Novel Air-Cooled Thermosyphon Cooling System for Desktop Computers

2021 ◽  
Author(s):  
Filippo Cataldo ◽  
Raffaele L. Amalfi ◽  
Jackson B. Marcinichen ◽  
John R. Thome
Keyword(s):  
Power Consumption ◽  
Cooling System ◽  
Electronics Cooling ◽  
Operating Conditions ◽  
Working Fluid ◽  
Maximum Heat ◽  
Desktop Computers ◽  
Fan Speed ◽  
Conventional Cooling ◽  
Power Densities

Abstract The trade-off between efficient cooling and low power consumption is a goal that has always been very desirable in electronics cooling, especially nowadays that power densities of processing units are increasing. Conventional cooling solutions do not have the necessary cooling capacities for these power densities or require significant power consumption. In this study, a novel air-cooled thermosyphon cooling system for desktop computers is presented and experimentally tested. The thermosyphon comprises a vertical micro-channel cold plate as the evaporator and a horizontal air-cooled multiport coil as the condenser. The thermosyphon has a total height of 12 cm and operates with a fan speed of 1700 RPM. The working fluid selected for the thermosyphon loop is R1234ze(E), chosen for its advantageous thermophysical properties and nearly zero-GWP (Global Warming Potential). The test results presented in this paper aim to analyze thermosyphon’s thermal and hydraulic performance by studying the trends of thermal resistance and mass flow rate as a function of different operating conditions. The maximum heat rejection under safe conditions is 250 W, corresponding to a heat flux of about 18 W/cm2.

The Effects of Spraying Parameters on Spray Cooling Heat Transfer Performance in the Non-Boiling Regime

2017 ◽  
Author(s):  
Azzam S. Salman ◽  
Jamil A. Khan
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Target Surface ◽  
Spray Cooling ◽  
Operating Conditions ◽  
Droplet Velocity ◽  
Inlet Pressure ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Spraying Parameters

Experiments were conducted in a closed loop spray cooling system working with deionized water as a working fluid. This study was performed to investigate the effect of the spraying parameters, such as Sauter mean diameter (SMD), the droplet velocity, and the residual velocity on the spray cooling heat transfer in the non-boiling region. Thermal effects on plain and modified surfaces with circular grooves were examined under different operating conditions. The inlet pressure of the working fluid was varied from 78.6 kPa to 183.515kPa, and the inlet temperature was kept between 21–22 °C. The distance between the nozzle and the target surface 10 mm. The results showed that increasing the coolant inlet pressure increases the droplet velocity and the number of droplets produced while decreasing the droplet size. As a consequence of these changes, increasing inlet pressure improved the heat transfer characteristics of both surfaces.

Performance and Development of a Miniature Rotary Shaft Pump

2005 ◽  
Vol 127 (4) ◽  
pp. 752-760 ◽  
Author(s):  
Danny Blanchard ◽  
Phil Ligrani ◽  
Bruce Gale
Keyword(s):  
Flow Rate ◽  
Pressure Rise ◽  
Electronics Cooling ◽  
Maximum Flow ◽  
Operating Conditions ◽  
Working Fluid ◽  
Hydraulic Efficiency ◽  
Potential Applications ◽  
Total Analysis ◽  
And Performance

The development and performance of a novel miniature pump called the rotary shaft pump (RSP) is described. The impeller is made by boring a 1.168 mm hole in one end of a 2.38 mm dia shaft and cutting slots in the side of the shaft at the bottom of the bored hole such that the metal between the slots defines the impeller blades. The impeller blades and slots are 0.38 mm tall. Several impeller designs are tested over a range of operating conditions. Pump performance characteristics, including pressure rise, hydraulic efficiency, slip factor, and flow rate, are presented for several different pump configurations, with maximum flow rate and pressure rise of 64.9ml∕min and 2.1 kPa, respectively, when the working fluid is water. Potential applications include transport of biomedical fluids, drug delivery, total analysis systems, and electronics cooling.

Experimental Validation and Design Simulations of a Passive Two-Phase Cooling System for Datacenters

2020 ◽  
Author(s):  
Jackson B. Marcinichen ◽  
John R. Thome ◽  
Raffaele L. Amalfi ◽  
Filippo Cataldo
Keyword(s):  
Thermal Performance ◽  
Experimental Validation ◽  
Cooling System ◽  
Electronics Cooling ◽  
Operating Conditions ◽  
Two Phase ◽  
Data Set ◽  
Pressure Drops ◽  
Wide Range ◽  
Important Challenge

