Concept Of Heat Transfer Research Articles

Solar Distillation as a Sustainable STEM Tool: Bridging Theory and Practice

This study addresses a gap in STEM education by integrating solar distillation as a sustainable, hands-on learning tool to enhance students’ comprehension of heat transfer concepts and increase their awareness of environmental challenges. Guided by Bruner’s constructivist theory, this project-inspired approach aims to bridge theoretical knowledge with real-world applications, particularly sustainability. Students participated actively in the solar still’s design, construction, and analysis phases, allowing them to apply scientific principles in practical contexts. The findings demonstrated that students understood heat and mass transfer concepts more profoundly and developed an appreciation for renewable energy technologies and sustainable practices. Additionally, the project highlighted the impact of external climatic conditions on system performance, promoting an awareness of environmental factors affecting sustainable solutions. This research illustrates the potential of combining constructivist learning with sustainable technology education, preparing students to address pressing global issues such as water scarcity and energy conservation.

Investigation of heat and mass transfer performance in Jeffrey fluid: impact of Prabhakar fractional operator

This theoretical study seeks to extend the concept of fractional Jeffrey fluid and heat transfer near an infinite vertical plate, governed by generalized boundary conditions, using a time-fractional Prabhakar operator. Initially, the momentum equation incorporating the fractional Jeffrey model is developed to examine the unsteady flow, focusing on pressure dynamics within the boundary layer. Additionally, the energy equation, along with convective heat and mass transfer under generalized conditions, is formulated using the extended Fourier’s law. The Prabhakar fractional operator is utilized to represent the fluid’s transport mechanisms. The study presents fractional governing equations to describe heat, mass, and flow transfer processes influenced by magnetic fields and radiation effects. A Prabhakar fractional derivative is applied to model the fractional system, and analytical solutions are derived using the Laplace transform technique. The accuracy and validity of the results are confirmed by comparing them with previous work and exact solutions. Furthermore, the strong agreement between our analytical solutions and earlier studies reinforces the method’s reliability. The effects of various parameters on the fluid’s velocity, mass, and temperature distribution are demonstrated graphically. Changes in the model’s parameters result in varying trends in the velocity, mass, and temperature profiles, highlighting the critical impact of each parameter on the behavior of fluid flow, mass, and heat transfer.

Air-Cooled Heat Exchangers as a Heat Sink: Heat Transfer

This paper discusses heat transfer concepts in air-cooled heat exchangers (ACHEs) and how ACHEs work like the principle of Heat Sink. A heat exchanger used for transferring heat between source and a working fluid. There use is for cooling and heating processes and have a huge impact on different industries coolers are an environmentally friendly solution as they do not require an additional water supply due to water loss from drift and evaporation, making them suitable for locations where water as a cooling medium is not readily available . These devices utilize air as a cooling medium, transferring heat from a hot source to the environment. As technology advances and demands for higher performance and energy efficiency increase, research on air-cooled heat exchangers continues to evolve. This research area offers significant opportunities to contribute to advancements in various fields, improve energy efficiency, and address environmental concerns. By exploring innovative design approaches and leveraging emerging technologies, researchers can develop air-cooled heat exchangers that meet the evolving demands of modern applications

Experimental study on flow and thermal transport characteristics of moving packed bed through a channel featuring single column of inline cylindrical pins

An experimental study is conducted to understand the fundamental flow and thermal transport characteristics of moving packed bed (MPB) through closely spaced parallel plates. An enhanced heat transfer concept based on cylindrical pins is experimentally investigated in this study. A simplified geometry involving two parallel plates as baseline configuration is considered, where the pin fin configuration involved a series of pin fins arranged in a single column, joining the two parallel plates. Steady-state heat transfer experiments have been conducted with particles of diameter ∼400μm and for three parallel plate spacings (3–7 mm) as well as three pin heights (3–7 mm). The heat transfer experiments involved parallel plates subjected to uniform heat flux with particles supplied at room temperature. The optical flow experiments were conducted to determine high spatio-temporal resolution near-wall flow-field of moving packed bed of particles. The experiments reveal that the separation between the parallel plates have a dominant effect on convective heat transfer, with lowest plate spacing yielding the highest heat transfer. Further, addition of pin fins results in local enhancement in flow velocities around the pin, while also resulting in a dead zone of stagnant or very slowly moving packed bed in the region upstream of the pins, and a void zone just downstream of the pin which does not feature particles. Pin fins also provide increased wetted surface area along with facilitating the conjugate heat transfer by transferring energy between the walls and the moving heat transfer media (HTM: particles). As a result of these complex mechanisms at play, the pin fin configurations had superior heat transfer performance compared to the baseline configurations.

