Experimental investigation of capillary-assisted solution wetting and heat transfer using a micro-scale, porous-layer coating on horizontal-tube, falling-film heat exchanger

2012 ◽  
Vol 35 (4) ◽  
pp. 1176-1187 ◽  
Author(s):  
Sangsoo Lee ◽  
Batikan Köroğlu ◽  
Chanwoo Park
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Exchanger ◽  
Porous Layer ◽  
Horizontal Tube ◽  
Falling Film ◽  
Micro Scale ◽  
Layer Coating

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.

Enhancement of Solution Wetting and Heat Transfer on Horizontal-Tube, Falling-Film Evaporator Using Porous-Layer Coating

2010 ◽  
Author(s):  
Sangsoo Lee ◽  
Chanwoo Park
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Porous Layer ◽  
Complete Solution ◽  
Horizontal Tube ◽  
Partial Solution ◽  
Falling Film ◽  
Micro Scale ◽  
Film Evaporator ◽  
Layer Coating

An experimental study using a porous-layer (wick) coating on a horizontal-tube, falling-film evaporator was conducted to investigate the solution wetting of evaporator tubes and its effects on the evaporator performance. The partial solution wetting and the local dry-out on the evaporator tubes are the commonly encountered problems for the horizontal-tube, falling-film evaporator. In this study, the porous-layer coating was used in an attempt to enhance the solution wetting on the tubes and thus the evaporator performance. An experimental setup was built to measure the solution wetting and the performance of the evaporators using micro-scale hatched tubes (baseline design) and porous-layer coated tubes. Distilled water was used as the solution and the heating fluids. The solution wetting and the falling-film flow modes were visually observed in the range of the solution Reynolds number from 6 to 61. The evaporator using the micro-scale hatched tubes had the partial solution wetting on the tubes in the range of the solution Reynolds number considered for the study. In contrast, the evaporator using the porous-layer coated tubes showed the complete solution wetting which was confirmed by a visual inspection. The evaporator performance was evaluated by a thermal resistance analysis for the ranges of the solution and the heating fluid Reynolds numbers from 18 to 154 and from 3070 to 7270 respectively. The evaporation thermal resistances for the micro-scale hatched and the porous-layer coated tubes were increased as the solution flow rates were increased. The evaporation heat transfer coefficients for the micro-scale hatched tubes were higher than those for the porous-layer coated tubes. However, the evaporation thermal resistances with the porous-layer coated tubes were lower than those with the micro-scale hatched tubes because the complete solution wetting was achieved using the porous-layer coating.

Experimental investigation on heat transfer in horizontal-tube falling-film evaporator

2014 ◽  
Vol 56 (6) ◽  
pp. 1440-1446 ◽  
Author(s):  
Shengqiang Shen ◽  
Xingsen Mu ◽  
Yong Yang ◽  
Gangtao Liang ◽  
Xiaohua Liu
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Horizontal Tube ◽  
Falling Film ◽  
Film Evaporator

Effects of Tube Row on Heat Transfer and Surface Wetting of Microscale Porous-Layer Coated, Horizontal-Tube, Falling-Film Evaporator

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Batikan Köroğlu ◽  
Nicholas Bogan ◽  
Chanwoo Park
Keyword(s):  
Heat Transfer ◽  
Porous Layer ◽  
Horizontal Tube ◽  
Flow Mode ◽  
Falling Film ◽  
Surface Wetting ◽  
Solution Flow ◽  
Flow Rates ◽  
Film Evaporator ◽  
Evaporation Heat

An experimental study was conducted to investigate the effects of tube row on surface wetting and heat transfer of a horizontal-tube, falling-film evaporator. Two types of the evaporator tubes were used for comparison: plain copper and copper coated with a microscale porous-layer. Distilled water was used as solution and heating fluids. A visual observation experiment performed in ambient with no heat input showed that when solution fluid was dripped onto the evaporator tubes from a solution dispenser, the plain tubes were partially wetted, while the porous-layer coated tubes were completely wetted due to capillary liquid spreading, even at low solution flow rates. It was found from the heat transfer experiment performed in a closed chamber under saturated conditions that the porous-layer coated tubes exhibited superior evaporation heat transfer (up to 100% overall improvement over the plain tubes at low solution flow rates) due to complete solution wetting and thin-film evaporation. It was also observed that the surface wetting and heat transfer are greatly influenced by both intertube flow mode of solution fluid and tube wall superheat. The effects of the tube row on the solution wetting and heat transfer were significant, especially for downstream tubes.

EXPERIMENTAL INVESTIGATION ON HEAT TRANSFER AUGMENTATION IN HORIZONTAL TUBE USING COILED WIRE INSERTS

2019 ◽  
Vol 26 (5) ◽  
pp. 513-534
Author(s):  
Madhu Sruthi Emani ◽  
Abhik Nayak ◽  
Achin Kumar Chowdhuri ◽  
Bijan Kumar Mandal ◽  
Sujoy Kumar Saha
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Horizontal Tube ◽  
Heat Transfer Augmentation
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