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M M Sarafraz - One of the best experts on this subject based on the ideXlab platform.
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nucleate pool Boiling Heat Transfer characteristics of dilute al2o3 ethyleneglycol nanofluids
International Communications in Heat and Mass Transfer, 2014Co-Authors: M M Sarafraz, F HormoziAbstract:Abstract Pool Boiling Heat Transfer coefficients of dilute stabilized Al2O3–ethyleneglycol nanofluids as possible coolant fluid are experimentally quantified. The influence of different parameters such as Heat flux, Heating surface nano-roughness, concentration of nanofluids and fouling resistance on the pool Boiling Heat Transfer coefficient of alumina nanofluids has experimentally been investigated and briefly discussed. Results demonstrated that there are two Heat Transfer regions with different mechanisms namely free convection and nucleate Boiling Heat Transfer. Studies on the influence of parameter demonstrated that with increasing the Heat flux, the pool Boiling Heat Transfer coefficient of nanofluids significantly increases. In contrast, with increasing the concentration of nanofluid, due to the deposition of nanoparticles on the surface, the average roughness of the surface and the Heat Transfer coefficient dramatically deteriorate, while a significant increase in fouling resistance is reported. Also, studies reveal asymptotic and rectilinear behaviors of fouling resistance parameter in nucleate Boiling and free convective domains.
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application of thermodynamic models to estimating the convective flow Boiling Heat Transfer coefficient of mixtures
Experimental Thermal and Fluid Science, 2014Co-Authors: M M Sarafraz, F HormoziAbstract:Abstract A large number of experiments has been performed to measure the forced convective and nucleate flow Boiling Heat Transfer coefficient of three different none-volatile mixtures at different Heat fluxes (up to 175 kW m−2) and five different volumetric concentrations (10–50% of heavier component). The test mixtures include water/glycerol, water/monoethylene glycol (MEG), and water/diethylene glycol (DEG). The experimental apparatus provides conditions to investigate the influence of the main operating parameters such as: Heat flux, concentration, and flow rate of fluid on the forced convective and flow Boiling Heat Transfer coefficient. It is shown that physical properties of the mixtures have a considerable effect on the prediction of flow Boiling Heat Transfer coefficients by the predictive correlations. In almost all of the predictive correlations, physical properties are strongly involved which can be estimated by different thermodynamic models. This work demonstrates that thermodynamic models for the calculation of specific Heat, liquid density and Heat of vaporization do not obtain identical results and consequently, the Heat Transfer coefficient obtained from a specified predictive correlation (Chen type model) can be tolerated according to the used thermodynamic model for the calculation of the physical properties. This point has been ignored by the investigators and they compare their experimental data with the correlations without specifying that, which one of the thermodynamic models has to be used for the obtaining of the thermo-physical properties. After reading the present study, a new vision can be opened to the readers interested in prediction of the flow Boiling Heat Transfer coefficient and may help the researchers to reliably predict the thermo-physical properties of fluids particularly for forced convective and Boiling phenomena.
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nucleate pool Boiling Heat Transfer of binary nano mixtures under atmospheric pressure around a smooth horizontal cylinder
Periodica Polytechnica Chemical Engineering, 2013Co-Authors: M M Sarafraz, S M Peyghambarzadeh, S Alavi A Fazel, N VaeliAbstract:Influence of Al 2 O 3 nanoparticles on nucleate pool Boiling Heat Transfer of diluted binary water-glycerol mixtures has been experimentally measured up to Heat flux 91 kW/m 2 at diluted volume fractions of 1% to 5% of glycerol into pure water at volumetric concentrations 0.5%, 1% and 1.5% of Al 2 O 3 nanoparticles. Obtained results indicate that presence of nanoparticles into the mixtures result in increasing the pool Boiling Heat Transfer coefficient values and also result in decreasing the wall superHeat temperature of surface. Increased values of Heat Transfer are increased with increasing the volume fractions of Al 2 O 3 too. Generally, it is concurred that Al 2 O 3 nanoparticles typically enhance the pool Boiling Heat Transfer coefficient of binary water-glycerol mixture in comparison with absence of nanoparticles circumstances, up to 25% at 1.5% Al 2 O 3 . Additionally, new simple semi - mathematical model has been proposed for a rough estimating of enhanced values with uncertainty about 8%.
