving the cooling capabilities of cooling systems, due to their increased surface area in contact with the cooling fluid. This thesis describes the design, development, and evaluation of a closed-loop liquid cooling test system. This system was utilised in analysing the thermal properties of porous microstructures for use in improving cooling capabilities. Flow rate and pressure sensors were fitted onto a standard closed loop liquid cooling system design, and thermocouples were attached to the system to measure the temperature at various points, as well as measure heat flux. Using these measurements, the thermal and hydraulic resistances of the system could be calculated. Various substrates were fabricated using both freeze casting and other techniques, and the thermal and hydraulic resistances of these substrates were characterized using the test system. The test system performed very well, with results matching the trends as expected from theory. However, no improvement in heat transfer was observed from microstructured silver surfaces compared to a solid copper reference surface. This may be due to the formation of oxides and/or sulphides on these silver surfaces, resulting in a reduction in the convective heat transfer from these layers.</p>

scholarly journals The development of a liquid cooling test system for the analysis of porous surfaces

2021 ◽  
Author(s):  
◽  
Benjamin Sherson
Keyword(s):  
Heat Transfer ◽  
Closed Loop ◽  
Cooling System ◽  
Pressure Sensors ◽  
Test System ◽  
Design Development ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Porous Microstructures ◽  
Silver Surfaces

<p>Closed-loop liquid cooling systems are used in a wide variety of high temperature environments, as liquids tend a higher thermal conductivity than air. Microchannels and porous microstructures have proved to be useful in improving the cooling capabilities of cooling systems, due to their increased surface area in contact with the cooling fluid. This thesis describes the design, development, and evaluation of a closed-loop liquid cooling test system. This system was utilised in analysing the thermal properties of porous microstructures for use in improving cooling capabilities. Flow rate and pressure sensors were fitted onto a standard closed loop liquid cooling system design, and thermocouples were attached to the system to measure the temperature at various points, as well as measure heat flux. Using these measurements, the thermal and hydraulic resistances of the system could be calculated. Various substrates were fabricated using both freeze casting and other techniques, and the thermal and hydraulic resistances of these substrates were characterized using the test system. The test system performed very well, with results matching the trends as expected from theory. However, no improvement in heat transfer was observed from microstructured silver surfaces compared to a solid copper reference surface. This may be due to the formation of oxides and/or sulphides on these silver surfaces, resulting in a reduction in the convective heat transfer from these layers.</p>

Study on Copper Cold Plate Designs for Electronics Liquid Cooling System

2006 ◽  
Author(s):  
Yi. Feng ◽  
Y. Wang ◽  
C. Y. Huang
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Cooling System ◽  
Pure Copper ◽  
Cold Plate ◽  
Performance Limits ◽  
Liquid Cooling ◽  
Cold Plates ◽  
Management Approaches ◽  
Liquid Cooling System

The increasing power consumption of microelectronic systems and the dense layout of semiconductor components leave very limited design spaces with tight constraints for the thermal solution. Conventional thermal management approaches, such as extrusion, fold-fin, and heat pipe heat sinks, are somehow reaching their performance limits, due to the geometry constraints. Currently, more studies have been carried out on the liquid cooling technologies, as the flexible tubing connection of liquid cooling system makes both the accommodation in constrained design space and the simultaneous cooling of multi heating sources feasible. To significantly improve the thermal performance of a liquid cooling system, heat exchangers with more liquid-side heat transfer area with acceptable flow pressure drop are expected. This paper focuses on the performance of seven designs of source heat exchanger (cold plate). The presented cold plates are all made in pure copper material using wire cutting, soldering, brazing, or sintering process. Enhanced heat transfer surfaces such as micro channel and cooper mesh are investigated. Detailed experiments have been conducted to understand the performance of these seven cooper cold plates. The same radiators, fan, and water pump were connected with each cooper cold plate to investigate the overall thermal performance of liquid cooling system. Water temperature readings at the inlets and outlets of radiators, pump, and colder plate have been taken to interpret the thermal resistance distribution along the cooling loop.

Relative Cooling With Liquid for Gas Turbines: Part I — A Solution for Exceeding 2000 K at Turbine Inlet

2001 ◽  
Author(s):  
Sandu Constantin ◽  
Dan Brasoveanu
Keyword(s):  
Thermal Efficiency ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Air Cooling ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Turbine Inlet ◽  
Cooling Methods ◽  
Current Operating