Rancangan e-LKPD Berbasis Collaborative Creativity Learning (CCL) Pokok Bahasan Perpindahan Kalor Pada Mesin Pembuatan Gula Pasir

Physics as a subject matter involves understanding concepts and mathematical applications that are often a challenge for students, for example the concept of heat transfer. To provide a memorable and interesting learning experience, the context of the e-LKPD design can be taken from everyday life, such as the process of making granulated sugar in a sugar factory. The process involves the concept of heat transfer, for example the stages of evaporation and crystallisation of neera. The purpose of this study was to analyse the validity of the design and learners' responses to the e-LKPD design. This type of research is development research with the ADDIE model and is limited to the development stage. Data collection involved literature study, observation, interviews, questionnaires, and documentation. The validation results obtained an average percentage value of 87.33%, with a very feasible category and learner responses showed a high level of interest, with a percentage value of 83%. Thus, e-LKPD based on collaborative creativity learning (CCL) on the subject of heat transfer in sugar making machines can be considered feasible and can be implemented effectively to students in learning activities.

Demonstration of charge-hold-vent (CHV) and no-vent-fill (NVF) in a simulated propellent storage tank during tank-to-tank cryogen transfer in microgravity

The space exploration from a low earth orbit to a high earth orbit, then to Moon, Mars, and possibly asteroids and moons of other planets is one of the biggest challenges for scientists and engineers for the new millennium. The enabling of in-space cryogenic rocket engines and the Lower-Earth-Orbit (LEO) cryogenic fuel depots for these future manned and robotic space exploration missions begins with the technology development of advanced cryogenic thermal-fluid management systems for the propellant transfer line and storage tank system. One of the key thermal-fluid management operations is the chilldown and filling of the propellant storage tank in space. As a result, highly energy efficient, breakthrough concepts for quenching heat transfer to conserve and minimize the cryogen consumption during chilldown have become the focus of engineering research and development, especially for the deep-space mission to Mars. In this paper, we introduce such thermal transport concepts and demonstrate their feasibilities in space for cryogenic propellant storage tank chilldown and filling in a simulated space microgravity condition on board an aircraft flying a parabolic trajectory. In order to maximize the storage tank chilldown thermal efficiency for the least amount of required cryogen consumption, the breakthrough quenching heat transfer concepts developed include the combination of charge-hold-vent (CHV) and no-vent-hold (NVF). The completed flight experiments successfully demonstrated the feasibility of the concepts and discovered that spray cooling combined with hold and vent is more efficient than the pure spray cooling for storage tank chilldown in microgravity. In microgravity, the data shows that the CHV thermal efficiency can reach 39.5%. The CHV efficiency in microgravity is 6.9% lower than that in terrestrial gravity. We also found that pulsing the spray can increase CHV efficiency by 6.1% in microgravity.

