Case Studies in Thermal Engineering 14 (2019) 100445
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Case Studies in Thermal Engineering
journal homepage: www.elsevier.com/locate/csite
Thermal cooling enhancement of dual processors computer with
thermoelectric air cooler module
T
Songkran Wiriyasart∗, Chootichai Hommalee, Paisarn Naphon
Thermo-Fluids and Heat Transfer Enhancement Lab. (TFHT), Department of Mechanical Engineering, Faculty of Engineering, Srinakharinwirot
University, 63 Rangsit-Nakhonnayok Rd, Ongkharak, Nakhonnayok, 26120, Thailand
A R T IC LE I N F O
ABS TRA CT
Keywords:
Thermal cooling
Thermoelectric air cooler module
Dual processor computer
The thermal cooling enhancement technique of dual processors workstation computer couple
thermoelectric air cooler module is studied experimentally. The monitored parameters mainly
focus on the computer load conditions, with and without thermoelectric air cooler module,
cooling fan turns on/off modes, and different cooling fan sizes. In experiment process, the
working computer load of 0–100% is performed. The temperature distribution inside the computer chassis depends on the density, position of the components inside the computer both active
and passive components. It is found that the thermoelectric air cooler module has a significant
effect on the air and the CPU temperatures of the dual processor computer. In addition, the
operating modes, positions and sizes of the cooling fan have significant effect on air distribution
inside the computer chassis. However, energy consumption is also increased. The results of this
study are expected to lead to guidelines that will allow the design of the cooling system with
improved heat transfer performance of the electronic equipment.
1. Introduction
Today, the performance of computer has been continuously developed to achieve various technological demanding that utilizing a
computer for daily activity. Therefore, higher heat dissipation is simply occurring on the electronic components used for a computer
such a chip laid on the print circuit board, and the CPU. The cooling techniques have been significant effect to increase its performance as the heat rising demand. The cooling technique thermoelectric cooler is one of various cooling technique which have been
continuously developed to achieve various applications. In the past decades, thermoelectric is continuously done. Chang et al. [1]
considered effects of the heat load of a heater and input current to the thermoelectric air-cooling module for electronic devices.
Martínez et al. [2] studied the novel concept of thermoelectric self-cooling, which can be introduced as the cooling and temperature
control of a device using thermoelectric technology without electricity consumption. Putra et al. [3] investigated the application of
nanofluids as the working fluid on a heat pipe liquid-block combined with thermoelectric cooling. Zhu et al. [4] theoretically
analyzed the optimization problems of thermoelectric cooler systems applied in electronic cooling. Ali et al. [5–8] continuously
performed on the heat transfer and thermal performance of various thermal systems with water/nanofluids as working fluids. Du
et al. [9] investigated a thermoelectric generator model coupled with exhaust and cooling channels for an exhaust-based TEG system.
Tan and Demirel [10] examined three thermoelectric cooling systems for cooling the CPU and motherboard. Zhang et al. [11] applied
the finite element analysis method to analyze the thermoelectric cooler for cooling semiconductor laser. Hu et al. [12] developed the
water-cooled thermoelectric cooler for the central processing unit. Gökçek and Şahin [13] experimentally studied the performance of
∗
Corresponding author.
E-mail address: songkranw@g.swu.ac.th (S. Wiriyasart).
https://doi.org/10.1016/j.csite.2019.100445
Received 21 February 2019; Received in revised form 29 March 2019; Accepted 31 March 2019
Available online 01 April 2019
2214-157X/ © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/BY/4.0/).
