High-temperature-glide (i.e., large difference in dew and bubble point temperature) zeotropic mixtures such as ammonia/water have the potential to improve efficiency as new working fluids in advanced energy cycles for heating, cooling and power. Furthermore, the high heat capacity of ammonia/water mixtures makes them particularly attractive for use in compact mini- and microchannel devices. The non-isothermal condensation process of zeotropic mixtures leads to coupled heat and mass transfer resistances in each phase, which are not accounted for by single-component in-tube condensation modeling and correlation techniques. Previous attempts to design zeotropic condensers have relied on use of non-equilibrium film theory or mixture resistance correction factors. The film theory models have been developed with many simplifying assumptions including annular flow, negligible condensate and vapor sensible heat loads, and/or laminar condensate film, while the correction factor approaches do not directly consider mass transfer resistances. In the present study of high-temperature-glide mixtures in small channels, these assumptions are relaxed, and a new design method for mini- and microchannel zeotropic condensers is introduced. The approach is validated with experiments conducted for a range of tube diameters (0.98 < D < 2.16 mm), mass fluxes (50 < G < 200 kg m−2 s−1) and mass fractions of ammonia (0.80 < xbulk < 0.96). The results can be used in the development of compact, highly efficient heat and mass transfer devices.
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ASME 2014 International Mechanical Engineering Congress and Exposition
November 14–20, 2014
Montreal, Quebec, Canada
Conference Sponsors:
- ASME
ISBN:
978-0-7918-4956-9
PROCEEDINGS PAPER
Improved Non-Equilibrium Film Method for the Design of High-Temperature-Glide, Mini- and Microchannel Condensers
Brian M. Fronk,
Brian M. Fronk
Georgia Institute of Technology, Atlanta, GA
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Srinivas Garimella
Srinivas Garimella
Georgia Institute of Technology, Atlanta, GA
Search for other works by this author on:
Brian M. Fronk
Georgia Institute of Technology, Atlanta, GA
Srinivas Garimella
Georgia Institute of Technology, Atlanta, GA
Paper No:
IMECE2014-38543, V08BT10A066; 11 pages
Published Online:
March 13, 2015
Citation
Fronk, BM, & Garimella, S. "Improved Non-Equilibrium Film Method for the Design of High-Temperature-Glide, Mini- and Microchannel Condensers." Proceedings of the ASME 2014 International Mechanical Engineering Congress and Exposition. Volume 8B: Heat Transfer and Thermal Engineering. Montreal, Quebec, Canada. November 14–20, 2014. V08BT10A066. ASME. https://doi.org/10.1115/IMECE2014-38543
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