Data centers are recognized as one of the most important aspects of the fourth industrial revolution since conventional data centers are inefficient and have dependency on high energy consumption, in which the cooling is responsible for 40% of the usage. Therefore, this research proposes the immersion cooling method to solving the high energy consumption of data centers by cooling its component using two types of dielectric fluids. Four stages of experimental methods are used, such as fluid types, cooling effectiveness, optimization, and durability. Furthermore, benchmark software is used to measure the CPU maximum work with the temperature data performed for 24 h. The results of this study show that the immersion cooling reduces 13°C lower temperature than the conventional cooling method which means it saves more energy consumption in the data center. The most optimum variable used to decrease the temperature is 1.5 lpm of flow rate and 800 rpm of fan rotation. Furthermore, the cooling performance of the dielectric fluids shows that the mineral oil (MO) is better than the virgin coconut oil (VCO). In durability experiment, there are no components damage after five months immersed in the fluid.
The rise of the fourth industrial revolution, in which any technology can interact using the same data, has increased the data center across the world. As a platform for combining the actual and digital worlds, an integration of computation, networking, and physical processes called the Cyber-Physical System (CPS) had been created. Consequently, the yearly percentage increase in the level of energy consumption, has now amounted to 2 percent of global electricity demand, which is expected to rise by 15–20 percent annually [
As shown in
Cooling demand for server data center needs tremendous electricity, which is the reason to reduce its cooling load. Therefore, the liquid of the cooling process is formulated as a substitute for the air medium. Furthermore, liquids have more conductivity than air, make it more efficient in heat transfer. With the introduction of the immersion cooling method, more prospective solution for cooling data center is available. Furthermore, multiple tests and projects have been conducted to minimize the energy consumption of data centers.
For several years, the immersion cooling method has been employed for cooling various electronic devices, few of the recorded and broadcast analyses are shown in
Type | Utilization | References |
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Single-phase | Solar cell | Han et al. [ |
Transformer | Pires et al. [ |
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IT equipment | Bunger et al. [ |
|
Two-phase | Server | Kanbur et al. [ |
In a Single-phase immersion cooling, the use of coolants to exchange heat without any phase is used. The cooling mechanism does not contain any gas or vapor, making this process safer. As a result, the system is protected from explosion due to under pressure. However, it is more adaptable than air cooling. In two-phase immersion cooling, the liquid-vapor phase changes, coolants are used to exchange heat. Two-phase immersion cooling has the advantage of reducing environmental impacts, having a simple model, increasing power density by up to ten times, and being economical.
Numerous studies adopted the immersion cooling method, which has been proved to reduce the energy consumption in the data center. Levin et al. designed the promising re-configurable computer system using immersion cooling [
Previous research show an adoption of immersion cooling on a computer data center, they use two phases in which the dielectric liquid was circulated by dripping from above with the open system [
With the method, some variables were eliminated because the best method has been investigated in the previous experiment. There were four stages research experiment to reduce the number of test variables, therefore data were obtained quickly and precisely. The first stage was to examine the two dielectric fluid of mineral oil and VCO. The second stage was an examination of cooling Effectiveness with the dependent variables
To represent the amount of work assigned to the CPU, the load was performed with benchmark software. The CPU temperature rises due to the benchmark load, therefore, temperature was used as control variable.
While collating the data, the CPU was placed in an empty glass container measuring 39 cm × 14 cm × 25 cm, where it was activated, and the results were obtained through a conventional cooling supplied by a blowing fan. To evaluate the similarities and differences, the next step was to put the oil in the container until it penetrates through the container for maximum heat absorption. Furthermore, the experiment was carried out with each variable with a factorial combination.
To increase the heat transfer rate, the coolant was used to penetrate and circulate through the radiator. The coolant was further passed to the outflow to the container again. To measure the accurate flow rate, a flow meter was installed in the outflow to determine the volume of the passing fluids. The loading software was installed and run on the CPU during measurement for the workload. In addition, the software also measured the computer temperature using a monitor chip, determines the voltage, and adjusts the fan speed.
The experimental scheme and results are presented in
This experiment showed that the cooling method by immersion was more effective than the conventional. However, the results of the difference between MO and VCO were not significant. It was important to note that the performance of dielectric fluids were measured based on their effectiveness.
