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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]

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]

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 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 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 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 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 this paper investigation numerically varies shape perforated area on enhancement in heat transfer was investigated along two-pass ribbed channel with internally of two-phase flow. Ribs have a curved shape with two cases. In this paper investigation numerically the effects of shape perforated area on enhancement in heat transfer was investigated along two-pass ribbed channel with internally of two-phase flow. Ribs have a curved shape with two cams with perforated same areas with various shapes; triangle, square, circle areas and comparison with solid case. The study performed at same conditions for all cases, of water & air velocities are (0.1684m/s) & (2.193m/s), respectively. Numerical simulation by ANSYS FLUENT 2021 R1 employed to study the heat transfer enhancement. The results showed that the circle area have high turbulence to increase enhancing in heat transfer coefficients in compared with other cases. However, the pressure decreased with ratio of passing from inlet to outlet ribbed region through bend region (S) to Hydraulic diameter (D) in ribbed region but in bend region a sharply in triangle and square cases decreased in pressure lead to increase pressure drop and increased losses. The percentage of enhancing heat convective was around (25% in case of square perforated area, 29% in triangle perforated area, 35% in circle perforated area) in comparison with solid curved ribs. [ABSTRACT FROM AUTHOR]

The main problem with food delivery service is its long distance. The longer time for food delivery will affect the food's freshness. This paper contributes to utilizing heat energy from motorcycle exhaust for food warming containers. The exhaust energy maintains the temperature of the food delivery container using a heat exchanger concentrically attached to the exhaust pipe. The medium for heat transfer uses water which is closely circulated from the food container and heat exchanger. The analysis was carried out using fluent ANSYS with a kappa-epsilon turbulence model with variation velocity of the inlet flow (0.18 m.s−1, 0.36 m.s−1, 0.54 m.s−1, and 0.72 m.s−1). The initial temperature of the box was 300 K, and the inlet temperature of the box was 333 K. The computation results showed that the higher velocity of inlet flow affects the higher Reynold number. It indicates the greater turbulence of fluid inside the system. The greater turbulent flow enhances the heat transfer rate between the water and the walls of the box. [ABSTRACT FROM AUTHOR]

In this paper, we study the investigation of the properties of a nonhomogeneous double nonlinear heat transfer equation in various media with respect to density and source. It is proved that for a given equation, the parameter values exist and have a numerical solution. The system of equations considered in this paper is based on most physical processes, for example, the reaction-diffusion process in this system, thermal conductivity, polytrophic filtration of gas and liquid in nonlinear media is described by a source. There are a lot of partial solutions to this equation. One of the main methods of studying the problem under consideration is the construction of an integral self-model solution. To do this, initially, when constructing a system of self-similar equations, a nonlinear subtraction method was used. The following results were obtained from this work: the front for the equation of nonlinear heat generation with doubled energy was estimated, the localization process was observed, new effects were observed, an algorithm was constructed in accordance with the obtained self-similar solution, a program code was created in the programming language, and the process modeling was visualized. [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]

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]

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 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]

Reaching the maximum level of the users' comfort in the building is an important role. At the same time, it is vital to have occurred minimum negative environmental effects. Having an atrium as a popular area in the building needs to investigate thermal performance. This paper finds out the effects of the floor heigh into the internal condition as the liner atrium with optimum shading device during the warm period. This paper illustrated the different results according to the atrium building height as floor numbers including 1, 3, and 5 floors in Famagusta, North Cyprus climate. As finding in all building height simulation models in August is the maximum discomfort condition month and maximum cooling loads as air-conditioning system, because of internal building gained and ventilation gains, (single floor Qz between 330 to-330 watts, Qv:-2000 to 2000 watts), (three floors Qz between 1200, 2200 watts to-1200,-2200 watts, Qv:-7000 to 7000 watts), and (five floors Qz between 2000, 4500 watts to-2000,-4500 watts, Qv:-12000 to 12000 watts) however, the optimum shading device as 35% over the south external facade of atrium applied but the fully air-conditioned is necessary especially from morning to afternoon time. It found that, while the floor height of the total building and atrium height increased, heat transferring massively occurred during morning time especially as passive performance. [ABSTRACT FROM AUTHOR]

