Modelling and transient analysis of a hybrid liquid Desiccant cooling system

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Makina Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2014

Öğrenci: ARASH KARSHENASS

Danışman: DEREK KEITH BAKER

Özet:

Desiccant Cooling Systems (DCS) are considered as an alternative method for conventional vapor compression cooling systems (VCCS) or at least a complimentary component to them. In conventional VCCS inlet air is cooled down to blow its dew point for dehumidification and then is reheated again to obtain air flow with desired temperature and humidity, and consequently inefficient consumption of energy. In DCS, dehumidification of air is done by utilizing of desiccant material to get desirable humidity and then dry air is cooled by evaporation method or cooling coils down to suiTABLE temperature. This thesis presents a study of the feasibility of a hybrid liquid desiccant cooling system with Lithium Chloride as the desiccant material. Mathematical models of desiccant contactors are adopted from the literature. The whole system is modeled in the TRNSYS platform and is simulated using Typical Metrological Year data. The building model has developed in accordance with the building construction and operation. Simulations are performed over the summer period of the year and the results are compared to the results assuming a VCCS from system characteristics and energy saving points of view. One of the most important outputs is that, DCS has to be investigated in a transient manner rather than steady state conditions. The results also indicate that consumed energy in both systems are approximately equal in magnitudes but different in type; DCS shifts required energy from electricity to thermal energy. Also for large supply-air flow rate applications, DCS would be more beneficial than VCCS. In addition, DCS provides suiTABLE conditions in lower supply-air flow rates in which VCCS cannot. This is due to low humidity ratio requirement of supply air which cannot be accessed in typical VCCS because of temperature limit of chiller.