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Pipes in heat exchanger systems are usually made of metallic materials to achieve a high level of thermal conductivity and thus high efficiency. However, substitution with polymer materials has a great potential. Plastics save weight, can be produced at lower cost and emissions, and are ideal for use in corrosive or chemically aggressive environments, where most metals fail. The challenge, however, is their much lower thermal conductivity in comparison. To reduce this disadvantage, fillers are used to transport thermal energy through the less conductive polymer matrix. In fact, high filler ratios are required to achieve an acceptable level of thermal conductivity for heat exchanger systems. However, these high filler ratios have a significant impact on the material properties of the polymer, such as the flexibility, which is drastically reduced. The result is a brittle material with limited suitability for use in heat exchanger systems. This paper describes a novel approach to effectively increase the thermal conductivity of polymer materials by optimizing the orientation of anisotropic filler particles by die design. Standard pipe extrusion dies result in continuous shear forces in the direction of extrusion. Accordingly, the resulting filler network has a higher thermal conductivity in the axial direction of the pipe than radially through the pipe wall. However, radial heat transfer is essential in pipe heat exchanger systems. To improve this, various die designs for targeted radial alignment of filler particles are discussed in this paper. Furthermore, the potential for improvement of the die designs is investigated. So far, the most efficient die design achieves an increase in thermal conductivity of up to 74 % compared to a standard pipe extrusion die. [ABSTRACT FROM AUTHOR]

Heat exchangers are a common heat transfer mechanism used in a variety of applications ranging from home to industrial, aircraft, and vehicles. The aim of this research is to study the hydrothermal efficiency of a double pipe heat exchanger with helical fins on annular side of counter flow heat exchanger numerically and compare the results of a double tube with and without screw tape. The investigation begins by employing numerical modeling of helical tapes under different configurations, with different pitches (10, 15, and 20) mm and one height of 10 mm as passive heat transfer augmentation strategies, which are simulated using ANSYS 2022 R1 software. The findings reveal that the current work's numerical results and earlier research's experimental findings are in good accord. Furthermore, while using (Helical Tap Insert) (HTI), the thermal performance of the new typical is found to be better than the typical model. Furthermore, it was found that the Nusselt number achieves the highest growth when the pitch (p) is (20) mm and increases the pressure drop. Furthermore, it was discovered that when the pitch (p) is (20) mm and pressure drop is increased, the Nusselt number grows the most. Furthermore, as associated to the typical model, the total thermal effectiveness of heat exchanger for the new model has greater by 9.9%. This difference is due to the fact that in the theoretical study, ideal conditions are assumed. The experimental design, the assumptions, operating circumstances, and accuracy of the devices are taken into account. It was noted that the value of the specified percentage of hydrothermal improvement achieved the highest value in performance for the same case that was with spiral fin and pitch length (20) mm, which is 1.6% compared to the traditional model. [ABSTRACT FROM AUTHOR]

Photovoltaic thermal, (PV-T) collector is hybrid collector utilized to convert solar rays to usable electrical as well as thermal energy. Lately, the research field on PV-T has focused on enhancing the PV-T collector efficiency via substituting conventional fluids as heat transfer medium with different types of nanofluid. This paper investigated the outcome of a mixture of hybrid nanofluid on useful outcome energy and the gained efficiency of PV-T collector by using a specific fractions of Al2O3-SiC-TiO2 nano particles with water as a cooling fluid. The work showed that at a mixture ratio of volume fraction of ternary hybrid nanofluid with an equal proportion of each component (0.4 vol. fraction), the electrical as well as the thermal efficiencies of PV-T collector at using Al2O3-SiC-TiO2)/water nanofluid are12.83% and 78.7%, respectively. Also, the cells temperatures drop by 15ᵒC with a volume flow-rate 4 L/m of Al2O3-SiC-TiO2/water nanofluid. This study concludes that by utilizing Al2O3-SiC-TiO2/water nanofluid an overall maximum thermal efficiency could reach to 85.3%, and this present 39.7% enhancement the collector performance compared to using pure water. A 42% improvement in electrical efficiency was also observed compare to that of uncooled PV panel efficiency. [ABSTRACT FROM AUTHOR]

The paper presents the efficient parallel algorithms for solving the heat equations for the permafrost models. By using the finite difference scheme, we transform the Stefan problem into the problem of solving multiple systems of linear algebraic equations. These systems have tridiagonal coefficient matrices and are solved by the sweep method. On the base of the parallel algorithms, we developed the codes for multicore CPU with OpenMP technology and for GPU with CUDA technology. The novel approach was proposed to achieve the efficient memory access patterns. Numerical experiments show that our new code is up to 2x faster than the previous one, and the GPU implementation achieves a tenfold speedup compared to the serial CPU code. [ABSTRACT FROM AUTHOR]