Reaching the maximum level of the users' comfort in the building is an important role. At the same time, it is vital to have occurred minimum negative environmental effects. Having an atrium as a popular area in the building needs to investigate thermal performance. This paper finds out the effects of the floor heigh into the internal condition as the liner atrium with optimum shading device during the warm period. This paper illustrated the different results according to the atrium building height as floor numbers including 1, 3, and 5 floors in Famagusta, North Cyprus climate. As finding in all building height simulation models in August is the maximum discomfort condition month and maximum cooling loads as air-conditioning system, because of internal building gained and ventilation gains, (single floor Qz between 330 to-330 watts, Qv:-2000 to 2000 watts), (three floors Qz between 1200, 2200 watts to-1200,-2200 watts, Qv:-7000 to 7000 watts), and (five floors Qz between 2000, 4500 watts to-2000,-4500 watts, Qv:-12000 to 12000 watts) however, the optimum shading device as 35% over the south external facade of atrium applied but the fully air-conditioned is necessary especially from morning to afternoon time. It found that, while the floor height of the total building and atrium height increased, heat transferring massively occurred during morning time especially as passive performance. [ABSTRACT FROM AUTHOR]

Heat exchanger is one of the key components for process-heat transfer application in industries. Heat transfer process is time variant, nonlinear and is subjected to disturbances due to fluid flow and reactions. To effectively control the entire process, intelligent and cognitive controllers are being employed due to their self-learning and adaptation properties. BELBIC is a bio-inspired process imitating the behaviour of limbic system of mammalian brain. In this paper a generalized approach for the formulation of BELBIC parameters is presented. The focus of the paper is on design of BELBIC and formulation of nonlinear emotional cues for process control, proposed emotional cues has high capability of adaptation, to improve the system performance in terms of transient and steady state performance. The steady state performance is improved by a factor of 10 with non-linear ECs. Performance measure of ISE is minimum with and without disturbances in the process of heat exchanger control, as compared to PID and existing controllers. [ABSTRACT FROM AUTHOR]

Taking advantage of the potential of daylighting in the building helps to save energy used for artificial lighting. In Russia and other countries, where most of the energy is consumed for heating in winter, the increased window area leads to a reduction in the energy costs of artificial lighting but increases the heat loss through the windows blocks. Some studies contain criteria for assessing the feasibility of increasing the area of window, however, the influence of artificial light sources have not included. In this paper, the thermal balance of the room is considered, including the influence of artificial light sources, heat gain from solar radiation and transmission heat loss through window blocks. By calculating the difference in the thermal balance of the room after and before the increase in the window area, an expression of the criterion for evaluating the benefits of increasing the window area by energy indicators was obtained. Based on the cost of heat and electricity, the expression of the criterion for assessing the benefits of economic indicators was proposed. According to the presented criteria, the calculation for different function spaces: residential, office and school classes designed for Moscow was carried out. It is shown that, according to energy indicators, an increase in the window area is unprofitable or low profitable for residential and office premises, but beneficial for the school class. In conclusion, the paper shows the possibility of evaluating the energy efficiency of increasing the area of the window using the developed criteria. [ABSTRACT FROM AUTHOR]

Taking advantage of the potential of daylighting in the building helps to save energy used for artificial lighting. In Russia and other countries, where most of the energy is consumed for heating in winter, the increased window area leads to a reduction in the energy costs of artificial lighting but increases the heat loss through the windows blocks. Some studies contain criteria for assessing the feasibility of increasing the area of window, however, the influence of artificial light sources have not included. In this paper, the thermal balance of the room is considered, including the influence of artificial light sources, heat gain from solar radiation and transmission heat loss through window blocks. By calculating the difference in the thermal balance of the room after and before the increase in the window area, an expression of the criterion for evaluating the benefits of increasing the window area by energy indicators was obtained. Based on the cost of heat and electricity, the expression of the criterion for assessing the benefits of economic indicators was proposed. According to the presented criteria, the calculation for different function spaces: residential, office and school classes designed for Moscow was carried out. It is shown that, according to energy indicators, an increase in the window area is unprofitable or low profitable for residential and office premises, but beneficial for the school class. In conclusion, the paper shows the possibility of evaluating the energy efficiency of increasing the area of the window using the developed criteria. [ABSTRACT FROM AUTHOR]

