REGIONAL CHILLING NETWORKS AT THE UNIVERSITY OF ARIZONA: ANTICIPATING AN EVENTUAL BAN ON 1,1,1,2-TETRAFLUOROETHANE

Abstract

1,1,1,2-tetrafluoroethane, or R134a, is a hydrofluorocarbon refrigerant currently used in the University of Arizona’s central chilling networks. Due to its high global warming potential, environmental regulators in the USA and the EU have begun its phase-out. To determine the suitability of R134a substitutes, the UA central chilling plants were simulated through a purpose-built computational thermodynamic model constructed in Microsoft Excel with extensive coding in Visual Basic for Applications. The best currently available alternative refrigerant was determined to be 2,3,3,3- tetrafluoropropene, or R1234yf. However, R1234yf was substantially less apt than R134a. The Coefficient of Performance, which is the ratio between the cooling capacity provided and the energy input to the system, was estimated to be 0.081 for R1234yf, versus 1.065 for R134a. Environmental analysis found that the CO2 equivalent emissions from an R1234yf system would greatly exceed those of a comparable R134a system under typical conditions. Similarly, economic analysis revealed that the price of an R1234yf plant surpassed the price of a similar R134a plant by roughly an order of magnitude. Our work found no suitable replacement for R134a in this application with today’s technology. Therefore, we discuss a number of recommendations on both a plant level and a nationwide policy level in order to establish a path forward towards effective emission reduction in district cooling applications.