Accepted Manuscripts

Meng Wang, Runqing Zang, Hai Feng, Chaoqun Yu, He Wang and Chenxu Zhang
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040284
The liquid refrigerant defrosting (LRD) is a method which leads the liquid refrigerant in the high pressure reservoir to the frosting evaporator. The refrigeration process is continuous during the defrosting period, which increases the defrosting frequency. Compared with the traditional defrosting method, no large fin spacing should be left to reduce the defrosting frequency. The system can recover all the defrosting cooling capacity to improve the subcooling, so that the indoor air temperature fluctuations are avoided. In order to explore the effect and the rule of the LRD, the defrosting experiments were carried out in different frosting mass under the condition of the cold storage temperature of -20?. The defrosting time, temperature rise value, cooling capacity and compressor power consumption value were calculated at the different frosting mass. Interpolation and applying the curve fitting equation helps to obtain remaining values. The relative humidity was calculated by the frosting mathematical model. Finally, the relationship between the coefficient of performance (COP) and the defrosting cycle (the sum of the defrosting time and the frosting time) was obtained. The experiments and theoretical research showed that the fluctuating value of cold storage temperature was about 5? and the defrosting time was about 30min during the defrosting process. In the case of the relative humidity of 70%, 80%, 90%, the optimum defrosting cycle of the experiment was 16.4, 10.9, 7.5h and the frosting mass was 2.66, 2.90, 3.22kg, and the maximum COP was 1.51, 1.48, 1.45.
TOPICS: Refrigerants, Temperature, Cooling, Storage, Cycles, Energy consumption, Interpolation, Subcooling, Curve fitting, Compressors, Reservoirs, Fluctuations (Physics), High pressure (Physics), Refrigeration
Technical Brief  
Peiyong Ma, Baogang Wang, Shuilin Chen, Xianwen Zhang, Changfa Tao and Xianjun Xing
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040276
The gradient porous materials (GPMs)-filled pipe structure has been proved to be effective in improving the heat transfer ability and reducing pressure drop of fluid. A GPMs-filled pipe structure in which radial pore-size gradient increased non-linearly has been proposed. The field synergy theory and tradeoff analysis on the efficiency of integrated heat transfer has been accomplished based on performance evaluation criteria (PEC). It was found that the ability of heat transfer was enhanced considerably, based on the pipe structure, in which the pore-size of porous materials increased as a parabolic opening up. The flow resistance was the lowest and the integrated heat transfer performance was the highest when radial pore-size gradient increasing as a parabolic opening down.
TOPICS: Porous materials, Pipes, Heat transfer, Fluids, Flow (Dynamics), Performance evaluation, Pressure drop, Tradeoffs
Boudjema Omari, Amina Mataoui and Abdelaziz Salem
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040277
This work investigates numerically by finite volume method, the forced convection through a channel roughened by seven heated ribs arranged transversely. These ribs of rectangular cross section have a blocking ratio H/h = 10 and pitch ratio 3. The modeling the problem parameters are Reynolds number, ranging from 5480 to 68500, and the width of the first rib ranging from 0.5h to 15h. The objective of this study is to look for the width of the first rib which induces the best heat transfer. The flow configurations of identical ribs from the first one generate a large eddy spreading along the top of the two first ribs, blocking the flow of the first cavity. The widening of the first rib may solve this problem. This flow configuration is required in several engineering applications necessitating the flow periodicity starting from the first cavity. The effect of the width of the first rib is highlighted by velocity, pressure, turbulent kinetic energy and temperature profiles. Nusselt number distributions confirm that the widening of the heated surface is not recommended for improving heat transfer in spite of flow periodicity in all cavities (roughness d-type). The best improvement in heat transfer of 18%, compared to a smooth wall is obtained for thinnest first rib of L1/h=0.5. However, this configuration provides a minor heat exchange at the first pitch and the second rib, which might be a disadvantage for the material structure.
TOPICS: Flow (Dynamics), Cavities, Heat transfer, Turbulence, Eddies (Fluid dynamics), Kinetic energy, Reynolds number, Surface roughness, Engineering systems and industry applications, Forced convection, Modeling, Finite volume methods, Temperature profiles, Heat, Pressure
Chao Liang, Darshil Patel and Maulik Shelat
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040278
An axisymmetric transient heat transfer model with boundary conditions varying both in time and length dimensions has been proposed and solved to obtain the temperature evolution along the inner surface of a finned tube heated in a multi-zone continuous furnace. Experiments for finned tube heating were conducted using a single-zone tubular batch furnace and the experimental data obtained was compared with the simulation results to establish reasonable confidence in the proposed model and boundary conditions. A parametric study on several important operating parameters was conducted to gain better insights that can be used in making design and operating decisions. If required, the model can conveniently be extended to other types of substrates and furnace dimensions.