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nucleate pool Boiling Heat Transfer to al2o3 water and tio2 water nanofluids on horizontal smooth tubes with dissimilar homogeneous materials
Chemical and Biochemical Engineering Quarterly, 2012Co-Authors: M M Sarafraz, S M PeyghambarzadehAbstract:Nucleate pool Boiling Heat Transfer coefficients of Al2O3-water and TiO2-water nanofluids have been experimentally measured on three horizontal tubes with different materials and similar roughness under atmospheric pressure. Results revealed that the presence of nanoparticles in the base fluid leads to an increase in pool Boiling Heat Transfer coefficients on stainless steel and brass tubes in contrast to copper tube. The effect of different materials on excess temperature around the surface of the tubes has also been investigated. In addition, experimental investigations on the effect of different nanoparticles on nucleate Boiling Heat Transfer have been conducted at volumetric concentrations of 0.1 %, 0.5 %, and 1 % of nanoparticles. Results indicated that the presence of nanoparticles have no effect on the pool Boiling Heat Transfer coefficient for the copper tube. Variations of surface excess temperature for the copper tube were higher in comparison with that of the other tubes tested.
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enhancement of nucleate pool Boiling Heat Transfer to dilute binary mixtures using endothermic chemical reactions around the smoothed horizontal cylinder
Heat and Mass Transfer, 2012Co-Authors: M M Sarafraz, S M Peyghambarzadeh, S A AlavifazelAbstract:Experimental studies on enhancing the pool Boiling Heat Transfer coefficient of binary dilute mixtures of water/glycerol, water/MEG (Mono-ethylene glycol) and water/DEG (di-ethylene glycol) have been carried out. Some particular endothermic chemical reactions related to ammonium salts were used to enhance the pool Boiling Heat Transfer coefficient, simultaneously with occurrence of pool Boiling Heat Transfer. Accordingly, 100 g of Ammonium nitrate, ammonium perborate and Ammonium sulfate were selected to dissolve into mixtures. High and extreme solution enthalpies of each of these ammonium salt powders are employed to reduce the surface temperature around the horizontal cylinder locally. Results demonstrated that presence of ammonium salts into the mixtures deteriorates the surface temperature of cylinder and as the result, higher pool Boiling Heat Transfer coefficient is reported for tested solutions. Results are also reported and compared for different ammonium salts to find the influence of inducing different enthalpies of solution on pool Boiling Heat Transfer coefficient. Obtained results also indicated that presence of endothermic reaction besides the pool Boiling Heat Transfer enhances the Heat Transfer coefficients in comparison with nucleate pool Boiling phenomenon solely.
Ali Abdollahi - One of the best experts on this subject based on the ideXlab platform.
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experimental study of the effect of various surfactants on surface sediment and pool Boiling Heat Transfer coefficient of silica di water nano fluid
Powder Technology, 2019Co-Authors: Ali Abdollahi, Sasan Etedali, Masoud Afrand, Zhe Tian, Marjan GoodarziAbstract:Abstract In this experimental study, the pool Boiling Heat Transfer of silica DI water nano-fluid with three various surfactants on the surface of copper Heaters at different concentrations at atmospheric pressure has been investigated experimentally. The nano-fluid has been synthesized by a two-step process and has suitable stability. The results show that the Boiling Heat Transfer of surfactant-DI water is higher than that of DI water. Moreover, surfactant-DI water has a higher Heat Transfer coefficient than silica-surfactant-DI water nano-fluid. For nano-fluids with fewer concentrations than 0.5% vol., the Boiling Heat Transfer coefficient for silica-DI water for all surfactants is larger than that of DI water. The Boiling Heat Transfer coefficient of the nano-fluids with anionic surfactant (SDS) is greater than cationic surfactant (CTAB) and cationic is larger than nonionic surfactant (PS20). Results also indicated that surface roughness and sediment are depends on surfactant type due to Boiling of the nano-fluid.
