Journal articles: 'The heat transfer coefficient'

1

English, M. J., and T. M. Hemmerling. "Heat transfer coefficient." European Journal of Anaesthesiology 25, no. 7 (July 2008): 531–37. http://dx.doi.org/10.1017/s0265021508003931.

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Hollworth, B. R., and L. R. Gero. "Entrainment Effects on Impingement Heat Transfer: Part II—Local Heat Transfer Measurements." Journal of Heat Transfer 107, no. 4 (November 1, 1985): 910–15. http://dx.doi.org/10.1115/1.3247520.

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Convective heat transfer was measured for a heated axisymmetric air jet impinging on a flat surface. It was found that the local heat transfer coefficient does not depend explicitly upon the temperature mismatch between the jet fluid and the ambient fluid if the convection coefficient is defined in terms of the difference between the local recovery temperature and target surface temperature. In fact, profiles of local heat transfer coefficients defined in this manner were found to be identical to those measured for isothermal impinging jets.

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Barrow, H. "On average heat transfer coefficient." International Journal of Heat and Fluid Flow 7, no. 3 (September 1986): 162–63. http://dx.doi.org/10.1016/0142-727x(86)90015-9.

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Li, Ya Nan, Yong An Zhang, Xi Wu Li, Zhi Hui Li, Guo Jun Wang, Hong Wei Yan, Long Bing Jin, and Bai Qing Xiong. "Effects of Heat Transfer Coefficients on Quenching Residual Stresses in 7055 Aluminum Alloy." Materials Science Forum 877 (November 2016): 647–54. http://dx.doi.org/10.4028/www.scientific.net/msf.877.647.

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The quenching process can produce great residual stresses in 7055 aluminum alloy plates. The main factor that affects the quenching residual stresses is the heat transfer coefficient in the quenching process. In this paper, the heat transfer coefficients of spray quenching under different spray water flows were measured by using the inverse method, and the heat transfer coefficients of immersion quenching under different water temperatures were measured by the iterative method. The heat transfer coefficient increases as the spray water flow increases while decreases as the water temperature increases. The basic differences of water temperatures/spray water flows/quenching methods are the different heat transfer coefficients. According to the heat transfer coefficients results of immersion and spray quenching, an orthogonal test was carried out to study the effects of heat transfer coefficients in different temperature regions on the quenching residual stresses. The heat transfer coefficients in the range of 100oC ~200oC have a great influence on the quenching residual stresses, especially for the heat transfer coefficient near 150oC.

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Taslim, M. E., and V. Nezym. "A New Statistical-Based Correlation for the Rib Fin Effects on the Overall Heat Transfer Coefficient in a Rib-Roughened Cooling Channel." International Journal of Rotating Machinery 2007 (2007): 1–11. http://dx.doi.org/10.1155/2007/68684.

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Heat transfer coefficients in the cooling cavities of turbine airfoils are greatly enhanced by the presence of discrete ribs on the cavity walls. These ribs introduce two heat transfer enhancing features: a significant increase in heat transfer coefficient by promoting turbulence and mixing, and an increase in heat transfer area. Considerable amount of data are reported in open literature for the heat transfer coefficients both on the rib surface and on the floor area between the ribs. Many airfoil cooling design software tools, however, require an overall average heat transfer coefficient on a rib-roughened wall. Dealing with a complex flow circuit in conjunction with180∘bends, numerous film holes, trailing-edge slots, tip bleeds, crossover impingement, and a conjugate heat transfer problem; these tools are not often able to handle the geometric details of the rib-roughened surfaces or local variations in heat transfer coefficient on a rib-roughened wall. On the other hand, assigning an overall area-weighted average heat transfer coefficient based on the rib and floor area and their corresponding heat transfer coefficients will have the inherent error of assuming a 100% fin efficiency for the ribs, that is, assuming that rib surface temperature is the same as the rib base temperature. Depending on the rib geometry, this error could produce an overestimation of up to 10% in the evaluated rib-roughened wall heat transfer coefficient. In this paper, a correction factor is developed that can be applied to the overall area-weighted average heat transfer coefficient that, when applied to the projected rib-roughened cooling cavity walls, the net heat removal from the airfoil is the same as that of the rib-roughened wall. To develop this correction factor, the experimental results of heat transfer coefficients on the rib and on the surface area between the ribs are combined with about 400 numerical conduction models to determine an overall equivalent heat transfer coefficient that can be used in airfoil cooling design software. A well-known group method of data handling (GMDH) scheme was then utilized to develop a correlation that encompasses most pertinent parameters including the rib geometry, rib fin efficiency, and the rib and floor heat transfer coefficients.

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Barta, Pavel. "OS18-1-5 Real-time identification method of the heat transfer coefficient." Abstracts of ATEM : International Conference on Advanced Technology in Experimental Mechanics : Asian Conference on Experimental Mechanics 2007.6 (2007): _OS18–1–5——_OS18–1–5—. http://dx.doi.org/10.1299/jsmeatem.2007.6._os18-1-5-.

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Kartashov, E. M. "Heat Conduction at a Variable Heat-Transfer Coefficient." High Temperature 57, no. 5 (September 2019): 663–70. http://dx.doi.org/10.1134/s0018151x19050079.