A solar air heater is a system that transforms solar power into a form that may be used for a variety of heating applications. Researchers are experimenting to increase the heat transfer by breaking down the laminar sub-layer near the adsorbing plate. To break the laminar sub layer, researchers have applied varieties of roughness with different shapes and sizes. The experimentation with varieties of roughness leads to an increase in cost as well as effort. So, the development of high-end computational software can minimize this. Computational fluid dynamics has emerged as a very efficient tool to perform the analysis with less cost and effort. The paper aims to give a comprehensive review of CFD analysis that has been used by various researchers to evaluate the thermo-hydraulic performance of artificially roughened solar air heaters. This paper represents the brief details of the CDF model, CFD domain, different roughness, and system and operating parameters to achieve the optimal thermal performance of solar air heaters. [ABSTRACT FROM AUTHOR]

Rotational moulding is a polymer powder processing technique used to make large, hollow plastic products. The heating phase in this process influences both the final product wall thickness distribution as well as the mechanical properties and aesthetical appearance. In this paper a model to calculate the heat transfer is developed. This is done using a 1D thermal finite difference technique with dynamically changing boundary conditions. Compared to the models found in the literature, the deposition process is done in a discrete manner. Density and thermal conductivity are changed according to the progress of the sinter process using Bellehumeur's equation for the coalescence of two grains. The first part of the paper will focus on a theoretical description of the model, the second part on the experimental validation. A close agreement between experimental data and numerical results was found. [ABSTRACT FROM AUTHOR]

Through means of this specific paper, we have likely embraced an investigation towards leading an examination in regards to "flow and heat transfer qualities in a second grade liquid through a permeable medium over a straight extending surface with two general cases, in particular PST and PHF, including the impact of viscous dissipation". Subsequently, fractional differential conditions administering the idea of "flow and heat movement are changed over into non-linear customary differential conditions and limit conditions by utilizing suit-capable similitude change", was regularly being thought of. Accordingly, the proposed issue identifying with our paper, was fundamentally being addressed systematically, by methods for power arrangement strategy, wherein subsequently graphical outcomes for "speed, skin-grinding coefficient, and temperature for PST and PHF cases are also introduced and talked about, close by thought of mathematical qualities identifying with divider grating coefficient, divider temperature slope θη (0), and divider temperature θ (0)" were in like manner being determined, organized, & examined subsequently. [ABSTRACT FROM AUTHOR]

This paper discusses the improvement of heat transfer rate and flow characteristics of fluid in the Solar Parabolic Trough Collector (PTC) receiver tube for different geometrical consideration. Numerical analysis using Computational Fluid Dynamics (CFD) was performed receiver tubes with circular, square, and elliptical geometrical shapes, with and without twisted tape insert. for receiver tubes with circular, square, and elliptical geometrical shapes, either with or without twisted tape inserts. The results of CFD numerical analysis were validated with the experimental results. The comparison graphs for friction factor, Nusselt number as well as thermal performance are plotted with respect to Reynolds number. Results shows that, the change in the geometrical shape of the receiver tube and tube with insets affects the internal and external convection heat transfer coefficients and rate of heat transfer. It was suggested that to use twisted tape inserts in the receiver tube for better heat transfer rate in Solar PTC. [ABSTRACT FROM AUTHOR]

The paper deals with a nonlinear heat transfer model based on the nonlinear second order degenerate parabolic equation with arbitrary form of nonlinearity. Boundary value problems with two non-stationary boundary conditions are discussed: the problem with a specified heat wave front and the problem with a condition specifying the desired function at some manifold. A new existence theorem is formulated. Time-step algorithms based on the boundary element method and the dual reciprocity method are developed. Iteration procedures converging to the continuous solution on each time step are proposed. The algorithms are verified by comparison with known exact solution. [ABSTRACT FROM AUTHOR]

Extracting clean Energy through different technologies and producing electricity has played a major role nowadays due to constant growing energy consumption because of increase in population as well as deteriorating effect on atmosphere due usage of fossil fuels. To have an efficient clean energy technology has become the necessity of time. Application of solar thermal energy as Solar cooker, Solar dryer, Solar Water Heater, Solar desalination etc, are widely used in industry and domestic applications. Among these different application of Solar Thermal Energy, Evacuated Tube Collectors are used extensively so far as it proposes less convection losses which arise in solar concentrators from the movement of air over hot receiver surfaces. It is found that use of nanofluid for the thermal performance enhancement of Evacuated tube collector using heat pipe significantly changed scenario of using ETC. With this paper various characteristics of using nano fluid with Evacuated tube collector has been critically reviewed for the thermal performance enhancement of ETC with effect of parameters like weight fraction, filling ratio, type of nano particle. [ABSTRACT FROM AUTHOR]

