scholarly journals Hypothesis: Heat Transfer and Elementary Carriers of Heat Energy

2019 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Energy

Free convection of a hybrid nanofluid past a vertical plate embedded in a porous medium with anisotropic permeability

2019 ◽  
Vol 30 (8) ◽  
pp. 4083-4101 ◽  
Author(s):  
Aneela Bibi ◽  
Hang Xu ◽  
Qiang Sun ◽  
Ioan Pop ◽  
Qingkai Zhao
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Stability Analysis ◽  
Flat Surface ◽  
Saturated Porous Medium ◽  
Heat Energy ◽  
Hybrid Nanofluid ◽  
Anisotropic Permeability ◽  
Content Type ◽  
Hybrid Nanofluids

Purpose This study aims to carry out an analysis for flow and heat transfer of a new hybrid nanofluid over a vertical flat surface embedded in a saturated porous medium with anisotropic permeability at high Rayleigh number. Here the hybrid nanofluid is considered as the working fluid, with different kinds of small particles in nanoscale being suspended. Design/methodology/approach The generalized homogenous model is introduced to describe the behaviors of hybrid nanofluid. Within the framework of the boundary layer approximations, the governing equations embodying the conservation equations of total mass, momentum and thermal energy are reduced to a set of fully coupled ordinary differential equations via relevant scaling transformations. A flow stability analysis is performed to examine the behavior of convective heat energy. Accurate solutions are obtained by means of a very efficient homotopy-based package BVPh 2.0. Findings Results show that the linear correlations of physical quantities among the base fluid and its suspended nanoparticles are adequate to give accurate results for simulation of behaviors of hybrid nanofluids. Heat enhancement can be also fulfilled by hybrid nanofluids. A flow stability analysis suggests the heat-related power index m > −1/3 for satisfying the increasing behavior of convective heat energy. Originality/value Free convection of a hybrid nanofluid near a vertical flat surface embedded in a saturated porous medium with anisotropic permeability is investigated for the first time. The simplified hybrid nanofluid model is proposed for describing nanofluid behaviors. The results of this proposed approach agree well with those given by the traditional hybrid nanofluid model and experiment. It is expected that, by using different combinations of various kinds of nanoparticles, the new generation of heat transfer fluids can be fabricated, which possess similar thermal-physical properties as regular nanofluids but with lower cost.

Experimental Study of Cylindrical Latent Heat Energy Storage Systems Using Lauric Acid as the Phase Change Material

2012 ◽  
Author(s):  
Chang Liu ◽  
Robynne E. Murray ◽  
Dominic Groulx
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Storage Systems ◽  
Heat Energy ◽  
Hot Water ◽  
Energy Storage Systems ◽  
Water Flows

Phase change materials (PCMs) inside latent heat energy storage systems (LHESS) can be used to store large amounts of thermal energy in relatively small volumes. However, such systems are complicated to design from a heat transfer point of view since the low thermal conductivity of PCMs makes charging and discharging those systems challenging on a usable time scale. Results of experiments performed on both a vertical and a horizontal cylindrical LHESS, during charging, discharging and simultaneous charging/discharging, are presented in this paper. Both LHESS are made of acrylic plastic, the horizontal LHESS has one 1/2″ copper pipe passing through its center. The vertical LHESS has two 1/2″ copper pipes, one through which hot water flows, and the other through which cold water flows. Each of the pipes has four longitudinal fins to enhance the overall rate of heat transfer to and from the PCM, therefore reducing the time required for charging and discharging. The objective of this work is to determine the phase change behavior of the PCM during the operation of the LHESS, as well as the heat transfer processes within the LHESS. Natural convection was found to play a crucial role during charging (melting) and during simultaneous charging/discharging (in the vertical LHESS). However, during discharging, the effect of natural convection was reduced in both systems.

Exploration of Hands-On Discovery Pedagogy in Heat Transfer

2013 ◽  
Author(s):  
Thomas E. Diller ◽  
Chris Williams
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Problem Solving ◽  
Conceptual Understanding ◽  
Heat Energy ◽  
Concept Inventory ◽  
Heat Flux Sensors ◽  
Hands On ◽  
Authentic Problems ◽  
Transfer Principles

Recent research in the development of the “Thermal and Transport Concept Inventory” test (TTCI) has shown that, despite completing several related courses, students have significant misconceptions of heat transfer principles such as the differences between heat, energy and temperature. This lack of conceptual understanding limits students’ problem-solving abilities (and thus their transition to expertise) and their ability to transfer knowledge to other courses and contexts. This research demonstrates how this problem can be addressed by integrating hands-on workshops into a traditional heat transfer lecture course. The workshops are designed to actively engage students in exploration and discovery using authentic problems. Using heat flux sensors allows students to physically observe abstract phenomena that cannot be easily observed.

