Journal articles: 'Resistance to enthalpy transfer'

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LEE, EUL-JONG, JUNG-PYO LEE, HYUN-MIN SIM, and NAE-HYUN KIM. "MODELING AND VERIFICATION OF HEAT AND MOISTURE TRANSFER IN AN ENTHALPY EXCHANGER MADE OF PAPER MEMBRANE." International Journal of Air-Conditioning and Refrigeration 20, no. 03 (September 2012): 1250015. http://dx.doi.org/10.1142/s2010132512500150.

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In this study, heat and moisture transfer model of an enthalpy exchanger is proposed. With separately measured sorption constant and diffusion coefficient, the model predicts the heat and moisture transfer effectiveness of an enthalpy exchanger. Two sample enthalpy exchangers were tested at a KS condition to verify the model. The model predicts the heat transfer effectiveness within 4%, and the moisture transfer effectiveness within 10%. Pressure drop is predicted within 6%. The spacer fin efficiency for heat transfer was 0.11 to 0.13. The fin efficiency for moisture transfer, however, was negligibly small. For heat transfer, the conduction resistance to total thermal resistance was less than 1%. For moisture transfer, however, membrane resistance was dominant to convective moisture transfer resistance.

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Zhang, L. Z., and J. L. Niu. "Effectiveness Correlations for Heat and Moisture Transfer Processes in an Enthalpy Exchanger With Membrane Cores." Journal of Heat Transfer 124, no. 5 (September 11, 2002): 922–29. http://dx.doi.org/10.1115/1.1469524.

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The performance correlations for the effectiveness of heat and moisture transfer processes in an enthalpy exchanger with membrane cores are presented. The physical phenomena relevant to the heat and moisture transfer in these devices have been used to develop a novel set of correlations based on the relevant dimensionless parameters. The total enthalpy effectiveness can be calculated from sensible effectiveness, latent effectiveness, and the ratio of latent to sensible energy differences across the unit. Studies show that the sensible effectiveness is a function of NTU, the number of transfer units for heat; while the latent effectiveness is a function of NTUL, the number of transfer units for moisture. The relations between NTUL and NTU are derived and studied with the proper separation of moisture resistance for membranes. This newly developed dimensionless parameter, NTUL, is to summarize the sorption characteristics of membrane material, the exchanger configurations, as well as the operating conditions. A number of experimental results on an enthalpy exchanger with novel hydrophilic membrane cores has been used to valid these correlations.

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Li, Yong An, Xue Lai Liu, Jia Jia Yan, and Teng Xing. "Research on Wet Thermal Recovery Plant Used by Air Conditioning." Advanced Materials Research 424-425 (January 2012): 1155–58. http://dx.doi.org/10.4028/www.scientific.net/amr.424-425.1155.

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Based on the simulation Computational Fluid Dynamics method, in view of air conditioning with wet thermal recovery plant for heat and mass transfer characteristic, establishes air channels in three-dimensional laminar flow and heat transfer, mass transfer coupling process of mathematical physics model, discusses the air conditioning with wet thermal recovery plant air channels in temperature, concentration and pressure parameters such as distribution, application enthalpy efficiency analysis method to the heat transfer performance is evaluated. The results indicate that structure parameters of wet thermal recovery plant used by air conditioning play important influence for the heat transfer performance and flow resistance performance. The research conclusion provides guidance for air conditioning with wet thermal recovery plant of optimization.

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El-Dessouky, H. T. A., A. Al-Haddad, and F. Al-Juwayhel. "A Modified Analysis of Counter Flow Wet Cooling Towers." Journal of Heat Transfer 119, no. 3 (August 1, 1997): 617–26. http://dx.doi.org/10.1115/1.2824150.

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The paper describes a theoretical investigation for the steady-state counter flow wet cooling tower with modified definitions for both the number of transfer units and the tower thermal effectiveness. The modified number of transfer units is dependent on both air and water heat capacity. The effectiveness is defined by the tower cooling range and the approach to equilibrium. A new expression relating the tower effectiveness to the modified number of transfer units and the capacity rate ratio has been developed. The model considered the resistance to heat transfer in the water film, the nonunity of the Lewis number, and the curvature of the saturated air enthalpy curve. A procedure for implementing the model in designing or rating cooling towers has been outlined and demonstrated through illustrative examples. The model compares very satisfactorily with other methods such as Logarithmic Mean Enthalpy Difference (LMED) and conventional effectiveness—NTU. Within the ranges used, the obtained results showed that substantial errors varied from +4.289 to −2.536 percent can occur in calculating the cooled water outlet temperature, and errors from +42.847 to −16.667 percent can occur in estimating the tower thermal characteristics.

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Kurose, Ryoichi, Naohisa Takagaki, Atsushi Kimura, and Satoru Komori. "Direct numerical simulation of turbulent heat transfer across a sheared wind-driven gas–liquid interface." Journal of Fluid Mechanics 804 (September 13, 2016): 646–87. http://dx.doi.org/10.1017/jfm.2016.554.

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Turbulent heat transfer across a sheared wind-driven gas–liquid interface is investigated by means of a direct numerical simulation of gas–liquid two-phase turbulent flows under non-breaking wave conditions. The wind-driven wavy gas–liquid interface is captured using the arbitrary Lagrangian–Eulerian method with boundary-fitted coordinates on moving grids, and the temperature fields on both the gas and liquid sides, and the humidity field on the gas side are solved. The results show that although the distributions of the total, latent, sensible and radiative heat fluxes at the gas–liquid interface exhibit streak features such that low-heat-flux regions correspond to both low-streamwise-velocity regions on the gas side and high-streamwise-velocity regions on the liquid side, the similarity between the heat-flux streak and velocity streak on the gas side is more significant than that on the liquid side. This means that, under the condition of a fully developed wind-driven turbulent field on both the gas and liquid sides, the heat transfer across the sheared wind-driven gas–liquid interface is strongly affected by the turbulent eddies on the gas side, rather than by the turbulent eddies and Langmuir circulations on the liquid side. This trend is quite different from that of the mass transfer (i.e. $\text{CO}_{2}$ gas). This is because the resistance to heat transfer is normally lower than the resistance to mass transfer on the liquid side, and therefore the heat transfer is controlled by the turbulent eddies on the gas side. It is also verified that the predicted total heat, latent heat, sensible heat and enthalpy transfer coefficients agree well with previously measured values in both laboratory and field experiments. To estimate the heat transfer coefficients on both the gas and liquid sides, the surface divergence could be a useful parameter, even when Langmuir circulations exist.

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Gallardo, Andres, and Umberto Berardi. "A simple method for validating a simulation model of a radiant ceiling panel with thermal energy storage." Journal of Physics: Conference Series 2069, no. 1 (November 1, 2021): 012119. http://dx.doi.org/10.1088/1742-6596/2069/1/012119.