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effect of different surfactants on the pool Boiling Heat Transfer of sio2 deionized water nanofluid on a copper surface
International Journal of Thermal Sciences, 2019Co-Authors: Sasan Etedali, Masoud Afrand, Ali AbdollahiAbstract:Abstract The Boiling Heat Transfer is one of the most widely applied Heat Transfer processes in today's industries. This study is an experimental investigation of the pool Boiling Heat Transfer in a nanofluid composed of deionized (DI) water and silicon dioxide (SiO2) nanoparticles with added surfactants (Ps20, CTAB, SLS) on a copper surface at various nanofluid concentrations, under atmospheric pressure conditions. The nanofluid was synthesized using a two-step method and showed acceptable stability. The concentration of surfactant in nanofluid for all prepared nanofluids is 1 20 of nanoparticles mass. For the sake of repeatability and accuracy of the experiments, the deionized water was measured three times and was found to match the relations proposed in the literature. The results show the Boiling Heat Transfer to be enhanced in the DI water with added surfactants compared with the deionized water. Moreover, the DI water with added surfactants observed a better Boiling Heat Transfer compared to the DI-water-based SiO2 nanofluid with added surfactant. In addition, the Boiling Heat Transfer was reduced as the concentration of the SiO2 nanofluid containing SLS and CTAB surfactants was increased. Meanwhile, increasing the concentration of the SiO2 nanofluid containing Ps20 surfactants from 0.01 to 0.1 vol% enhanced the Heat Transfer. However, increasing the concentration to 1 vol% reduced the Heat Transfer drastically. Therefore, at all Heat fluxes, the nanofluid specimens with added SLS surfactants were associated with the highest Boiling Heat Transfer, which was followed by the nanofluid with added CTAB, and the nanofluid with Ps20 (SLS > CTAB > Ps20). In conclusion, ranking them by impact, anionic, cationic, and nonionic surfactants (nonionic
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experimental study of the optimum size of silica nanoparticles on the pool Boiling Heat Transfer coefficient of silicon oxide deionized water nanofluid
Powder Technology, 2019Co-Authors: Asghar Norouzipour, Ali Abdollahi, Masoud AfrandAbstract:Abstract This research has experimentally investigated the effect of the size of silicon oxide nanoparticles in a base fluid of deionized water on the coefficient of pool Boiling Heat Transfer on a copper surface at atmospheric pressure. Silicon oxide nanoparticles with concentrations of 0.01, 0.1, 0.5 and 1.0 vol% have been used. The sizes of silicon oxide nanoparticles have been determined by TEM tests. The test results indicate that these nanoparticles have a roughly spherical structure and their average sizes are 11, 50 and 70 nm. Moreover, the degree of nanofluid stability (lack of coagulation of nanoparticles) has been determined by the Zeta-Potential test. The Boiling results of the pure water sample show that the curve of Boiling Heat Transfer flux versus the excess temperature difference of surface is very close to the Rohsenow's curve. The results obtained for nanofluid Boiling on copper surface indicates that, at all the considered concentrations and nanoparticle sizes (except nanoparticle size of 70 nm size and concentration of 0.1 vol%), the Boiling Heat Transfer coefficient for the nanofluid sample is much smaller than that of the pure water sample. The findings show that by increasing the diameter of silica nanoparticles from 11 to 70 nm, the Boiling Heat Transfer coefficient is increased. These results show that for all the considered nanoparticle sizes and concentrations, the highest Boiling Heat Transfer coefficient is achieved by the silicon oxide/deionized water nanofluid with the concentration of 0.1 vol% and particle size of 70 nm.
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experimental analysis of magnetic field effect on the pool Boiling Heat Transfer of a ferrofluid
Applied Thermal Engineering, 2017Co-Authors: Ali Abdollahi, Mohammad Reza Salimpour, Nasrin EtesamiAbstract:Abstract In this research, an experimental study was conducted to investigate the pool Boiling Heat Transfer of Fe3O4/water nanofluid (ferrofluid) in the atmospheric pressure. This study also investigated the influence of the magnetic field on the rate of Boiling Heat Transfer of nanofluid. Deionized (DI) water was used to examine the repeatability, integrity and precision of the experimental apparatus where a well agreement with the existing correlations was observed. The investigation of various volume concentrations of nanofluid revealed that Boiling Heat Transfer in high concentrations decreases with an increase of concentration while it rises with the increase of concentration in low concentrations. The Boiling Heat Transfer coefficient at 0.1% volume concentration nanofluid was evaluated as optimal (increasing up to 43%). In addition, experimental studies showed that the presence of positive and negative magnetic field gradients decrease and increase the Boiling Heat Transfer, respectively. The findings of this study showed that at higher concentrations of nanofluid, the effect of the magnetic field on nanoparticles is boosted. The results of the experiments indicated that adding nanoparticles would not necessarily increase the Boiling Heat Transfer coefficient. In fact, the surface roughness and the magnetic field gradient on the Boiling surface were the main factors that could affect the Boiling Heat Transfer coefficient, significantly.