The inlet, outlet, and wet bulb cooling temperatures were measured to determine the effectiveness of the system. The inlet temperature was measured in the location of the liquid pumped from the vessel to the condenser for the cooling process as shown in
A thermocouple recorded data every minute, and its average was calculated every 2 h to facilitate the data presented. The value of the range,
No. | Period | Immersion cooling effectiveness | |||||||||||
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VCO | MO | VCO | MO | VCO | MO | VCO | MO | VCO | MO | VCO | MO | ||
1 | 18:01–20:00 | 29.45 | 28.54 | 27.26 | 27.27 | 27.01 | 27.08 | 2.19 | 1.28 | 0.25 | 0.18 | 89.73 | 87.39 |
2 | 20:01–22:00 | 30.96 | 30.37 | 28.05 | 28.44 | 27.62 | 28.20 | 2.91 | 1.93 | 0.43 | 0.24 | 87.14 | 88.91 |
3 | 22:01–24:00 | 31.79 | 31.39 | 28.93 | 29.44 | 28.46 | 29.24 | 2.86 | 1.95 | 0.48 | 0.20 | 85.76 | 90.72 |
4 | 24:01–02:00 | 31.57 | 32.19 | 29.01 | 30.44 | 28.70 | 30.25 | 2.56 | 1.74 | 0.31 | 0.19 | 89.16 | 89.94 |
5 | 02:01–04:00 | 31.30 | 32.96 | 28.85 | 31.31 | 28.55 | 31.11 | 2.45 | 1.65 | 0.30 | 0.19 | 89.06 | 89.45 |
6 | 04:01–06:00 | 31.19 | 33.75 | 28.70 | 32.19 | 28.40 | 31.99 | 2.49 | 1.56 | 0.30 | 0.20 | 89.21 | 88.41 |
7 | 06:01–08:00 | 31.27 | 34.40 | 28.55 | 32.95 | 28.25 | 32.75 | 2.72 | 1.45 | 0.30 | 0.20 | 90.07 | 87.89 |
8 | 08:01–10:00 | 32.99 | 34.85 | 29.32 | 33.34 | 28.84 | 33.14 | 3.68 | 1.50 | 0.48 | 0.20 | 88.51 | 88.09 |
9 | 10:01–12:00 | 35.06 | 35.22 | 30.88 | 33.71 | 30.10 | 33.51 | 4.18 | 1.51 | 0.78 | 0.20 | 84.33 | 88.33 |
10 | 12:01–14:00 | 36.98 | 35.30 | 32.41 | 33.80 | 31.61 | 33.60 | 4.57 | 1.50 | 0.80 | 0.20 | 85.14 | 88.24 |
11 | 14:01–16:00 | 37.40 | 35.30 | 34.02 | 33.80 | 33.19 | 33.60 | 3.38 | 1.50 | 0.83 | 0.20 | 80.38 | 88.24 |
12 | 16:01–18:00 | 37.40 | 35.30 | 34.99 | 33.80 | 34.09 | 33.60 | 2.41 | 1.50 | 0.90 | 0.20 | 72.79 | 88.24 |
Average | 85.94 | 88.65 |
From the experiment, it was known that MO's effectiveness was better than VCO. As shown in
In the second stage, it had known that MO's effectiveness was better than VCO. Therefore, the third stage focused on MO's performance. The results at the beginning of the experiment showed that the graphs tend to overlap, revealing that the variables of flowrate and fan rotation have no significant effect on temperature at the time of set-up. During it operation, it was more than 14 h, the results substantially impact the temperature by fan rotation and flow rate. During the experiment, each fan rotation variable has a stability point. A larger flow rate and fan rotation result in an earlier stable temperature than the lower flow rate and fan rotation. According to the a research, using natural convection heat sink, Cheng et al. found that coolant flow was the most influential, and heat sink material did not significantly affect the performance [
Approximately five months after the immersion process, necessary deductions were made to determine any destructive physical changes. The results of observations were as follows:
For five months, the conditions of the immersed CPU were monitored to evaluate what damages or physical effects on each of the components. This was also to establish if there were any negative adverse effects due to the mineral oil fluid used. The possible damages were delaminating (detachment of the motherboard), warpage (bending on the Printed Circuit Board- PCB), and swelling of the PCB [
This research provided a more prominent and better way of cooling a data center through the immersion cooling method to solving the high energy consumption of data centers, which, according to several reports were considered not a modern technique. Immersion Cooling was a system that employs the principle of convection heat transfer to immerse CPU components. The heat generated from the CPU was absorbed by the mineral oil and pumped to be cooled in the radiator before being poured back into the container.
This study showed that heat loss occurrence at 13°C is lower than conventional cooling with air. The reason for this was because the heat absorption capacity of mineral oil was greater than air. The effect of the flow rate and rotation had a significant influence on temperature reduction. The lowest temperature can be achieved with the highest flow rate and fan rotation variable of 1.5 lpm and 800 rpm. This was more influential in reducing CPU temperature compared to VCO. This was confirmed by the maximum temperature the CPU produces when using a 47°C mineral oil coolant, lower than the VCO coolant of 51°C. Inflow temperature and liquid mineral oil outflow were lower than VCO, meaning that CPU heat absorption using mineral oil is much preferred to a temperature of 35.3°C mineral oil inlet, while VCO 37.4°C, and 33.8°C, at 35°C, respectively. In this study, CPU components also were immersed for five months, with the effects ranging from delaminating, warpage, and swelling. This shows that the immersion method of cooling is an appropriate cooling system and meets technological development and progress demands.
More analysis will be considered to investigate the data center's ability to leverage the capacities of electronic devices and the impact this approach as well as for the environment as a whole. Immersion cooling was also found to reduce component temperature, simplify data center layout, and allow for higher power density. Therefore, immersion cooling can reduce energy consumption in the data center which leads to more energy saving.
Cyber-Physical System Central Processing Unit Computer Room Air Conditioning Virgin coconut oil Information Technology International Telecommunications Union Terra Watt Hour Power Supply Unit Liter Per Minutes Rotation per Minutes Printed Circuit Board Uninterruptible Power Supply