Experimental investigation of the supercritical heat transfer of the low GWP refrigerant R1234ze(E): calibration and validation of test rig

Heat transfer of supercritical refrigerants is applied in practical systems such as the transcritical organic Rankine cycle or supercritical heat pump. The concept of supercritical heat transfer is not new and has already been studied and applied for decades in several applications. However, results on one fluid cannot be directly translated to another one. This is because the thermohydraulic behavior of fluids is heavily influenced in the near-supercritical region due to sudden variations in the thermophysical properties when the fluid is heated or cooled close to its critical point. For refrigerants under horizontal flow, the research is limited. Most studies in literature are on small diameter tubes and on R134a, which has a high global warming potential. Therefore, an experimental test rig has been built to measure the supercritical heat transfer of low global warming potential refrigerants over a large temperature and pressure range in the supercritical region. In this work, the calibration and validation of this test rig is presented using the refrigerant R1234ze(E). The test section consists of a 4 m long horizontal tube with an inner diameter of 22.9 mm, equipped with thermocouples at both the tube wall and in the bulk of the flow, and is heated by resistance wires wrapped around the tube. For the calibration, the temperature profiles under both non-heating and heating conditions are evaluated. For the validation, the average Nusselt numbers obtained through experiments under subcritical conditions are compared to the average Nusselt numbers calculated based on the Dittus-Boelter and Gnielinski correlation.

Development of statistical model for the indoor solar cooking system

The use of solar energy for the cooking has taken place for the last few decades. This type of cooking has conducted outside the door. But this attempt has been conducted to cook the food inside the kitchen as a conventional cooking type. This cook-friendly device introduces a new solar heat transfer concept for indoor cooking by developing a special types of cooking utensils, i.e., pans and pots. The present study investigated the different parameters associated with the performance of indoor solar cooking systems. During the study of indoor solar cooking, it has been observed that the most important parameters that affect the performance, considering them as independent parameters, are the time duration of the system exposed to the sun, solar intensity, mass flow rate of the working fluid, and the type of working fluid. Also, the performance is measured in terms of output parameters such as the temperature of the pan, pot, and thermal storage system. In this study, a mathematical relationship has developed between these independent parameters and dependent parameters. The ANOVA method is used to develop mathematical relationships. The experimentation has been carried out for different times ranging from 0 to 8 hours, with solar intensity ranging from 100 W/m2 to 800 W/m2 and mass flow rate in lpm (6, 9, and 12) with heat transfer oils such as Therminol 55 and Soyabean Oil. Further, the equation is formulated and established for each independent parameter in terms of the actual factor. The accuracy of the equations was measured in terms of R2 and found to be 0.9615, 0.9629, and 0.9886 for the temperature of the pan, the temperature of the pot, and the temperature of the thermal storage system, respectively.

EXERGOECONOMIC ANALYSIS OF A HYBRID SYSTEM OF WASTE INCINERATION AND ABSORPTION REFRIGERATION

The current global scenario presents a significant increase in energy demand for HVAC-R (Heating, Ventilation, Air Conditioning and Refrigeration) systems. Considering also that Brazil has the sixth most expensive energy in the world and that there is currently a greater scarcity of natural resources for energy generation, it is necessary to seek viable alternatives with lower energy consumption to the currently most used models, without any quality loss. On the other hand, absorption refrigeration and waste incineration systems can be lines of studies and research to be considered, considering that it is possible to reduce electrical energy consumption and also the environmental impacts that the usual compression refrigeration systems provide. . . In this context, one of the segments of Thermal Systems Engineering studied is the exergoeconomic analysis that comprises the concepts of Heat Transfer, Fluid Mechanics and Thermodynamics, based on the Second Law of Thermodynamics and which uses the notions of optimization and economic analysis. Therefore, this work aims to perform an exergoeconomic analysis of a hybrid system of waste incineration and absorption refrigeration, with the specific objective of developing an exergoeconomic model for the hybrid system. Absorption incinerator-refrigerator. This is an exploratory bibliographic research using an absorption refrigerator from the Center for Research and Development of Self-Sustainable Energy (NPDEAS) of the Federal University of Paraná, in which a model was made with a macroscopic approach of the mass and heat transfer phenomena of a absorption refrigeration cycle, applying the principles of conservation of mass and energy in steady state for each component of the cycle, that is, each component will be considered as a single control volume. It is expected that it will be possible to predict the behavior of the absorption refrigeration system and that it will be possible to develop a scientific analysis tool to design, control and optimize absorption refrigeration systems, using waste incineration. The highest exergy destroyed was verified in the desorber with about 0.9461 kW and through the exergoeconomic analysis of the incinerator, it was found that the cost rate associated with the product of the incineration gases was $ 39,926.31 per year.