Assessment of Heat Transfer Effectiveness: Application to Shell Bitumen Plant, Takoradi, Ghana

2008 ◽  
Author(s):  
Anthony Simons ◽  
Solomon Nunoo
Keyword(s):  
Heat Transfer ◽  
Heat Losses ◽  
Heat Energy ◽  
Fuel Oil ◽  
High Rate ◽  
Liquefied Petroleum Gas ◽  
Temperature Range ◽  
The Face ◽  
Selection Of ◽  
Current Heat

At Shell Bitumen Plant, Takoradi, Beverley Thermal Fluid Heater (BTFH) generates heat energy to heat thermal fluid (Thermia B) which flows through heat exchanger and then heats bitumen which is to be maintained at temperature range of 140 °C to 160 °C before it is discharged. High rate of heat losses have been observed and in order to maintain the temperature range of bitumen at (140 °C to 160 °C), a lot of heat energy is needed to be generated which means higher fuel consumption for BTFH. Industrial fuel oil is used to fuel the BTFH. This paper assesses the existing insulation system on the plant and seeks to improve on it so as to cut down heat losses. Consequently, the work looked at the estimation of heat losses, selection of materials for heat transfer and lagging purposes. In this wise, the existing laggings were modified by introducing fibreglass between the asbestos and masonry and thus reducing the current heat lost by 78%. Heat from the exhaust gas which would have otherwise, gone wasted, was utilised by redesigning the chimney and this yielded 0.868 kW of heat energy to aid the heating of the bitumen. In the face of rising cost of fuel and taking cognizance of the fact that cheaper natural gas and liquefied petroleum gas could be produced in Ghana, it is recommended that the heater should be fueled by either of these gases.

A Heat Transfer Model of Grinding Process Based on Energy Partition Analysis and Grinding Fluid Cooling Application

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Guoxu Yin ◽  
Ioan D. Marinescu
Keyword(s):  
Heat Transfer ◽  
Contact Area ◽  
Frictional Resistance ◽  
Heat Transfer Model ◽  
Heat Energy ◽  
Grinding Wheel ◽  
Transfer Model ◽  
Grinding Process ◽  
Energy Partition ◽  
Grinding Fluid

In the grinding process, high temperature in grinding area is generated by the frictional resistance between workpiece and abrasive grains on the grinding wheel cylindrical surface. Grinding fluid application is an optimal option to reduce the thermal effect and crack on the workpiece ground surface. In this paper, a grinding process heat transfer model with various grinding fluid application is introduced based on computational fluid dynamics (CFD) methodology. The effect of specific heat, viscosity, and surface tension of grinding fluid are taken into account. In the model, the grinding contact area is considered as a heating resource. Most of the heat energy is conducted into the workpiece. The rest of the energy is taken away by the grinding wheel, grinding fluid, and chips. How many percentage of the generated heat is conducted into the workpiece is a key issue, namely, the energy partition ratio ε. An energy partition equation is introduced in this paper with the cooling effect of different grinding fluid. Generated heat energy based on the calculation from energy partition equation is applied on the grinding contact area in the heat transfer model.

scholarly journals Heat transfer analysis in fluidized bed dryer with heat exchanger pipe for corn material

2021 ◽  
Vol 913 (1) ◽  
pp. 012039
Author(s):  
Sukmawaty ◽  
G M D Putra ◽  
I Asmoro ◽  
S Syahrul ◽  
M Mirmanto
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Fluidized Bed ◽  
Pipe Flow ◽  
Heat Energy ◽  
Heat Transfer Analysis ◽  
Air Velocity ◽  
Fluidized Bed Dryer ◽  
Air Speed ◽  
Flow Treatment

Abstract This research aims to know the heat transfer process on the fluidized bed dryer for corn material. In this study conducted observations on the temperature and heat produced during the drying process, with three different pipe heat exchanger: spiral, parallel, and combination; The air of the air was 2 m/s, 4 m/s, and 6 m/s and the mass of corn material was1.5 kg with an initial moisture content of 24%. Test results showed that the highest-produced temperature in the combination heat exchanger pipe with a drying room temperature averaged 54°C. The value of the highest convection coefficient of heat transfer in the combination heat exchanger pipe flow treatment with the air velocity of 6 m/s by 29.4 W/m2K. The heat energy that enters at the treatment of combination heat exchanger pipe with the air speed of 6 m/s by 1774 Watts. Heat energy is lost through the highest wall drying chamber at the combination heat exchanger pipe flow treatment with the air velocity of 6 m/s by 409 Watts. The heat energy used is 335 Watts to dry the highest material in the combination heat exchanger pipe flow treatment with the air speed of 6 m/s.

