Investigation of cryogenic energy storage for air conditioning applications

Ahmad, Abdalqader Y. H. (2018). Investigation of cryogenic energy storage for air conditioning applications. University of Birmingham. Ph.D.

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This research aims to develop an efficient air conditioning technology that exploits cold energy storage to reduce energy consumption and CO2 emissions and shift the cooling load to off peak times to achieve better national electricity grid stability. The investigation includes the use of commonly used cold storage materials (ice, Phase Change Materials PCM) to enhance the existing air conditioning systems and using cryogenic cold storage namely, liquid nitrogen/air (LN2/Lair) to provide air conditioning for domestic and office buildings. Computational Fluid Dynamic (CFD) modelling of the main two components in the cryogenic cooling system namely, cryogenic heat exchanger and expander were also carried out. An experimental test facility was developed to validate the CFD modelling of the liquid nitrogen evaporation process and assess its potential to provide cooling. Results showed that integrating existing Air Conditioning systems with cold storage tank can lead to energy saving of up to 26% and shifting the cooling load to off peak times, but this energy saving is highly dependent on the storage medium and its storage temperature. Also, using cryogenic fluids (LN2/Lair) to provide air conditioning for domestic and office buildings can recover up to 94% of the energy stored in LAir and up to 78% of the energy stored in LN2, and based on LN2/Lair prices of 3.5 pence per kg the system showed cost saving of the energy consumption of up to 73% when LAir is used and 67% when LN2 is used compared with the conventional system. The CFD modelling of cryogenic heat exchanger showed good agreement with the experimental work with maximum deviation 7.6%.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Engineering, Department of Mechanical Engineering
Funders: None/not applicable
Subjects: T Technology > TJ Mechanical engineering and machinery


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