Analysis of Contact Thermal Resistance and the Use of Coatings on Heat Transfer in Cemented Carbide Metal Cutting Tools

Objective: The objective of this study is to investigate the thermal behavior of coated cutting tools in industrial turning processes, aiming to enhance machining efficiency and prolong tool lifespan. Theoretical Framework: The study is grounded in the concepts of heat transfer, thermally insulating coatings, and their impact on cutting tool performance. Key theories and models include thermal conductivity, thermal insulation, and heat dissipation mechanisms. Methodology: The research employs numerical simulation using the COMSOL® Multiphysics package to model transient heat transfer within coated tools and their holders. Thermal contact resistance at the tool-holder interface is also considered. Two coating configurations (Model 1 and Model 2) with different materials are analyzed, resulting in six simulation scenarios. Results and Discussion: The simulations demonstrate significant temperature reductions in the coated tools compared to uncoated ones, with Model 2 showing the most substantial decrease. These findings indicate the effectiveness of thermally insulating coatings in mitigating heat generation and improving tool performance. Research Implications: The study's findings have practical implications for the manufacturing industry, suggesting that the use of specific coatings can lead to higher cutting velocities and prolonged tool lifespan. These insights can inform decision-making in tool selection and process optimization. Originality/Value: This research contributes to the literature by providing a detailed analysis of the thermal behavior of coated cutting tools under extreme temperatures. The study's innovative approach and practical implications offer valuable insights for improving machining processes and tool performance.

Investigating the intensity of urban heat island and the impacts of local climate using verified WRF data: A case study of Rasht, Northern Iran

Due to the complicated and uncertain dynamics of the urban heat island (UHI) in humid subtropical areas, the diurnal, seasonal and long-term variations of the UHI were investigated in Rasht, Iran. Besides, the study utilizes the heat and moisture transfer concepts to analyze the impacts of daytime rainfall duration on UHI. Meteorological data at five virtual stations was acquired by verified Weather Research and Forecasting (WRF) model. Overall, the nighttime UHI peaks in summer (3.4 °C) and is lowest in fall (1.4 °C) over 2017–2019. Moreover, the maximum and minimum daytime UHI occurred in winter (1.2 °C) and summer (0.6 °C), respectively. In hot seasons, an increase in daytime precipitation duration initially leads to an increase in daytime UHI, followed by a subsequent decrease. Conversely, in cold seasons, daytime UHI shows a decreasing trend regardless of rain conditions. Additionally, extended daytime precipitation attenuates nocturnal UHI in hot seasons, while no significant influence is observed in cold seasons. An increase in midday cloud cover during hot seasons reduces the nighttime UHI. The nighttime UHI is inversely proportional to the third root of wind speed, in low cloudiness conditions of hot seasons. Furthermore, the Ladsat-5/7/8 imageries revealed an increasing trend in the surface UHI (SUHI) during hot seasons over the past two decades, while SUHI in cold seasons remains insignificant. The article reports the most influential parameters on daytime, nighttime and seasonal UHI and the best mitigation policies for the humid subtropical climate, particularly in hot seasons.