TOPICS: Modeling, Furnaces, Boundary-value problems, Dimensions, Design, Simulation results, Transient heat transfer, Heating, Temperature
Tasawar Hayat, Aneela Bibi, Humaira Yasmin and Fuad Alsaadi
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040282
This article scrutinizes the impact of thermal radiation and applied magnetic field on Jeffrey fluid with peristalsis. The effects of Joule heating and viscous dissipation are retained. Convective conditions are imposed for the heat and mass transfer analysis. Lubrication approach is considered for the analysis. Expressions for pressure gradient, stream function, temperature, concentration and heat transfer coefficient are developed and physically interpreted through illustrations. From obtained outcomes it is revealed that temperature enhances for higher estimation of Brinkman and Hartmann numbers while it decays for larger Biot number. Furthermore, the concentration decreases for varying Schmidth number. Heat transfer coefficient has an oscillatory behavior for larger estimation of radiation parameter.
TOPICS: Heat, Magnetic fields, Thermal radiation, Convection, Peristaltic flow, Heat transfer coefficients, Temperature, Mass transfer, Fluids, Radiation (Physics), Performance, Joules, Energy dissipation, Lubrication, Pressure gradient, Heating
Zhang Ligang, Xiao Fei Fu, Qu Si ning, Li Shi bin and Guan Bing
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040279
Wax deposition in oil pipelines brings a critical operational challenge in the oil development, and the indirect thermal washing is a most common and effective method of wax cleaning. The temperature field in thermal washing is the basis for making a reasonable plan to wash and remove wax well. In this paper, the wells of sucker rod pump in Da Qing oil field is selected as research objects, a new method which is based on heat-fluid coupling method is proposed for predicting temperature field during the thermal washing process. The temperature field of the annulus of tubing and casing, and rod and tubing are simulated with different thermal washing parameters. In the indirect thermal washing, the temperature in annulus of tubing and casing gradually decreases from wellhead to the bottom, while the temperature in the annulus of rod and tubing increases from bottom to the wellhead. With the increase of temperature and flow rate of thermal washing fluid, the temperature in annulus of tubing and casing, and rod and tubing are both increasing, but the rise rate is different at different depths. Compared to the measured results, the coincidences rate is in the range of 93.67%-99.31%. The research results can guide effectively the thermal washing operation.
TOPICS: Temperature, Computer simulation, Tubing, Annulus, Fluids, Wells, Flow (Dynamics), Heat, Pipelines, Pumps, Oil fields
Austin Phoenix and Evan Wilson
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040280
The novel adaptive thermal metamaterial developed in this paper provides a unique thermal management capability that can address the needs of future spacecraft. While advances in metamaterials have provided the ability to generate materials with a broad range of material properties, relatively little advancement has been made in the development of adaptive metamaterials. This metamaterial concept enables the development of materials with a highly nonlinear thermal conductivity as a function of temperature. Through enabling active or passive control of the metamaterials bulk effective thermal conductivity this metamaterial that can improve the spacecraft's thermal management systems performance. This variable thermal conductivity is achieved through induced contact that results in changes in the F path length and the conductive path area. The contact can be generated internally using thermal strain from shape memory alloys, bimetal springs, and mismatches in coefficient of thermal expansion or it can be generated externally using applied mechanical loading. The metamaterial can actively control the temperature of an interface by dynamically changing the bulk thermal conductivity controlling the instantaneous heat flux through the metamaterial. The design of thermal stability regions (regions of constant thermal conductivity vs. temperature) into the nonlinear thermal conductivity as a function of temperature can provide passive thermal control. While this concept can be used in a wide range of applications, this paper focuses on the development of a metamaterial that achieves highly nonlinear thermal conductivity as a function of temperature to enable passive thermal control of spacecraft systems on orbit.
TOPICS: Thermal conductivity, Metamaterials, Temperature, Thermal management, Space vehicles, Springs, Thermal expansion, Thermal stability, Heat flux, Passive control, Shape memory alloys, Materials properties, Design
Aritra Mukherjee and Pranab Mondal
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040283
This article deals with analysis of combined dual-phase-lag heat conduction and radiation in a concentric spherical enclosure with diffuse-grey surfaces. The enclosed medium is optically participating, i.e., it is radiatively absorbing, emitting and scattering. Lattice Boltzmann method is used to solve the energy equation and finite volume method is used to compute the radiative information. To establish the accuracy of this approach, the combined energy equation is also solved with finite difference method. Radial temperature profiles and energy contributions by conduction and radiation at transience and steady state are elaborated for different kind of thermal perturbations Influence of numerous conductive and radiative parameters over the heat transport process have been investigated in detail. It is observed that higher contribution of radiation to the heat transport process can destroy the thermal wave in the medium completely. Sample results for pure non-Fourier heat conduction, pure radiation and steady state response of combined Fourier conduction and radiation in spherical geometry are compared with the results available in literature. In all the cases, comparison shows good agreement with the reported results.
