The Use of Water as a Refrigerant: Impact of Cycle Modifications on Commercial Feasibility

Abstract

The purpose of this research was to investigate the economic feasibility of a water-based vapor compression chiller with a nominal capacity of 1000 tons. Low-level models of various potential cycle configurations have been constructed and the results of simulations for each cycle configuration are described. More detailed component level models were developed to accurately size equipment and predict system performance for the most attractive cycle configuration. These component models address issues that are particularly crucial in water as refrigerant cycles, such as compressor discharge superheat and refrigerant side pressure drop. Where possible, these component models were verified through comparison against the current state-of-the-art technology for large chillers using R-134a as a refrigerant. The capital cost and the expected operating costs are determined to quantify the payback time associated with using water as a refrigerant relative to traditional halocarbon refrigerants currently in use. Other issues that may have an economic impact on the feasibility of water as a viable alternative to R-134a such as the possibility of using direct contact heat exchangers, purging issues, and condensation at the compressor inlet have been discussed.