Synergistic Heat Transfer in Enclosures: A Hybrid Nanofluids Review

This review aims to comprehensively explore the concepts of heat transfer (HT) and entropy generation (Egen) within cavities containing hybrid nanofluids (HN). Additionally, the review encompasses various enclosure shapes, such as triangle, square, rectangle, wave, trapezoid, hexagon, octagon, semicircle, circle, cube, C-shaped, L-shaped, M-shaped, T-shaped, W-shaped, irregular shaped, and other types of cavity designs. Also, different types of hybrid nanoparticles such as silver-magnesium oxide, copper-aluminum oxide, multi-walled carbon nanotubes-iron oxide, copper-titanium dioxide, silver-copper, aluminum oxide-titanium dioxide, carbon nanotubes-aluminum oxide, multi-walled carbon nanotubes-magnesium oxide, carbon nanotubes-iron oxide, carbon nanotubes-copper, aluminum oxide-silicon dioxide, aluminum oxide-silver, nanodiamond-cobalt oxide, etc., and base fluids such as water, ethylene glycol, carboxymethyl cellulose, etc are presented in this research. In addition, a thorough analysis of the extensive literature underscores the significant influence of elements like blocks, obstacles, fins, or cylinders within cavities on both HT and Egen. These findings carry substantial practical implications for the study of thermofluid systems.

Modeling of an Electric-fired Brick Oven, Directly Heated

The purpose of this article is to propose a model of an electric-fired brick oven, with the aim of eliminating the imperfections presented by traditional brick ovens. To complete this study, we used the concepts of heat transfer, and material resistance, as well as those of computer-aided mechanical design. Deemed satisfactory, the results found give a yield of 94.5% and a cooking time of 7.29 hours based on 2000 bricks cooked.

Integrating Local Science and School Science: The Benefits for Preserving Local Wisdom and Promoting Students’ Learning

<p dir="ltr"><span>Integrating local science into science learning benefits students and the culture. However, science teaching tends to focus only on the scientific content presented in the books but ignores the local culture. This paper explores local science in community cultural activities to be implemented in science learning to introduce students to cultural values following the concept of science. It identifies local science, describes the oral arguments produced by the tribal council, and analyzes the lesson plan by five science teachers in the Nagekeo district, East Nusa Tenggara. The data used in this analysis are observation and identification, interviews, and assessment sheets. The findings show that the local science in Nagekeo cultural activities that can be integrated into science learning includes the traditional unit and measurement systems, Newton's laws in their application to the traditional game, biodiversity in the traditional hunt, the concept of heat transfer, and its application in the construction of traditional houses, and vibrations, waves, and sounds in the traditional musical instrument. Recommendations from this research are embracing local science in science learning to provide meaningful learning for students and preserve local culture for each generation in the future so that it does not become extinct. </span></p><div><span><br /></span></div>

Mobile Learning Simulation (MLS) for Learning Physics in Heat Transfer Concept

This research aims to develop Mobile Learning Simulation (MLS) media that is valid for learning the concept of heat transfer. The method used in this research is the Research and Development method with the ADDIE model (Analyze, Design, Develop, Implement and Evaluate). MLS was developed to make it easier for students to learn the concept of expansion and increase their understanding of the microscopic nature of heat transfer. MLS can display six 2D simulations, namely the processes of length expansion, area expansion, volume expansion, and heat transfer by conduction, convection, and radiation. The product effectiveness test was carried out with correspondents of 35 students in one of the schools in western Indonesia, obtaining an average score of 84.3% and was in the very good category. Based on the test results, the MLS application is efficient and suitable for use as a physics learning medium in high school.

Sosialisasi Alat Peraga IPA Perpindahan Kalor di SDN Kedai Runding, Kec. Kluet Selatan, Kab. Aceh Selatan

This dedication was motivated by a problem among the students of SDN Kedai Runding, namely that some students had difficulty in understanding the concept of science and the learning outcomes were still low. This happens because teachers only use lectures, questions and answers and assignments in learning, not moving students' enthusiasm to actively participate in learning. To overcome this, Apperpa is used in learning, because by using Apperpa students can be actively involved directly and discover for themselves the concept of science so as to help students who have learning difficulties. The approach or method that I use in this socialization, namely Participatory Action Researc (PAR) is a research approach that involves active participation of community groups that are the subject of research, this method aims to produce knowledge that is relevant, useful, and can be applied in everyday life. This activity was carried out at SDN Kedai Runding in Class V. With the Apperpa Science Props which contains experiments on heat transfer, students can easily understand the concept of heat transfer using teaching aids.