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Abstract This paper focuses on validating a simulation model of a radiant ceiling panel (RCP) incorporating phase change materials (PCM) for heating and cooling applications in buildings. The development of an RCP with thermal energy storage capacity aims to encourage high thermal mass radiant systems in existing buildings to replace the traditional all-air HVAC system. First, a heat flow meter (HFM) is used to perform enthalpy measurements at a product scale (macro-encapsulated PCM). Then, a small test chamber is constructed to measure the dynamic thermal performance of an RCP with PCM under well-known and realistic boundary conditions. A known thermal resistance is used to establish a realistic heat transfer coefficient between room air (represented by the temperature of a temperature-controlled metal plate) and ceiling. The results show that HFM enthalpy measurements of products incorporating PCM are within ± 2% of manufacturers’ data. Additionally, results indicate that a test chamber can be used for validating a dynamic simulation model of the RCP with PCM installed in a room. The proposed method can be helpful during the system optimization phase, as many conditions and sample configurations can be tested without spending too much time or money on test rooms or real building monitoring.

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Mahir, Maha, Anas El Maakoul, Ismail Khay, Said Saadeddine, and Mohamed Bakhouya. "An Investigation of Heat Transfer Performance in an Agitated Vessel." Processes 9, no. 3 (March 5, 2021): 468. http://dx.doi.org/10.3390/pr9030468.

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Agitated vessels (or mechanically stirred reactors) are heat exchange devices that are most widely used in many chemical and biochemical process industries, such as anaerobic digestion process. The mixing and heat transfer performances in these vessels are of crucial importance for increasing the energy efficiency in both batch and continuous processes. In this paper, a series of experiments were conducted to investigate heat transfer performance in agitated vessels for various configurations. In fact, this study examines the effects of heat transfer geometry (wall jacket and helical coils), heating power, and stirring speed, on the heating performance of two stirred fluids—water alone and a mixture of water and food waste. The experiments were conducted using a jacketed insulation tank with a helical coil and a propeller agitator. In each experiment, a transient method, based on measuring the temperature dependency on time, and solving the unsteady enthalpy balance, was used to determine the overall heat transfer coefficients between the agitated fluid and the heating surface. Finally, an extensive analysis of the reduced data was conducted based on temperature, heating time, heat transfer rate, heat transfer coefficient, and thermal resistance. The main finding was that the presence of food waste in agitated vessels reduces the heat rate of the agitated fluid with an average of 18.13% and 49.51%, respectively, for the case of JHX and CHX, and creates additional fouling, which further limits the heat transfer.

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Khan, Zakir, and Zulfiqar Ahmad Khan. "Performance Evaluation of Coupled Thermal Enhancement through Novel Wire-Wound Fins Design and Graphene Nano-Platelets in Shell-and-Tube Latent Heat Storage System." Energies 14, no. 13 (June 22, 2021): 3743. http://dx.doi.org/10.3390/en14133743.

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Technological development in latent heat storage (LHS) systems is essential for energy security and energy management for both renewable and non-renewable sources. In this article, numerical analyses on a shell-and-tube-based LHS system with coupled thermal enhancement through extended fins and nano-additives are conducted to propose optimal combinations for guaranteed higher discharging rate, enthalpy capacity and thermal distribution. Transient numerical simulations of fourteen scenarios with varied combinations are investigated in three-dimensional computational models. The shell-and-tube includes paraffin as phase change material (PCM), longitudinal, radial and wire-wound fins and graphene nano-platelets (GNP) as extended fins and nano-additives, respectively. The extended fins have demonstrated better effectiveness than nano-additives. For instance, the discharging durations for paraffin with longitudinal, radial and wire-wound fins are shortened by 88.76%, 95.13% and 96.44% as compared to 39.33% for paraffin with 2.5% GNP. The combined strengths of extended fins and nano-additives have indicated further enhancement in neutralising the insulative resistance and stratification of paraffin. However, the increase in volume fraction from 1% to 3% and 5% is rather detrimental to the total enthalpy capacity. Hence, the novel designed wire-wound fins with both base paraffin and paraffin with 1% GNP are proposed as optimal candidates owing to their significantly higher heat transfer potentials. The proposed novel designed configuration can retrieve 11.15 MJ of thermal enthalpy in 1.08 h as compared to 44.5 h for paraffin in a conventional shell-and-tube without fins. In addition, the proposed novel designed LHS systems have prolonged service life with zero maintenance and flexible scalability to meet both medium and large-scale energy storage demands.

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Núñez González, J., A. Beltrán Morales, M. Rivero Corona, and J. Vega Munguía. "Numerical simulation of a polymer melting process using solar energy." Suplemento de la Revista Mexicana de Física 1, no. 2 (July 16, 2020): 18–24. http://dx.doi.org/10.31349/suplrevmexfis.1.2.18.

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In this work, the melting process of a polymeric material is numerically investigated. In general, the heat required for melting plastics is obtained throughout electrical resistances or by burning fossil fuels. The heat transfer mechanisms of these common practices correspond to conduction and convection, respectively. This work explores the feasibility of using radiation as the primary mechanism of energy supply, which has not been widely studied. The energy to achieve the phase change from solid to liquid can be obtained by concentrated solar energy radiation. The total energy required is calculated solving the energy equation using the enthalpy formulation. An explicit formulation with an enthalpy linearization was implemented in the Mathematica programming language and compared with the solution in the commercial softwares Ansys Fluent and COMSOL Multiphysics showing a good agreement. Based upon numerical predictions, it is examined the effects of the relevant parameters, such as incident radiation and convective heat transfer coefficient, on the melting process. It is observed that under weather conditions commonly attained in different cities worldwide, with a radiation of 1000 W/m$^2$ and low convective losses with $h=8$ W/m$^2\cdot$K, the melting process of a cylindrical rod of 3/4 inches diameter can be carried out in around 2 hours.

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Ceglia, Francesca, Adriano Macaluso, Elisa Marrasso, Maurizio Sasso, and Laura Vanoli. "Modelling of Polymeric Shell and Tube Heat Exchangers for Low-Medium Temperature Geothermal Applications." Energies 13, no. 11 (May 29, 2020): 2737. http://dx.doi.org/10.3390/en13112737.

