The viability of ultra low temperature waste heat recovery using organic Rankine cycle in dual loop data center applications

For data center operating conditions, R134a and R245fa are identified as the optimum selections for the server coolant and ORC working fluid, respectively, but other environmentally friendly options are considered in the case that a data center operator is forced to swap out a fluid due to changes in environmental regulations. This gives data center operators greater insight into the performance of the system in the face of possible constraints. The analysis also considers the use of superheaters to increase the temperature at which the waste heat is recovered. This is often considered to be beneficial in waste heat recovery systems. However, the results show that while increasing the temperature at which the waste heat is recovered improves ORC system performance, the addition of superheaters in either the ORC loop or the server cooling loop results in an overall performance decrease due to the additional power required for their operation. A payback period of between 4-8 years for the use of ORC in data center environments is estimated.