Study on heat transfer of falling film evaporation characteristics on heat pipes in negative pressure

2009 ◽  
Vol 10 (1-3) ◽  
pp. 311-316 ◽  
Author(s):  
Penghui Gao ◽  
Lixi Zhang ◽  
Hefei Zhang
Keyword(s):  
Heat Transfer ◽  
Negative Pressure ◽  
Heat Pipes ◽  
Falling Film ◽  
Film Evaporation ◽  
Falling Film Evaporation

Numerical Simulation of the Liquid Flowing and Heat-Transfer outside the Tube of the Horizontal-Tube Falling Film Evaporator

2012 ◽  
Vol 614-615 ◽  
pp. 296-300 ◽  
Author(s):  
Wei Kang Hu ◽  
Li Yang ◽  
Lei Hong Guo
Keyword(s):  
Heat Transfer ◽  
Horizontal Tube ◽  
Water Desalination ◽  
Falling Film ◽  
Transfer Enhancement ◽  
Film Evaporation ◽  
Film Evaporator ◽  
Spray Density ◽  
Performance Of Heat Transfer ◽  
Falling Film Evaporation

This paper mainly studies the falling film evaporator in the field of water desalination. Using the method of fluent simulates the process of the liquid flowing and heat-transfer on the horizontal-tube falling film evaporation. The author analyses the distribution of the liquid film, and obtain the rule that spray density, evaporation temperature, temperature difference and pipe diameter affect the performance of heat-transfer in a certain range. So the paper plays a guiding role in heat transfer enhancement in the falling film evaporator.

Falling Film Evaporation of Water on Horizontal Configured Tube Bundles

2010 ◽  
Author(s):  
Wei Li ◽  
Xiaoyu Wu ◽  
Zhong Luo
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Inlet Temperature ◽  
Falling Film ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Film Evaporation ◽  
Tube Bundles ◽  
Falling Film Evaporation

This paper reports an experimental study on falling film evaporation of water on 6-row horizontal configured tube bundles in a vacuum. Three types of configured tubes, Turbo-CAB-19fpi and −26fpi, Korodense, including smooth tubes for reference, were tested in a range of film Reynolds number from about 10 to 110. Results show that as the falling film Reynolds number increases, falling film evaporation goes from tubes partial dryout regime to fully wet regime; the mean heat transfer coefficients reach peak values in the transition point. Turbo-CAB tubes have the best heat transfer enhancement of falling film evaporation in both regimes, but Korodense tubes’ overall performances are better when tubes are fully wet. The inlet temperature of heating water has hardly any effects on the heat transfer, but the evaporation pressure has controversial effects. A correlation with errors within 10% was also developed to predict the heat transfer enhancement capacity.

Heat Transfer and Fouling Performance During Falling Film Evaporation in Vertical Porous Tubes

2020 ◽  
Author(s):  
Lei Wang ◽  
Weiyu Tang ◽  
Limin Zhao ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Smooth Tube ◽  
Outer Diameter ◽  
Falling Film ◽  
Film Evaporation ◽  
Falling Film Evaporation ◽  
The Heat Transfer Coefficient

Abstract An experimental investigation was conducted on falling film evaporation along two porous tubes, which were sintered by stainless-steel powder with a diameter of 0.45 and 1 um, respectively. The test section is a 2 m long sintered tube with an outer diameter of 25 mm and a wall thickness of 2 mm. During the experiment, the pressure inside the tube was maintained at 1 atm, the inlet temperature was 373 K, and mass flux ranged from 0.51 to 1.36 kg/ (m s). Conditions of the steam outside the pipe, which was the heat source, were fixed, while the fouling tests were carried out at a constant mass flow of 0.74 kg/ (m s) using high-concentration brine as work fluid. The overall heat transfer coefficient under different working conditions was tested and compared with the stainless steel smooth tube of the same dimensions. The heat transfer coefficient of the two porous stainless tubes are about 35% and 20% lower than that of the smooth one, showing an inferior effect because the steam in the pores of the pipe wall during the infiltration process will reduce the heat conductivity. The heat transfer coefficient of the smooth tube deteriorated severely due to the deposition of calcium carbonate, which had little effect on the sintered tubes. Besides, the fouling weight of porous tubes is 2.01 g and 0 g compared with 5.52 g of the smooth tube.

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.

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