Tsing-fa Lin - One of the best experts on this subject based on the ideXlab platform.
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subcooled flow Boiling Heat Transfer of r 407c and associated bubble characteristics in a narrow annular duct
International Journal of Heat and Mass Transfer, 2008Co-Authors: C.a. Chen, Y.m. Lie, W R Chang, Tsing-fa LinAbstract:An experiment is conducted here to investigate how the channel size affects the subcooled flow Boiling Heat Transfer and the associated bubble characteristics of refrigerant R-407C in a horizontal narrow annular duct with the gap of the duct fixed at 1.0 and 2.0 mm. The measured Boiling curves indicate that the temperature overshoot at ONB is relatively significant for the subcooled flow Boiling of R-407C in the duct. Besides, the subcooled flow Boiling Heat Transfer coefficient increases with a reduction in the duct gap, but decreases with an increase in the inlet liquid subcooling. Moreover, raising the Heat flux imposed on the duct can cause a significant increase in the Boiling Heat Transfer coefficients. However, the effects of the refrigerant mass flux and saturated temperature on the Boiling Heat Transfer coefficient are slighter. Visualization of the subcooled flow Boiling processes in the duct reveals that the bubbles are suppressed to become smaller and less dense by raising the refrigerant mass flux and inlet subcooling. Raising the imposed Heat flux, however, produces positive effects on the bubble population, coalescence and departure frequency. Meanwhile, the present Heat Transfer data for R-407C are compared with the R-134a data measured in the same duct and with some existing correlations. We also propose empirical correlations for the present data for the R-407C subcooled flow Boiling Heat Transfer and some quantitative bubble characteristics such as the mean bubble departure diameter and frequency and the active nucleation site density.
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Saturated flow Boiling Heat Transfer of refrigerant R-410A in a horizontal annular finned duct
International Journal of Heat and Mass Transfer, 2006Co-Authors: Y.y. Hsieh, Y.m. Lie, Tsing-fa LinAbstract:An experiment is conducted here to investigate the saturated flow Boiling Heat Transfer characteristics of ozone friendly refrigerant R-410A in a horizontal annular finned duct. Meanwhile the associated bubble characteristics in the duct are also inspected from the flow visualization. The experimental data are presented in terms of saturated flow Boiling curves, Boiling Heat Transfer coefficients and flow photos. In addition, empirical correlation equations for the saturated flow Boiling Heat Transfer coefficient and mean bubble departure diameter are proposed. The saturated flow Boiling curves show that Boiling hysteresis is insignificant in the flow and the wall superHeat needed for the onset of nucleate Boiling is slightly affected by the refrigerant mass flux. Besides, the Boiling curves are mainly affected by the imposed Heat flux and refrigerant mass flux. Moreover, the measured saturated flow Boiling Heat Transfer coefficient increases with the imposed Heat flux and refrigerant mass flux. Furthermore, at a higher refrigerant mass flux the departing bubbles are smaller.