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Mokheimer, Esmail M. "Heat transfer from extended surfaces subject to variable heat transfer coefficient." Heat and Mass Transfer 39, no. 2 (January 2003): 131–38. http://dx.doi.org/10.1007/s00231-002-0338-3.

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Su, Yu. "Finite Element Simulation of Enhanced Cooling Cutting of Stainless Steel." Applied Mechanics and Materials 312 (February 2013): 445–49. http://dx.doi.org/10.4028/www.scientific.net/amm.312.445.

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This paper develops a 2D finite element model for the enhanced cooling cutting of stainless steel. The enhanced cooling effect is modeled with a convective heat transfer coefficient assigned to a heat transfer window of cutting zone. Five convective heat transfer coefficients are defined to simulate different enhanced cooling effects. The simulation results suggest that increase of convective heat transfer coefficient results in a very small reduction of maximum tool-chip interface temperature, even when a very large convective heat transfer coefficient is used. In addition, no significant effect on cutting force and thrust force is observed with the increase of convective heat transfer coefficient.

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Sarafraz, M. M., S. M. Peyghambarzadeh, and Alavi Fazel. "Experimental studies on nucleate pool boiling heat transfer to ethanol/MEG/DEG ternary mixture as a new coolant." Chemical Industry and Chemical Engineering Quarterly 18, no. 4-1 (2012): 577–86. http://dx.doi.org/10.2298/ciceq111116033s.

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In this paper, nucleate pool boiling heat transfer coefficient of ternary mixtures of ethanol, monoethylene glycol (MEG) and diethylene glycol (DEG) as a new coolant with higher heat transfer coefficient has been investigated. Therefore, at varied concentrations of MEG and DEG and also at different heat fluxes, pool boiling heat transfer coefficients, have been experimentally measured. Results demonstrated the higher heat transfer coefficient in comparison with Water/MEG/DEG ternary mixture. In particular, at high heat fluxes, for ethanol/MEG/DEG mixture, higher boiling heat transfer coefficient is reported. Besides, experimental data were compared to well-known existing correlations. Results of this comparison express that the most accurate correlation for predicting the heat transfer coefficient of ethanol/MEG/DEG is modified Stephan - Preu?er which has been obtained in our earlier work.

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Roudgar, M., and J. De Coninck. "Condensation heat transfer coefficient versus wettability." Applied Surface Science 338 (May 2015): 15–21. http://dx.doi.org/10.1016/j.apsusc.2015.02.087.

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Chu, Ju Chin, M. Dmytryszyn, W. Tichy, K. C. Kubik, and O. L. Smith. "Heat-transfer coefficient of condensing vapours." Journal of Applied Chemistry 1, no. 2 (May 4, 2007): 73–80. http://dx.doi.org/10.1002/jctb.5010010203.

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13

Sun, Youhong, Xiaofeng Wang, Baochang Liu, Dali Ding, and Qingnan Meng. "Inverse solution to heat transfer coefficient during heat assembly of aluminum alloy drill pipes." Advances in Mechanical Engineering 9, no. 7 (July 2017): 168781401771497. http://dx.doi.org/10.1177/1687814017714970.

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With the rapid development of oil and gas industry, as well as geological exploration industry, the requirements on properties of aluminum alloy drill pipes are increasing. During heat assembly of aluminum alloy drill pipes, the cooling process inside the pipes has a direct impact on the connection performance of pipes. Thus, study of the convective heat transfer coefficient between the cooling water and the internal wall of aluminum alloy pipes is important. Conventional algorithms cannot easily solve the problem of determining the heat transfer coefficient at the complex structure of aluminum alloy drill pipes. Therefore, this article conducts a heat assembly experiment between aluminum alloy drill pipes and steel joints to obtain adequate, accurate temperature data. Based on these experimental data and an inverse heat conduction model, the heat transfer coefficients during the heat assembly process are determined by a finite element program and the differential evolution algorithm. The correlation curve between the cooling water flowrate and the convective heat transfer coefficient obtained in this article is important in the accurate prediction of heat transfer capacity and temperature field distribution during heat assembly at different cooling water flowrates. The analysis results show that the heat transfer coefficients are nonlinear functions of cooling water flowrates. The temperature is highest at location A1 and gradually declines backward along the axis of the drill pipe. The heat transfer coefficient gradually declines backward along the axis of the drill pipe. The increasing flowrate of cooling water will cause the convective heat transfer coefficient along the axis of the drill pipe to escalate irregularly.

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Zhang, Xiao Yan, Fang Fang Jiang, Shan Yuan Zhao, Wen Fei Tian, and Xiao Hang Chen. "Experimental Study on Heat Transfer Characteristics and Pressure Drops for Water Flowing in Spiral Coil Heat Exchanger." Advanced Materials Research 732-733 (August 2013): 593–99. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.593.

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The heat transfer and pressure drop characteristics for water flowing in four spiral coils with different shapes and different sizes were experimental studied. Reynolds number range from 4000 to 9000, volume flow rate range from 200 to 350 L/h and heating power range from 80-350 W. Based on the experimental results, the regularity of Reynolds number and heating power influencing on heat transfer and pressure drop characteristics was analyzed and discussed. The results indicate: the Nu increases with increasing Re, the greatest average heat transfer coefficient appears in the smaller circular spiral coil. The heat transfer coefficients increase with increasing heating power, the greatest average heat transfer coefficient also appears in the smaller circular spiral coil. The pressure drops increase with increasing Re, the pressure drop in big ellipse spiral coil is greatest. The resistance coefficients gradually decrease with increasing Re. The resistance coefficient of small circular spiral coil is always greatest, and the resistance coefficient of big circular spiral coil is smallest.

