Understanding the transient behavior of the dew point evaporative cooler from the first and second law of thermodynamics

Lin, Jie, Thu, Kyaw, Karthik, Somasundaram, Shahzad, Muhammad Wakil, Wang, Ruzhu and Chua, Kian Jon (2021) Understanding the transient behavior of the dew point evaporative cooler from the first and second law of thermodynamics. Energy Conversion and Management, 244. p. 114471. ISSN 0196-8904

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Official URL: https://doi.org/10.1016/j.enconman.2021.114471

Abstract

Owing to its high energy efficiency without using greenhouse gases, dew point evaporative cooling offers a desired solution for thermal management of electronic and electrical devices. This paper elucidates the transient behavior of a dew point evaporative cooler and its significant influence on the dynamic cooling performance. A large time constant (400 s) of the product air temperature was observed under a zero-state response, leading to a pronounced deviation of the time-average cooling performance below its steady state by 13.8%–26.4% over a long period (2500 s). To capture this phenomenon, a modified transient lumped parameter model and a new partial differential exergy model were developed. An air mixing process in the dry channel was identified to account for the slow cooler’s transient responses. A detailed exergy analysis revealed that the specific exergy destruction at the dry channel entrance was above 400 W/kg, owing to the air mixing. This finding demonstrates that the transient behavior should be judiciously considered in the cooler design and optimization, together with the steady-state performance. Accordingly, a detailed sensitivity analysis of the cooler’s objective variables is proposed to gain insights into the future improvement of the dew point evaporative cooler.

Item Type: Article
Additional Information: Funding information: The authors gratefully acknowledge the funding from (1) the National Research Foundation (NRF) Singapore under the Energy Innovation Research Programme (EIRP) Funding Scheme (R-265-00-543-279); (2) the National Research Foundation Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme; (3) the UK Engineering and Physical Sciences Research Council (EPSRC) Translational Energy Storage Diagnostics (TRENDs) project; and (4) the STFC Futures Early Career Award.
Uncontrolled Keywords: Dew point evaporative cooling, Transient, Lumped parameter model, Exergy analysis, Sensitivity analysis
Subjects: H300 Mechanical Engineering
H800 Chemical, Process and Energy Engineering
Department: Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User: Elena Carlaw
Date Deposited: 23 Jul 2021 15:42
Last Modified: 31 Jul 2021 10:03
URI: http://nrl.northumbria.ac.uk/id/eprint/46751

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