Impact of the Anticorrosion Films on the Condensing Heat Transfer of Flue Gas in Fin-Tube Heat Exchangers

2010 ◽  
Author(s):  
Sui-lin Wang ◽  
Yuan-yuan Wu ◽  
Shu yuan Pan ◽  
Yong zheng Shi
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Organic Compound ◽  
Transfer Coefficient ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Convection Heat Transfer ◽  
Experimental Results ◽  
Convection Heat ◽  
Fin Tube

The forced convective heat transfer with condensing was experimentally investigated when wet flue gas was flowing in the fin-tube heat exchangers with three anticorrosion films respectively, including the nickel-phosphorus amorphous composite eletroless and organic compound (NPACE&OC) surface, the nickel-phosphorus amorphous composite eletroless (NPACE) surface, and the organic compound (OC) surface. The experimental results indicate the convection heat transfer characteristics as following: Among the three heat exchangers, the convection heat transfer for the heat exchanger with NPACE&OC surface is the best, the convection heat transfer coefficient is about 18%∼25% higher than that of the other two heat exchangers. It could be caused by the lower surface energy of the NPACE&OC surface that forms the drop condensate. The experimental results of heat transfer coefficient relative to Reynolds Number and Jakob Number were also presented in this paper. Based on the experimental results and the analysis, the correlation of the measurements was achieved.

scholarly journals An experimentally investigate the fin thermal performance to the different fin spaces by natural convections

2018 ◽  
Vol 2 (1) ◽  
pp. 1-13
Author(s):  
Hazim Mohammed Al-Jewaree
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Transfer Coefficient ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Environmental Condition ◽  
Convection Heat

In oil and gas industries there are a lot off heat transfer devices used for different purposes. These devices are widely used in various industrial, transportation, or domestic applications such as heat exchangers thermal power plants, means of transport, heating and air conditioning systems, electronic equipments and space vehicles. In all these applications, improvements in the efficiency of heat exchangers can lead to substantial cost, space and materials savings. The research work summarized in this articles presents an experimental investigation on the effect of fin space (s)  and aluminum materials on the fin performance using rectangular  fins. The steady-state natural convection heat transfer from vertical rectangular fins extending perpendicularly from horizontal square base was investigated experimentally at new range not found in the previous works, this range of temperatures from 50 to 150 Co  . The effects of fin space parameter and base-to-ambient temperature difference on the heat transfer performance of fin arrays were observed and the environmental condition were determined. Five fin space settings,( 22, 27, 30, 35 and 38 mm) with a constant fin height is 50mm for all types of configuration are presented in this work  were employed under free convection heat transfer conditions. This range of fin space not found on previous study or research. The heat transfer area was kept the same. The performance of the fin expressed in terms of fin efficiency, effectiveness and thermal resistance as a function of the ambient temperature and fin space parameters has been study in this work. The dimensionless parameter Biot no. on the locally variable environmental condition is examined for different fin spaces to the fin heat transfer rate. Also, the effect of environmental condition is study.  Experimental results show that the effect fin space on fin performance is more significant.. The maximum increase in convection heat transfer coefficient value obtained is about 22 percent. The increase in heat transfer coefficient value is also manifested by a corresponding decrease in the fin base temperature. Also, it is concluded from the experimental results that the performance of heat transfer rate increase with decreasing the fin space  in respect of heat transfer coefficient, thermal resistance ,overall efficiency and effectiveness.

scholarly journals Experimental and Theoretical Investigation of the Natural Convection Heat Transfer Coefficient in Phase Change Material (PCM) Based Fin-and-Tube Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 716
Author(s):  
Saulius Pakalka ◽  
Kęstutis Valančius ◽  
Giedrė Streckienė
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Energy Storage ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

Latent heat thermal energy storage systems allow storing large amounts of energy in relatively small volumes. Phase change materials (PCMs) are used as a latent heat storage medium. However, low thermal conductivity of most PCMs results in long melting (charging) and solidification (discharging) processes. This study focuses on the PCM melting process in a fin-and-tube type copper heat exchanger. The aim of this study is to define analytically natural convection heat transfer coefficient and compare the results with experimental data. The study shows how the local heat transfer coefficient changes in different areas of the heat exchanger and how it is affected by the choice of characteristic length and boundary conditions. It has been determined that applying the calculation method of the natural convection occurring in the channel leads to results that are closer to the experiment. Using this method, the average values of the heat transfer coefficient (have) during the entire charging process was obtained 68 W/m2K, compared to the experimental result have = 61 W/m2K. This is beneficial in the predesign stage of PCM-based thermal energy storage units.