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Improvements in using geothermal sources can be attained through the installation of power plants taking advantage of low and medium enthalpy available in poorly exploited geothermal sites. Geothermal fluids at medium and low temperature could be considered to feed binary cycle power plants using organic fluids for electricity “production” or in cogeneration configuration. The improvement in the use of geothermal aquifers at low-medium enthalpy in small deep sites favours the reduction of drilling well costs, and in addition, it allows the exploitation of local resources in the energy districts. The heat exchanger evaporator enables the thermal heat exchange between the working fluid (which is commonly an organic fluid for an Organic Rankine Cycle) and the geothermal fluid (supplied by the aquifer). Thus, it has to be realised taking into account the thermodynamic proprieties and chemical composition of the geothermal field. The geothermal fluid is typically very aggressive, and it leads to the corrosion of steel traditionally used in the heat exchangers. This paper analyses the possibility of using plastic material in the constructions of the evaporator installed in an Organic Rankine Cycle plant in order to overcome the problems of corrosion and the increase of heat exchanger thermal resistance due to the fouling effect. A comparison among heat exchangers made of commonly used materials, such as carbon, steel, and titanium, with alternative polymeric materials has been carried out. This analysis has been built in a mathematical approach using the correlation referred to in the literature about heat transfer in single-phase and two-phase fluids in a tube and/or in the shell side. The outcomes provide the heat transfer area for the shell and tube heat exchanger with a fixed thermal power size. The results have demonstrated that the plastic evaporator shows an increase of 47.0% of the heat transfer area but an economic installation cost saving of 48.0% over the titanium evaporator.

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Kerslake, T. W., and M. B. Ibrahim. "Two-Dimensional Model of a Space Station Freedom Thermal Energy Storage Canister." Journal of Solar Energy Engineering 116, no. 2 (May 1, 1994): 114–21. http://dx.doi.org/10.1115/1.2930498.

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The Solar Dynamic Power Module being developed for Space Station Freedom uses a eutectic mixture of LiF-CaF2 phase-change salt contained in toroidal canisters for thermal energy storage. This paper presents results from heat transfer analyses of the phase-change salt containment canister. A two-dimensional, axisymmetric finite difference computer program which models the canister walls, salt, void, and heat engine working fluid coolant was developed. Analyses included effects of conduction in canister walls and solid salt, conduction and free convection in liquid salt, conduction and radiation across salt vapor-filled void regions, and forced convection in the heat engine working fluid. Void shape and location were prescribed based on engineering judgment. The salt phase-change process was modeled using the enthalpy method. Discussion of results focuses on the role of free convection in the liquid salt on canister heat transfer performance. This role is shown to be important for interpreting the relationship between ground-based canister performance (in 1-g) and expected on-orbit performance (in micro-g). Attention is also focused on the influence of void heat transfer on canister wall temperature distributions. The large thermal resistance of void regions is shown to accentuate canister hot spots and temperature gradients.

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Xiaohong, Gui, Song Xiange, Li Tie, Liang Shiqiang, Yuan Dazhong, and Tang Dawei. "Influence of void ratio on phase change of thermal energy storage for heat pipe receiver." Thermal Science 19, no. 3 (2015): 967–76. http://dx.doi.org/10.2298/tsci130627135x.

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In this paper, influence of void ratio on phase change of thermal storage unit for heat pipe receiver under microgravity is numerically simulated. Accordingly, mathematical model is set up. A solidification-melting model upon the enthalpy-porosity method is specially provided to deal with phase changes. The liquid fraction distribution of thermal storage unit of heat pipe receiver is shown. The fluctuation of melting ratio in PCM canister is indicated. Numerical results are compared with experimental ones in Japan. The results show that void cavity prevents the process of phase change greatly. PCM melts slowly during sunlight periods and freezes slowly during eclipse periods as void ratio increases. The utility ratio of PCM during both sunlight periods and eclipse periods decreases obviously with the improvement of void ratio. The thermal resistance of void cavity is much higher than that of PCM canister wall. Void cavity prevents the heat transfer between PCM zone and canister wall.

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Chang, Shyy-Woei, Yn-An Tsai, and Cheng-Lin Tsai. "Comparative Thermal Performances between Pumped Thermosyphon Loops with Different Condenser Configurations Using R245fa as Working Fluid." Energies 15, no. 2 (January 17, 2022): 635. http://dx.doi.org/10.3390/en15020635.

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A pumped two-phase thermosyphon loop is broadly utilized to intensify the cooling duties of electronic chipsets/systems and the effectiveness for harvesting thermal energy. The configuration of a condenser not only affects the heat transfer in the condenser, but also has an effect on the saturation pressures during the boiling and condensation processes to alter the hydrothermal performance of a pumped thermosyphon loop. The influence of the condenser configuration on the hydrothermal performance of a pumped thermosyphon loop is rarely studied. The present study comparatively examined the thermal performances of two pumped thermosyphon loops with a conventional tube-fin condenser and the expansion-tank condenser. The thermodynamic cycles in pressure-temperature and pressure-enthalpy diagrams, Nusselt numbers of evaporator and condenser, thermal resistances and various performance indexes evaluated at constant pumping powers at the controlled through-flow Reynolds numbers, boiling numbers and condenser thermal resistances were measured. At the similar thermal loads, flow rates, and fluid entry temperatures of condenser, the operating pressure of the thermosyphon loop with expansion tank condenser was considerably reduced from that with tube fin condenser, leading to the lower saturation temperature for reducing the thermal resistance and the lesser pressure drop across the loop with a noticeable hydrothermal performance improvement. At the parametric conditions tested, the ratio of dimensionless overall thermal resistances between the loops with expansion tank condenser and tube fin condenser fell in the range of 0.81–0.99. When the loop performance was compared at a constant cooling airflow rate without considering the more pumping power consumption for the loop with tube fin condenser, the ranges of thermal resistance for the loops with expansion tank condenser and tube fin condenser were 0.13–0.21 (KW−1) and 0.15–0.23 (KW−1). The merit indices evaluating the comparative hydrothermal performances of evaporator, condenser and loop between the two looped thermosyphons highlighted the significance of condenser design and affirmed the performance improvement by changing tube fin condenser into expansion tank condenser. The empirical correlations of evaporator Nusselt number, condenser Nusselt number, and overall thermal resistance using Reynolds number, boiling number, and condenser thermal resistance as the controlling parameters were generated for relevant applications.

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Huang, Peng, Zhi Ming Hao, Wei Fen Li, and Shao Quan Hu. "Finite Element Thermal Analysis of the Packing Container in Fire Environment." Applied Mechanics and Materials 444-445 (October 2013): 1539–44. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1539.

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The packing container is used in storage and transport of the high explosive (HE) material. The study concerns the safety of the packing container in fire environment. The spruce wood filled in the packing container can effectively resist heat transfer and protect HE material. The thermal analysis of the packing container in the pool fire environment is presented with the finite element method. When considering the water evaporation and the wood pyrolysis, the enthalpy curve of wood is presented in this study. Heat can be transferred from the fire to the packing container via convection and radiation. Thus, two thermal boundary conditions are applied to the thermal model of the packing container. The simulations show the inner temperature distributions of the packing container are significantly affected by the wood-column thickness. For the same time, the simulations show there is a slight difference in the char layer thickness between two thickness wood columns. The computed results show there are large temperature gradients in the interface of char and wood. This demonstrates the spruce wood is the excellent thermal resistance material.