Abstract Thermosyphon cooling systems represent the future of datacenter cooling, and electronics cooling in general, as they provide high thermal performance, reliability and energy efficiency, as well as capture the heat at high temperatures suitable for many heat reuse applications. On the other hand, the design of passive two-phase thermosyphons is extremely challenging because of the complex physics involved in the boiling and condensation processes; in particular, the most important challenge is to accurately predict the flow rate in the thermosyphon and thus the thermal performance. This paper presents an experimental validation to assess the predictive capabilities of JJ Cooling Innovation’s thermosyphon simulator against one independent data set that includes a wide range of operating conditions and system sizes, i.e. thermosyphon data for server-level cooling gathered at Nokia Bell Labs. Comparison between test data and simulated results show good agreement, confirming that the simulator accurately predicts heat transfer performance and pressure drops in each individual component of a thermosyphon cooling system (cold plate, riser, evaporator, downcomer (with no fitting parameters), and eventually a liquid accumulator) coupled with operational characteristics and flow regimes. In addition, the simulator is able to design a single loop thermosyphon (e.g. for cooling a single server’s processor), as shown in this study, but also able to model more complex cooling architectures, where many thermosyphons at server-level and rack-level have to operate in parallel (e.g. for cooling an entire server rack). This task will be performed as future work.

Nano Heat Pipe: Nonequilibrium Molecular Dynamics Simulation

2016 ◽  
Author(s):  
Mohammad Moulod ◽  
Gisuk Hwang
Keyword(s):  
Molecular Dynamics ◽  
Heat Flux ◽  
Heat Pipe ◽  
Thermal Management ◽  
Operating Conditions ◽  
Dynamics Simulation ◽  
Nonequilibrium Molecular Dynamics ◽  
Management Systems ◽  
Working Fluid ◽  
Maximum Heat

A heat pipe has been known as a thermal superconductor utilizing a liquid-vapor phase change, and it has drawn significant attentions for advanced thermal management systems. However, a challenge is the size limitation, i.e., the heat pipe cannot be smaller than the evaporator/condenser wick structures, typically an order of micron, and a new operating mechanism is required to meet the needs for the nanoscale thermal management systems. In this study, we design the nanoscale heat pipe employing the gas-filled nanostructure, while transferring heat via ballistic fluid-particle motions with a possible returning working fluid via surface diffusions along the nanostructure. The enhanced heat flux for the nano heat pipe is demonstrated using the nonequilibrium molecular dynamics simulations (NEMDS) for the argon gas confined by the 20 nm-long Pt nanogap with a post wall with the temperature difference between the hot and cold surfaces of 20 K. The predicted results show that the maximum heat flux through the gas-filled nanostructure (heat pipe) nearly doubles that of the nanogap without the post wall at 100 < T < 140 K. The optimal operating conditions/material selections are discussed. The results for the nanogap agree with those obtained from the kinetic theory, and provide insights into the design of advanced thermal management systems.

Experimental Study on Miniature-Refrigeration System

2012 ◽  
Vol 531-532 ◽  
pp. 584-587
Author(s):  
Juan Juan Yang ◽  
Ke Li ◽  
Xin Yang Cui
Keyword(s):  
Power Consumption ◽  
Water Temperature ◽  
Compression Ratio ◽  
Cooling System ◽  
Operating Conditions ◽  
Operation Condition ◽  
Environment Temperature ◽  
Chilled Water ◽  
Compressor Power ◽  
System Power

A prototype of miniature cooling system was developed, which mainly consists of the miniature compressor from DONG YUAN and a spiral-tube evaporator designed by ourselves. The performances of the prototype with different parameters were tested. The influence of ambient temperature, chilled water temperature on the performance of the cooling system were analyzed. The best operating conditions and the optimum amount of refrigerant were obtained. Conclusions were gotten as follows:1) With environment temperature rising, compression ratio increases, system power consumption increases and refrigerating capacity COP decreases. 2) With chilled water temperature rising, compression ratio and power consumption decrease, refrigerating capacity increases, and COP increases rapidly.3) Paper gets system performance: refrigerating capacity is 63 W, compressor power consumption is 24.5 W, COP value is 2.57. in operation condition: refrigerant amount is 40g, environment temperature is 30°C, chilled water temperature is 40 °C, chilled water mass flow is 45 kg/h.

Pool Boiling Heat Transfer With Binary Mixture on Open Microchannel Surface

2013 ◽  
Author(s):  
Ankit Kalani ◽  
Satish G. Kandlikar
Keyword(s):  
Binary Mixture ◽  
Heat Dissipation ◽  
Surface Effect ◽  
Pure Water ◽  
Pool Boiling ◽  
Electronics Cooling ◽  
Working Fluid ◽  
Two Phase ◽  
Maximum Heat ◽  
Fluid Medium