Heat transfer enhancement is vital in the technological dependence era in every aspect of life, particularly in engineering applications and industry. In this paper, numerical investigation is conducted on the geometrical parameters of jet impinging system with twisted tape as swirl generator. The focus of this research is the average Nusselt number on the heated plate, effect of different value of Reynolds number, jet-to-plate distance (L/D) and twisted tape ratio (y/w) which are inserted in the jet nozzle. The numerical simulations are performed at four different Reynolds number of 4000, 8000, 12000 and 16000, four (L/D) which is 2, 4, 6 and 8, and also four different (y/w). The grid independent test is conducted based on the average plate temperature to obtain optimal grid number without affecting the numerical results. The outcomes of this research are in line with the previous reported journals of similar scope of study. It is observed that, under similar operating conditions, swirling impinging jet (SIJ) offer better heat transfer rate with higher Nusselt number which performed 18.98% better than conventional impinging jets (CIJ). Finally, the best heat transfer enhancement based on the highest average Nusselt number over the heated plate is obtained with high twist ratio at 7, high Reynold number at 16000 and also high jet-to-plate distance at 8. [ABSTRACT FROM AUTHOR]

In the study of errors, the error function is a special function that appears in many scientific theories; it appears in the solutions of many physical and engineering problems, such as vibrating beams, heat and mass transfer, and many other problems that contain an error function (erf.) and a complementary error function (erfc.). As part of solving physical and engineering problems, integral transforms have been used to find the results of errors and complementary errors. In this paper, the efficiency of the novel integral transform, the SEE integral transform, has been demonstrated by providing an exact solution to the improper integrals for some applications that contain error functions without unnecessary calculations. [ABSTRACT FROM AUTHOR]

A heat exchanger is used in different applications like cooling or heating of a fluid stream of single or multi component fluid streams. Air-conditioning, chemical plants, petrochemical plants etc. It is utilized to move thermal energy (enthalpy) between minimum of two fluids, between a solid body and a fluid, at numerous temperatures in heat interaction. There are typically no external heat and work connections. Heat transfer should be possible in sequences of action in fluids, liquid to gas. Heat exchangers are used to reheat a cold fluid, cool a hot fluid, or combine the two. In this paper design the spiral plate heat exchanger and tested with fluid is water and MATLAB code is written for spiral plate heat exchanger according to our design point of view and compare different fluids i.e water and unused engine oil and graph is generated for effectiveness Vs Mass flow rate of cold fluid. [ABSTRACT FROM AUTHOR]

This paper illustrates the numerical investigation of natural convection inside a partially opened cavity (Aspect Ratio = 1) with an internal heat source. The cavity is bounded by two insulated walls (top and bottom) and two fixed temperature walls (Left and right walls). Simulation has been done for different Rayleigh number ranging from Ra = 10 4 to Ra = 106. Prandtl number was fixed to 0.71. The internal heat source was placed at various locations inside the square cavity and the average Nusselt number was evaluated to study the impact of natural convection. The results show a higher heat transfer rate when the heat source placed at the side-section of the cavity. [ABSTRACT FROM AUTHOR]

Building components in terms of thermal protection are being addressed with standard requirements to related thermal performance design. In this relation, thermal conductivity parameters play a highly relevant role that may affect heat transfer greatly. This represents a key factor in building performance assessments for steady-state conditions and corresponding calculation models on thermal effectiveness as well as temperature distribution of building components. Generally, these parameters are known from declared values given by their producers. For this purpose, standard tests are performed to provide data under steady-state conditions. However, limitations may occur in real cases due to not constant and changing thermal conductivity that is temperature, moisture, and time-depending variables. Therefore, in the design process, several governing factors should be carefully considered in thermal calculations. Accordingly, a standard methodology using the transformation of declared values to design values is adopted in practice. In this paper, the usefulness of transformation formulas based on standard methods is demonstrated and discussed as compared with real subjections obtained in the laboratory. One of the representatives of thermal insulation based on mineral fibrous material was used and studied experimentally to obtain transformation factors on both moisture and temperature relations. Based on the data measured, coefficients of transformation formulas were derived from experimental measurements. Results identify a certain discrepancy between experimental data and theoretically calculated values used by available standard methods. [ABSTRACT FROM AUTHOR]

