Open Access

ARTICLE

Assessment of Low Global Warming Potential Refrigerants for Waste Heat Recovery in Data Center with On-Chip Two-Phase Cooling Loop

by Yuming Zhao¹, Jing Wang¹, Bin Sun², Zhenshang Wang¹, Huashan Li², Jiongcong Chen^2,*

1 Shenzhen Power Supply Bureau Co., Ltd., Shenzhen, 518020, China
2 Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640, China

* Corresponding Author: Jiongcong Chen. Email:

(This article belongs to the Special Issue: Innovative Heat Transfer Fluids for Enhanced Energy Sustainability in Thermal Systems)

Frontiers in Heat and Mass Transfer 2024, 22(4), 1171-1188. https://doi.org/10.32604/fhmt.2024.054594

Received 02 June 2024; Accepted 18 July 2024; Issue published 30 August 2024

Abstract

Data centers (DCs) are highly energy-intensive facilities, where about 30%–50% of the power consumed is attributable to the cooling of information technology equipment. This makes liquid cooling, especially in two-phase mode, as an alternative to air cooling for the microprocessors in servers of interest. The need to meet the increased power density of server racks in high-performance DCs, along with the push towards lower global warming potential (GWP) refrigerants due to environmental concerns, has motivated research on the selection of two-phase heat transfer fluids for cooling servers while simultaneously recovering waste heat. With this regard, a heat pump-assisted absorption chiller (HPAAC) system for recovering waste heat in DCs with an on-chip two-phase cooling loop driven by the compressor is proposed in the present paper and the low GWP hydrofluoroolefin refrigerants, including R1224yd(Z), R1233zd(E), R1234yf, R1234ze(E), R1234ze(Z), R1243zf and R1336mzz(Z), are evaluated and compared against R245fa as server coolant. For the HPAAC system, beginning with the development of energy and economic models, the performance is analyzed through both a parametric study and optimization using the coefficient of performance (COP), energy saving ratio (ESR), payback period (PBP) and net present value (NPV) as thermo-economic indicators. Using a standard vapor compression cooling system as a benchmark, the results indicate that with the evaporation temperature between 50°C and 70°C and the subcooling degree ranging from 5°C to 15°C, R1233zd(E) with moderate compressor suction pressure and pressure ratio is the best refrigerant for the HPAAC system while R1234yf performs the worst. More importantly, R1233zd(E) is also superior to R245fa based on thermo-economic performance, especially under work conditions with relatively lower evaporation temperature as well as subcooling degree. Under the given working conditions, the overall COP, ESR, NPV, and PBP of R1233zd(E) HPAAC with optimum subcooling degree range from 4.99 to 11.27, 25.53 to 64.59, 1.13 to 4.10 × 107 CNY and 5.77 to 2.22 years, respectively. Besides, the thermo-economic performance of R1233zd(E) HPAAC under optimum working conditions in terms of subcooling degree varying with the evaporation temperature is also investigated.

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