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Avramenko, A. A., M. M. Kovetskaya, E. A. Kondratieva, and T. V. Sorokina. "HEAT TRANSFER IN GRADIENT TURBULENT BOUNDARY LAYER." Thermophysics and Thermal Power Engineering 41, no. 4 (December 22, 2019): 19–26. http://dx.doi.org/10.31472/ttpe.4.2019.3.

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Effect of pressure gradient on heat transfer in turbulent boundary layer is constantly investigated during creation and improvement of heat exchange equipment for energy, aerospace, chemical and biological systems. The paper deals with problem of steady flow and heat transfer in turbulent boundary layer with variable pressure in longitudinal direction. The mathematical model is presented and the analytical solution of heat transfer in the turbulent boundary layer problem at positive and negative pressure gradients is given. Dependences for temperature profiles and coefficient of heat transfer on flow parameters were obtained. At negative longitudinal pressure gradient (flow acceleration) heat transfer coefficient can both increase and decrease. At beginning of acceleration zone, when laminarization effects are negligible, heat transfer coefficient increases. Then, as the flow laminarization increases, heat transfer coefficient decreases. This is caused by flow of turbulent energy transfers to accelerating flow. In case of positive longitudinal pressure gradient, temperature profile gradient near wall decreases. It is because of decreasing velocity gradient before zone of possible boundary layer separation.

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Ong, K. S., C. F. Tan, K. C. Lai, and K. H. Tan. "Heat spreading and heat transfer coefficient with fin heat sink." Applied Thermal Engineering 112 (February 2017): 1638–47. http://dx.doi.org/10.1016/j.applthermaleng.2016.09.161.

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Taler, Dawid, Sławomir Grądziel, and Jan Taler. "Measurement of heat flux density and heat transfer coefficient." Archives of Thermodynamics 31, no. 3 (September 1, 2010): 3–18. http://dx.doi.org/10.2478/v10173-010-0011-z.

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Measurement of heat flux density and heat transfer coefficientThe paper presents the solution to a problem of determining the heat flux density and the heat transfer coefficient, on the basis of temperature measurement at three locations in the flat sensor, with the assumption that the heat conductivity of the sensor material is temperature dependent. Three different methods for determining the heat flux and heat transfer coefficient, with their practical applications, are presented. The uncertainties in the determined values are also estimated.

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18

Taslim, M. E., and C. M. Wadsworth. "An Experimental Investigation of the Rib Surface-Averaged Heat Transfer Coefficient in a Rib-Roughened Square Passage." Journal of Turbomachinery 119, no. 2 (April 1, 1997): 381–89. http://dx.doi.org/10.1115/1.2841122.

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Turbine blade cooling, a common practice in modern aircraft engines, is accomplished, among other methods, by passing the cooling air through an often serpentine passage in the core of the blade. Furthermore, to enhance the heat transfer coefficient, these passages are roughened with rib-shaped turbulence promoters (turbulators). Considerable data are available on the heat transfer coefficient on the passage surface between the ribs. However, the heat transfer coefficients on the surface of the ribs themselves have not been investigated to the same extent. In small aircraft engines with small cooling passages and relatively large ribs, the rib surfaces comprise a large portion of the passage heat transfer area. Therefore, an accurate account of the heat transfer coefficient on the rib surfaces is critical in the overall design of the blade cooling system. The objective of this experimental investigation was to conduct a series of 13 tests to measure the rib surface-averaged heat transfer coefficient, hrib, in a square duct roughened with staggered 90 deg ribs. To investigate the effects that blockage ratio, e/Dh and pitch-to-height ratio, S/e, have on hrib and passage friction factor, three rib geometries corresponding to blockage ratios of 0.133, 0.167, and 0.25 were tested for pitch-to-height ratios of 5, 7, 8.5, and 10. Comparisons were made between the rib average heat transfer coefficient and that on the wall surface between two ribs, hfloor, reported previously. Heat transfer coefficients of the upstream-most rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared. It is concluded that: 1 The rib average heat transfer coefficient is much higher than that for the area between the ribs; 2 similar to the heat transfer coefficient on the surface between the ribs, the average rib heat transfer coefficient increases with the blockage ratio; 3 a pitch-to-height ratios of 8.5 consistently produced the highest rib average heat transfer coefficients amongst all tested; 4 under otherwise identical conditions, ribs in upstream-most position produced lower heat transfer coefficients than the midchannel positions, 5 the upstream-most rib average heat transfer coefficients decreased with the blockage ratio; and 6 thermal performance decreased with increased blockage ratio. While a pitch-to-height ratio of 8.5 and 10 had the highest thermal performance for the smallest rib geometry, thermal performance of high blockage ribs did not change significantly with the pitch-to-height ratio.

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Dieng, B., G. Jaw, A. Kane, I. Diagne, M. Dieng, and G. Sissoko. "Determination of the Global Heat Transfer Coefficient of a Double Heat Exchanger Battery in a Dry Mode." International Journal of Scientific Engineering and Technology 4, no. 12 (December 1, 2015): 545–48. http://dx.doi.org/10.17950/ijset/v4s12/1201.