The experimental process carried out in this paper is to determine the convection heat transfer coefficient, overall heat transfer coefficient, and nanofluid heat transfer rate based on DWCNT (double-wall carbon nanotube) nanotubes applied to a shell and tube heat exchanger. The advantage of using DWCNT nanoparticles is the high thermal conductivity value. The volume fractions of nanoparticles were 0.1%, 0.3%, and 0.5% with the addition of PVP surfactant. Experimental tests were conducted to determine the heat transfer performance applied to a shell and tube type heat exchanger with upright baffles. This study aims to improve the heat transfer performance by utilizing nanofluids based on DWCNTs nanoparticles. As a result, using DWCNT nanofluids instead of base fluids increases the convective heat transfer coefficient values and overall heat transfer. The increase in the volume fraction of DWCNTs nanoparticles is also accompanied by an increase in the heat generated. The highest thermal conductivity was obtained by adding 0.5% volume of DWCNTs nanoparticles, which was 0.640 W/m.K. The highest heat transfer rate was produced by adding 0.5% volume fraction and 0.02% PVP with a result value of 70.191 W. [ABSTRACT FROM AUTHOR]

The present paper studies the scientific investigation of heat convection and mass transmission of flow past through exponentially expedite parabolic motion effects over a upright plate through cross diffusion and taking an account of the soret and dufourimpacts. The fluid past a dramatically quickened boundless isothermal plate is vertical in the presence of time, flexible heat and mass are elevated linearly has been considered. Utilizing explicit finite difference technique, the undimensioned principal equations are explained graphically through the profiles of velocity,temperature and concentration for pertinent measures of skin-friction, Sherwood number and Nusselt number. [ABSTRACT FROM AUTHOR]

This paper aims to improve the thermal performance of Closed loop pulsating heat pipe (CLPHP) with nanofluid fused with refrigerants. In this paper, the thermal studies were carried out by SWCNT and MWCNT nanofluids fused with R-134a. Experimentation was conducted at 10W heating power and 90° inclination angle, temperature difference from evaporator and condenser were validated. Results indicate that using nanofluid fused with R-134a, could improve the thermal performance of heat pipes. And the readings were taken every two minutes. And the obtained result was plotted to and the result shows the addition of CNT nanofluid to the refrigerant improves the Thermal performance of the closed-loop heat pipe (CLPHP). Compare to SWCNT, MWCNT with R-134a shows better heat transfer and improve the cooling capacity. [ABSTRACT FROM AUTHOR]

This paper explores the characteristics of heterogeneous reactions occurring during the release of gas bubbles upon contact with a solid reducing agent. The investigation considers the hydrodynamics and heat/mass transfer features involved in the reduction reaction within the coke zone of an ore-thermal furnace. The complexity arises from the presence of a gas phase bubbling through the melt. The conditions created by the formation of bubbles enhance mixing, thereby activating chemical and metallurgical reduction processes. A fundamental element of the reaction involves the reagent actively diffusing due to vigorous mixing, causing a transition of the reduction process into the kinetic domain. Key considerations at this juncture encompass the temperature within the reaction zone and the concentration of the reagent. The interplay of the reduction reaction and the creation of gas bubbles affects the development of convective currents, with their formation being influenced by both temperature and reagent concentration. [ABSTRACT FROM AUTHOR]

This paper presents the desired characteristics of adsorbent and adsorbate in adsorption cooling system. The development of competitive market ready adsorption chiller is hindered by the physics of the adsorbent-adsorbate pairs, the main component of this cooling system. A breakthrough is required to produce adsorbent-adsorbate pairs with superior characteristics. The adsorbent-adsorbate pair must have low heat of adsorption compared to the latent heat of vaporization of refrigerant. The adsorbent uptake must be sensitive to its temperature, to reduce energy usage for sensible heating during transition from adsorption to desorption phase. An increase on the rate of adsorption and desorption must be accompanied by increase in rate of heat transfer to make sure optimum performance can be achieved. For a quick assessment on performance of adsorbent, refrigerant and heat exchange surface, adsorption calorimeter could be used. [ABSTRACT FROM AUTHOR]

In the present paper the steady two-dimensional MHD viscous flow through a heated two region vertical channel with the occurrence of chemical reaction and radiation has been considered. It has been assumed that the channel contains two regions, one is clear region and other is occupied with porous material. Channel boundaries are set on fixed distance but temperature and concentration of fluid at boundaries are different. The governing equations of the velocity, temperature and mass transfer are derived, and their closed-form results are also obtained. With the effect of radiation, Reynolds number and chemical reaction coefficient, velocity can be slower. The temperature of the fluid can be reduced in both regions by using thermal radiation and increasing thermal conductivity ratio. In addition, shear stress, rate of heat transfer and rate of mass transfer are also calculated for pertained flow constraints. The current problem is also very useful in many areas of geothermal engineering. [ABSTRACT FROM AUTHOR]

