Accepted Manuscripts

Qimei Gu, Tejashree Joglekar, Charles Bieberich, Ronghui Ma and Liang Zhu
J. Heat Transfer   doi: 10.1115/1.4042298
In vivo animal experiments were performed on grafted PC3 tumors implanted in mice to investigate whether local heating via exposing the tumor to an alternating magnetic field for 25 minutes resulted in nanoparticle spreading from the intratumoral injection site to tumor periphery. Nanoparticle redistribution is evaluated via comparing microCT images of resected tumors with heating to that in the control group without heating. A previously obtained calibration relationship between microCT Hounsfield Unit (HU) values and local nanoparticle concentrations in the tumors was used to determine the distribution of volumetric heat generation rate. SAS, MATLAB, and EXCEL were used to process the scanned data to determine the total heat generation rate and the nanoparticle distribution volumes in individual HU ranges. The nanoparticle distribution volume in the high q'''MNH range > 1.8*10^6 W/m^3 is 10% smaller in the heating group, while in the low q'''MNH range of 0.6-1.8*10^6 W/m^3, it is 94.54% larger in the heating group. Based the calculated heat generation rate in individual HU ranges, the percentage in the HU range larger than 2000 decreases significantly from 46% in the control to 34% in the heating group, while the percentages in the HU ranges of 500-1000 and 1000-1500 in the heating group are much higher than that in the control group. We conclude that heating PC3 tumors for 25 minutes resulted in significant nanoparticle migration from high concentration region to low concentration regions.
TOPICS: Nanoparticles, Tumors, Heating, Heat, Magnetic fields, Calibration, Matlab
Hongchuang Sun, Jiang Qin, Huang Hongyan and Peigang Yan
J. Heat Transfer   doi: 10.1115/1.4042299
Air turbine power generation system is considered as a feasible power generation system for hypersonic aircraft with Mach 6. However, the incoming air with high temperature cannot be used as coolant while turbine has to be cooled. Since hydrocarbon fuel is the only cooling source onboard, the scheme of fuel cooling air turbine is put forward. In this paper, square cooling channel, including inlet part, outlet part and U-duct, is established based on the typical air turbine. The hydraulic diameter of the channel is 2 mm and four types of U-ducts are used to compare the performance with simulation using k-Epsilon turbulence model. The density and specific heat capacity of fuel are considered as constant as the temperature difference in this study is small. The Reynolds number varies from 2760 to 16559 and rotating number ranges from 0 to 6.9. The results show that the pressure distribution in radial direction is proportional to the square of radial distance and the square of rotating speed. The regulations of velocity and normalized Nusselt number distributions depend on rotating number. Furthermore, the heat transfer is enhanced with fin while the pressure loss is also increased. The position of fins cannot significantly influence pressure loss but can influence heat transfer obviously. The normalized Nusselt number of inlet-fin U-duct is higher than the outlet-fin U-duct both on leading side surface and trailing side surface, while the pressure losses for the two types of ducts are almost same.
TOPICS: Flow (Dynamics), Heat transfer, Fuels, Computer simulation, Ducts, Turbines, Pressure, Cooling, Energy / power systems, Density, Aircraft, Reynolds number, Simulation, Coolants, Turbulence, Specific heat, Temperature, Fins, Regulations, High temperature
Review Article  
Anita Penkova, Rex Moats, Mark S. Humayun, Scott Fraser and S.S. Sadhal
J. Heat Transfer   doi: 10.1115/1.4042297
In relation to intravitreal drug delivery, predictive mathematical models for drug transport are being developed, and to effectively implement these for retinal delivery, the information on biophysical properties of various ocular tissues is fundamentally important. It is therefore necessary to accurately measure the diffusion coefficient of drugs and drug surrogates in the vitreous humor. In this review, we present the studies conducted by various researchers on such measurements over the last several decades. These include imaging techniques (fluorescence and MRI) that make use of introducing a contrast agent or a labeled drug into the vitreous and tracking its diffusive movement through at various time points. A predictive model for the same initial conditions when matched with the experimental measurements provides the diffusion coefficient, leading to results for various molecules ranging in size from approximately 100 Da to 150 kDa. For real drugs, the effectiveness of this system depends on the successful labeling of the drugs with suitable contrast agents such as fluorescein and gadolinium or manganese so that fluorescence or MR imagining could be conducted. Besides this technique, some work has been carried out using the diffusion apparatus for measuring permeation of a drug across an excised vitreous body from a donor chamber to the receptor by sampling assays from the chambers at various time intervals. This has the advantage of not requiring labeling but is otherwise more disruptive to the vitreous. Some success with nanoparticles has been achieved using dynamic light scattering, and presently, radioactive labeling is being explored.