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Sim, Yong-Sub, and Nae-Hyun Kim. "Pool Boiling Performance of Notched Tubes in Lithium Bromide Solution." International Journal of Air-Conditioning and Refrigeration 23, no. 02 (May 27, 2015): 1550013. http://dx.doi.org/10.1142/s2010132515500133.

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In the present study, pool boiling heat transfer coefficients in Lithium Bromide ( LiBr ) solution were obtained for smooth, floral, notched fin and notched floral tubes. Test range covered saturation pressure from 7.38 to 101.3 kPa, LiBr concentration from 0% to 50%. Floral tube yielded the highest heat transfer coefficient, and smooth tube yielded the lowest heat transfer coefficient. Effect of notching on heat transfer coefficient was dependent on tube shape. When applied to the smooth tube (notched fin tube), notching increased the heat transfer coefficient. When applied to the floral tube (notched floral tube), on the other hand, notching decreased the heat transfer coefficient. The reason has been attributed to the balance of advantage of added nucleation sites and disadvantage of added flow resistance. Boiling heat transfer correlations were developed which are applicable for saturation pressure from 7.38 to 101.3 kPa and LiBr concentration from 0% to 50%.

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Li, Jianhua, and Wanlin Cao. "The Heat Transfer Coefficient of Recycled Concrete Bricks Combination with EPS Insulation Board Wall." Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/695962.

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Four tectonic forms samples were conducted to test their heat transfer coefficients. By analyzing and comparing the test values and theoretical values of the heat transfer coefficient, a corrected-value calculation method for determining the heat transfer coefficient was proposed; the proposed method was proved to be reasonably correct. The results indicated that the recycled concrete brick wall heat transfer coefficient is higher than that of the clay brick wall, the heat transfer coefficient of recycled concrete brick wall could be effectively reduced when combined with the EPS insulation board, and the sandwich insulation type was better than that of external thermal insulation type.

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Sessler, Daniel I., and Andrew M. Sessler. "Experimental Determination of Heat Flow Parameters during Induction of General Anesthesia." Anesthesiology 89, no. 3 (September 1, 1998): 657–65. http://dx.doi.org/10.1097/00000542-199809000-00015.

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Background Alterations in body temperature result from changes in tissue heat content. Heat flow is a complex function of vasomotor status and core, peripheral, and ambient temperatures. Consequently it is difficult to quantify specific mechanisms responsible for observed changes in body heat distribution. Therefore the authors developed two mathematical models that independently express regional tissue heat production and the motion of heat through tissues in terms of measurable quantities. Methods The equilibrium model expresses the effective regional heat transfer coefficient in terms of cutaneous heat flux, skin temperature, and temperature at the center of the extremity. It applies at steady states and provides a ratio of the heat transfer coefficients before and after an intervention. In contrast, the heat flow model provides a time-dependent estimate of the heat transfer coefficient in terms of ambient temperature, skin temperature, and temperature at the center of the extremity. Results Each model was applied to data acquired in a previous evaluation of heat balance during anesthesia induction. The relation between the ratio of steady state regional heat transfer coefficients calculated using each model was linear. The effective heat transfer coefficient for the forehead (a core site) decreased approximately 20% after induction of anesthesia. In contrast, heat transfer coefficients in the six tested extremity sites more than doubled. Conclusions Effective heat transfer coefficients can be used to evaluate the thermal effects of various clinical interventions, such as induction of regional anesthesia or administration of vasodilating drugs. The heat transfer coefficient for the forehead presumably decreased because general anesthesia reduces brain perfusion. In contrast, increased heat transfer coefficients in the extremity sites indicate that thermoregulatory and anesthetic-induced vasodilation more than doubles the core-to-peripheral flow of heat. This flow of heat causes redistribution hypothermia, which is usually the major cause of core hypothermia during anesthesia.

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Cieśliński, Janusz T., Artur Fiuk, Krzysztof Typiński, and Bartłomiej Siemieńczuk. "Heat transfer in plate heat exchanger channels: Experimental validation of selected correlation equations." Archives of Thermodynamics 37, no. 3 (September 1, 2016): 19–29. http://dx.doi.org/10.1515/aoter-2016-0017.

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Abstract This study is focused on experimental investigation of selected type of brazed plate heat exchanger (PHEx). The Wilson plot approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The results obtained revealed that Hausen and Dittus-Boelter correlations underestimated heat transfer coefficient for the tested PHEx by an order of magnitude. The Aspen Plate code overestimated heat transfer coefficient by about 50%, while Muley-Manglik correlation overestimated it from 1% to 25%, dependent on the value of Reynolds number and hot or cold liquid side.

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He, Hong Ping, Hu Gen Ma, and Jian Mei Bai. "Influencing Factors on Heat Transfer Performance for Flow Boiling of R410A in Horizontal Micro-Fin Tubes." Advanced Materials Research 472-475 (February 2012): 1676–80. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.1676.