Case Studies in Thermal Engineering 14 (2019) 100445
S. Wiriyasart, et al.
mini-channel water cooled-thermoelectric refrigerator. Karwa et al. [14] demonstrated a low thermal resistance water-cooled heat
sink design for the hot side of a commercial low cost thermoelectric refrigerator. Naphon et al. [15,16] experimentally and numerically investigated the fluid flow and heat transfer in the mini-rectangular fin heat sink for cooling CPU. Huang et al. [17]
investigated the thermal performance of a thermoelectric water-cooling device for electronic equipment. Gould et al. [18] demonstrated the thermoelectric cooling and micro-power generation from waste heat within a standard desktop computer. Zhou and Yu
[19] studied the generalized theoretical model for the optimization of thermoelectric cooling system. Zhao and Tan [20] presented a
prototype thermoelectric system integrated with phase change material heat storage unit for space cooling. Kiflemariam and Lin [21]
numerically investigated the net power generation with the micro-channel heat sink. Liu et al. [22] experimentally studied a thermoelectric mini cooler coupling with a micro thermo syphon cooling system for the CPU cooling. Cai et al. [23] investigated effect of
thermoelectric properties and the scale of extender block on cooling performance under different operating conditions. Cai et al. [24]
presented a multi-objective optimization based on thermoelectric heat exchanger module CPU cooler. Liu et al. [25] investigated
effect of heat exchanger configuration under the temperature-controller module in the thermoelectric cooling system on thermal
cooling. Sun et al. [26] investigated on the thermoelectric cooling system to remove the heat in the electronic device. Ali et al.
[27–29] experimentally studied on the nanofluids heat transfer, pressure drop and thermal performance of the heat sinks with various
configurations. Wiriyasart and Naphon [30] numerically investigated the heat transfer characteristics and fluid dynamics of the cold
plate with micro-channel for cooling high heat fluxes of the supercomputer.
Based on the literature reviews, thermoelectric cooling system have been continuously developed for various applications both
analytically and numerically approaches. The objective of this study is to enhance thermal cooling of dual processor workstation
computer with thermoelectric air cooler module. The monitored parameters mainly focus on the load conditions of the computer
operation loads, with and without thermoelectric air cooler module, air cooling fan turns on/off modes, with and without air duct
connected between the heat sink and outer chassis. The results obtained from the study are lead to a guideline to enhancing the
cooling electronic applications.
Fig. 1. A photograph of the experimental test setup.
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S. Wiriyasart, et al.
Fig. 2. Schematic diagram of the thermoelectric air cooler module for PC cooling.
2. Experimental apparatus and test method
2.1. Experimental apparatus
A photograph of the dual processor computer with thermoelectric air cooler module is shown in Fig. 1. Experiment apparatus is
consisted of a high-performance computer (workstation) with dual CPU, the thermoelectric air cooler module, and the data acquisition system. The midrange computer with very broad range and live in capacity between high-end PC servers and mainframes is
used for experimental processes. The full system of the computer is consisted of a chassis, motherboard, CPU, CPU cooler (heat sink),
memories, power supply, and graphics card. The commercial sizing computer chassis of a standard E-ATX platform has dimension of
540 mm × 236 mm x 560 mm. The workstation motherboard is a mid-range ATX (12 × 9 inch) size for dual CPU with the dual
middle range CPU model Intel Xeon-X5550 and 50 W power supply. A thermoelectric air cooler module is consisted of a thermoelectric plate, 350 ml cylindrical storage tank, a heat sink, DC water pump, and a radiator with cooling fan as shown in Fig. 2. The
thermoelectric plate has dimension of 40 mm × 40 mm x 2 mm. For the hot side of the thermoelectric plate, the glycol-based liquid is
used as coolant for cooling process. The coolant flows into the water block to absorb the generated heat from the thermoelectric and
then flows into the radiator and returns to the storage tank. To increase the hot and cold side performance of thermoelectric, the cold
and hot sides are a couple with the water block with the thermal interface material (TIM) among these surfaces. For cold side of the
thermoelectric, it is attached directly to the aluminum plate fin heat sink with dimension of 60 mm × 40 mm x 30 mm, and a cooling
fan is placed on the top of the heat sink. The outside air is induced by the axial cooling fan through the inlet air duct and flows
through the heat sink to decrease temperature and distributes into the chassis computer for cooling the computer and then flow out of
the chassis computer at the rear zone as shown in Fig. 2.
2.2. Test methods
As shown in Fig. 2, the power supply of the thermoelectric cooling module is fitted and connected on the motherboard and then
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Table 1
Accuracy and uncertainty of measurements.
