Evaporation Heat Transfer of HFO-1233zd (E) in Falling Film Type Plate-fin Evaporator

2021 ◽  
Vol 56 (3) ◽  
pp. 373-378
Author(s):  
Junichi Ohara
Keyword(s):  
Heat Transfer ◽  
Falling Film ◽  
Film Type ◽  
Evaporation Heat ◽  
Evaporation Heat Transfer

Effects of Inclination Angle on Falling Film Evaporation Using R-134a

2005 ◽  
Author(s):  
Liang-Han Chien ◽  
Hung-Ta Lin
Keyword(s):  
Heat Transfer ◽  
Inclination Angle ◽  
Falling Film ◽  
Film Evaporation ◽  
Evaporation Heat ◽  
Finned Surface ◽  
Falling Film Evaporation ◽  
Plain Surface ◽  
Evaporation Heat Transfer ◽  
R 134A

This manuscript discusses the effect of inclination angle and surface geometries on the falling film evaporation performance. Falling film evaporation experiments were conducted on a smooth plate and finned plates using refrigerant R-134a at 18 °C system temperature. The plate was inclined with angles between 10° and 40°, and the heat fluxes are between 36 and 73.5kW/m2. The local heat transfer coefficients are measured, and the falling film flow distribution is observed through a sight glass. The test results showed that the falling film evaporation heat transfer coefficient increases as the inclination angle increases or the heat flux increases. The finned surface yields better falling film evaporation heat transfer performance than the smooth surface. The ratio of the heat transfer coefficient of the finned surface versus the plain surface is between 2.5 and 12.4 folds. This ratio increases as the inclination angle increases. The visualization observation showed that bubble nucleation is more pronounced on the finned surface than the plain surface. The effect of boiling on falling film evaporation is discussed.

Experimental Study of Tube Row Effects on Evaporation Heat Transfer Using a Micro-Scale, Porous-Layer Coating on a Horizontal-Tube, Falling-Film Heat Exchanger

2012 ◽  
Author(s):  
Batikan Köroğlu ◽  
Nicholas Bogan ◽  
Chanwoo Park
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Porous Layer ◽  
Horizontal Tube ◽  
Falling Film ◽  
Solution Flow ◽  
Micro Scale ◽  
Evaporation Heat ◽  
Evaporation Heat Transfer ◽  
Layer Coating

An experimental study was conducted to investigate the effects of tube row and a micro-scale porous-layer coating on solution fluid wetting and heat transfer of a horizontal-tube, falling-film heat exchanger using an inline tube arrangement. A uniform layer of micro-scale copper particles was directly bonded onto plain copper tubes by sintering to create a porous-layer coating on the tubes. Distilled water was used as solution and heating fluids. The visual observation performed in open ambient condition revealed that when the solution was dripped onto horizontal tubes from a solution dispenser, the conventional plain tubes were always partially wetted while the porous-layer coated tubes were completely wetted due to capillary action, even at low solution flow rates. It was shown from the comparison of the evaporation heat transfer results of the plain and porous-layer coated tubes tested in a closed chamber under saturated conditions that the porous-layer coated tubes exhibited a superior evaporation heat transfer rate (around 70% overall improvement at low solution flow rates) due to the complete solution wetting and thin solution liquid film on the evaporator tubes. It was also observed that the heat transfer and surface wetting of the horizontal-tube, falling-film heat exchanger are greatly affected by both the flow mode of the solution fluid between the tubes and tube wall superheats. The effect of the tube row of the falling-film heat exchanger on the solution wetting and heat transfer was significant.

Electrohydrodynamic Enhancement of Falling Film Evaporation Heat Transfer and its Long-Term Effect on Heat Exchangers

1997 ◽  
Vol 119 (2) ◽  
pp. 339-347 ◽  
Author(s):  
K. Yamashita ◽  
A. Yabe
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Heat Exchangers ◽  
Industrial Applications ◽  
Falling Film ◽  
Film Evaporation ◽  
Evaporation Heat ◽  
Falling Film Evaporation ◽  
Evaporation Heat Transfer

Electrohydrodynamic (EHD) enhancement of vertical falling film evaporation heat transfer has been experimentally studied using HCFC123, which is an alternative working fluid for CFCs. This research verified that EHD enhancement of HCFC123 condensation was as effective as that of conventional working fluids. The electrodes used for EHD enhancement of vertical falling film evaporation utilized the following two EHD phenomena: extracting the liquid by a nonuniform electric field, and surface granulation by a nearly uniform electric field. As a result, an electrode with vertically arrayed offset-slits that is suitable for industrial applications has been developed that showed a six-fold enhancement of evaporation heat transfer over that for a smooth tube. The long-term effects of the high voltages associated with EHD on heat exchanger performance have been evaluated. Operation of EHD heat exchangers for 1000 hours indicates they do not sustain serious damage, and are, therefore, suitable for industrial applications.

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