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Flow boiling heat transfer performances of refrigerant R410A in the horizontal micro-fin tubes with different geometric parameters were investigated. The dependencies of forced flow boiling heat transfer coefficient of R410A on mass flow rate, heat flux and were studied and the mechanism of flow boiling heat transfer under different working conditions were discussed. For a comparison, the influences of fin number and fin height of micro-fin tubes on heat transfer were also studied. The differences of heat transfer coefficient between R22 and R410A were analyzed. It is found that the heat transfer coefficients were nearly same for R22 and R410A and, in fact, the heat transfer coefficient of R22 was just a little higher than that of R410A by 4-7%.

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Bury, Tomasz, and Małgorzata Hanuszkiewicz Drapała. "Evaluation of selected methods of the heat transfer coefficient determination in fin-and-tube cross-flow heat exchangers." MATEC Web of Conferences 240 (2018): 02004. http://dx.doi.org/10.1051/matecconf/201824002004.

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The work is a part of a thermodynamic analysis of a finned cross-flow heat exchanger of the liquid-gas type. The heat transfer coefficients on the liquid and the gas side and the area of the heat transfer are the main parameters describing such a device. The basic problem in computations of such heat exchangers is determination of the coefficient of the heat transfer from the finned surfaces to the gas. The differences in the heat transfer coefficient local values resulting from the non-uniform flow of mediums through the exchanger complicates the analysis additionally. Six Nusselt number relationships are selected as suitable for the considered heat exchanger, and they are used to calculate the heat transfer coefficient for the air temperature ranging from 10°C to 30°C and for the velocity values ranging from 2 m/s to 20 m/s. In the next step, the gas-side heat transfer coefficient is determined by means of numerical simulations using a numerical model of a repetitive fragment of the heat exchanger under consideration. Finally, the Wilson plot method is also used. The work focuses on an analysis of the in-house HEWES code sensitivity to the method of the heat transfer coefficient determination. The authors believe that the analysis may also be useful for the evaluation of different methods of the heat transfer coefficient computation.

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Wilk, Joanna, Sebastian Grosicki, and Krzysztof Kiedrzyński. "Preliminary research on mass/heat transfer in mini heat exchanger." E3S Web of Conferences 70 (2018): 02016. http://dx.doi.org/10.1051/e3sconf/20187002016.

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In the paper the authors present the facility for model investigations of heat/mass transfer in the exchanger characterised by small dimensions. Determination of heat transfer coefficients is an important issue in the design of mini heat exchangers. The built facility enables measurements of mass transfer coefficients with the use of limiting current technique. The coefficients received from the experiment are converted into heat transfer coefficients basing on the analogy between mass and heat transfer. The exchanger considered consists of nine parallel minichannels with a square cross-section of 2mm. In real conditions during the laminar flow through the minichannels the convective heat transfer occurs. Analogous conditions are maintained during the model mass transfer experiment. The paper presents the experimental facility and the preliminary results of measurements in the form of voltammograms. The voltammograms show the limiting currents being the base of mass transfer coefficient calculations.

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Anderson, Ann M. "Decoupling Convective and Conductive Heat Transfer Using the Adiabatic Heat Transfer Coefficient." Journal of Electronic Packaging 116, no. 4 (December 1, 1994): 310–16. http://dx.doi.org/10.1115/1.2905703.

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In many heat transfer situations, such as those found in the electronics cooling field, more than a single mode of heat transfer occurs. For example, modules on a printed circuit board dissipate heat through convection to the air, through conduction to the board and through radiation to the surroundings. The adiabatic heat transfer coefficient, had, works well in such situations because it describes the change in wall temperature due to each incremental change in the convective heat transfer rate (due to conduction, radiation, or generation in the wall). The value of had is independent of the surface heat transfer distribution and can be used with the superposition method to interface between a convection solver and a conduction solver and “decouple” a conjugate heat transfer problem. If one uses the heat transfer coefficient based on the mean fluid temperature, hm, the problem is complicated because the value of hm is a function of the surface heat transfer distribution. This decoupling strategy is demonstrated through a series of numerical computations which solve the fully conjugate problem for laminar flow in a duct. These results are then compared to the decoupled solution. Excellent agreement between the fully conjugate and the decoupled solution is found for all cases when had and Tad are used to decouple the problem. Using hm and Tm can result in temperature prediction errors as large as 50 percent (for the cases studied here). The results show that when the Biot number (formulated as the resistance to axial wall conduction over the resistance to convection) is greater than 1.0 the adiabatic heat transfer coefficient should be used to decouple the problem. If the Biot number is below this value, h based on the mean temperature (for uniform surface temperature) can be used as the decoupler.

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Wang, Bin, Tien-Mo Shih, and Chen-Xu Wu. "Characteristics of instantaneous heat transfer rates in three heat-transfer-coefficient regimes." International Journal of Heat and Mass Transfer 93 (February 2016): 889–95. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.10.063.

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Singh, Punit, S. Venkatachalapathy, and G. Kumaresan. "Heat Transfer Studies on Condensation Using Heat Pipes." Applied Mechanics and Materials 592-594 (July 2014): 1617–21. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1617.

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This experimental study finds the effect of condensation on the thermal performance of heat pipe. Condensation heat transfer rate, heat transfer coefficient and variation of temperature over the heat pipe are measured at vertical and horizontal position of HP, by varying the steam-to-surface temperature difference. It is found that the condensation heat transfer rate for vertical position of heat pipe with CuO nanofluid is 2.07 times higher than the horizontal position, whereas the increase in heat transfer coefficient is 1.94 times. Using CuO nanofluid instead of deionized water in the heat pipe enhances the heat transfer rate and heat transfer coefficient by 1.25 and 1.42 times respectively for the vertical orientation.