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Krishnan, Shankar, Jayathi Y. Murthy, and Suresh V. Garimella. "A Two-Temperature Model for Solid-Liquid Phase Change in Metal Foams." Journal of Heat Transfer 127, no. 9 (November 13, 2004): 995–1004. http://dx.doi.org/10.1115/1.2010494.

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Transient solid-liquid phase change occurring in a phase-change material (PCM) embedded in a metal foam is investigated. Natural convection in the melt is considered. Volume-averaged mass and momentum equations are employed, with the Brinkman-Forchheimer extension to the Darcy law to model the porous resistance. Owing to the difference in the thermal diffusivities between the metal foam and the PCM, local thermal equilibrium between the two is not assured. Assuming equilibrium melting at the pore scale, separate volume-averaged energy equations are written for the solid metal foam and the PCM and are closed using an interstitial heat transfer coefficient. The enthalpy method is employed to account for phase change. The governing equations are solved implicitly using the finite volume method on a fixed grid. The influence of Rayleigh, Stefan, and interstitial Nusselt numbers on the temporal evolution of the melt front location, wall Nusselt number, temperature differentials between the solid and fluid, and the melting rate is documented and discussed. The merits of incorporating metal foam for improving the effective thermal conductivity of thermal storage systems are discussed.

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Krishnan, Shankar, Jayathi Y. Murthy, and Suresh V. Garimella. "Analysis of Solid–Liquid Phase Change Under Pulsed Heating." Journal of Heat Transfer 129, no. 3 (August 14, 2006): 395–400. http://dx.doi.org/10.1115/1.2430728.

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Solid/liquid phase change occurring in a rectangular container with and without metal foams subjected to periodic pulsed heating is investigated. Natural convection in the melt is considered. Volume-averaged mass and momentum equations are employed, with the Brinkman–Forchheimer extension to Darcy’s law used to model the porous resistance. A local thermal nonequilibrium model, assuming equilibrium melting at the pore scale, is employed for energy transport through the metal foams and the interstitial phase change material (PCM). Separate volume-averaged energy equations for the foam and the PCM are written and are closed using a heat transfer coefficient. The enthalpy method is employed to account for phase change. The governing equations for the PCM without foam are derived from the porous medium equations. The governing equations are solved implicitly using a finite volume method on a fixed grid. The coupled effect of pulse width and natural convection in the melt is found to have a profound effect on the overall melting behavior. The influence of pulse width, Stefan number, and Rayleigh number on the temporal evolution of the melt front location and the melting rate for both the cases with and without metal foams is investigated.

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Tabakova, Sonia, François Feuillebois, and Stefan Radev. "Freezing of a supercooled spherical droplet with mixed boundary conditions." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2116 (November 25, 2009): 1117–34. http://dx.doi.org/10.1098/rspa.2009.0491.

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The freezing of a supercooled droplet occurs in two steps: recalescence, that is, a rapid return to thermodynamic equilibrium at the freezing temperature leading to a liquid–solid mixture and a longer stage of complete freezing. The second freezing step can be modelled by the one-phase Stefan problem for an inward solidification of a sphere, assuming the droplet to be spherical. A convective heat transfer with the ambient immiscible fluid is modelled by a mixed boundary condition on the outer surface of the droplet. This condition depends on the Biot number (ratio of the heat transfer resistances inside the droplet and at its surface). A novel asymptotic solution is developed for a small Stefan number and an arbitrary Biot number. Applying the method of matched asymptotic expansions, uniformly valid solutions are obtained for the temperature profile and freezing front evolution in the whole stage of complete freezing. For an infinite Biot number, that is, for a fixed temperature at the droplet outer boundary, known solutions are recovered. In parallel, numerical results are obtained for an arbitrary Stefan number using a finite-difference scheme based on the enthalpy method. The asymptotic and numerical solutions are in good agreement.

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Ganiev, I. N., F. A. Aliev, H. O. Odinazoda, A. M. Safarov, and J. H. Jayloev. "Heat capacity and thermodynamic functions of aluminum conductive alloy E-AlMgSi (Aldrey) doped with gallium." Izvestiya Vysshikh Uchebnykh Zavedenii. Materialy Elektronnoi Tekhniki = Materials of Electronics Engineering 22, no. 3 (January 19, 2020): 219–27. http://dx.doi.org/10.17073/1609-3577-2019-3-219-227.

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Aluminum — a metal whose scope of application is constantly expanding. At present, aluminum and its alloys in a number of areas successfully displace traditionally used metals and alloys. The widespread use of aluminum and its alloys is due to its properties, among which, first of all, low density, satisfactory corrosion resistance and electrical conductivity, ability to apply protective and decorative coatings should be mentioned. All this, combined with the large reserves of aluminum in the earth’s crust, makes the production and consumption of aluminum very promising. One of the promising areas for the use of aluminum is the electrical industry. Conductive aluminum alloys type E-AlMgSi (Aldrey) are representatives of this group of alloys.One of the promising areas for the use of aluminum is the electrical industry. Conducting aluminum alloys of the E-AlMgSi type (Aldrey) are representatives of this group of alloys. The paper presents the results of a study of the temperature dependence of heat capacity, heat transfer coefficient, and thermodynamic functions of an aluminum alloy E-AlMgSi (Aldrey) with gallium. Research conducted in the “cooling” mode. It is shown that the temperature capacity and thermodynamic functions of the E-AlMgSi alloy (Aldrey) with gallium increase, while the Gibbs energy decreases. Gallium additives up to 1 wt.% Reduce the heat capacity, enthalpy, and entropy of the initial alloy and increase the Gibbs energy.

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SHA, Minggong, Yuri A. UTKIN, Olga V. TUSHAVINA, and Polina F. PRONINA. "EXPERIMENTAL STUDIES OF HEAT AND MASS TRANSFER FROM TIP MODELS MADE OF CARBON-CARBON COMPOSITE MATERIAL (CCCM) UNDER CONDITIONS OF HIGH-INTENSITY THERMAL LOAD." Periódico Tchê Química 17, no. 35 (July 20, 2020): 988–97. http://dx.doi.org/10.52571/ptq.v17.n35.2020.81_sha_pgs_988_997.pdf.