Instrument
Accuracy (%)
Uncertainty
Watt-hour meter (W/h)
Thermocouple type (T)
Data logger (oC)
Multi-meter
0.5
0.1
0.1
0.1
± 0.2
± 0.1
± 0.2
± 0.2
placed into the computer chassis. Before assembled the thermoelectric air cooler module, however, a computer is evaluated to make
sure that it is working properly. The thermoelectric air cooler module is installed at the bottom zone of the computer chassis nearby
the front panel. In experiments, the test conditions are performed at room temperature of 25–28 °C within the period time of 30 min
or until the steady state conditions. The water flowing inside a hot water loop can be done by using DC water pump which the inlet
temperature of coolant before entering the cooling section is kept between 28–30 °C. 12 Type T copper-constantan thermocouples are
employed to measure the temperatures at various positions inside the chassis computer. The temperatures at various positions are
recorded in the period time of 300s a data acquisition system (Data taker DT85). All thermocouples are pre-calibrated with the dry
block temperature calibrator. Before recorded data, the computer system is allowed to approach the steady state conditions. To
repeatability of experimental results, the temperatures at various positions are recorded three times with a data acquisition system
(Data taker DT85). The test parameters focus on the variations of the computer load conditions, with and without thermoelectric air
cooler module, cooling fan turns on/off modes, with and without air duct connected between a heat sink and outer chassis.
3. Data reduction and uncertainty analysis
The uncertainty and accuracy of the measurement are given in Table 1. Uncertainty estimates by considering the errors of the
instruments and calibration errors. The uncertainty in the measured temperature is less than ± 0.1 °C. Based on the maximum
operating load, the maximum variation of the measured surface temperatures is ± 0.2 °C. The total thermal resistance of the heat sink
(CPU) can be calculated from the different temperature between the heat sink and inlet air temperature entering the heat sink divide
with power input as follows;
Rheatsink
=
Theat − source − Tair − inlet
IV
(1)
Where Theat − source is heat sink temperature, Tair − inlet is inlet air temperature. I and V are the supplied ampere and voltage to the
electrical heater. The uncertainty of the total thermal resistance is about ± 5%. Based on the Coleman and Steele [31], the uncertainty of the total thermal resistance is determined from
2
Uncertainty of Rheatsink =
2
2
2
⎛ ∂Rheatsink ΔTheat − source⎞ + ⎛ ∂Rheatsink ΔTheat − source⎞ + ⎛ ∂Rheatsink ΔI⎞ + ⎛ ∂Rheatsink ΔV⎞
∂I
⎝
⎠
⎝ ∂V
⎠
⎠
⎠
⎝ ∂Tair − inlet
⎝ ∂Theatsink − base
⎜
⎟
⎜
⎟
(2)
4. Results and discussion
4.1. Effect of thermoelectric air cooler module
In the present study, the measured data are performed to verify with those obtained from the conventional cooling system. As
shown in Fig. 2, outside air is induced by axial cooling fan and flows through the aluminium heat sink to decrease temperature before
distributes inside the computer chassis. 12 thermocouples are used to measure temperature at various positions. It can be clearly seen
that average air temperatures inside the computer chassis with and without the thermoelectric air cooler module tend to increase and
then reach the steady state condition. Average air temperatures inside the computer chassis with thermoelectric air cooler module are
average 3 °C lower than those without thermoelectric air cooler module. This indicates that the thermoelectric air cooler module
response to air temperature effectively by decreasing its temperature before distributing in the computer chassis. The CPUs temperatures of the computer with and without thermoelectric air cooler module for computer load of 100% are shown in Fig. 3. The
CPU1 temperature is higher than CPU2 temperature for with and without thermoelectric air cooler module. This is because cool air
flows entering the CPU1 before CPU2 as shown in Fig. 2. This means that the air temperature entering the CPU1 lower than those
entering the CPU2 which results in heat transfer rate from CPUs to air coolant. Therefore, the CPU1 gives temperatures lower than
CPU2. In addition, the obtained CPUs temperatures with the thermoelectric air cooler module are lower than those without thermoelectric air cooler module as shown in Fig. 3. As compared with the results from Naphon et al. [32], it can be found that the
maximum CPUs temperature obtained from this study is higher than those from Naphon et al. [32]. This is because the computer
system for this study is workstation and cooling system with thermoelectric which different form Naphon et al. [32].