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Liu, Z., A. Levtsev, and Y. Zhou. "Experimental Study on a Pulsation-enhanced Heat Transfer Device." Bulletin of Science and Practice 6, no. 4 (April 15, 2020): 243–51. http://dx.doi.org/10.33619/2414-2948/53/28.

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The pulsation-enhanced heat transfer technology is introduced, and a volume coil heat exchanger is designed. A pulsation valve is installed at the heat exchanger outlet of the heat exchanger to pulsate the heat medium, and the same heat exchanger is subjected to pulsation and non-pulsation heat transfer tests. Based on the experiments, combined with the theory of pulsation-enhanced heat transfer technology, heat transfer capacity, heat flow, and convective heat transfer coefficient coefficients, the effective temperature difference, heat flow, and convective heat transfer coefficient of the heat exchanger at different pulse frequencies are analyzed. The relationship between the pulsation frequency of the heat transfer effect of the heat exchanger is obtained. The test results show that the heat exchanger has higher heat exchange efficiency when there is pulsation under the test conditions.

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Yuan, Suo Xian, Ming Hu, and Guang Qi Cai. "Research on the Heat Partition Ratios in Grinding Area." Advanced Materials Research 76-78 (June 2009): 72–75. http://dx.doi.org/10.4028/www.scientific.net/amr.76-78.72.

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Grinding temperature is the main factor to limit the improvement of grinding efficiency. The main reason of grinding temperature rise is amount of heat transfer into the workpiece in grinding process. How to determine the proportion ratio, which heat transfers into the workpiece, is the main research issue to the precise machining scholars. In this paper, the heat resistance model is used to analyze the proportional coefficient about how much heat transfer into the grinding wheel, and the factors which to influence this coefficient are discussed. The moving heat source method is used to calculate the temperature field caused by single grain heat source, and the heat integral method is used to calculate the heat contains by the grinding chip, and then the heat proportional coefficients transferring into the chip and workpiece are determined respectively.

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Sharma, V. B., and S. C. Mullick. "Calculation of Hourly Output of a Solar Still." Journal of Solar Energy Engineering 115, no. 4 (November 1, 1993): 231–36. http://dx.doi.org/10.1115/1.2930055.

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An approximate method for calculation of the hourly output of a solar still over a 24-hour cycle has been studied. The hourly performance of a solar still is predicted given the values of the insolation, ambient temperature, wind heat-transfer coefficient, water depth, and the heat-transfer coefficient through base and sides. The proposed method does not require graphical constructions and does not assume constant heat-transfer coefficients as in the previous methods. The possibility of using the values of the heat-transfer coefficients for the preceding time interval in the heat balance equations is examined. In fact, two variants of the basic method of calculation are examined. The hourly rate of evaporation is obtained. The results are compared to those obtained by numerical solution of the complete set of heat balance equations. The errors from the approximate method in prediction of the 24-hour output are within ±1.5 percent of the values from the numerical solution using the heat balance equations. The range of variables covered is 5 to 15 cms in water depth, 0 to 3 W/m2K in a heat-transfer coefficient through base and sides, and 5 to 40 W/m2K in a wind heat-transfer coefficient.

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Baldauf, S., M. Scheurlen, A. Schulz, and S. Wittig. "Heat Flux Reduction From Film Cooling and Correlation of Heat Transfer Coefficients From Thermographic Measurements at Enginelike Conditions." Journal of Turbomachinery 124, no. 4 (October 1, 2002): 699–709. http://dx.doi.org/10.1115/1.1505848.

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Heat transfer coefficients and the resulting heat flux reduction due to film cooling on a flat plate downstream a row of cylindrical holes are investigated. Highly resolved two-dimensional heat transfer coefficient distributions were measured by means of infrared thermography and carefully corrected for local internal testplate conduction and radiation effects. These locally acquired data are processed to lateral average heat transfer coefficients for a quantitative assessment. A wide range variation of the flow parameters blowing rate and density ratio as well as the geometrical parameters streamwise ejection angle and hole spacing is examined. The effects of these dominating parameters on the heat transfer augmentation from film cooling are discussed and interpreted with the help of highly resolved surface results of effectiveness and heat transfer coefficients presented earlier. A new method of evaluating the heat flux reduction from film cooling is presented. From a combination of the lateral average of both the adiabatic effectiveness and the heat transfer coefficient, the lateral average heat flux reduction is processed according to the new method. The discussion of the total effect of film cooling by means of the heat flux reduction reveals important characteristics and constraints of discrete hole ejection. The complete heat transfer data of all measurements are used as basis for a new correlation of lateral average heat transfer coefficients. This correlation combines the effects of all the dominating parameters. It yields a prediction of the heat transfer coefficient from the ejection position to far downstream, including effects of extreme blowing angles and hole spacing. The new correlation has a modular structure to allow for future inclusion of additional parameters. Together with the correlation of the adiabatic effectiveness it provides an immediate determination of the streamwise heat flux reduction distribution of cylindrical hole film-cooling configurations.