Abstract The thermal efficiency of gas turbines is critically dependent on the temperature of burnt gases at turbine inlet, the higher this temperature the higher the efficiency. Stochiometric combustion would provide maximum efficiency, but in the absence of an internal cooling system, turbine blades cannot tolerate gas temperatures that exceed 1300 K. Therefore, for this temperature, the thermal efficiency of turbine engine is 40% less than theoretical maximum. Conventional air-cooling techniques of turbine blades allow inlet temperatures of about 1500 K on current operating engines yielding thermal efficiency gains of about 6%. New designs, that incorporate advanced air-cooling methods allows inlet temperatures of 1750–1800 K, with a thermal efficiency gain of about 6% relative to current operating engines. This temperature is near the limit allowed by air-cooling systems. Turbine blades can be cooled with air taken from the compressor or with liquid. Cooling systems with air are easier to design but have a relatively low heat transfer capacity and reduce the efficiency of the engine. Some cooling systems with liquid rely on thermal gradients to promote re-circulation from the tip to the root of turbine blades. In this case, the flow and cooling of liquid are restricted. For best results, cooling systems with liquid should use a pump to re-circulate the coolant. In the past, designers tried to place this pump on the engine stator and therefore were unable to avoid high coolant losses because it is impossible to reliably seal the stator-rotor interface. Therefore it was assumed that cooling systems with liquid could not incorporate pumps. This is an unwarranted assumption as shown studying the system in a moving frame of reference that is linked to the rotor. Here is the crucial fact overlooked by previous designers. The relative motion of engine stator with respect to the rotor is sufficient to motivate a cooling pump. Both the pump and heat exchange system that is required to provide rapid cooling of liquid with cold ambient air, could be located within the rotor. Therefore, the entire cooling system can be encapsulated within the rotor and the sealing problem is circumvented. Compared to recent designs that use advanced air-cooling methods, such a liquid cooling system would increase the thermal efficiency by 8%–11% because the temperatures at turbine inlet can reach stoichiometric levels and most of the heat extracted from turbine during cooling is recuperated. The appreciated high reliability of the system will permit a large applicability in aerospace propulsion.

Application of Micro-Channel Fin for Cold Plate of Liquid Cooling System and Vapor Chamber

2009 ◽  
Author(s):  
Koichi Mashiko ◽  
Masataka Mochizuki ◽  
Yuji Saito ◽  
Yasuhiro Horiuchi ◽  
Thang Nguyen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Cooling System ◽  
Cold Plate ◽  
Micro Channel ◽  
Vapor Chamber ◽  
Liquid Cooling ◽  
Liquid Cooling System ◽  
Heat Spreading

Recently energy saving is most important concept for all electric products and production. Especially, in Data-Center cooling system, power consumption of current air cooling system is increasing. For not only improving thermal performance but also reducing electric power consumption of this system, liquid cooling system has been developed. This paper reports the development of cold plate technology and vapor chamber application by using micro-channel fin. In case of cold plate application, micro-channel fin technology is good for compact space design, high thermal performance, and easy for design and simulation. Another application is the evaporating surface for vapor chamber. The well-known devices for effective heat transfer or heat spreading with the lowest thermal resistance are heat pipes and vapor chamber, which are two-phase heat transfer devices with excellent heat spreading and heat transfer characteristics. Normally, vapor chamber is composed of sintered power wick. Vapor chamber container is mechanically supported by stamped pedestal or wick column or solid column, but the mechanical strength is not enough strong. So far, the application is limited in the area of low strength assembly. Sometime the mechanical supporting frame is design for preventing deformation. In this paper, the testing result of sample is described that thermal resistance between the heat source and the ambient can be improved approximately 0.1°C/W by using the micro-channel vapor chamber. Additionally, authors presented case designs using vapor chamber for cooling computer processors, and proposed ideas of using micro-channel vapor chamber for heat spreading to replace the traditional metal plate heat spreader.

On Development of a Semi-Mechanistic Wall Boiling Model

2013 ◽  
Author(s):  
Saurish Das ◽  
Hemant Punekar
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Thermal Stresses ◽  
Cooling System ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Wall Heat Transfer ◽  
Cooling Systems ◽  
Transfer Phenomenon

In modern cooling systems the requirement of higher performance demands highest possible heat transfer rates, which can be achieved by controlled nucleate boiling. Boiling based cooling systems are gaining attention in several engineering applications as a potential replacement of conventional single-phase cooling system. Although the controlled nucleate boiling enhances the heat transfer, uncontrolled boiling may lead to Dry Out situation, adversely affecting the cooling performance and may also cause mechanical damage due to high thermal stresses. Designing boiling based cooling systems requires a modeling approach based on detailed fundamental understanding of this complex two-phase heat and mass transfer phenomenon. Such models can help analyze different cooling systems, detect potential design flaws and carry out design optimization. In the present work a new semi-mechanistic wall boiling model is developed within commercial CFD solver ANSYS FLUENT. A phase change mechanism and wall heat transfer augmentation due to nucleate boiling are implemented in mixture multiphase flow framework. The phase change phenomenon is modeled using mechanistic evaporation-condensation model. Enhancement of wall heat transfer due to nucleate boiling is captured using 1D empirical correlation, modified for 3D CFD environment. A new method is proposed to calculate the local suppression of nucleate boiling based on the flow velocity, and hence this model can be applied to any complex shaped coolant passage. For different wall superheat, the wall heat fluxes predicted by the present model are validated against experimental data, in which 50-50 volume mixture of aqueous ethylene glycol (a typical anti-freeze coolant mixture) is used as working fluid. The validation study is performed in ducts of different sizes and shapes with different inlet velocities, inlet sub-cooling and operating pressures. The results are in good agreement with the experiments. This model is applied to a typical automobile Exhaust Gas Recirculation (EGR) system to study boiling heat transfer phenomenon and the results are presented.

