TY  - JOUR
AU  - Seiler, Jan
AU  - Lanzerath, Franz
AU  - Jansen, Christoph
AU  - Bardow, André
TI  - Only a wet tube is a good tube: understanding capillary-assisted thin-film evaporation of water for adsorption chillers
JO  - Applied thermal engineering
VL  - 147
SN  - 1359-4311
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2020-02335
SP  - 571 - 578
PY  - 2019
AB  - Efficient evaporation of water at low temperatures is challenging due to its low saturation pressure. As a consequence, the preferred evaporation by nucleate boiling can only be achieved at the cost of high superheats. However, low superheats can still lead to efficient evaporation by thin-film evaporation. In this work, we experimentally characterize the heat transfer for thin-film evaporation on coated copper tubes, which use capillary action to create a thin film on their surface. The overall heat transfer through the tubes is determined at all filling levels for evaporator inlet temperatures of 10, 15 and 20 °C with varied driving force. Our experiments reveal that poor coatings suffer from dry-out at high driving forces whereas tubes with good coatings remain fully wetted even at high driving force. Furthermore, we show the impact of surface properties on thin-film evaporation: high porosity, surface extension and roughness promote the creation of a thin film on the tube. Thereby, the heat transfer UA-value is increased up to a factor of 10.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000454974700051
DO  - DOI:10.1016/j.applthermaleng.2018.08.024
UR  - https://juser.fz-juelich.de/record/877620
ER  -