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Wang, Z., P. T. Ireland, and T. V. Jones. "Detailed Heat Transfer Coefficient Measurements and Thermal Analysis at Engine Conditions of a Pedestal With Fillet Radii." Journal of Turbomachinery 117, no. 2 (April 1, 1995): 290–97. http://dx.doi.org/10.1115/1.2835658.

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The heat transfer coefficient over the surface of a pedestal with fillet radii has been measured using thermochromic liquid crystals and the transient heat transfer method. The tests were performed at engine representative Reynolds numbers for a geometry typical of those used in turbine blade cooling systems. The heat conduction process that occurs in the engine was subsequently modeled numerically with a finite element discretization of the solid pedestal. The measured heat transfer coefficients were used to derive the exact boundary conditions applicable to the engine. The temperature field within the pedestal, calculated using the correct heat transfer coefficient distribution, is compared to that calculated using an area-averaged heat transfer coefficient. Metal temperature differences of 90 K are predicted across the blade wall.

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Baloyo, Jan Mary, and Yuyuan Zhao. "Heat Transfer Performance of Micro-Porous Copper Foams with Homogeneous and Hybrid Structures Manufactured by Lost Carbonate Sintering." MRS Proceedings 1779 (2015): 39–44. http://dx.doi.org/10.1557/opl.2015.699.

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ABSTRACTThe heat transfer coefficients of homogeneous and hybrid micro-porous copper foams, produced by the Lost Carbonate Sintering (LCS) process, were measured under one-dimensional forced convection conditions using water coolant. In general, increasing the water flow rate led to an increase in the heat transfer coefficients. For homogeneous samples, the optimum heat transfer performance was observed for samples with 60% porosity. Different trends in the heat transfer coefficients were found in samples with hybrid structures. Firstly, for horizontal bilayer structures, placing the high porosity layer by the heater gave a higher heat transfer coefficient than the other way round. Secondly, for integrated vertical bilayer structures, having the high porosity layer by the water inlet gave a better heat transfer performance. Lastly, for segmented vertical bilayer samples, having the low porosity layer by the water inlet offered the greatest heat transfer coefficient overall, which is five times higher than its homogeneous counterpart.

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Jensen, M. K., and J. T. Hsu. "A Parametric Study of Boiling Heat Transfer in a Horizontal Tube Bundle." Journal of Heat Transfer 110, no. 4a (November 1, 1988): 976–81. http://dx.doi.org/10.1115/1.3250601.

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Boiling heat transfer outside of a section of a uniformly heated horizontal tube bundle in an upward crossflow was investigated using R-113 as the working fluid. The inline tube bundle had five columns and 27 rows with a pitch-to-diameter ratio of 1.3. Heat transfer coefficients obtained from the 14 instrumented tubes are reported for a range of fluid and flow conditions; slightly subcooled liquid inlet conditions were used. At most heat fluxes there was no significant variation in the local heat transfer coefficients throughout the tube bundle. However, at low heat fluxes and mass velocities, the heat transfer coefficient increased at positions higher in the tube bundle. As pressure and mass velocity increased so did the heat transfer coefficients. For the local heat transfer coefficient, a Chen-type correlation is compared to the data; the data tend to be overpredicted by about 20 percent. Reasons for the overprediction are suggested.

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Coumaressin, T., K. Palaniradja, and K. Velmurugan. "Optimize the Evaporating Heat Transfer Coefficient of Refrigeration System Using Nano Fluid." Applied Mechanics and Materials 592-594 (July 2014): 951–55. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.951.

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Improving heat transfer characteristics in refrigeration and air conditioning systems has been intensively studied by many investigators. In the present work the effect of using CuO-R134a in the vapour compression system on the evaporating heat transfer coefficient is investigated by CFD heat transfer analysis using the FLUENT software. An experimental test rig is designed for this purpose. The test section is a horizontal tube in the tube heat exchanger made from copper. The refrigerant is evaporated inside an inner copper tube and the heat load is provided from hot water that passing in an annulus surrounding the inner tube. Heat transfer coefficients were evaluated using FLUENT for heat flux ranged from 10 to 40 kW/m2, using nanoCuO concentrations ranged from 0.05 to 1% and particle size from 15 to 70 nm. The measurements indicated that for a certain nanoconcentration as heat flux or mass flux increases the evaporating heat transfer coefficient increases and also that the evaporating heat transfer coefficient increases with increasing nanoCuO concentrations up to certain value then decreases. The obtained evaporating heat transfer coefficient result have been optimized at its maximum value for the best CuOnano particles concentration in R134a refrigerant.

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Oon, C. S., A. Badarudin, S. N. Kazi, and M. Fadhli. "Simulation of Heat Transfer to Turbulent Nanofluid Flow in an Annular Passage." Advanced Materials Research 925 (April 2014): 625–29. http://dx.doi.org/10.4028/www.scientific.net/amr.925.625.

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The heat transfer in annular heat exchanger with titanium oxide of 1.0 volume % concentration as the medium of heat exchanger is considered in this study. The heat transfer simulation of the flow is performed by using Computational Fluid Dynamics package, Ansys Fluent. The heat transfer coefficients of water to titanium oxide nanofluid flowing in a horizontal counter-flow heat exchanger under turbulent flow conditions are investigated. The results show that the convective heat transfer coefficient of the nanofluid is slightly higher than that of the base fluid by several percents. The heat transfer coefficient increases with the increase of the mass flow rate of hot water and also the nanofluid.