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saturated flow Boiling Heat Transfer and associated bubble characteristics of r 134a in a narrow annular duct
International Journal of Heat and Mass Transfer, 2005Co-Authors: Y.m. Lie, Tsing-fa LinAbstract:Experiments are conducted here to investigate how the channel size affects the subcooled flow Boiling Heat Transfer and associated bubble characteristics of refrigerant R-134a in a horizontal narrow annular duct. The gap of the duct is fixed at 1.0 and 2.0 mm in this study. From the measured Boiling curves, the temperature undershoot at ONB is found to be relatively significant for the subcooled flow Boiling of R-134a in the duct. The R-134a subcooled flow Boiling Heat Transfer coefficient increases with a reduction in the gap size, but decreases with an increase in the inlet liquid subcooling. Besides, raising the imposed Heat flux can cause a substantial increase in the subcooled Boiling Heat Transfer coefficient. However, the effects of the refrigerant mass flux and saturated temperature on the Boiling Heat Transfer coefficient are small in the narrow duct. Visualization of the subcooled flow Boiling processes reveals that the bubbles are suppressed to become smaller and less dense by raising the refrigerant mass flux and inlet subcooling. Moreover, raising the imposed Heat flux significantly increases the bubble population, coalescence and departure frequency. The increase in the bubble departure frequency by reducing the duct size is due to the rising wall shear stress of the liquid flow, and at a high imposed Heat flux many bubbles generated from the cavities on the Heating surface tend to merge together to form big bubbles. Correlation for the present subcooled flow Boiling Heat Transfer data of R-134a in the narrow annular duct is proposed. Additionally, the present data for some quantitative bubble characteristics such as the mean bubble departure diameter and frequency and the active nucleation site density are also correlated.
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Saturated flow Boiling Heat Transfer and pressure drop of refrigerant R-410A in a vertical plate Heat exchanger
International Journal of Heat and Mass Transfer, 2002Co-Authors: Y.y. Hsieh, Tsing-fa LinAbstract:Abstract Saturated flow Boiling Heat Transfer and the associated frictional pressure drop of the ozone friendly refrigerant R-410A (a mixture of 50 wt% R-32 and 50 wt% R-125) flowing in a vertical plate Heat exchanger (PHE) are investigated experimentally in the study. In the experiment two vertical counter flow channels are formed in the exchanger by three plates of commercial geometry with a corrugated sinusoidal shape of a chevron angle of 60°. Upflow Boiling of saturated refrigerant R-410A in one channel receives Heat from the downflow of hot water in the other channel. The experimental parameters in this study include the refrigerant R-410A mass flux ranging from 50 to 125 kg/m2 s and imposed Heat flux from 5 to 35 kW/m2 for the system pressure fixed at 1.08, 1.25 and 1.44 MPa, which respectively correspond to the saturated temperatures of 10, 15 and 20 °C. The measured data showed that both the Boiling Heat Transfer coefficient and frictional pressure drop increase almost linearly with the imposed Heat flux. Furthermore, the refrigerant mass flux exhibits significant effect on the saturated flow Boiling Heat Transfer coefficient only at higher imposed Heat flux. For a rise of the refrigerant pressure from 1.08 to 1.44 MPa, the frictional pressure drops are found to be lower to a noticeable degree. However, the refrigerant pressure has very slight influences on the saturated flow Boiling Heat Transfer coefficient. Finally, empirical correlations are proposed to correlate the present data for the saturated Boiling Heat Transfer coefficients and friction factor in terms of the Boiling number and equivalent Reynolds number.
Chi Young Lee - One of the best experts on this subject based on the ideXlab platform.
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morphological change of plain and nano porous surfaces during Boiling and its effect on nucleate pool Boiling Heat Transfer
Experimental Thermal and Fluid Science, 2012Co-Authors: Chi Young Lee, Bong June Zhang, Kwang J KimAbstract:In order to investigate nucleate pool Boiling Heat Transfer characteristics in saturated water, a plain aluminum alloy surface (6061, untreated) and a uniquely fabricated aluminum oxide Nano-Porous Surface (NPS) sample were prepared. Generally, the NPS exhibited a lower wall superHeat at the onset of nucleate Boiling and a higher nucleate Boiling Heat Transfer coefficient than the plain surface. It was also noted that the nucleate Boiling Heat Transfer coefficient decreased by 30% on the plain surface and by 37% on the NPS after five repeated Boiling tests. It was found that such performance-degradation in both of the test samples was due primarily to the formation of aluminum hydroxide on the Boiling surfaces. It is our belief that the aluminum hydroxide, formed on both Boiling surfaces, significantly altered the surface morphologies as shown in the microscopic images of the post-Boiling surfaces, which resulted in the decrease of the active nucleation sites. Although NPS is an excellent tool to enhance the nucleate pool Boiling Heat Transfer coefficient, its life span and usefulness can be impeded by undesirable surface reactions with working fluids.