Forced Convection Heat Transfer of Nanofluids: A Review

2017 ◽  
Author(s):  
Aditya Kuchibhotla ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Specific Heat ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
Convection Heat

Stable homogeneous colloidal suspensions of nanoparticles in a liquid solvents are termed as nanofluids. In this review the results for the forced convection heat transfer of nanofluids are gleaned from the literature reports. This study attempts to evaluate the experimental data in the literature for the efficacy of employing nanofluids as heat transfer fluids (HTF) and for Thermal Energy Storage (TES). The efficacy of nanofluids for improving the performance of compact heat exchangers were also explored. In addition to thermal conductivity and specific heat capacity the rheological behavior of nanofluids also play a significant role for various applications. The material properties of nanofluids are highly sensitive to small variations in synthesis protocols. Hence the scope of this review encompassed various sub-topics including: synthesis protocols for nanofluids, materials characterization, thermo-physical properties (thermal conductivity, viscosity, specific heat capacity), pressure drop and heat transfer coefficients under forced convection conditions. The measured values of heat transfer coefficient of the nanofluids varies with testing configuration i.e. flow regime, boundary condition and geometry. Furthermore, a review of the reported results on the effects of particle concentration, size, temperature is presented in this study. A brief discussion on the pros and cons of various models in the literature is also performed — especially pertaining to the reports on the anomalous enhancement in heat transfer coefficient of nanofluids. Furthermore, the experimental data in the literature indicate that the enhancement observed in heat transfer coefficient is incongruous compared to the level of thermal conductivity enhancement obtained in these studies. Plausible explanations for this incongruous behavior is explored in this review. A brief discussion on the applicability of conventional single phase convection correlations based on Newtonian rheological models for predicting the heat transfer characteristics of the nanofluids is also explored in this review (especially considering that nanofluids often display non-Newtonian rheology). Validity of various correlations reported in the literature that were developed from experiments, is also explored in this review. These comparisons were performed as a function of various parameters, such as, for the same mass flow rate, Reynolds number, mass averaged velocity and pumping power.

Thermal Response Characteristics of Flat Plate Heated by High Temperature and High Speed Flow

2013 ◽  
Vol 448-453 ◽  
pp. 3316-3319
Author(s):  
Chuang Sun ◽  
Yang Zhao ◽  
De Fu Li ◽  
Qing Ai ◽  
Xin Lin Xia
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
High Speed ◽  
Convection Heat Transfer ◽  
Thermal Response ◽  
Convection Heat ◽  
Convection Heat Transfer Coefficient

According to the view of heat transfer, the process of the fluid flow with high temperature and high speed over a flat plate may be considered as the heat transfer process within a compressible thermal boundary layer. Based on the numerical results of thermal isolation assumption, combining the temperature comparison with modification method, a coupled method of convection heat transfer coefficient with temperature field of the plate is established, and the characteristics of the thermal response for the flat plate is dominated. Take some ribbed plates as instances, the convection heat transfer coefficient and temperature field of the plate are simulated through the provided coupled method. The results show that, not only the position and materials of the plate influence the convection heat transfer coefficient, but also the time.

Forced Convection Heat Transfer for Helium Gas Under Exponentially Decreasing Flow Condition

2017 ◽  
Author(s):  
Qiusheng Liu ◽  
Li Wang ◽  
Makoto Shibahara ◽  
Katsuya Fukuda
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Forced Convection ◽  
Flow Rate ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Rate Condition ◽  
Initial Flow ◽  
Helium Gas

Knowledge of the heat transfer phenomenon during flow decay transient condition is important for the safety assessment of very high temperature reactor (VHTR) during the loss of coolant accident. In this study, transient heat transfer from a horizontal cylinder to helium gas under exponentially decreasing flow rate condition was experimentally studied. The experiment was performed by using a forced convection heat transfer test loop. A flow control value with its control system was used to realize the flow decay condition. Helium gas was used as coolant and platinum cylinder with 1 mm in diameter was used as the test heater. A uniform heat generation rate was added to the cylinder by a power source. The cylinder temperature was maintained at an initial value under a definite initial flow rate of the helium gas. Then, the mass flow rate of the helium gas starts to decrease exponentially with different time constants ranged from 4.3 s to 15.4 s. The initial flow velocity ranged from 10 m/s to 4 m/s. The surface temperature, heat flux, and heat transfer coefficient were measured during the flow decay transient process under wide experimental conditions such as initial flow rate, flow decay time constant. It was found that the temperature of the test heater shows rapid increase during this process, the increasing rate of the temperature is higher for a shorter time constant. The heat transfer coefficient versus time during the flow rate decreasing process was also obtained. The transient heat transfer process during exponentially decreasing flow rate condition was clarified based on the experimental data.

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