TOPICS: Fluorescence, Diffusion (Physics), Assaying, Nanoparticles, Biological tissues, Drug delivery systems, Magnetic resonance imaging, Drugs, Gadolinium, Imaging, Dynamic light scattering
David Eckmann, Abhay Ranganathan, Shawn Owiredu and David Jang
J. Heat Transfer   doi: 10.1115/1.4042186
The intracellular production and transport of energetic substrate adenosine triphosphate (ATP) produced by mitochondria is dependent on multiple factors. These include local metabolic demand, mitochondrial motility and intracellular location, mitochondrial intermembrane potential, bioenergy substrate diffusion within the cell cytosol and energy transport to the cell nucleus, which itself does not contain any mitochondria. Herein we demonstrate via cell-based experiment and scaling argument that intracellular bioenergy transport is readily compartmentalized into perinuclear and peripheral regions of the cell. We draw on direct fluorescence-based measurement of quantum dot tracking, high-resolution respirometry, mitochondrial dynamics and intermembrane potential to assess intracellular quantum dot diffusion to define the intracellular milieu for small molecule transport, and chemical perturbations which challenge cells by altering bioenergetics states. We identify a heterogeneous environment for intracellular bioenergy transport, with a dominant feature being present: the intracellular bioenergy distribution in response to pharmacologically-induced cell challenge is determined to be preservation of perinuclear mitochondrial ATP-linked respiration in order to preserve, maintain or otherwise support bioenergy delivery to meet the metabolic requirements of the cell nucleus whereas there is a decrement in bioenergetic capacity in the cell periphery. This dynamic effect of motile intracellular bioenergy production yields efficient transport of ATP in the maintenance of cellular health.
TOPICS: Dynamics (Mechanics), Fluorescence, Diffusion (Physics), Maintenance, Preservation, Resolution (Optics), Quantum dots, Bioenergy conversion
Sunil K. Dwivedi and Sandip K. Saha
J. Heat Transfer   doi: 10.1115/1.4042148
The present experimental study on rhombic shaped microchannel is to understand the effect of low acute side angle on the Nusselt number and compare with the published numerical results for H1 (axially constant heat flux and circumferentially constant temperature) and H2 (constant axial and circumferential wall heat flux) boundary conditions. The hydraulic and heat transfer characteristics of rhombic geometry with a side angle of 30° for different mass flow rates and heat flux inputs are obtained using a three-dimensional conjugate heat transfer model, which is validated with the experimental results. It is found that the average Nusselt number obtained from the experimental and numerical results can be approximated closely with that computed using H1 boundary condition. The local Nusselt number of hydrodynamically and thermally developed region obtained from numerical analysis is compared with the correlation, published for H1 boundary condition. These results will be useful in design and optimization of rhombic shaped microchannel for electronic cooling applications.
TOPICS: Heat transfer, Microchannels, Heat flux, Boundary-value problems, Geometry, Computer cooling, Flow (Dynamics), Temperature, Design, Numerical analysis, Optimization
John H. Lienhard V
J. Heat Transfer   doi: 10.1115/1.4042158
The radiation fractional function is the fraction of black body radiation below a given value of λ-T. Edwards and others have distinguished between the traditional, or "external", radiation fractional function and an "internal" radiation fractional function. The latter is used for simplified calculation of net radiation from a non-gray surface when the temperature of an effectively black source is not far from the surface's temperature, without calculating a separate total absorptivity. This paper examines the analytical approximation involved in the internal fractional function, with results given in terms of the incomplete zeta function. A rigorous upper bound on the difference between the external and internal emissivity is obtained. Calculations using the internal emissivity are compared to exact calculations for several models and materials. A new approach to calculating the internal emissivity is developed, yielding vastly improved accuracy over a wide range of temperature differences. The internal fractional function can be useful for certain simplified calculations.
TOPICS: Radiation (Physics), Emissivity, Temperature, Approximation, Blackbody radiation
Yuanwei Lyu, Jing-zhou Zhang, Xicheng Liu and Yong Shan
J. Heat Transfer   doi: 10.1115/1.4042159
Impinging heat transferred by a pulsed jet induced by a 6-chevron nozzle on a semi-cylindrical concave surface is investigated. The semi-cylindrical concave surface has a cylinder diameter-to-nozzle diameter ratio (D/d) of 10. Results show that the nozzle-to-surface distance has a significant impact on the impingement heat transfer of the pulsed chevron jet. An optimal nozzle-to-surface distance for achieving the maximum stagnation Nusselt number appears at H/d=6. In the wall jet zone, the averaged Nusselt number is the largest at H/d=2 and the smallest at H/d=8. In comparison with the chevron steady jet impingement, the effect of nozzle-to-surface distance on the convective heat transfer becomes less notable for the pulsed chevron jet impingement. The stagnation Nusselt number under the pulsed chevron jet impingement is mostly less than that under the chevron steady jet impingement. However, at H/d=8, the pulsed chevron jet is more effective than the steady jet. This study confirmed that the pulsed chevron jet produced higher azimuthally-averaged Nusselt numbers than the steady chevron jet in the wall jet flow zone at large nozzle-to-surface distances. The stagnation Nusselt numbers by the pulsed chevron jet impingement has a maximum reduction of 21.0% (f=20Hz, H/d=4, Re=2000) compared with the steady chevron jet impingement. The pulsed chevron jet impingement heat transfer on a concave surface is less effective than compared to a flat surface.