The impact of various types of G-jitter on the stability of Oldroyd-B nano-liquid filled in Hele-Shaw cell are investigated in this study. The Oldroyd-B liquid model is significant because of its many applications, including the production of plastic sheets, biological solution pant tars glues, and so on. In the present paper, we observed the Nusselt number on heat transfer for fluid and particle phases and mass transportation for non-linear stability exploration. Both Mathematica NDSolve and RKF-45 methods are used to analyze heat/mass transportation in the region, with the result that they both yield exactly the same heat/mass transportation rate. Consequently, the RKF-45 method has verified that all Mathematica NDSolve solutions are converging. In heat and mass transfer, the Deborah number, retardation parameter, G-jitter, and H-S number all play significant roles. Heat/mass transportation in the region is improved by increasing the amount of the Deborah number, while raises the Hele-Shaw number reduces heat and mass transportation in the region. As the retardation parameter is increased, the heat and mass transportation in the system reduces. [ABSTRACT FROM AUTHOR]

Solar energy is one of the most widely used renewable energy sources. Various collectors were made, tested, and refined to perform in various temperature ranges. The parabolic trough solar collectors (PTC) are the most frequent in steam production and heat process applications. The receiver tube is the heating element and a crucial device (PTC) component. Many studies have focused on improving the thermal efficiency of receiver tubes. A detailed evaluation of the experimental and numerical investigations carried out to improve heat transmission in receiver tubes in four different ways. 1. Use to reduce heat loss (glass cover, selective coating, and evacuated tube) 2. They increase the heat transfer coefficient by using (turbulent flow, Nanofluid, and different gaseous). 3. Increase the surface area of heat transmission using (fins, porous material, surface modification). 4. Combine two or more of these methods. The aims of the current review papers is to improve heat transfer in the receiver tube and reduce heat loss, resulting in improved heat transfer to the thermal fluid. [ABSTRACT FROM AUTHOR]

The paper presents results from the investigation of heat transfer through six types of face masks and respirators used for protection against particulate matter (PM) and virus transmission. The masks/respirators were studied in terms of the number of layers, thickness, mass per unit area (weight) and bulk density. The heat flow through the masks was measured in two directions: from the human face to the environment (In-Out) and from the environment to the face (Out-In). The results obtained were presented in the function of the samples' thickness, mass per unit area and bulk density. A strong relationship between the mask's thickness and its heat resistance was established. [ABSTRACT FROM AUTHOR]

The use of externally bonded Fiber Reinforced Polymer (FRP) systems is becoming more relevant due to their superior performance in many structural applications. However, fire or elevated temperature exposure is a major concern for FRP systems due to the deterioration of the epoxy adhesive. This paper investigates the fire performance of unstrengthened and Carbon FRP (CFRP) strengthened Reinforced Concrete (RC) columns with and without fireproofing insulation. Four columns were modeled using the finite element software package ABAQUS to carry out the heat transfer analysis. All four columns were exposed to fire according to the ASTM E119 standard fire curve with an exposure period of three hours. The temperature-time curves were plotted 50 mm deep into the concrete, and 100 mm deep into the concrete, and at the longitudinal reinforcement. The results showed no noticeable improvement in the fire performance of RC columns with the addition of CFRP layers, where the temperature readings were almost the same. However, the use of the fireproofing insulation significantly affected the fire performance where the temperature at different times was significantly lower for the insulated columns compared to the uninsulated columns. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cell systems are a novel concept for combined heat and power (CHP) generation with high total efficiency and low emissions of harmful gases. In order to successfully review the operational processes of such a system, thermodynamic analyses are normally employed. The aim of this paper is to propose a SOFC system topology based on a preselected SOFC and determine the heat transfer rates as well as the overall efficiency of the plant by means of a mathematical model. The results indicate a total system efficiency of 0.628 without evaluating the energy available from the combustion of the remaining anode off-gas (AOG). Analysis of the effects of the steam to carbon (S/C) ratio on the system's behavior and outcomes is also performed. The analysis reveals that increasing the S/C ratio of the system leads to a decrease in the electrical efficiency, while the total efficiency of the system experiences a slight increase. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study on the use of oscillatory flow mechanisms to enhance turbulent incompressible heat transfer within a circular tube. Simulations were performed to analyze the effect of oscillations on heat transfer. Simulations were first performed at a steady-state (at Re=12500) to serve as a basis for comparison with the time-accurate oscillation results. The objective of the study proposes the best dimensions of VG as a function of the thickness of the Stokes boundary layer, which enhances the effective thermal conductivity of the fluid. The results showed that the improvement in the heat transfer process in the steady state is better than the improvement in the unsteady state. [ABSTRACT FROM AUTHOR]