TOPICS: Radiation (Physics), Heat conduction, Heat transfer, Steady state, Transport processes, Heat, Lattice Boltzmann methods, Temperature profiles, Scattering (Physics), Waves, Radiation scattering, Electromagnetic scattering, Finite difference methods, Finite volume methods, Geometry
Zicheng Cai, Asad Ul Haq, Michael Cholette and Dragan Djurdjanovic
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040281
This paper presents evaluation of the energy consumption and tracking performance associated with the use of a recently introduced dual-mode model predictive controller (DMMPC) for control of a heating, ventilation, and air conditioning (HVAC) system. The DMMPC overcomes some key computational and stability limitations of traditional model predictive controllers (MPC) by requiring only a finite number of iterations for the underlying optimization and yet guaranteeing closed-loop stability. The study was conducted using detailed simulations of an HVAC system, which included a multi-zone air loop, a water loop, and a chiller. Energy consumption and tracking performance are computed from the simulations and evaluated in the presence of different types and magnitudes of noise and disturbances. Performance of the DMMPC is compared with a baseline PID control structure commonly used for HVAC system control, and this comparison showed clear and consistent superiority of the DMMPC.
TOPICS: HVAC equipment, Energy efficiency, Performance evaluation, Predictive control, Engineering simulation, Energy consumption, Stability, Control equipment, Simulation, Air conditioning, Ventilation, Noise (Sound), Optimization, Water, Heating
Myo Min Zaw, William D. Hedrich, Timothy Munuhe, Mohamad Hossein Banazadeh, Hongbing Wang, Stephen Andrew Gadsden, Liang Zhu and Ronghui Ma
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040134
We fabricated a polydimethylsiloxane (PDMS) cell culture plate using PDMS casting method with a mold printed by Fused Deposition Modeling (FDM) method and performed thermal analysis of the curing process to understand thermal damage to the mold at elevated temperatures. The cell co-culture plate is designed to study drug efficacy and toxicity simultaneously. Cell viability study indicates that the produced PDMS plate has the suitable biocompatibility, surface properties, and transparency for cell culture purposes. The mold printed from acrylonitrile-butadiene-syrene was reusable after curing at 65°C, but was damaged after being heated at 75°C, although both temperatures are far below the glass transition temperature of ABS. A heat transfer model was developed considering conduction, convection, and radiation in the oven to predict temperature distribution in the ABS mold during the curing process. The simulated temperature distribution was consistent with the observed mold deformation. As the maximum temperature difference in the mold did not change appreciably with the curing temperature, we speculate that temperature gradient is not the only cause of the observed thermal deformation. Air expansion in the porous structure at high temperatures may also be responsible for the damage. Therefore, in addition to low curing temperatures, reducing the porosity of the printed mold may help avoid thermal damage to the mold. With careful control of the curing process, the affordable and accessible fused deposition modeling method has great potential for fast prototyping of custom-designed cell culture devices for biomedical research.
TOPICS: Casting, Manufacturing, Plasma desorption mass spectrometry, Thermal analysis, Additive manufacturing, Hardening (Curing), Temperature, Damage, Temperature distribution, Modeling, Surface properties, Drugs, Glass transition, Ovens, Porosity, Transparency, Biocompatibility, Thermal deformation, High temperature, Biomedicine, Heat transfer, Radiation (Physics), Convection, Heat conduction, Deformation, Temperature gradient
Alexandra Mironova, Paolo Mercorelli and Andreas Zedler
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040135
Deformation-free clamping plays an important role in manufacturing systems towards zero-defect production. The fixture of workpieces during machining processes poses challenges not only for micro parts, but also for thin-walled pieces or freeform surfaces in the macro manufacturing. For this purpose, a new non-traditional adhesive technique, using frozen water to clamp, is introduced in this paper. By increasing the cooling power and thus decreasing the low temperature, higher clamping and holding forces and, therefore, a safer clamping system during machining process can be achieved. The objective of this investigation is to ensure a stable low temperature and to compensate thermal disturbances. Thanks to their structural robustness, Lyapunov based control strategies demonstrate an appropriate capability to achieve these results in real industrial applications. Model design as well as simulation and experimental results are shown and discussed.
TOPICS: Deformation, Cooling, Machining, Adhesives, Manufacturing, Simulation, Clamps (Tools), Design, Ice, Low temperature, Manufacturing systems, Robustness, Water, Thermoelectric coolers
Tasawar Hayat, Ikram Ullah, Ahmed Alsaedi and Saleem Asghar
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040032
The current research concentrates on melting heat transfer in MHD flow of Sisko fluid bounded by a sheet with nonlinear stretching velocity. Modeling and analysis have been carried out in presence of heat generation/absorption and magnetic field. Transformation procedure is implemented in obtaining nonlinear differential system. Convergence series solutions are developed. The solution for different influential parameters are analyzed. Skin friction coefficient and heat transfer rate are analyzed. It is observed that qualitative results of magnetic field and melting heat transfer on velocity are similar.