TOPICS: Heat transfer, Nozzles, Cylinders, Jets, Convection, Heat
Hai-Dong Wang
J. Heat Transfer   doi: 10.1115/1.4042106
Erratum for the published paper "Non-Fourier heat conduction in carbon nanotubes"
TOPICS: Heat conduction, Carbon nanotubes
Design Innovation Paper  
Federico Belfi, Filomena Iorizzo, Claudio Galbiati and Fabio Lepore
J. Heat Transfer   doi: 10.1115/1.4042082
In this paper is described the development and the experimental study of a Flat Plate Pulsating Heat Pipe (FPPHP) built by means of metal additive manufacturing. In the recent years, small/medium aerospace companies have gained interest in the development of small satellites. The small dimensions, coupled with the need of high power devices for science and communications, increase the interest in thermally functional structures. The space business is characterized by a very small production lot, and custom designs from project to project. The Additive Manufacturing (AM) exactly fits these needs and, in the past years, the use of this technology in aerospace projects has grown significantly. This paper, after a brief review of the Pulsating Heat Pipe (PHP), focuses on the development and testing of a panel with an embedded closed loop Flat Plate Pulsating Heat Pipe built by means of metal AM technique. The article presents a trade-off analysis between the metal AM technologies available on the market; by means of the trade-off analysis a design strategy is proposed by the authors. A comparison between available FPPHP results in literature and the 3D printed structure will show the differences between the common subtractive technology and the innovative AM technique.
TOPICS: Space frame structures, Flat plates, Technology development, Additive manufacturing, Heat pipes, Metals, Aerospace industry, Tradeoffs, Testing, Design, Dimensions, Satellites
Wang Qiang, Qian Zuoqin, Cheng Junlin, Ren Jie and Huang Weilong
J. Heat Transfer   doi: 10.1115/1.4042008
The numerical simulation was carried out to investigate mechanism of the heat transfer enhancement in the fin-and-tube heat exchangers. As known, the vortex generators were widely used to improve the thermal performance with bad flow resistance characteristics and led to bad comprehensive performance. This paper was aimed to expound the mechanism of thermal hydraulic characteristics and explore the effect of vortex generators position on the comprehensive performance. Three types of fins (Type 1, Type 2, and Type 3) were discussed in this paper. The j factor, f factor and PEC of three types of vortex generators in different positions were discussed and compared. Based on the numerical results, a detailed description of the effect of three types of vortex generators on the heat transfer performance and flow resistance characteristics was presented at different Reynolds number in the range between 1300 and 2000. In addition, local velocity distribution, local temperature distribution and local pressure drop distribution were analyzed and discussed. And the effect of VG angle on the thermal performance and flow resistance were presented. It can be concluded that the main heat transfer occurred in the region before the tube, and the wake region behind the tube was harmful to improve the thermal performance and reduce the flow resistance. Besides, vortex generator in the wake region was obviously beneficial to the enhancement of the thermal performance with less energy loss.
TOPICS: Flow (Dynamics), Heat transfer, Heat exchangers, Vortices, Generators, Wakes, Pressure drop, Temperature distribution, Fins, Computer simulation, Reynolds number, Energy dissipation
Pradeep GV and K Rama Narasimha
J. Heat Transfer   doi: 10.1115/1.4041953
This paper describes the experimental investigations conducted on a closed loop pulsating heat pipe (CLPHP) for assessing the thermal performance. The pulsating heat pipe has a single closed loop made of copper. The working fluids used are water and titanium-di-oxide nano fluids with varying concentrations of TiO2 nano particles (1.5% and 1%) on weight basis. The TiO2 particles are mixed in water to form a stable suspension using a sonicator. The heat input is varied between 40W-100W in steps of 20W. All experiments are conducted in the bottom heating mode (evaporator at the top) in vertical and horizontal orientations. The parameters considered for evaluating the thermal performance are the temperature difference between evaporator and condenser, thermal resistance, heat transfer coefficient and thermal conductivity. The results of the investigation reveals that, the vertical orientation and increase in nano particle concentration favors better heat transfer performance of the PHP
TOPICS: Heat pipes, Nanofluids, Water, Nanoparticles, Thermal conductivity, Condensers (steam plant), Weight (Mass), Heat, Temperature, Heat transfer, Fluids, Copper, Particulate matter, Heating, Heat transfer coefficients, Thermal resistance, Titanium
Oguzhan Der, Dr. Marco Marengo and Volfango Bertola
J. Heat Transfer   doi: 10.1115/1.4041952
A low-cost, flexible pulsating heat pipe (PHP) was built in a composite polypropylene sheet consisting of three layers joint together by selective laser welding, to address the demand of heat transfer devices characterized by low weight, small unit thickness, low cost, and high mechanical flexibility. A thin, flexible and lightweight heat pipe is advantageous for various aerospace, aircraft and portable electronic applications where the device weight and its mechanical flexibility are essential. The concept is to sandwich a serpentine channel, cut out in a polypropylene sheet and containing a self- propelled mixture of a working fluid with its vapour, between two transparent sheets of the same material; this results into a thin, flat enclosure with parallel channels hence the name "pulsating heat stripes" (PHS). The transient and steady- state thermal response of the device was characterised for different heat input levels and different configurations, either straight or bent at different angles. The equivalent thermal resistance was estimated by measuring the wall temperatures at both the evaporator and the condenser, showing a multi- fold increase of the equivalent thermal conductance with respect to solid polypropylene.
