TY - JOUR
T1 - Horizontal-Tube Falling-Film evaporation with structured surfaces
AU - Chyu, M. C.
AU - Bergles, A. E.
PY - 1989/5
Y1 - 1989/5
N2 - Extensive experimental tests for tubes with commercial structured surfaces in a horizontal single-tube falling-film evaporator were conducted. The test sections were hollow copper cylinders with GEWA-T, Thermoexcel-E, or High Flux surfaces electrically heated by inserted cartridge heaters. A smooth surface cylinder was also tested for reference. All tubes were tested in both pool boiling and falling-film evaporation with water. The results reveal that falling-film evaporation provides much higher heat transfer coefficients than pool boiling in the low heat flux, convective region. The GEWA-T surface enhances heat transfer through its increased and accessible area, while Thermoexcel-E and High Flux demonstrate high heat transfer performances because of enhanced nucleate boiling. The falling-film evaporation data for the structured surfaces either merge or show a tendency to merge with the respective pool boiling curves at high heat fluxes. Unusual incipient boiling behavior of Thermoexcel-E and the effects of factors such as surface aging, surface subcooling, film flow rate, liquid feed height, and rate of heat flux change, are described.
AB - Extensive experimental tests for tubes with commercial structured surfaces in a horizontal single-tube falling-film evaporator were conducted. The test sections were hollow copper cylinders with GEWA-T, Thermoexcel-E, or High Flux surfaces electrically heated by inserted cartridge heaters. A smooth surface cylinder was also tested for reference. All tubes were tested in both pool boiling and falling-film evaporation with water. The results reveal that falling-film evaporation provides much higher heat transfer coefficients than pool boiling in the low heat flux, convective region. The GEWA-T surface enhances heat transfer through its increased and accessible area, while Thermoexcel-E and High Flux demonstrate high heat transfer performances because of enhanced nucleate boiling. The falling-film evaporation data for the structured surfaces either merge or show a tendency to merge with the respective pool boiling curves at high heat fluxes. Unusual incipient boiling behavior of Thermoexcel-E and the effects of factors such as surface aging, surface subcooling, film flow rate, liquid feed height, and rate of heat flux change, are described.
KW - Augmentation and Enhancement
KW - Evaporation
KW - Natural Convection
UR - http://www.scopus.com/inward/record.url?scp=0024663635&partnerID=8YFLogxK
U2 - 10.1115/1.3250708
DO - 10.1115/1.3250708
M3 - Article
AN - SCOPUS:0024663635
SN - 0022-1481
VL - 111
SP - 518
EP - 524
JO - Journal of Heat Transfer
JF - Journal of Heat Transfer
IS - 2
ER -