Two-phase cooling is considered an attractive option for electronics cooling due to its ability to dissipate large quantities of heat. In recent years, pool boiling has shown tremendous ability in high heat dissipation applications. Researchers have used various fluid medium for pool boiling including water, alcohol, refrigerants, nanofluids and binary mixture. In the current work, binary mixture of water with ethanol was chosen as the working fluid. Plain copper chip was used as the boiling surface. Effect of various concentrations of binary mixture was investigated. A maximum heat flux of 1720 kW/m2 at a wall superheat of 28°C was recorded for 15% ethanol in water. It showed a 1.5 fold increase in CHF over pure water.

scholarly journals A Compact Thermally Driven Cooling System Based on Metal Hydrides

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2482 ◽  
Author(s):  
Christoph Weckerle ◽  
Marius Dörr ◽  
Marc Linder ◽  
Inga Bürger
Keyword(s):  
Internal Combustion Engines ◽  
Cooling System ◽  
Heating System ◽  
Operating Conditions ◽  
Specific Power ◽  
Working Fluid ◽  
Cooling Power ◽  
Half Cycle ◽  
Exhaust Heat ◽  
Thermally Driven

Independent of the actual power train, efficiency and a high driving range in any weather conditions are two key requirements for future vehicles. Especially during summertime, thermally driven air conditioning systems can contribute to this goal as they can turn the exhaust heat of internal combustion engines, fuel cells or of any additional fuel-based heating system into a cooling effect. Amongst these, metal hydride cooling systems (MHCSs) promise very high specific power densities due to the short reaction times as well as high reaction enthalpies. Additionally, the working fluid hydrogen has a very low global warming potential. In this study, the experimental results of a compact and modular MHCS with a specific cooling power of up to 585 W kg MH − 1 referred to one cold generating MH are presented, while reactor and MH weight in total is less than 30 kg and require a volume < 20 dm3. The system is driven by an auxiliary fuel heating system and its performance is evaluated for different operating conditions, e.g., temperature levels and half-cycle times. Additionally, a novel operation optimization of time-shifted valve switching to increase the cooling power is implemented and investigated in detail.

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.

Fluid Damping and Power Consumption of Active Devices Used in Cooling Electronics

2012 ◽  
Author(s):  
Longzhong Huang ◽  
Smita Agrawal ◽  
Terrence Simon ◽  
Min Zhang ◽  
Taiho Yeom ◽  
...  
Keyword(s):  
Power Consumption ◽  
Cooling System ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Operating Conditions ◽  
High Heat Flux ◽  
Active Device ◽  
Active Devices ◽  
Fluid Damping ◽  
Oscillating Plate

Active devices, such as synthetic jets and oscillating plate agitators were found to be effective in cooling of high-heat-flux electronics. These devices generate unsteady flows, thinning the thermal boundary layer and enhancing turbulent transport. However, the active devices cause extra power consumption due to flow friction and separation. It is important to understand the factors influencing power consumption in these devices if they are to be applied in cooling system designs. The present study analyzes fluid damping and power consumption in high-frequency (about 1000 Hz) synthetic jets and oscillating plate agitators driven by piezoelectric stacks. This analysis is done numerically, since it is difficult to measure fluid damping. In the simulations, the moving part of the active device is modeled with the moving wall boundary condition. The mesh is updated and the flow is calculated every time the moving part changes its position. The coherent vortex structures generated by theses active devices, like vortices in the synthetic jet cavity or in the oscillating plate tip gap region, are found to cause fluid damping and power consumption. Fluidic power consumption levels with different geometries and different operating frequencies and amplitudes are studied. A correlation is developed to predict fluidic power consumption at different operating conditions.

A high-performance solid-state electrocaloric cooling system

Science ◽  
2020 ◽  
Vol 370 (6512) ◽  
pp. 129-133 ◽  
Author(s):  
Yunda Wang ◽  
Ziyang Zhang ◽  
Tomoyasu Usui ◽  
Michael Benedict ◽  
Sakyo Hirose ◽  
...  
Keyword(s):  
Heat Flux ◽  
Solid State ◽  
High Performance ◽  
Cooling System ◽  
Electronics Cooling ◽  
Multilayer Ceramic Capacitors ◽  
Maximum Heat ◽  
Maximum Heat Flux ◽  
System Temperature ◽  
Performance System

Electrocaloric (EC) cooling is an emerging technology that has broad potential to disrupt conventional air conditioning and refrigeration as well as electronics cooling applications. EC coolers can be highly efficient, solid state, and compact; have few moving parts; and contain no environmentally harmful or combustible refrigerants. We report a scalable, high-performance system architecture, demonstrated in a device that uses PbSc0.5Ta0.5O3 EC multilayer ceramic capacitors fabricated in a manufacturing-compatible process. We obtained a system temperature span of 5.2°C and a maximum heat flux of 135 milliwatts per square centimeter. This measured heat flux is more than four times higher than other EC cooling demonstrations, and the temperature lift is among the highest for EC systems that use ceramic multilayer capacitors.

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