Assessment of energy performance became a necessary part of everyday architectural design as the building stock is a significant energy consumer. Different stages of a project require different granularities of evaluation. Typically, as the project moves forward, the level of geometry (LOG) of the digital assets increase, which proposes minor issues in the case of superstructure design. Although simplified 1D modelling of constructions is usually sufficient at the architectural concept stage, detailed planning requires a higher overall geometrical and metadata quality, where 2D and 3D energy performance evaluation could be used. It is different in the case of ground contact structures because 1D simulation and simplified boundary conditions do not yield satisfactory results, as the heat and moisture transfer near the construction is a three-dimensional, time-dependent phenomenon depending on the moisture content, respectively. Our previous studies showed promising results in using highly detailed BIM in thermal simulation workflows. In this paper, with the help of an existing experimental case study, we compared the temperature distribution results of a numerical modelling tool, KIVA, with our BIM-based finite element simulation workflow using Comsol Multiphysics. We showed that the mainstream BIM-based architectural design workflows could be extended to include simulation methods for evaluating the thermal performance of constructions in direct contact with the soil. [ABSTRACT FROM AUTHOR]

The global production of fired ceramic bricks represents a large environmental burden in form of energy consumption and greenhouse gasses emission. The production process has therefore become an object of interests of several studies aiming at its optimization to reduce the negative environmental impacts. Within these optimizations, the precise knowledge of thermal properties of clays undergoing the firing process is one of the key information that conditions the successful solution of the problem. This paper therefore aims at determination of temperature-dependent thermal conductivity of clays. Using a set of thermocouples, the temperature distribution in the sample is monitored, being exposed to one-sided heating. The temperature field deformation due to presence of metal wires is then overcame using computational modelling that is able to distinguish the particular contributions of clay/thermocouples to the ongoing heat transfer. Based on this assumption, such a thermal conductivity of clay is then sought, that provides the same temperature distribution as the experiment. The thermal conductivity values of clays were found to range between 0.58 W·m−1·K−1 and 1.97 W·m−1·K−1, depending on the temperature. [ABSTRACT FROM AUTHOR]

Due to the high crystallization point of 240 °C of the solar salt used as a heat transfer media in solar tower power plants, all pipes that are carrying the molten salt must be preheated to prevent the solidification of the solar salt and thus plugging and damaging the pipes. In commercial power plants the preheating of the pipes is mainly done electrically by using conventional resistance heaters. Due to the high incident solar radiation during solar operation, this approach cannot be used for preheating the absorber tubes of the receiver. Instead, the receiver will be preheated by the reflected energy of the sun. In order to ensure a frictionless start of the plant a preheat strategy must be developed that leads to a homogeneous temperature distribution independently of the day in the year, the time of the day and of the ambient conditions. For the preheating strategy of the HPMS-II test receiver several boundary conditions were defined; the most important being: The receiver must reach a target temperature of 350 °C and have to maintain the maximum temperature ramp of 30 K/min specified by the absorber coating producer. Within the scope of this paper, an optical and thermal simulation model of the solar preheat strategy for an external molten salt test receiver was developed and the preheating strategy was simulated. [ABSTRACT FROM AUTHOR]

In this paper, receiver designs for 3D printing are analyzed by CFD calculations that are based on Reynolds-averaged Navier-Stokes (RANS) steady state simulations. The results show the surface and channel temperatures as well as dimensionless values to analyze the characteristics of the sodium flow. Helical installations induce a rotational flow inside the channels and enhance the heat transfer. For larger scale receivers, "Cold spray" is described as an additive manufacturing process. [ABSTRACT FROM AUTHOR]