TOPICS: Magnetohydrodynamics, Heat, Heat transfer, Absorption, Melting, Stagnation flow, Magnetic fields, Skin friction (Fluid dynamics), Modeling, Fluids, Flow (Dynamics)
Samruddhi Deshpande, Bharath Viswanath Ravi, Jaideep Pandit, Ting Ma, Scott Huxtable and Dr. Srinath V. Ekkad
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4040033
Vortex generators have been widely used to enhance heat transfer in various heat exchangers. Out of the two types of vortex generators: Transverse vortex generators (TVGs) and longitudinal vortex generators (LVGs), LVGs have been found to show better heat transfer performance. Past studies have shown that the implementation of these LVGs can be used to improve heat transfer in thermoelectric generator systems. Here a built in module in COMSOL Multiphysics® was used to study the influence of the location of LVGs in the channel on the comprehensive performance of an integrated thermoelectric device (ITED). The physical model under consideration consists of a copper interconnector sandwiched between p-type and n-type semiconductors and a flow channel for hot fluid in the center of the interconnector. Four pairs of, LVGs are mounted symmetrically on the top and bottom surfaces of the flow channel. Thus, using numerical methods, the thermo-electric-hydraulic performance of the ITED with a single module is examined. By fixing the material size D, the fluid inlet temperature , and attack angle ß; the effects of the location of LVGs and Reynolds number were investigated on the heat transfer performance, power output, pressure drop and thermal conversion efficiency. The location of LVGs did not have significant effect on the performance of TEGs in the given model. However, the performance parameters show a considerable change with Reynold’s number and best performance is obtained at Reynold number of Re = 500.
TOPICS: Vortices, Generators, Heat transfer, Fluids, Flow (Dynamics), Temperature, Copper, Semiconductors (Materials), Reynolds number, Heat exchangers, Numerical analysis, Pressure drop, Thermoelectric devices
Technical Brief  
Subhashish Dasgupta, Anurag Nandwana and K RaviKumar
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4039927
Most oil-cooled equipment like transformers are provided with radiators or heat exchangers, for the heated oil to exchange heat with the surrounding air by natural convection cooling, assisting the overall cooling process. While such radiators are effective accessories in controlling equipment temperature rise, it is ever desirable to further enhance the cooling capacity by design modifications or incorporating simplistic and cost effective cooling technologies. In this study, computational fluid dynamic (CFD) analysis has been performed to evaluate the possibility of improving radiator performance by flow channelizing structures. Significant benefits (up to 17% increase in heat transfer coefficient) of imposing such structures, like a top chimney and an enclosure surrounding the radiator, were obtained. Although several past studies have confirmed that natural convection cooling effect can be intensified by flow channelization, the phenomenon is unique to a particular application. Given the wide variety in applications, in terms of shape, size and structural features, it is necessary to study the effect in a given application of interest. This study points to a new direction in enhancing cooling capacity of transformer radiators, inducing flow channelization, an easy to implement and cost effective technology. Further, the study offers interesting learnings regarding flow channelization effects, which are invaluable guidelines for designers of future radiators.
TOPICS: Cooling, Flow (Dynamics), Natural convection, Computational fluid dynamics, Design, Heat exchangers, Shapes, Heat transfer coefficients, Heat, Temperature
Kangil Choe, Jaeou Chae, Woon Yong Cheah and Sangkwon Na
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4039928
In order to improve low combustion efficiency of typical incinerators like a stoker type, a new unique cyclone combustor, Three-Way Swirling Combustion (TSC), is being introduced through a commercial scale pilot plant experiment for Refused Plastic Fuel (RPF). TSC provides air curtain insulation, substituting the refractory brick and lowering the generation of flying ash, for clinker prevention at the boiler. Its excellent emission measurement has also been reported. Through the study of three dimensionless numbers (Swirl Number, Strouhal Number, and Reynolds Number) and previous researches conducted on cyclone combustors, geometrical parameters, operational parameters and their design criteria have been identified and suggested for future designs.
TOPICS: Combustion, Solid wastes, Insulation, Swirling flow, Combustion chambers, Boilers, Design, Emissions, Dimensionless numbers, Fuels, Bricks, Reynolds number, Incinerators, Cement clinkers
Mohsen Ali Mandegari, Somayeh Farzad and Hassan Pahlavanzadeh
J. Thermal Sci. Eng. Appl   doi: 10.1115/1.4032332
TOPICS: Exergy, Optimization, Wheels

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