Analysis and Optimization of Flow and Heat Transfer in a Liquid Cooling System for an LED Array

2011 ◽  
Vol 8 (2) ◽  
pp. 72-82
Author(s):  
Samhitha Poonacha ◽  
Basawaraj ◽  
Hemanth Kumar T.R. Seetharam ◽  
K.N. Seetharamu
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Liquid Cooling ◽  
Flow And Heat Transfer ◽  
Led Array ◽  
Liquid Cooling System

Design of Air and Liquid Cooling Systems for Electronic Components Using Concurrent Simulation and Experiment

Volume 4 ◽  
2004 ◽  
Author(s):  
T. Icoz ◽  
N. Verma ◽  
Y. Jaluria
Keyword(s):  
Heat Transfer ◽  
The Other ◽  
Simple Problem ◽  
Electronic Systems ◽  
Efficient Design ◽  
Electronic Components ◽  
Liquid Cooling ◽  
Cooling Systems ◽  
Simulation And Experiment ◽  
Concurrent Simulation

The design of cooling systems for electronic equipment is getting more involved and challenging due to increase in demand for faster and more reliable electronic systems. Therefore, robust and more efficient design and optimization methodologies are required. Conventional approaches are based on sequential use of numerical simulation and experiment. Thus, they fail to use certain advantages of using both tools concurrently. The present study is aimed at combining simulation and experiment in a concurrent manner such that outputs of each approach drives the other to achieve better engineering design in a more efficient way. In this study, a relatively simple problem involving heat transfer from multiple heat sources, simulating electronic components, located in a horizontal channel was investigated experimentally and numerically. Two experimental setups were fabricated for air and liquid cooling experiments to study the effects of different coolants. De-ionized water was used as the liquid coolant in one case and air in the other. The effects of separation distance and flow conditions on the heat transfer and fluid flow characteristics were investigated in details for both coolants. Cooling capabilities of different cooling arrangements were compared and the results from simulations and experiments were combined to provide quantitative inputs for the design. The domains over which experimental or the numerical approach is superior to the other are determined. Simulations are used to guide the experiments and vice versa. It is found that the proposed optimization methodology can be implemented in the design of cooling systems for electronic components for faster and more efficient convergence. This methodology can also be extended to more complex and practical electronic systems.

COMPUTER SIMULATION OF TRANSFER PROCESSES IN MICROJET BURNER DEVICES WITH SPECIAL COOLING SYSTEMS

2017 ◽  
Author(s):  
Nataliia Fialko ◽  
Viktor Prokopov ◽  
Sergiy Alioshko ◽  
Julii Sherenkovskiy ◽  
Nataliia Meranova ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Computer Simulation ◽  
Cooling System ◽  
Cooling Systems ◽  
Transfer Processes ◽  
Flow And Heat Transfer ◽  
Inner Surface ◽  
Air Blowing

The analysis of efficiency of cooling system of the microjet stabilization burner devices is performed. The features of the flow and heat transfer in cooling systems with air blowing of the inner surface of flame stabilizator and with flat and circular impact jets are studied.

Flow and heat transfer in a closed loop thermosyphon Part II – experimental simulation

2007 ◽  
Vol 18 (4) ◽  
pp. 41-48 ◽  
Author(s):  
J.C. Ruppersberg ◽  
R.T. Dobson
Keyword(s):  
Heat Transfer ◽  
Closed Loop ◽  
Cooling System ◽  
Operating Conditions ◽  
Experimental Simulation ◽  
Theoretical Modelling ◽  
Working Fluid ◽  
Small Scale ◽  
System A ◽  
Test Loop

A closed loop thermosyphon is an energy transfer device that employs thermally induced density gra-dients to induce circulation of the working fluid thereby obviating the need for any mechanical moving parts such as pumps and pump controls. This increases the reliability and safety of the cool-ing system and reduces installation, operation and maintenance costs. These characteristics make it a particularly attractive option for the cavity cooling system of the Pebble Bed Modular Reactor (PBMR). Loop thermosyphons are however, known to become unstable under certain initial and operating conditions. It is therefore necessary to conduct an experimental and theoretical study of the start-up and transient behaviour of such a system. A small scale test loop was built representing a section of a concept cooling system. A number of representative yet typical experimental temperature and flow rate curves for a range of initial and boundary condi-tions were generated, plotted and are given as a function of time. These curves show that oscillatory temperature and flow occurred that was dependent on the differing design and operating conditions. A number of theoretical modelling and actual cooling system design problem areas were identified. These problem areas need to be addressed if more accu-racy is required to capture the erratic and ostensibly chaotic heat transfer behaviour of the loop.

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