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da Veiga, W. R., and J. P. Meyer. "Heat transfer coefficient of a snow bag." International Journal of Refrigeration 25, no. 8 (December 2002): 1043–46. http://dx.doi.org/10.1016/s0140-7007(02)00027-0.

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Spierings, D., F. Bosman, T. Peters, and F. Plasschaert. "Determination of the convective heat transfer coefficient." Dental Materials 3, no. 4 (August 1987): 161–64. http://dx.doi.org/10.1016/s0109-5641(87)80027-1.

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Conti, Rosaria, Aurelio Agliolo Gallitto, and Emilio Fiordilino. "Measurement of the Convective Heat-Transfer Coefficient." Physics Teacher 52, no. 2 (February 2014): 109–11. http://dx.doi.org/10.1119/1.4862118.

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Khalifa, Abdul-Jabbar N. "Natural convective heat transfer coefficient – a review." Energy Conversion and Management 42, no. 4 (March 2001): 491–504. http://dx.doi.org/10.1016/s0196-8904(00)00042-x.

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Khalifa, Abdul-Jabbar N. "Natural convective heat transfer coefficient – a review." Energy Conversion and Management 42, no. 4 (March 2001): 505–17. http://dx.doi.org/10.1016/s0196-8904(00)00043-1.

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Zuev, A. A., A. A. Arngold, V. A. Levko, I. A. Maksimov, and A. D. Leonenkov. "Heat transfer coefficient of laminar rotational flow." IOP Conference Series: Materials Science and Engineering 734 (January 29, 2020): 012029. http://dx.doi.org/10.1088/1757-899x/734/1/012029.

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Veloo, Peter S., and James G. Quintiere. "Convective heat transfer coefficient in compartment fires." Journal of Fire Sciences 31, no. 5 (March 11, 2013): 410–23. http://dx.doi.org/10.1177/0734904113479001.

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Singer, Saša. "Sensitivity of the Heat-Transfer Coefficient Calculation." Materials Performance and Characterization 3, no. 4 (September 12, 2014): 20140006. http://dx.doi.org/10.1520/mpc20140006.

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KOSHIMIZU, Takao, Tetsushi BIWA, Masamichi KOHNO, and Yasuyuki TAKATA. "D03 Heat Transfer Coefficient in Oscillatory Flows." Proceedings of the Symposium on Stirlling Cycle 2011.14 (2011): 65–66. http://dx.doi.org/10.1299/jsmessc.2011.14.65.

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Dutta, S., P. Dutta, R. E. Jones, and J. A. Khan. "Heat Transfer Coefficient Enhancement With Perforated Baffles." Journal of Heat Transfer 120, no. 3 (August 1, 1998): 795–97. http://dx.doi.org/10.1115/1.2824356.

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Alvis, Armando, Carlos Vélez, Maite Rada-Mendoza, Mar Villamiel, and Héctor S. Villada. "Heat transfer coefficient during deep-fat frying." Food Control 20, no. 4 (April 2009): 321–25. http://dx.doi.org/10.1016/j.foodcont.2008.05.016.

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Korotky, G. J., and M. E. Taslim. "Rib Heat Transfer Coefficient Measurements in a Rib-Roughened Square Passage." Journal of Turbomachinery 120, no. 2 (April 1, 1998): 376–85. http://dx.doi.org/10.1115/1.2841416.

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Three staggered 90 deg rib geometries corresponding to blockage ratios of 0.133, 0.167, and 0.25 were tested for pitch-to-height ratios of 5, 8.5, and 10, and for two distinct thermal boundary conditions of heated and unheated channel walls. Comparisons were made between the surface-averaged heat transfer coefficients and friction factors for ribs with rounded corners and those with sharp corners, reported previously. Heat transfer coefficients of the furthest upstream rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared. It was concluded that: (a) For the geometries tested, the rib average heat transfer coefficient was much higher than that for the area between the ribs. For the sharp-corner ribs, the rib average heat transfer coefficient increased with blockage ratio. However, when the corners were rounded, the trend depended on the level of roundness. (b) High-blockage-ratio (e/Dh = 0.25) ribs were insensitive to the pitch-to-height ratio. For the other two blockage ratios, the pitch-to-height ratio of 5 produced the lowest heat transfer coefficient. Results of the other two pitch-to-height ratios were very close, with the results of S/e = 10 slightly higher than those of S/e = 8.5. (c) Under otherwise identical conditions, ribs in the furthest upstream position produced lower heat transfer coefficients for all cases except that of the smallest blockage ratio with S/e of 5. In that position, for the rib geometries tested, while the sharp-corner rib average heat transfer coefficients increased with the blockage ratio, the trend of the round-corner ribs depended on the level of roundness, r/e. (d) Thermal performance decreased with the blockage ratio. While the smallest rib geometry at a pitch-to-height ratio of 10 had the highest thermal performance, thermal performance of high blockage ribs at a pitch-to-height ratio of 5 was the lowest. (e) The general effects of rounding were a decrease in heat transfer coefficient for the midstream ribs and an increase in heat transfer coefficient for ribs in the furthest upstream position.

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Journal articles on the topic 'The heat transfer coefficient'

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