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Carbon-carbon composite materials are characterized by high heat resistance and thermostability for which they, in most of their physical and mechanical characteristics, can be attributed to the most promising materials. Approximately 81% of all carbon-carbon composite materials are used for the manufacture of brake rotors for aircraft, 18% – in space rocket technology, and only 1% – for all other areas of application. While the need for composites for rocket and space technology is constantly decreasing – the volume of production of brake disc rotors for aircraft is steadily growing, and therefore research on the properties of carbon-carbon composite materials (CCCM) under conditions of high-intensity thermal loading is extremely urgent at the moment. In this paper, we consider a method for introducing silicates and oxides hardening them with the addition of refractory, chemical elements into CCCM. Tests of tips from CCCM were carried out under conditions of high-intensity thermo-force loading. The objectives of the experiment were to obtain scalded forms of the tip model and to record the temperature on the surface during the action of a jet flowing out of the nozzle of the propulsion system (PS). The tip of the CCCM is blown by means of a propulsion system with a supersonic flow of a highly enthalpy oxygencontaining gas. The results of experimental studies were determined using video recording on the basis of which sequences of frames were obtained on the basis of which the burning forms were built. Using thermal imaging measurements, the temperature field on the model surface was determined during the entire time the supersonic gas flow was exposed to it.

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Zhang, C., A. C. M. Sousa, and J. E. S. Venart. "The Numerical and Experimental Study of a Power Plant Condenser." Journal of Heat Transfer 115, no. 2 (May 1, 1993): 435–45. http://dx.doi.org/10.1115/1.2910696.

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A numerical and experimental study to evaluate the performance of a power plant condenser has been carried out. Numerically, physically relevant effects are taken into consideration through a quasi-three-dimensional approach. The equations governing the conservation of mass, momentum, and air mass fraction are solved in primitive variable form using a semi-implicit consistent control-volume formulation in which a segregated pressure correction linked algorithm is employed. The modeling of the condenser geometry, including tube bundle and baffle plates, is carried out based on a porous medium concept using applicable flow, heat, and mass transfer resistances. The measurement program included determinations of the steam pressures on the tube bundle perimeter (96 points), steam temperatures (96 locations), inlet tube sheet water pressure distributions (26 measurements), outlet tube sheet flows and temperatures (26 points), hot well flow, and enthalpy in addition to all makeup and extraction flow rates as a function of load. The measurement program and its implementation are briefly described. One data set is compared with the numerical predictions.

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Nam, Seungkyun, Chan-Yang Lee, Soon-Mi Shim, Dong-Un Lee, and Suyong Lee. "Functional Characterization of Marigold Powder as a Food Ingredient for Lutein-Fortified Fresh Noodles." Applied Sciences 11, no. 2 (January 18, 2021): 861. http://dx.doi.org/10.3390/app11020861.

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Marigold powder was utilized as a food ingredient to produce lutein-fortified fresh noodles for eye health, and its functionalities were characterized in terms of thermo-rheological, structural, and antioxidant properties. The pasting parameters and starch-gelatinization enthalpy values of wheat flour had a tendency to decrease with increasing levels of marigold powder. The use of marigold powder led to decreases in the storage and loss moduli of wheat flour pastes by weakening their cellular microstructure, which was confirmed by the scanning electron microscopic images. When marigold powder was incorporated into the formulation of fresh noodles, the cooking loss and water absorption of the noodles were not negatively affected at a level of 2% (w/w). Also, the noodles with 2% marigold powder were not significantly different from the control for the maximum resistance to extension. The levels of lutein in the noodles prepared with marigold powder (61.2 to 204.9 mg/100 g) were reduced by almost 50% after cooking. However, they seemed to satisfy the recommended daily dose of lutein for visual functions. Moreover, the use of marigold powder provided antioxidant properties for noodles by enhancing the 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical-scavenging activities.

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Gudlaugsson, E., A. Humbert, T. Kleiner, J. Kohler, and K. Andreassen. "The influence of a model subglacial lake on ice dynamics and internal layering." Cryosphere Discussions 9, no. 4 (July 28, 2015): 3859–86. http://dx.doi.org/10.5194/tcd-9-3859-2015.

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Abstract. As ice flows over a subglacial lake, the drop in bed resistance leads to an increase in ice velocities and a subsequent draw-down of isochrones and cold ice from the surface. The ice surface flattens as it adjusts to the lack of resisting forces at the base. The rapid transition in velocity induces changes in temperature and ice viscosity, releasing deformation energy which raises the temperature locally. Recent studies of Antarctic subglacial lakes indicate that many lakes experience very fast and possibly episodic drainage, during which the lake size is rapidly reduced as water flows out. A question is what effect this would have on internal layers within the ice, and whether such past events could be inferred from isochrone structures downstream. Here, we study the effect of a subglacial lake on the dynamics of a model ice stream as well as the influence that such short timescale drainage would have on the internal layers of the ice. To this end, we use a Full–Stokes, polythermal ice flow model. An enthalpy gradient method is used to account for the evolution of temperature and water content within the ice. We find that the rapid transition between slow-moving ice outside the lake, and full sliding over the lake, releases large amounts of deformational energy, which has the potential to form a temperate layer at depth in the transition zone. In addition, we provide an explanation for a characteristic surface feature, commonly seen at the edges of subglacial lakes, a hummocky surface depression in the transition zone between little to full sliding. We also conclude that rapid changes in lake geometry or basal friction create a travelling wave at depth within the isochrone structure that transfers downstream with the advection of ice, thus indicating the possibility of detecting past events with ice penetrating radar.

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Gudlaugsson, Eythor, Angelika Humbert, Thomas Kleiner, Jack Kohler, and Karin Andreassen. "The influence of a model subglacial lake on ice dynamics and internal layering." Cryosphere 10, no. 2 (April 5, 2016): 751–60. http://dx.doi.org/10.5194/tc-10-751-2016.

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Abstract. As ice flows over a subglacial lake, the drop in bed resistance leads to an increase in ice velocities and a draw down of isochrones and cold ice. The ice surface flattens as it adjusts to the lack of resisting forces at the base. The rapid transition in velocity induces changes in ice viscosity and releases deformation energy that can raise the temperature locally. Recent studies of Antarctic subglacial lakes indicate that many lakes experience very fast and possibly episodic drainage, during which the lake size is rapidly reduced as water flows out. Questions that arise are what effect this would have on internal layers within the ice and whether such past drainage events could be inferred from isochrone structures downstream. Here, we study the effect of a subglacial lake on ice dynamics as well as the influence that such short timescale drainage would have on the internal layers of the ice. To this end, we use a full Stokes, polythermal ice flow model. An enthalpy-gradient method is used to account for the evolution of temperature and water content within the ice. We find that a rapid transition between slow-moving ice outside the lake, and full sliding over the lake, can release considerable amounts of deformational energy, with the potential to form a temperate layer at depth in the transition zone. In addition, we provide an explanation for a characteristic surface feature commonly seen at the edges of subglacial lakes, a hummocky surface depression in the transition zone between little to full sliding. We also conclude that rapid changes in the horizontal extent of subglacial lakes and slippery patches, compared to the average ice column velocity, can create a traveling wave at depth within the isochrone structure that transfers downstream with the advection of ice, thus indicating the possibility of detecting past drainage events with ice penetrating radar.