To get the OTTV value, you must first calculate the solar radiation value. Solar radiation occurs as a result of the sun's heat being exposed to the surface of the building and then goes inside so that the air temperature inside the building gets hotter. The solar factor is one of the elements of solar radiation which is important in determining the overall thermal transfer value for each outer area of a building. The availability of solar factor data in one place is very important to use for building design purposes. Calculating the solar factor is very difficult, moreover, SNI only contains data for the city of Jakarta. There are several ways to calculate the solar factor, with available SNI tables or by laboratory experiments or direct measurements of sunlight. So to make it easier for the designer, we propose to use the rule of thumb formula. The method used is based on local solar factor data, then a radian angle is made from 0 ° -360 °, which results in an ellipse shape in an equation. This paper concludes that the Rule of thumb formula is very helpful for architects in calculating the SF value and can also complete the table in SNI: 2011, which only contains the SF value for the city of Jakarta, meaning that it only applies in Jakarta, so similar research is needed to get the SF value for other cities in Indonesia. [ABSTRACT FROM AUTHOR]

The mass transfer process in the single and binary mixture cases are very high comparing the multi-component mixtures. In the multicomponent there is a very strong relationship between the Heat and Mass transfer which limits the evaporation process rate. This paper is an attempt to shed some light on the previous researches and the correlations that were given in pool boiling of the ternary mixtures. [ABSTRACT FROM AUTHOR]

With the advancement of computational facilities, the hybrid methods gained popularity in last two decades for solving the inverse heat transfer problems (IHTP). The current paper gives a brief review about the hybrid methods used for solving IHTP. A hybrid inverse algorithm can be formed by coupling two algorithms which could be either stochastic od deterministic. Different IHTP like inverse conduction problems, inverse convection-diffusion problems, and inverse radiative heat transfer problems were considered. The hybrid algorithms successfully applied for the estimation of boundary conditions, simultaneous estimation of unknown parameters, physical properties of materials, estimation of surface properties of radiative surfaces as well as estimation of mass transfer characteristics. The hybrid algorithms are found to be more accurate and more computationally economical than the single inverse algorithms. In initial era of hybrid algorithms, the stochastic algorithms are coupled with deterministic algorithms but with increasing the computational power and versatility in stochastic algorithms, more and more stochastic algorithms are coupled to form hybrid algorithms. With proper tuning, structure and training, the hybrid algorithm can be very versatile and accurate for solving IHTP. [ABSTRACT FROM AUTHOR]

The localization of heat in the machining zone of hard to cut materials leads to tool wear and increased surface roughness. Cutting fluids are used to minimize these effects, but their use is discouraged due to their detrimental effects on human health and environment. One of the potential solutions to reduce the use of cutting fluids is surface texturing on machining tools. Available literatures have mainly focused on tool wear reduction aspect only and there is a literature gap regarding quantitative analysis of the enhancement in cooling rates. In this paper an iterative numerical approach using DEFORM-3D and Ansys-Fluent has been discussed to understand the heat transfer phenomenon on textured tools. Results show that the heat transfer coefficient has increased by 32% with textured tool at moderate to high Reynolds number. The average cutting tool tip temperature dropped by 100°C due to tool-chip contact length reduction and increased heat dissipation. [ABSTRACT FROM AUTHOR]

The convection-diffusion-reaction equation is one of the most useful equations in predicting many physical and chemical phenomena such as heat transfer, chemical species transport and reaction and the pollutants adsorption in wastewater. The widely used Upwind Forward Euler method may produce a negative solution because a time step size value is more than 0.005 and may form numerical oscillations. An improvement in the proper selection of time step size values is suggested, which removes the numerical oscillation and significantly improves the accuracy and convergence of the solution. In this paper, we add two explicit finite difference methods: Forward Time Central Space (FTCS) and Lax-Friedrichs, together with the previous method, Upwind, to solve the convection-diffusion-reaction equation with the improvement of time step size. An example is drawn from the literature to test the results of the numerical methods. The exact solution is used for comparison. Finally, the Upwind method solves the convection-diffusion-reaction problem satisfactorily with the restricted time step size, while the FTCS and Lax method form unstable solutions and thus causes the methods to be inapplicable for solving the convection-diffusion-reaction equation. [ABSTRACT FROM AUTHOR]