Novel Design and Integration of Air Conditioning/Thermal Energy Storage with Phase Change Material

This study evaluates the use of phase change composite (PCC) material, consisting of paraffin (namely, n-Tetradecane) and expanded graphite, as a potential storage medium for cold thermal energy storage (TES) systems to support air conditioning (AC) applications. The PCC-TES system is to be integrated with the vapor compression refrigeration cycle of an AC system. The use of this proposed solid PCC material is novel. The PCC has excellent material and thermal characteristics as compared to ice or chilled water that are predominantly used in commercial TES systems for air cooling applications. This study proposed and tested a hypothesis, which suggests that integrating a conventional AC with a PCC-TES would result in significant benefits concerning compressor size, compressor efficiency, electricity consumed and CO2 emissions. A multi-layer study was thoroughly conducted involving: (1) literature review (2) material characterization (3) experimental work (4) proof of concept simulation (5) numerical modeling (6) real-life implementation evaluation. The study examined several key thermo-physical properties of PCC material. Actual experimental benchtop system has been built and tested. A simulation model using Aspen Plus® was successfully generated to perform overall system-level assessment and proof of concept. The simulation model also compared the use of PCC materials as the energy storage medium versus the use of ice. A detailed numerical model was also successfully built to describe in detail the transient heat transfer problem of a PCC-TES systems exchanging heat with a heat transfer fluid (namely Ethylene Glycol). The actual experimental benchtop validated the analytical/numerical simulation models. The study was wrapped up by addressing real-life implementation of proposed integration between the AC and PCC-TES for hot and humid climate region with high electricity demand.