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Isakhodjayev, Kh, F. Mukhtarov, D. Kodirov, and I. Toshpulatov. "Development of a laboratory nozzle chamber installation for the humidification of buildings." IOP Conference Series: Earth and Environmental Science 939, no. 1 (December 1, 2021): 012025. http://dx.doi.org/10.1088/1755-1315/939/1/012025.

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Abstract The nozzle chamber, in which water is sprayed into the air stream using mechanical nozzles, is the main unit for these processes in central air conditioning systems (AHUs). The types of nozzles used do not have a sufficiently high effect of interfacial surface forming due to increased metal usage and the broad total dimensions of certain chambers, i.e., they do not have intensive heat and mass transfer. The authors performed testing of the apparatus in the direct iso-enthalpic air cooling mode to improve the performance of the nozzle chamber. Thus, the experiments conducted confirm the relatively high efficiency of FET operation at small values of irrigation coefficient B ≥ 1.0. The area highlighted is characterised by the unstable operation of other nozzle types. Therefore, FET nozzles can be operated at irrigation factor values B = 0.1…1.0. Experiments have shown that this equation is applicable for practical calculations, with a relative error of ±6.7%. The aerodynamic resistance of the spray chamber nozzle chambers is also according to the data not exceeding 160 Pa.

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Arulanantha Samy, S., T. Shanmuganathan, and J. Godwin John. "Discussions about the Thermodynamic Entropy Property and its Existence in Vehicle Dynamics of Automobiles for Improving the Mileage." Applied Mechanics and Materials 812 (November 2015): 118–23. http://dx.doi.org/10.4028/www.scientific.net/amm.812.118.

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The recent vehicle management systems have been developing to improve the quality of the combustion process and transmission systems. In thermodynamic approach, the water molecule can exists in different phases like ice, water, wet steam, dry steam, and superheated steam. The phase change occurs in the steam formation process can be compared to the various stages of any vehicle dynamic system such starting, idling, normal speed, high speed and very high speed. There may be an identical value in the increment of energy level in both steam formation process and any vehicle dynamic system. Thermodynamic approach always deals with system, surroundings, boundary and energy transformation across boundaries. Entropy is a very good property which is used to find the energy degradation in a particular system, and this property existence in the vehicle dynamics of automobiles will be used to improve the efficiency of the control module of a vehicle management system. This paper initiates a new angle research in the field of vehicle dynamics to study and investigate the kinetic energy transformation and distance moved by the vehicle thermodynamically. From this paper, Entropy is found as a very good property for increasing the mileage of the vehicle. In the vehicle health monitoring, there should be an entropy measurement to reduce the unavailability of energy as it is the measure of the distance travelled by the vehicle per unit energy supplied to the same vehicle at various operating speeds. In manual transmission method, it has been found that driver is not able to press the accelerator pedal continuously due to body strain. Driver has to run the vehicle at constant speed by pressing the accelerator pedal continuously. In automatic transmission, the data required for the ECU module is given by the thermodynamic relations such as enthalpy, entropy and internal energy. This paper aims thermodynamically to describe the speed, acceleration, fuel consumption, kinetic energy and various resistances offered to the vehicles. Generally, Thermodynamic system deals with heat and mass transfer, likewise vehicle dynamics deals with work and vehicle’s motion.

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Roth, Michal. "Enthalpy of transfer in supercritical fluid chromatography." Journal of Chromatography A 543 (January 1991): 262–65. http://dx.doi.org/10.1016/s0021-9673(01)95778-4.

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Jeong, Dahai, Brian K. Haus, and Mark A. Donelan. "Enthalpy Transfer across the Air–Water Interface in High Winds Including Spray." Journal of the Atmospheric Sciences 69, no. 9 (September 1, 2012): 2733–48. http://dx.doi.org/10.1175/jas-d-11-0260.1.

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Abstract Controlled experiments were conducted in the Air–Sea Interaction Saltwater Tank (ASIST) at the University of Miami to investigate air–sea moist enthalpy transfer rates under various wind speeds (range of 0.6–39 m s−1 scaled to equivalent 10-m neutral winds) and water–air temperature differences (range of 1.3°–9.2°C). An indirect calorimetric (heat content budget) measurement technique yielded accurate determinations of moist enthalpy flux over the full range of wind speeds. These winds included conditions with significant spray generation, the concentrations of which were of the same order as field observations. The moist enthalpy exchange coefficient so measured included a contribution from cooled reentrant spray and therefore serves as an upper limit for the interfacial transfer of enthalpy. An unknown quantity of spray was also observed to exit the tank without evaporating. By invoking an air volume enthalpy budget it was determined that the potential contribution of this exiting spray over an unbounded water volume was up to 28%. These two limits bound the total enthalpy transfer coefficient including spray-mediated transfers.

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Liu, Xiaochen, Xiaohua Liu, Tao Zhang, and Ying Xie. "Experimental analysis and performance optimization of a counter-flow enthalpy recovery device using liquid desiccant." Building Services Engineering Research and Technology 39, no. 6 (May 30, 2018): 679–97. http://dx.doi.org/10.1177/0143624418780852.

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The liquid desiccant enthalpy recovery is an efficient way to save energy in air-conditioning systems. In this study, a counter-flow liquid desiccant enthalpy recovery device was proposed and experimentally analyzed. Enthalpy transfer capacity, enthalpy efficiency and pressure drop per height of packing were used as indices to describe its performances. Based on the experiment results, the heat and mass transfer model of a packed tower was used to simulate and optimize the performance of this device. The maximum enthalpy efficiency and enthalpy transfer capacity were achieved when the optimal air velocity (1.9–2.1 m/s in this study) maintained to be slightly below the air velocity at the loading point and the thermal capacity ratio of air to desiccant ( m*) equaled to 1. These conclusions are valuable to both design and operation of such an enthalpy recovery device. Practical application: A counter-flow enthalpy recovery device with liquid desiccant was proposed and experimentally investigated. Based on the experiment results, a numerical model for this device was built and validated. The optimal air and desiccant mass fluxes were analyzed to maximize the enthalpy efficiency of this device, which could be higher than the conventional device with cross-flow pattern. These results could provide guidelines for both design and operation management of counter-flow enthalpy recovery devices in liquid desiccant-based air-conditioning systems.

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Mills, Eric A., and Steven S. Plotkin. "Protein Transfer Free Energy Obeys Entropy-Enthalpy Compensation." Journal of Physical Chemistry B 119, no. 44 (October 26, 2015): 14130–44. http://dx.doi.org/10.1021/acs.jpcb.5b09219.

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SKILLER, C. P., and B. M. KELLY. "Solvent Vapor Transfer across an Enthalpy Energy System." American Industrial Hygiene Association Journal 50, no. 6 (June 1989): 320–24. http://dx.doi.org/10.1080/15298668991374732.