Wind Velocity and Forced Heat Transfer Model for Photovoltaic Module

This study proposes a computational model to define the wind velocity of the environment on the photovoltaic (PV) module via heat transfer concepts. The effect of the wind velocity and PV module is mostly considered a cooling effect. However, cooling and controlling the PV module temperature leads to the capability to optimize the PV module efficiency. The present study applied a nominal operating cell temperature (NOCT) condition of the PV module as a reference condition to determine the wind velocity and PV module temperature. The obtained model has been examined in contrast to the experimental heat transfer equation and outdoor PV module performance. The results display a remarkable matching of the model with experiments. The model’s novelty defines the PV module temperature in relation to the wind speed, PV module size, and various ambient temperatures that were not included in previous studies. The suggested model could be used in PV module test specification and provide analytical evaluation.

Eulerian CFD simulation of biomass thermal conversion in an indirect slow pyrolysis rotary kiln unit to produce biochar from recycled waste wood

Producing energy and higher value bio-products from waste wood recycled from construction and demolition (C&D) debris has been proposed as an economically viable opportunity in the biomass and bioenergy sectors. However, several challenges associated with the thermal conversion processes remain to be solved. This study introduces a 3D numerical simulation to study thermal conversion of wood chips. Combined biomass combustor, and indirect pyrolysis unit is used to create a self-sustainable biomass unit which does not rely on fossil fuel. Multizone heat distribution in the rotary kiln unit is investigated by employing CFD, an analytical algorithm and measurement tools in different zones of the equipment. A multizone heat transfer concept, the overall yield rate of biochar, thermochemical conversion of the bed, the volume shrinkage in the wood chips during the pyrolysis process, as well as biomass volatile and tar composition, and finally the potential of energy savings is widely investigated. CFD results and experimental evidence confirm that at least 31 % energy saving in drying zone can be achievable if drying and pyrolysis zone are separated in the indirect slow pyrolysis rotary kiln unit. The quality of biochar improved by 21 % increase in fixed carbon content and tar condensation is controlled.

Simulation of fast-firing densification by the discrete element method

The macroscopic behavior of powder compacts during the sintering process originates at the microscopic level. Despite the marked advance in analytical techniques, the characteristics of microscale densification, including heat transfer phenomena in particulate systems under fast firing, still need to be determined. Here, a numerical approach is used to explore macro and microscale densification gaps aiming to predict the behavior of parts consolidated by non-isothermal sintering. The model was built integrating concepts of heat transfer, transient temperature regime, sintering, and contact forces and implemented within the Discrete Element Method (DEM) framework. The scope of the article includes an alumina-based case study in which simulations were compared with the experimental investigation. The simulation results showed good agreement with the experimental data. Densification microkinetics depicted the evolution of densification gradients inside the sample. The model demonstrated its value for predicting high heating rate sintering features.

Goufo-Caputo fractional viscoelastic photothermal model of an unbounded semiconductor material with a cylindrical cavity

In order to describe the photothermal dynamic behavior of viscoelastic semiconductor materials, the authors of this work propose a fractional modification of the Kelvin-Voigt type. The generalized Mittag-Leffler function method with two parameters was utilized as the non-local, nonsingular kernel of the Goufo-Caputo fractional operator, which is similar to the AB fractional derivative. Also, a new concept of photovoltaic heat transfer has been developed to describe the process of photothermal heating in semiconductors, in which light energy is converted into thermal energy by absorption. This unique model is grounded in the theoretical framework of the Moore-Gibson-Thompson (MGT) equation, and it offers additional insights into the underlying process of light sensitive heat transfer, as well as the intricate interaction between heating signals, elasticity, and plasma. As a direct application of the proposed model, the photothermal interactions that occur when an infinitely rotating semiconductor material with a cylindrical hole is subjected to a laser thermal flux and immersed in a constant axial magnetic field have been investigated. These findings may have implications for developing optically absorbent nanostructures and their use in photothermal energy generation. For this reason, the comparison of modified photoelasticity models with spherical derivatives and classical models applied to semiconducting materials seems interesting.