A techno-economic evaluation of low global warming potential heat pump assisted organic Rankine cycle systems for data center waste heat recovery

The increased use of cloud-based technology services in recent years has led to a global rise in data centers. Data centers consume vast amounts of electricity for server cooling. Servers are typically cooled using air-source vapour compression chillers which exhaust low-grade waste heat to the outdoors via a cooling tower. This waste heat can be recovered to a large degree by integrating an organic Rankine “power” cycle into the system. Although heat pump assisted organic Rankine cycle cooling systems have recently emerged as an efficient alternative to conventional air-source chiller systems, they may be considered to be as harmful to the environment due to their use of high global warming potential working fluids. The objective of this work is to determine the thermodynamic performance of several key heat pump assisted organic Rankine cycles that utilize low global warming potential working fluids and assess the economic impact of their utilization relative to a conventional air-source vapour compression chiller. Results show that heat pump assisted organic Rankine cycle systems utilizing low global warming potential working fluids are able to achieve efficiencies that are comparable to systems utilizing conventional working fluids. Additionally, these systems are found to be up to 65% less expensive than air-source vapour compression chillers and are less sensitive to variations in economic parameters. These results show promise with regards to their future implementation in both existing and future data centers. • Cooling accounts for up to 50% of total data center energy consumption. • Heat pump assisted organic Rankine cycles are proposed as an alternative to air source chillers. • High global warming potential refrigerants are replaced with environmentally friendly alternatives. • Proposed cycles achieve similar efficiencies at approximately half the cost. • Unlike air source chillers, the profitability of proposed cycles increases as server utilization increases.