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31

Andersson, Barbro, Kurt Andersson, Jan Sundell, and Per-Anders Zingmark. "Mass Transfer Of Contaminants In Rotary Enthalpy Exchangers." Indoor Air 3, no. 2 (June 1993): 143–48. http://dx.doi.org/10.1111/j.1600-0668.1993.t01-1-00009.x.

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32

Kim, Nae-Hyun. "Moisture Diffusion Characteristics of a Paper Membrane Used for a Cross Flow Enthalpy Exchanger." International Journal of Air-Conditioning and Refrigeration 26, no. 03 (September 2018): 1850023. http://dx.doi.org/10.1142/s2010132518500232.

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An enthalpy exchanger is the key component of an enthalpy recovery ventilator, which is installed in apartments or office buildings to maintain proper indoor air quality. In this study, the performance data of the enthalpy exchanger made of paper membrane were obtained for wide range of temperature and humidity conditions. Using the data, diffusion coefficient correlations were developed through modeling of heat and moisture transfer. The heat transfer effectiveness was relatively constant independent of outdoor temperature condition. On the other hand, the moisture transfer effectiveness was highly dependent on outdoor humidity and temperature. In general, moisture transfer effectiveness increased as relative humidity increased. The moisture transfer effectiveness also increased as temperature difference between indoor and outdoor increased. Moisture diffusion coefficient correlations were developed from the data, which predicted the moisture transfer effectiveness was within [Formula: see text]%.

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Ngo, Chinh Thi. "THERMOCHEMICAL PARAMETERS OF ERGOTHIONEINE: A DFT STUDY USING M06, WB97XD AND TPSSTPSS METHODS." Vietnam Journal of Science and Technology 54, no. 2C (March 19, 2018): 299. http://dx.doi.org/10.15625/2525-2518/54/2c/11850.

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Antioxidant properties of ergothioneine (ESH) have been investigated via hydrogen atomtransfer (HAT), single electron transfer-proton transfer (SET-PT) and sequential proton losselectron transfer (SPLET) mechanisms. Three new DFT methods including M06, WB97XD andTPSSTPSS at the 6-311++G(2df,2p) basis set were used to compute the thermochemicalparameters of ESH in the gas phase. Based on these methods, bond dissociation enthalpy (BDE),ionization energy (IE), proton dissociation enthalpy (PDE), proton affinity (PA) and electrontransfer enthalpy (ETE) were calculated. The results were also compared with the valuesobtained by B3LYP method. The calculated results show that ergothioneine plays a role as apotential antioxidant via HAT mechanism.

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LEE, EUL-JONG, NAE-HYUN KIM, GIL-SUB SONG, and JUNG-PYO LEE. "HEAT AND MOISTURE TRANSFER CHARACTERISTICS OF A PLATE-TYPE ENTHALPY EXCHANGER MADE OF PAPER." International Journal of Air-Conditioning and Refrigeration 19, no. 01 (March 2011): 85–92. http://dx.doi.org/10.1142/s2010132511000429.

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In this study, heat and moisture transfer data of an enthalpy exchanger were obtained varying the indoor and outdoor condition systematically. At the same time, equilibrium water content ratios of the membrane were measured. It is shown that equilibrium water content ratio of the membrane increases with the increase of relative humidity. The effect of temperature on equilibrium water content ratio, however, is rather complex. It decreases with the increase of temperature to a certain value, and then increases with further increase of temperature. Moisture transfer effectiveness of the enthalpy exchanger is also affected by relative humidity and temperature. Heat transfer effectiveness, however, is independent of relative humidity and temperature. Moisture transfer effectiveness of the enthalpy exchanger was successfully correlated by equilibrium water content ratio of the membrane.

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Zhou, Huakang, Xiangzhou Li, Yaxuan Shang, and Kai Chen. "Radical Scavenging Activity of Puerarin: A Theoretical Study." Antioxidants 8, no. 12 (November 26, 2019): 590. http://dx.doi.org/10.3390/antiox8120590.

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Puerarin is a C-glycoside of daidzein, one of the major bioactive ingredients isolated from the root of Pueraria lobata, which has a wide spectrum of pharmacological effects. Although puerarin is well-known for its effective antioxidant activity, there is seldom a systematic theoretical study on its radical scavenging activity. Herein, the free radical scavenging ability of puerarin was investigated systematically by density functional theory (DFT) calculations. The reaction activity was compared with daidzein as well. Three reaction pathways: hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were discussed and compared by thermodynamic parameters such as bond dissociation enthalpy (BDE), ionization potential (IP), proton dissociation enthalpy (PDE), proton affinity (PA), and electron transfer enthalpy (ETE). The reaction kinetics of puerarin with special radicals •OH and •OOH were also studied. The results obtained may be of great significance for better understanding the relationship between the antioxidant properties and structural design of puerarin, as well as other antioxidants.

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36

Le, Tien Dung. "COMPUTATIONAL STUDY OF MOLECULAR STRUCTURES AND ANTIOXIDANT MECHANISM OF OVOTHIOLS." Vietnam Journal of Science and Technology 54, no. 2C (March 19, 2018): 328. http://dx.doi.org/10.15625/2525-2518/54/2c/11854.

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In this paper, the molecular structure and antioxidant activity of ovothiols (OSH) have beenstudied by using four DFT functionals, namely B3LYP, B3PW91, X3LYP, M06 with the basisset of 6-311++G(2df,2p). Two major antioxidant mechanisms, namely, hydrogen atom transfer(HAT) and stepwise electron transfer-proton transfer (SET-PT) have been investigated andapplied on three optimized conformations of ovothiols. Bond dissociation enthalpy (BDE),vertical ionization energy (IE), proton dissociation enthalpy (PDE), chemical potential (μ),chemical hardness (η) and global electrophilicity (ω), have been calculated and discussed in thegas phase.

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37

Abrahamson, S. D., and J. K. Eaton. "Heat Transfer Through a Pressure-Driven Three-Dimensional Boundary Layer." Journal of Heat Transfer 113, no. 2 (May 1, 1991): 355–62. http://dx.doi.org/10.1115/1.2910569.

