A first and second law analysis of a thermoresponsive polymer desiccant dehumidification and cooling cycle
- Arizona State Univ., Tempe, AZ (United States); Georgia Institute of Technology, Atlanta, GA (United States)
- Georgia Institute of Technology, Atlanta, GA (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Arizona State Univ., Tempe, AZ (United States)
Herein, we present a theoretical description for a new desiccant air conditioning cycle that uses thermoresponsive polymers instead of traditional desiccants. We use a combined first and second law analysis to demonstrate that this new cycle has three major advantages relative to the traditional case: (i) it can regenerate at lower temperatures, (ii) it can harvest liquid water and (iii) it has significantly higher coefficients of performance (COPs). For example, this new cycle can achieve a COP of 5.1 when regenerated at 95 degrees C, whereas the traditional desiccant cycle is limited to a COP of ~ 1. The fundamental origins of these advantages can be traced to the method of regeneration. The traditional desiccant cycle regenerates by flowing hot air over the desiccant, which provides a medium for gaseous water desorption. However, this also generates entropy and places a minimum temperature constraint on the hot air. In contrast, the thermoresponsive polymer cycle regenerates through a polymer phase transition. The polymer absorbs water vapor in humid air, and then it expels liquid water when raised above its transition temperature. This regeneration method generates liquid water that can be harvested and relaxes constraints on entropy generation and minimum temperature. The minimum regeneration temperature of the thermoresponsive cycle is only limited by the transition temperature of the polymer, which can be tuned through materials science. Due to its liquid water harvesting capability, the new cycle potentially eliminates water consumption when used with evaporative cooling, or it can be directly used for atmospheric water harvesting.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
- Grant/Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1841363
- Report Number(s):
- NREL/JA-5500-81918; MainId:82691; UUID:54576d09-4eec-4b23-9e57-1d9382d69458; MainAdminID:63677
- Journal Information:
- Energy Conversion and Management, Journal Name: Energy Conversion and Management Vol. 253; ISSN 0196-8904
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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