Film condensation heat transfer characteristics of R134a on horizontal stainless steel integral-fin tubes at low heat transfer rate

2009 ◽  
Vol 32 (5) ◽  
pp. 865-873 ◽  
Author(s):  
Rin Yun ◽  
Jaehyeok Heo ◽  
Yongchan Kim
Keyword(s):  
Heat Transfer ◽  
Stainless Steel ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Condensation Heat Transfer ◽  
Film Condensation ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Fin Tubes

Pressure Drop and Heat Transfer Characteristics of Louvered Fin Heat Exchangers

2013 ◽  
Vol 465-466 ◽  
pp. 500-504 ◽  
Author(s):  
Shahrin Hisham Amirnordin ◽  
Hissein Didane Djamal ◽  
Mohd Norani Mansor ◽  
Amir Khalid ◽  
Md Seri Suzairin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Three Dimensional ◽  
Considerable Effect ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Louvered Fin

This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer characteristics of louvered fin heat exchanger numerically. Three dimensional simulation using ANSYS Fluent have been conducted for six different configurations at Reynolds number ranging from 200 to 1000 based on louver pitch. The performance of this system has been evaluated by calculating pressure drop and heat transfer coefficient. The result shows that, the fin pitch and the louver pitch have a very considerable effect on pressure drop as well as heat transfer rate. It is observed that increasing the fin pitch will relatively result in an increase in heat transfer rate but at the same time, the pressure drop will decrease. On the other hand, low pressure drop and low heat transfer rate will be obtained when the louver pitch is increased. Final result shows a good agreement between experimental and numerical results of the louvered fin which is about 12%. This indicates the capability of louvered fin in enhancing the performance of heat exchangers.

Numerical Research on Heat Transfer Characteristics Analysis of Two Particles in Supercritical Water

2021 ◽  
Author(s):  
Xiaoyu Li ◽  
Zhenqun Wu ◽  
Huibo Wang ◽  
Hui Jin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Phase Flow ◽  
Heat Transfer Characteristics ◽  
Particle Cluster ◽  
Two Phase ◽  
Transfer Characteristics

Abstract In the supercritical water (SCW)-particle two-phase flow of fluidized bed, the particles that make up the particle cluster interact with each other through fluid, and it will affect the flow and heat transfer. However, due to the complex properties of SCW, the research on particle cluster is lacking, especially in terms of heat transfer. This research takes two particles as an example to study the heat transfer characteristics between SCW and another particle when one particle exists. This research uses the distance and angle between the two particles as the influencing factors to study the average heat transfer rate and local heat transfer rate. In this research, it is found that the effect is obvious when L/D = 1.1. When L = 1.1D, the temperature field and the flow field will partially overlap. The overlap of the temperature field will weaken the heat transfer between SCW and the particle. The overlap of the flow field has an enhanced effect on the heat transfer between SCW and the particle. The heat transfer between SCW and particles is simultaneously affected by these two effects, especially local heat transfer rate. In addition, this research also found that as the SCW temperature decreases, the thermal conductivity and specific heat of SCW increases, which enhances the heat transfer between SCW and the particles. This research is of great significance for studying the heat transfer characteristics of SCW-particle two-phase flow in fluidized bed.

Experimental Research on Heat Transfer Characteristics of Pulsating Heat Pipe

2008 ◽  
Author(s):  
Li Jia ◽  
Yan Li
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Rate ◽  
Experimental Research ◽  
Transfer Rate ◽  
Experimental Results ◽  
Pulsating Heat Pipe ◽  
Heat Transfer Characteristics ◽  
Fill Ratio ◽  
Transfer Characteristics

Experimental research was conducted to understand heat transfer characteristics of pulsating heat pipe in this paper. The PHP is made of high quality glass capillary tube. The heat transfer rate and many other influence factors, the flow patterns were observed in the start-up, transition and stable stage under different fill ratio. The effects of heating position on heat transfer were discussed. The experimental results indicate that no annular flow appeares in top heating condition. The flow pattern in PHP is transferred form bulk flow to semi-annual flow and annual flow, and the performance of heat transfer is improved for down heating case under different fill ratios and heat transfer rate. The experimental results show that the total heat resistant of PHP is increased with fill ratio, and heat transfer rate achieves optimum at filling rate 50%. But for pulsating heat pipe with changing diameters the thermal resistance is higher than that with uniform diameters.