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pool Boiling Heat Transfer with nano porous surface
International Journal of Heat and Mass Transfer, 2010Co-Authors: Chi Young Lee, Mainul Hossain Bhuiya, Kwang J KimAbstract:Anodizing technique has been recognized as an efficient way to grow the well-ordered oxide nano-structures on metal substrate. In the present experimental study, the nucleate pool Boiling Heat Transfer coefficient and long-term performance of nano-porous surface fabricated by the cost-effective and simple anodizing technique were investigated with water. The incipient wall superHeat of pool Boiling in nano-porous surface was lower than that in non-coating surface. The nucleate Boiling Heat Transfer coefficient of nano-porous coating surface appeared higher than that of non-coating surface particularly at the low Heat flux condition. The higher coefficient remained throughout 500 h of operation.
S Z Qiu - One of the best experts on this subject based on the ideXlab platform.
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experimental investigations on single phase convection and two phase flow Boiling Heat Transfer in an inclined rod bundle
Applied Thermal Engineering, 2019Co-Authors: Ke Zhang, W X Tian, Yandong Hou, Yuelang Zhang, S Z QiuAbstract:Abstract Single-phase convection and steam-water two-phase flow Boiling Heat Transfer experiments in an electrically Heated 4 × 25 staggered inclined rod bundle were carried out for the following range: 15 kg m−2 s−1 ≤ G ≤ 50 kg m−2 s−1, 20.0 kW m−2 ≤ q ≤ 55.0 kW m−2, 0.05 ≤ xout ≤ 0.79 and 117 kPa ≤ Pin ≤ 260 kPa. Single-phase convective results show that the independence principle can be applied to the case that all tubes were Heated in inclined rod bundles. With respect to two-phase results, the local flow Boiling Heat Transfer coefficient increases from the bottom row to the eleventh row and then can be considered as a constant value from the eleventh row to the top row. An increasing Heat flux results in a decrease of the flow Boiling Heat Transfer coefficient. However, no significant effects of mass velocity and quality were observed. The inclination angle has a small effect on the flow Boiling Heat Transfer coefficient at low Heat fluxes. However, when Heat flux is high, the flow Boiling Heat Transfer coefficient in the inclined rod bundle is the minimum while that in the vertical rod bundle is the maximum compared with that in the horizontal rod bundle. In a general, a Chen-type correlation was developed to predict 98.5 percent of local flow Boiling Heat Transfer coefficient data in the inclined rod bundle with a maximum deviation of ±20%.
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experimental investigation on steam water two phase flow Boiling Heat Transfer in a staggered horizontal rod bundle under cross flow condition
Experimental Thermal and Fluid Science, 2018Co-Authors: Kui Zhang, W X Tian, Yandong Hou, Y P Zhang, S Z QiuAbstract:Abstract Single-phase convection and steam-water two-phase flow Boiling Heat Transfer experiments in an electrically Heated 4 × 16 staggered horizontal rod bundle under cross-flow condition have been carried out for the following range: 45 kg m−2 s−1 ≤ G ≤ 383 kg m−2 s−1, 20.0 kW m−2 ≤ q ≤ 55.0 kW m−2, 0.02 ≤ xout ≤ 0.57 and 112 kPa ≤ Pin ≤ 190 kPa. The major effects on local flow Boiling Heat Transfer coefficients in horizontal rod bundles were analyzed. Firstly, the row number has a significant effect on local flow Boiling Heat Transfer coefficients since the vapor bubbles generated from the lower rods impinge on the surface of the upper rods and enhance the turbulence there. Secondly, an increasing Heat flux contributes to an increase of the average bundle flow Boiling Heat Transfer coefficient at all mass velocities. Thirdly, the local quality can also slightly enhance the flow Boiling Heat Transfer. Fourthly, the flow Boiling Heat Transfer can be enhanced with an increasing mass velocity under lower Heat fluxes. In a general, a Chen-type correlation was developed to predict local flow Boiling Heat Transfer coefficients in horizontal rod bundles with a maximum deviation of ±20%.