In the present paper, numerical computations have been carried out to investigate the mixed convection developing within a cavity ventilated by injection / suction of a cold jet of isothermal air, interacting with the external environment through two openings arranged in the middle of the left and right vertical walls. The remaining portions of the left vertical wall are subjected to a constant heat flux, while, the remaining walls of the cavity are perfectly insulated. The combined effects of the basic parameters namely the Reynolds number, 20≤Re≤3000, the walls emissivity, 0≤ε ≤ 0.85, and the imposed external flow mode (injection or suction) on the flow characteristics and heat transfer are examined. The results revealed that, for both modes of ventilation, the contribution of radiation to the total heat transfer is significant even for a predominant forced convection regime particularly for high values of wall emissivity. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study of the thermoconvective effects induced by the presence of two inverted trapezoidal isothermal blocks of height h and width l = 0.109, in an annular space confined between two isothermal coaxial horizontal cylinders filled with air, Pr = 0.7, and of radii ratio, R = 2. This investigation gives an accurate description of the influence of the height of blocks on the flow pattern and on the average heat transfer rate, Nug, for a range of Rayleigh numbers Ra up to 104 and for an angular position of blocks φm = 0.82π. The steady solutions obtained are either uni- or bi-cellular flows. A critical height hc,a is determined, characterizing the appearance of the bicellular flow. The numerical study identified a heat transfer enhancement strategy by properly selecting adequate heating block heights. In particular, it appears that increasing h for a given Rayleigh number does not always lead to better heat transfer rates. [ABSTRACT FROM AUTHOR]

One of the most important techniques of the convective process is by means of fins, which have a significant impact in the manufacture of cooling and heat transfer transformers used in many of the devices used. These fins have the ability to increase the area of heat transfer as they work on turbulence of the fluid used and thus increase the process heat transfer. In this research paper, the presence and distribution of fins in a mini-channel and irrigation system were studied to improve heat transfer in it. The effect of this disturbance on the deformation and stress affecting the fins was studied. The results showed an improvement in heat transfer in the use of distributed fins. [ABSTRACT FROM AUTHOR]

As with the development of heat exchangers, especially in the fields of energy and microelectronics, where the mini-channel used in heat exchanger operations is used, as increasing the efficiency of heat exchangers depends on transferring the largest amount of heat to and from the used band. To increase this transfer, obstacles must be used to improve heat transfer, as these barriers disturb the used fluid and increase heat transfer by convection. In this research paper, a mini-channel containing obstacles of variable thickness was used to study the extent of their effect on heat transfer and its strength to withstand the flow pressures in the mini-channel and prevent its deformation. The results proved that with the increase in the thickness of the obstacle, it increases its strength to withstand stresses but at the same time reduces its strength in convective heat transfer. The reason for this is that the increase in the thickness of the obstacle increases the area for heat transfer and thus increases the resistance and heat and prevents heat transfer significantly. [ABSTRACT FROM AUTHOR]

In the cooling industry, micro-channel heat sinks are regarded a revolutionary technology since they allow for the evacuation of a great quantity of heat through a little space. As a viable alternative to the traditional method of heat exch ange that relies on conventional finned tube heat exchangers, micro-channel heat exchangers have swept the world by storm, owing to the numerous advantages they provide. Micro-channel heat exchangers are now employed in automotive, air conditioning, and refrigeration sectors. Thermally conductive heat sinks like silicon or copper have micro-channels carved into their surfaces. Coolant is forced to flow via a large number of parallel micro-channels that are generally present on the cooling surface in order to remove heat from a heated surface. When compared to the qualities of a base fluid, nano-fluids have the potential to increase the thermal conductivity and convective properties of the base fluid. This paper introduces the principle of heat transfer enhancement of micro-channels and reviews some of the experimental, numerical and analytical works done by researchers on this technique in recent years, also it focuses on the various methods or geometries used to produce laminar flow and its eff ect on the heat transfer rate. [ABSTRACT FROM AUTHOR]

Efficient lighting is a goal for energy efficiency and sustainable development. There are designs for electrically powered public lighting fixtures with solar panels installed in hard-to-reach areas or protected areas without an electrical power supply network. In this paper, a LED luminaire has been modeled by solving the heat equation using a heat source (LED 50W) to observe its behavior. The simulations were developed at ambient temperatures of 24°C and 35°C. It is important because these luminaires are installed in areas with this usual temperature, for example, the Ecuadorian Amazon or the Galapagos Islands. 51.7°C was obtained in LED for an ambient temperature of 24°C, which is the normal laboratory case, and 62.5°C in LED for an ambient temperature of 35°C. These results must be analyzed since it has a direct impact on the expected life of the luminaire and therefore on the maintenance and replacement plans. Through the results obtained, it was determined by Arrhenius model a reduction of 160 days in the maintenance plan. [ABSTRACT FROM AUTHOR]