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Fig. 3. Variation of CPU temperature rise with time for with and without.
4.2. Effect of operating computer load
Effect of computer loads on CPUs temperature in the computer is shown in Fig. 4. The variation of computer load can be
performed by adjusting operating mode of computer system. The generated heat from the computer system depends on operating
frequency of CPUs and energy consumption of various components in computer. In addition, higher computer load gives increasing
CPUs temperature which results in increase air temperatures inside the computer as shown in Fig. 4.
Fig. 4. Variation of transient CPU1, CPU2 temperatures with computer load.
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Fig. 5. Variation of CPU temperatures for turn on/off modes of cooling fan.
4.3. Effects cooling fan sizes and working modes
Fig. 5 shows the CPUs temperature with turns on/off cooling fan modes at 100% computer load. As seen in Fig. 2, outside air is
induced by axial cooling fan and flows through the heat sink to decrease temperature and then distributes inside the computer
chassis. Distribution of air inside the computer chassis depends on the density and positions of various components inside the
computer, and cooling fan position. It can see clearly that CPUs temperature with for turn on cooling fan mode is lower than that for
turn off cooling fan mode. The comparing of CPUs temperatures within the computer chassis with different the sizing of cooling fans
of 60 mm × 60 mm and 120 mm × 120 mm is shown in Fig. 5. 120 mm × 120 mm cooling fan shows the lower air temperature as
comparing with the smaller one.
4.4. The thermal resistance of the heat sink and energy consumption
The total thermal resistance of the heat sink is defined as the difference between the temperature at heat source of the heat sink
that constructed on the top surface of the CPUs and inlet air temperature entering the heat sink divided with input power. Fig. 6
shows the transient thermal resistance curve of both CPU1 and CPU2 with and without thermoelectric air cooler module at computer
load 100%. It can be clearly seen that the thermal resistance curve is nearly constant for both CPU1 and CPU2 after 50s. Thermal
resistance of CPU2 is higher than that of CPU1 which corresponding with CPUs temperature as mentioned above. The curve tends
with thermoelectric air cooler module gives lower than without thermoelectric air cooler module. It indicated that with thermoelectric air cooler module has a significant effect on the thermal resistance of the heat sink. The cooling enhancement technique using
thermoelectric air cooler module has a significant effect on the thermal cooling of the computer module. The computer system with
thermoelectric air cooler module gives the lower air and lower CPUs temperature. However, the energy consumption also increases as
shown in Table 2.
5. Conclusions
Air cooling in the electronics chassis has many advantages for long life expanding of the electronic component. This study
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Fig. 6. Transient thermal resistance curve of the heat sinks for with and without.
Table 2
Comparison of the temperature and power consumption between with and without thermoelectric air cooler module at computer load 100%.
Cooling techniques
Conventional cooling system
Thermoelectric air cooler module system
Air Temperature (oC)
CPU temperature (oC)
36.621
35.982
Energy consumption (%)
CPU 1
CPU 2
43.707
42.111
47.805
45.426
0
21
investigates the cooling enhancement of the dual processor computer using thermoelectric air cooler module. In an experiment, the
working computer load of 0–100% is performed. From the results, the temperatures of the computer chassis and CPUs have been
increased with increasing computer load and also lower for the computer with thermoelectric air cooler module. In addition, the
thermoelectric air cooler module with different sizes and operating modes of cooling fan have significant effect on the distribution of
coolant air inside the computer chassis and results in effect on the cooling performance. For transient condition, the speed response of
CPUs temperature is fairly fast for with thermoelectric air cooler module. However, energy consumption thermoelectric air cooler
module system is also increased.
Acknowledgments
The authors would like to express their appreciation to the Excellent Center for Sustainable Engineering (ECSE) of the
Srinakharinwirot university (SWU), Thailand for providing financial support for this study with the research grant No. 337/2561.
Nomenclature
Q
R
T
V
I
Total power input, [W]
Thermal resistance, [°C W−1]
Temperature, [°C]
Voltage, [V]
Current, [A]
Subscripts
air
heat sink
heat source
inlet
Appendix. ASupplementary data
Supplementary data related to this article can be found at https://doi.org/10.1016/j.csite.2019.100445.
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