Compact Refrigeration System for Electronics Cooling Based ...

July 11-14, 2016

Compact Refrigeration System for Electronics Cooling Based

on a Novel Two-Phase Jet Impingement Heat Sink

Pablo A. de Oliveira, Post doctoral researcherJader R. Barbosa Jr., Associate professorPolo Research Laboratories for Emerging Technologies in Cooling and ThermophysicsFederal University of Santa Catarina (UFSC), Florianópolis, Brazil

July 11-14, 2016 2Purdue Conferences

Learning objectives

1. Introduce an innovative thermal management solution for

electronics cooling, i.e., a two-phase jet impingement heat sink

capable of dissipating high heat loads;

2. Present the compact vapor compression refrigeration system in

which the novel jet heat sink operates;

3. Present a thermodynamic performance evaluation for the

proposed active cooling system.


1. Motivation (alternatives for electronics cooling)

2. State of the art

3. The object of investigation

4. Experimental apparatus

5. Experimental analysis of the refrigeration system

6. Summary and conclusions

Outline


Alternatives for electronics cooling(a) Two-phase flow enhanced heat transfer schemes

(i) High HTC;(ii) Non-linear relation between the heat flux and

the surface-to-fluid temperature difference;(iii) Expressive reduction of the surface temperature

and its fluctuations.

(b) Direct liquid cooling (sprays and impinging jets)

(i) Eliminate thermal resistances on the component;(ii) Reduction of both weight and volume of the

cooling system.

(c) Active cooling solutions (relies on refrigeration)

(i) Below-ambient junction temperature;(ii) Higher speed;(iii) Increased reliability;(iv) Expanded lifetime.

Combination of (a), (b) and (c):Hybrid active cooling system


Principal findings:

1. Very few investigations have focused on the integration of direct liquidcooling techniques with vapor compression refrigeration systems (Yan etal., 2010; Chunqiang et al., 2012; Tan et al., 2013; Xu et al., 2014; Houet al., 2015; Chen et al., 2015);

2. The existing works used primarily spray cooling and did not devotespecific attention to the miniaturization aspect of the application;

3. Ancillary expansion valves were needed (Yan et al., 2010; Chunqiang etal., 2012; Tan et al., 2013; Xu et al., 2014) and oil-lubricatedcompressors were used (Chunqiang et al., 2012; Xu et al., 2014; Hou etal., 2015; Chen et al., 2015);

4. An active cooling system that integrates two-phase impinging jets andmechanical vapor compression refrigeration cycle has not been reportedyet in the open literature;

5. The thermodynamic performance of these systems was not quantified.

State of the art


New compact active cooling systemEnhanced heat

transfer scheme for direct liquid cooling

+Single cooling

device

The object of investigation

Small-scale oil-freelinear motor compressor


Experimental apparatus

Refrigerant: R-134a

Secondary fluid: 90%/10% vol. WEG mixture

5

5’

6



Condenser dimensions: 154 mm (length)

X 74 mm (width) X 32 mm (height)

Oil-free linear motor R-134a compressor

Setup main components:



External dimensions: 80 mm (width) X

80 mm (depth) X 112.5 mm (height)

Two-phase jet heat sink (jet cooler)



Internal orifice plenum

Bottom

part of

the jet

cooler

Bottom side of the orifice plenum


Experimental apparatusInvestigated parameters: (i) applied thermal load, (ii) number of orifices

and (iii) geometrical arrangement of the orifices (jets)


Experimental analysisOperating conditions:Hot reservoir temperature - 25ºC;Compressor inlet superheating - 10ºC;WEG mass flow rate - 180 kg/h;Orifice diameter - 300 µm;Orifice-to-heater distance - 28.84 mm.

First performance metrics: !"#$%

Second and third performance metrics: second-law efficiency &$% and ratio &$%∗


Experimental analysis

Proposed by Miner and Ghoshal (2006)


Experimental analysisOperating conditions:Hot reservoir temperature - 25ºC;Compressor inlet superheating - 10ºC;WEG mass flow rate - 180 kg/h;Orifice diameter - 300 µm;Orifice-to-heater distance - 28.84 mm.

Lower values for: &()* and +,- + +/(0





High evaporation efficiencies(i.e., vapor quality) are

achieved (up to 75%)

Refrigerant mass flow rate increases as a result of density increase at the compressor inlet (due to higher evaporating pressures)

1. The applicability of the novel two-phase jet heat sink in the removal ofhighly concentrated heat loads was demonstrated (up to 160 W and 200W from a 6.4-cm² impingement surface for single and multiple orificeconfigurations, respectively, maintaining the surface temperature lowerthan 40°C with heat transfer coefficients ranging from around 14,000 to16,000 W/(m²K);

2. The thermal performance of both the jet cooler and the refrigerationsystem were evaluated and a comprehensive thermodynamic analysiswas performed using different performance metrics;

3. For a fixed orifice diameter and a fixed jet length, operating the systemwith the multiple orifice configurations resulted in a betterthermodynamic performance than the single orifice configuration;

4. The proposed compact vapor compression cooling solution can befurther developed for specific applications in thermal management ofpower electronics for a variety of stationary and mobile systems (forinstance, hybrid and electric vehicles).


Summary and conclusions


References

1. YAN, Z. B.; TOH, K. C.; DUAN, F.; WONG, T. N.; CHOO, K. F.; CHAN, P. K.; CHUA, Y. S.Experimental study of impingement spray cooling for high power devices. Applied ThermalEngineering, v. 30, n. 10, p. 1225–1230, jul. 2010.

2. CHUNQIANG, S.; SHUANGQUAN, S.; CHANGQING, T.; HONGBO, X. Development andexperimental investigation of a novel spray cooling system integrated in refrigeration circuit.Applied Thermal Engineering, v. 33-34, p. 246–252, feb. 2012.

3. TAN, Y. B.; XIE, J. L.; DUAN, F.; WONG, T. N.; TOH, K. C.; CHOO, K. F.; CHAN, P. K.; CHUA, Y.S. Multi-nozzle spray cooling for high heat flux applications in a closed loop system. AppliedThermal Engineering, v. 54, n. 2, p. 372–379, may. 2013.

4. XU, H.; SI, C.; SHAO, S.; TIAN, C. Experimental investigation on heat transfer of spraycooling with isobutane (R600a). International Journal of Thermal Sciences, v. 86, p. 21–27,dec. 2014.

5. HOU, Y.; LIU, J.; SU, X.; QIAN, Y.; LIU, L.; LIU, X. Experimental study on the characteristicsof a closed loop R134-a spray cooling. Experimental Thermal and Fluid Science, v. 61, p.194–200, feb. 2015.

6. CHEN, S.; LIU, J.; LIU, X.; HOU, Y. An experimental comparison of heat transfercharacteristic between R134-a and R22 in spray cooling. Experimental Thermal and FluidScience, v. 66, p. 206–212, sep. 2015.


POLO Research Laboratories for Emerging Technologies in Cooling and Thermophysics

Questions?

Jader R. Barbosa [email protected]

Federal University of Santa CatarinaDepartment of Mechanical Engineering88040-900 – Florianópolis – SC - Brazil

Phone +55 (48) 3721-7970http://www.polo.ufsc.br

Pablo A. de [email protected]

Compact Refrigeration System for Electronics Cooling Based ...

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