TOPICS: Heat, Plastics, Weight (Mass), Heat pipes, Aircraft, Condensers (steam plant), Thermal resistance, Transparency, Wall temperature, Heat transfer, Fluids, Composite materials, Transients (Dynamics), Laser welding, Thermal conductivity, Aerospace industry
Sam Darr, Dr. Jason Hartwig, Jun Dong, Hao Wang, Alok Majumdar, Andre LeClair and Prof. Jacob Chung
J. Heat Transfer   doi: 10.1115/1.4041830
Recently, two-phase cryogenic flow boiling data in liquid nitrogen (LN2) and liquid hydrogen (LH¬2) were compared to the most popular two-phase correlations, as well as correlations used in two of the most widely used commercially available thermal/fluid design codes in Hartwig et al. (2016a). Results uncovered that the correlations performed poorly, with predictions significantly higher than the data. Disparity is primarily due to the fact that most two-phase correlations are based on room temperature fluids, and for the heating configuration, not the quenching configuration. The penalty for such poor predictive tools is higher margin, safety factor, and cost. Before control algorithms for cryogenic transfer systems can be implemented, it is first required to develop a set of low-error, fundamental two-phase heat transfer correlations that match available cryogenic data. This paper presents the background for developing a new set of quenching/chilldown correlations for cryogenic pipe flow on thin, shorter lines, including the results of an exhaustive literature review of 61 sources. New correlations are presented which are based on the consolidated database of 79,915 quenching points for a 1.27 cm diameter line, covering a wide range of inlet subcooling, mass flux, pressure, equilibrium quality, flow direction, and even gravity level. Functional forms are presented for LN2 and LH2 chilldown correlations, including film, transition, and nucleate boiling, critical heat flux, and the Leidenfrost point.
TOPICS: Quenching (Metalworking), Hydrogen, Nitrogen, Pipes, Flow (Dynamics), Temperature, Heat transfer, Fluids, Safety, Equilibrium (Physics), Boiling, Design, Pipe flow, Subcooling, Thermofluids, Nucleate boiling, Heating, Control algorithms, Critical heat flux, Databases, Errors, Pressure, Gravity (Force)
Fabio Villa, Marco Marengo and Joël De Coninck
J. Heat Transfer   doi: 10.1115/1.4041708
Heat pipe characteristics are linked to the surface properties of the diabatic surfaces, and, in the evaporator, surface properties influence both the onset boiling temperature (TONB) and the critical heat flux (CHF). In this work the effect of surface wettability in pool boiling heat transfer is studied in order to understand if there could be a path to increment heat pipe thermal performance. This work analyses the effects of surface wettability on boiling (tested fluid is pure water) and proposes a new super-hydrophobic polymeric coating [1], which can have a very important effect in improving the heat pipe start-up power load and increasing the thermal performance of heat pipes when the flux is lower than the critical heat flux. The polymeric coating is able to reduce the TONB (-11% from 117°C to about 104°C) compared with the uncoated surfaces, as it inhibits the formation of a vapour film on the solid-liquid interface, avoiding CHT conditions up to maximum wall temperature (125°C). This is realized by the creation of a heterogeneous surface with SHS zones dispersed on top of a hydrophilic surface (stainless steel surface). The proposed coating has an outstanding thermal resistance: No degradation of SH properties of the coating has been observed after more than 500 thermal cycles.
TOPICS: Heat pipes, Coating processes, Coatings, Critical heat flux, Boiling, Surface properties, Cycles, Pool boiling, Stainless steel, Thermal resistance, Wall temperature, Water, Stress, Temperature, Heat transfer, Fluids

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