Investigation of Separated Two-Phase Thermosiphon Loop for Relieving the Air-Conditioning Loading in Datacenter

Hafiz Daraghmeh,Chi-Chuan Wang,Mohammed Sulaiman,Kai-Shing Yang

doi:10.3390/en12010105

Hafiz Daraghmeh, Chi-Chuan Wang + Show 2 more

Open Access

https://doi.org/10.3390/en12010105

Copy DOI

Abstract

This study investigates the feasibility of using R-134a filled separated two-phase thermosiphon loop (STPTL) as a free cooling technique in datacenters. Two data center racks one of them is attached with fin and tube thermosiphon were cooled by CRAC unit (computer room air conditioning unit) individually. Thermosiphon can help to partially eliminate the compressor loading of the CRAC; thus, energy saving potential of thermosiphon loop was investigated. The condenser is a water-cooled design and perfluoroalkoxy pipes were used as adiabatic riser/downcomer for easier installation and mobile capability. Tests were conducted with filling ratio ranging from 0 to 90%. The test results indicate that the energy saving increases with the rise of filling ratio and an optimum energy savings of 38.7% can be achieved at filling ratios of 70%, a further increase of filling ratio leads to a reduction in energy saving. At a low filling ratio like 10%, the evaporator starves for refrigerant and a very uneven air temperature distribution occurring at the exit of data rack. The uneven temperature distribution is relieved considerably when the evaporator is fully flooded. It is also found that the energy saving is in line with the rise of system pressure. Overfilling of the evaporator may lead to a decline of system pressure. A lower thermal resistance occurs at high filling ratios and higher ambient temperature.

Highlights

Effective thermal management in datacenter has become more and more important
The results showed that cooling capacity and circulation flow rate increased with the riser diameter of thermosiphon and air flow rate but decreased with the tube length
25 ◦ C, While the inlet and outlet air temperature at fronttemperatures and back door rack, which were measured by the multi-meter, namely measuring the inlet and with outlet air temperature at front and The back doorconsumptions of the rack, power in association filling ratio ranging from

Summary

Introduction

Effective thermal management in datacenter has become more and more important. This is because nowadays the electrical energy consumption of datacenters represents 1.1~1.5% of the world’s total electricity consumption. According to industry predictions, data centers’ annual power demand can reach up to 20% [1] In this regard, recent researches had focused on implementing new efficient cooling techniques that might help to minimize the electrical power usage and minimize the costs spent on thermal energy management. Mechanical piping system of such techniques requires long distance transportation of air or water. In other words, they consume a lot of electrical energy through fans or pumps. Two electrical heaters were installed inside each rack Both heaters reject a maximum heating load of 4 kW to the ambient.

Methods

Results

Conclusion