SUMMARY

As global temperatures continue to rise and urbanization intensifies, so grows the need for efficient, cost-effective, low global warming potential (GWP) space cooling technologies. Accordingly, there is an ongoing focus surrounding research into new space cooling cycles that are more efficient and use zero GWP refrigerants. This dissertation will: (i) investigate a new thermodynamic cycle, (ii) evaluate the extent to which it can provide both dehumidification and refrigeration, (iii) demonstrate a proof-of-concept system driven by relatively low temperature (< 50 °C) heat, and (iv) evaluate the cost effectiveness of the system.
The thermodynamic cycle to be studied utilizes aqueous mixtures that possess a lower critical solution temperature (LCST). These mixtures are homogenous (single-phase) and will mix with water at room temperature, but when they are heated above the LCST they separate into two phases. The first phase is water-rich (WR), while the second phase is water-scarce (WS); this difference in composition leads to a chemical potential difference when the phases are physically separated and cooled down to ambient temperature. A thermodynamic analysis of this new “LCST cycle” is performed, and existing LCST mixtures reported in literature are characterized. Several experimental demonstrations of this new cycle are performed, and the temperature drop, humidity drop, and coefficient of performance (COP) of the cycle are reported. Models are developed for the chemical potential of hypothetical LCST mixtures with greater chemical potential differences between the two phases that could be discovered in the future (provided the right chemistries are found). These hypothetical mixtures would provided greater temperature and humidity drops. Using these models, the performance of the cycle will be modeled, revealing the capital and operating expenditures associated with the LCST cycle if these hypothetical LCST mixtures are used.