Experimental Investigation on the Heat Transfer Characteristics of Nanofluids in Self-Exciting Mode Oscillating-Flow Heat Pipe

2011 ◽  
Vol 396-398 ◽  
pp. 250-254 ◽  
Author(s):  
Fu Min Shang ◽  
Jian Hong Liu ◽  
Deng Ying Liu
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Working Fluid ◽  
Oscillating Flow ◽  
Filling Rate ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow Heat

The objective of this article is to provide the heat transfer characteristics of Cu-H2O nanofluids in self-exciting mode oscillating-flow heat pipe under different laser heating input, and to compare with the heat transfer characteristics of the same heat pipe with distilled water as working fluids. In this paper, the peculiarity of heat transfer rate of the SEMOS heat pipe with Cu-H2O fluid has been experimentally confirmed by changing the proportion of working fluid and Cu nanoscale particles in the heat pipe. As the results, it has been confirmed that the parameter of filling rate of working fluid determine the heat transfer rate of SEMOS heat pipe, although under certain condition heat transfer performance could be improved because of the addition of nanofluids.

Inaccuracy of Heat Transfer Characteristics for Pin Fins Considering the Influence of Heat Radiation

2011 ◽  
Vol 199-200 ◽  
pp. 1513-1517
Author(s):  
Fu Jen Wang ◽  
Jung Chieh Chang ◽  
Kuo Chien Lin ◽  
King Leung Wong
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Radiation Effect ◽  
Heat Radiation ◽  
Convection Coefficient ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Pin Fins

Pin fins are widely applied in heat exchanger industry. The heat transfer characteristics of pin fins can be found in many textbooks and handbooks related to heat transfer or heat exchanger. However, most heat transfer experts recognized from their own experiences that the heat radiation effect equation contained the fourth order exponential of temperature and the emissivity of oxidized metal are higher, the inaccuracy of heat transfer rate might be higher while ignoring the effect of heat radiation. In this study, numerical simulation using computational fluid dynamics (CFD) code was conducted to verify the heat transfer characteristics of pin fins. It is found that the error of heat transfer rate generated by ignoring heat radiation will be as high as 45 % while heat convection coefficient is 10 (Wm-2K-1 ) associated with the emissivity of fin surface is 1.0. It also revealed the heat radiation effect cannot be neglected for pin fins, especially for the application under high emissivity and low heat convection coefficient conditions.

Heat Transfer Enhancement of Impinging Jet from Pulse Jet Combustor

2014 ◽  
Vol 931-932 ◽  
pp. 1228-1232
Author(s):  
Pathomporn Narato ◽  
Kittinan Maliwan ◽  
Chayut Nuntadusit
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Flow Characteristics ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Heat Flux Sensor ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Pulse Jet

The aims of this study are to investigate flow characteristics in pulse jet combustor and heat transfer characteristics of impinging jet from pulse jet combustor. The combustor is Helmholtz type which has single combustor chamber and single tailpipe. The inner diameter (D) of tailpipe was 47 mm and tailpipe length was about 16D. The effect of number of air inlets: single inlet, double inlets with 90o apart, double inlets with 180o apart and triple inlets with 90o apart on flow and heat transfer characteristics were studied. A water cooled heat flux sensor was applied to measure heat transfer rate on the surface at stagnation point. The jet-to-plate distance was varied at L=1D, 2D, 4D, 6D and 8D. Two of pressure transducers were mounted on the wall of combustion chamber and on the wall of tailpipe at 4D from tailpipe outlet to measure pressure simultaneously. It is found that the variation of pressure near the tailpipe outlet is strongly depended on air inlet configurations. The pressure variations in pulse jet combustor could be preliminary related to the temperature and velocity of jet from tailpipe and heat transfer rate on jet impingement surface.

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