Novel Multifunctional Composites by Functionally Dispersed Carbon Nanotubes Throughout the Matrix of Carbon/Carbon Composites

2008 ◽  
Author(s):  
Mohamed S. Aly-Hassan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Carbon Fiber ◽  
Carbon Matrix ◽  
Heat Energy ◽  
Carbon Composites ◽  
Multifunctional Composites ◽  
Infrared Measurements ◽  
The Matrix

Recently, increasing demands for smarter and smaller products calls for the development of multifunctional composites. These materials are used not only as structural materials but also satisfy the needs for additional functionalities such as thermal, electrical, magnetic, optical, chemical, biological, etc. In this research, a novel carbon nanotubes dispersion approach leads to a new generation of multifunctional composites with additionally novel thermal functionality, we called it heat-directed functionality. These distinctive composites have unique capability which can conduct the majority of the transferred heat by conduction to the preferred area or direction of the thermal structure. This unique heat-directed property can be attained by varying the in-plane thermal conductivity. Varying the in-plane thermal conductivity of the composites functionally is achieved by dispersing highly heat-conductive materials such as carbon nanotubes throughout the matrix functionally, not uniformly. Therefore, in this research three phase carbon/carbon composites have been fabricated with functionally dispersed carbon nanotubes throughout the carbon matrix of continuously plain woven carbon fiber fabrics in order to attain this useful property. The fabricated heat-directed carbon/carbon composites have been examined experimentally and numerically. The in-situ full-field infrared measurements and finite element analysis of the designed composites showed that the heat transfer direction can be substantially controlled by just functionally dispersed a few percentages of carbon nanotubes through the matrix of traditional long carbon fiber-reinforced carbon matrix composites. This exceptional property can play a significant performance improvement in heat transfer process along the in-plane of the materials as well as helping to decrease the heating up of the Earth, global warming, due to the escaped heat of many engineering applications. In other words, the efficient heat energy management or heat energy saving via using the introduced multifunctional carbon/carbon composites with heat-directed functionality can significantly help with both sides of the equation of efficient energy consumption and friendly-environment applications.

Radiofrequency Thermal Ablation Heat Energy Transfer in an Ex-Vivo Model

2017 ◽  
Vol 83 (12) ◽  
pp. 1373-1380 ◽  
Author(s):  
Shivani Thakur ◽  
Sandi Lavito ◽  
Elizabeth Grobner ◽  
Mark Grobner
Keyword(s):  
Heat Transfer ◽  
Energy Transfer ◽  
Ex Vivo ◽  
Heat Energy ◽  
Tissue Temperature ◽  
Ex Vivo Model ◽  
Temperature Changes ◽  
Ablation Therapy ◽  
Heat Degradation ◽  
Human Calf

Little work has been done to consider the temperature changes and energy transfer that occur in the tissue outside the vein with ultrasound-guided vein ablation therapy. In this experiment, a ex-vivo model of the human calf was used to analyze heat transfer and energy degradation in tissue surrounding the vein during endovascular radiofrequency ablation (RFA). A clinical vein ablation protocol was used to determine the tissue temperature distribution in 10 per cent agar gel. Heat energy from the radiofrequency catheter was measured for 140 seconds at fixed points by four thermometer probes placed equidistant radially at 0.0025, 0.005, and 0.01 m away from the RFA catheter. The temperature rose 1.5°C at 0.0025 m, 0.6°C at 0.005 m, and 0.0°C at 0.01 m from the RFA catheter. There was a clinically insignificant heat transfer at the distances evaluated, 1.4 ± 0.2 J/s at 0.0025 m, 0.7 ± 0.3 J/s at 0.0050 m, and 0.3 ± 0.0 J/s at 0.01 m. Heat degradation occurred rapidly: 4.5 ± 0.5 J (at 0.0025 m), 4.0 ± 1.6 J (at 0.0050 m), and 3.9 ± 3.6 J (at 0.01 m). Tumescent anesthesia injected one centimeter around the vein would act as a heat sink to absorb the energy transferred outside the vein to minimize tissue and nerve damage and will help phlebologists strategize options for minimizing damage.

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