Design and optimization of an air-based phase change cold storage unit through cascaded construction for emergency cooling in IDC

Abstract

This paper proposed an air-based phase change cold storage (APCCS) unit for emergency cooling in Internet Data Center (IDC). Firstly, the self-developed phase change material (PCM) applicable to IDC cooling was prepared. Then, experiments including both charging and discharging process of the APCCS unit were carried out. Next, a numerical model was developed to evaluate the thermal performance during the discharging process for emergency cooling and was validated with experimental results. Further, a cascaded arrangement of PCM from one to five stages was constructed and optimized based on exergy analysis. The results demonstrated that the average exergy efficiency has increased by 7.8% together with an increase of 19 kJ on exergy from single stage to five stages. In addition, heat transfer optimization was performed by rearranging the (PCM) containers from in-line to staggered form. A four-stage staggered arrangement outperformed the single-stage unit in terms of an increase of 25 kJ on exergy as well as nearly 10% on average exergy efficiency. Meanwhile, the discharging rate for the four-stage staggered unit could be maintained above 2.5 kW for 30 min, providing enough cooling capacity for a typical cabinet with 10 2U servers (intel M70KLP4S2UHH) in IDC during electricity emergency.