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An experimental investigation of heat transfer through a three-dimensional boundary layer has been performed. An initially two-dimensional boundary layer was made three dimensional by a transverse pressure gradient caused by a wedge obstruction, which turned the boundary layer within the plane of the main flow. Two cases, with similar streamwise pressure gradients and different lateral gradients, were studied so that the effect of the lateral gradient on heat transfer could be deduced. The velocity flowfield agreed with previous hydrodynamic investigations of this flow. The outer parts of the mean velocity profiles were shown to agree with the Squire-Winter theorem for rapidly turned flows. Heat transfer data were collected using a constant heat flux surface with embedded thermocouples for measuring surface temperatures. Mean fluid temperatures were obtained using a thermocouple probe. The temperature profiles, when plotted in outer scalings, showed logarithmic behavior consistent with two-dimensional flows. An integral analysis of the boundary layer equations was used to obtain a vector formulation for the enthalpy thickness, HH≜∫0∞ρuisdyρ∞ii,o(u∞2+w∞2)1/2,0,∫0∞ρwisdyρ∞is,o(u∞2+w∞2)1/2 (where is is the stagnation enthalpy), which is consistent with the scalar formulation used for two-dimensional flows. Using the vector formulation, the heat transfer data agreed with standard two-dimensional correlations of the Stanton number and enthalpy thickness Reynolds number. It was concluded that although the heat transfer coefficient decreased faster than its two-dimensional counterpart, it was similar to the two-dimensional case. The vector form of the enthalpy thickness captured the rotation of the mean thermal energy flux away from the free-stream direction. Boundary layer three dimensionality increased with the strength of the transverse pressure gradient and the heat transfer coefficients were smaller for the stronger transverse gradient.

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Koester, S., M. Falkenberg, M. Logemann, and M. Wessling. "Modeling heat and mass transfer in cross-counterflow enthalpy exchangers." Journal of Membrane Science 525 (March 2017): 68–76. http://dx.doi.org/10.1016/j.memsci.2016.10.030.

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Tikhomirov, V. A., A. V. Soudackov, and M. V. Basilevsky. "Enthalpy Surfaces for Hydrogen Atom Transfer in a Molecular Crystal." Journal of Physical Chemistry A 105, no. 13 (April 2001): 3226–31. http://dx.doi.org/10.1021/jp000334a.

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40

Malloum, Alhadji, and Jeanet Conradie. "Proton transfer free energy and enthalpy from water to methanol." Computational and Theoretical Chemistry 1199 (May 2021): 113189. http://dx.doi.org/10.1016/j.comptc.2021.113189.

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41

Velve Casquillas, G., F. Bertholle, M. Le Berre, S. Meance, L. Malaquin, J. J. Greffet, and Y. Chen. "Thermo-resistance based micro-calorimeter for continuous chemical enthalpy measurements." Microelectronic Engineering 85, no. 5-6 (May 2008): 1367–69. http://dx.doi.org/10.1016/j.mee.2007.12.074.

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Sheng, Qiang, and Yu Ming Xing. "Numerical Analysis on Solid-Liquid Phase Change Heat Transfer Process between PCM and FCPCM." Advanced Materials Research 732-733 (August 2013): 37–41. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.37.

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Due to enthalpy-porosity technique, mathematical models of phase change material (PCM) and foam composite phase change material (FCPCM) in two-dimensional rectangular canister were established in the conditions of gravity and natural convection. It solved phase change problems by the enthalpy method coming from computational fluid dynamics. The numerical results show good agreement with reference findings. The numerical comparison between PCM and FCPCM verifies that metal foam can not only enhance the thermal conductivity of the PCMs but also improve the thermal performance of the heat storage system.

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Barrett, Michael J., and D. Keith Hollingsworth. "Heat Transfer in Turbulent Boundary Layers Subjected to Free-Stream Turbulence—Part I: Experimental Results." Journal of Turbomachinery 125, no. 2 (April 1, 2003): 232–41. http://dx.doi.org/10.1115/1.1538622.

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Turbulent boundary layers were subjected to grid-generated free-stream turbulence to study the effects of length scale and intensity on heat transfer. Relative to conventional boundary layer thickness measures, test conditions included very small-scale free-stream turbulence. The boundary layers studied ranged from 400–2700 in momentum-thickness Reynolds number and from 450–1900 in enthalpy-thickness Reynolds number. Free-stream turbulence intensities varied from 0.1–8.0%. Ratios of free-stream length scale to boundary-layer momentum thickness ranged from 4.4–32.5. The turbulent-to-viscous length-scale ratios presented are the smallest found in the heat-transfer literature; the ratios spanned from 115–1020. The turbulent-to-thermal ratios (using enthalpy thickness as the thermal scale) are also the smallest reported; the ratios ranged from 3.2–12.3. Relative to clean-free-stream expectations based on the momentum- and enthalpy-thickness Reynolds numbers, the skin friction coefficient increased by up to 16%, and the Stanton number increased by up to 46%.

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Belozerov, L. S., and A. A. Kazin. "Study of erosion resistance of graphite MPG-7." Journal of «Almaz – Antey» Air and Space Defence Corporation, no. 2 (June 30, 2018): 26–28. http://dx.doi.org/10.38013/2542-0542-2018-2-26-28.

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The study focuses on the erosion resistance of graphite samples with an electrospark coating. To compare the experimental results, we chose titanium, tantalum, tungsten, stellite as a hardening coating. For erosion, we used an installation to obtain high-enthalpy gas flows, the installation combining a plasma gun and an aerodynamic device, by means of the latter a gas flow is formed.

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Nie, Jinzhe, Jianrong Yang, Lei Fang, and Xiangrui Kong. "Experimental evaluation of enthalpy efficiency and gas-phase contaminant transfer in an enthalpy recovery unit with polymer membrane foils." Science and Technology for the Built Environment 21, no. 2 (February 13, 2015): 150–59. http://dx.doi.org/10.1080/10789669.2014.967165.

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Klein, H., S. A. Klein, and J. W. Mitchell. "Analysis of regenerative enthalpy exchangers." International Journal of Heat and Mass Transfer 33, no. 4 (April 1990): 735–44. http://dx.doi.org/10.1016/0017-9310(90)90171-p.

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Gai, S. L., and M. J. Hayne. "Heat Transfer Behind a Step in High-Enthalpy Laminar Hypersonic Flow." Journal of Thermophysics and Heat Transfer 24, no. 4 (October 2010): 839–41. http://dx.doi.org/10.2514/1.49300.

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Gai, S. L., and W. S. Joe. "Laminar heat transfer to blunt cones in high-enthalpy hypervelocity flows." Journal of Thermophysics and Heat Transfer 6, no. 3 (July 1992): 433–38. http://dx.doi.org/10.2514/3.379.

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Fripiat, J. J., and X. Lin. "Hydrogen intercalation within transition metal oxides: entropy, enthalpy, and charge transfer." Journal of Physical Chemistry 96, no. 3 (February 1992): 1437–44. http://dx.doi.org/10.1021/j100182a075.

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Koester, S., A. Klasen, J. Lölsberg, and M. Wessling. "Spacer enhanced heat and mass transfer in membrane-based enthalpy exchangers." Journal of Membrane Science 520 (December 2016): 566–73. http://dx.doi.org/10.1016/j.memsci.2016.06.002.

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Journal articles on the topic 'Resistance to enthalpy transfer'

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