Papers by Keyword: Heat Transfer

Abstract: The role of Heat exchanger’s in the present scenario of Industries and production applications is growing in a rapid manner. Heat Exchanger types such as shell and tube, plate type, are the most used one at present. Heat Exchanger’s major problems are generally deposits of flowing mixture, increased pressure in the shell, efficient performance and poor design. To solve this issues regarding the heat exchanger we are willing to develop an optimised standard design of shell and tube heat exchanger. This design will enhance the previous results by the usage of base fluid water blended with ethylene glycol 16A. Considering the fluid flow through the heat exchanger with varying volume fraction from 0.40% to 1%. Based on the few of the previous results that could be enhanced with slight modification in the design of shell, we are analysing for an optimised valuation that could give similar effectiveness as expensive fluid that is 60% to & 70% with pressure under 1 bar and temperature limited up to 160 degree Celsius which is obtained in our optimised analysis. This design is maintained as the best possible valuation validated by a practical experiment which could feasibly be the solution for most of the problems and that can be used for long run usage.

Abstract: Increasing demand for reliable and passive thermal management in modern energy systems, particularly in nuclear reactors, has elevated interest in natural circulation loops. Among the influencing factors, loop geometry and heating power are critical in natural circulation systems. This study investigates the effect of heating power on heat transfer in a rectangular VHVC natural circulation loop with an enlarged upper elbow radius of 350 mm. The analysis was conducted using CFD under steady-state conditions, employing a pressure-based solver with the realizable k-epsilon turbulence model and energy equation to simulate buoyancy-driven flow. Three power inputs 750 W, 1100 W, and 1540 W were applied to evaluate their effect on temperature distribution and energy absorption. Results show that increasing the heating power enhances buoyancy forces, leading to higher mass flow rate and stronger natural circulation within the loop. The fluid temperature difference between the heating and cooling sections rises with power input, which directly increases the convective heat transfer coefficient. Consequently, the obtained Nusselt number increased from 25.69 at 750 W to 31.23 at 1540 W. This finding confirms that higher heating power significantly improves the loop heat transfer performance, providing insight into the optimization of passive cooling systems in nuclear safety applications.

Abstract: Transient laminar mixed convection of air (Pr = 0.71) in a vertical plane channel is numerically investigated for opposing buoyancy at Re=100. The channel walls include symmetric, discrete, isothermal heated sections applied on the external side of a central wall zone, resulting in a conjugate heat-transfer problem through the solid wall and the fluid domain. The two-dimensional unsteady Navier–Stokes and energy equations are solved using a finite-volume method on a staggered grid with SIMPLE pressure–velocity coupling. The Grashof number is varied over 10³ ≤ Gr ≤ 10⁵. Instability onset is identified using a quantitative criterion based on the growth and persistence of velocity/temperature fluctuations and a domain-integrated fluctuation energy. The effects of wall thickness Δ and heated length L_h on the critical Grashof number are reported. Increasing L_h lowers the instability threshold, whereas increasing Δ stabilizes the flow by damping thermal gradients transmitted to the fluid. The results provide a stability map and physical interpretation of the transition from steady to unsteady mixed convection at low Reynolds number.

Abstract: Thermal management of solar panels is a major challenge, particularly in hot climates, and has attracted growing interest from both researchers and professionals in the photovoltaic (PV) sector. In this study, a two-dimensional numerical analysis was conducted to evaluate the thermal performance of an aluminum box filled with a phase change material (PCM) used for cooling a solar panel. The impact of integrating horizontal fins placed either on one side or on both sides of the PV/PCM system, was also examined to optimize heat transfer and stabilize temperature. The simulations indicate that a configuration with five fins arranged on one side, spaced 18.25 mm apart, provides effective cooling. The use of RT25 PCM maintains the surface temperature at 28 °C for 100 minutes before it gradually increases without exceeding 65 °C. Similarly, RT35 also demonstrates good thermal performance, maintaining the temperature between 35 and 43 °C for 252 minutes before eventually reaching a peak of 61 °C. These results highlight the effectiveness of the fins and the critical role of PCM selection in enhancing the thermal regulation of solar panels.

Abstract: This study investigates the thermal distribution characteristics during the pyrolysis of mahogany wood biomass in conjunction with a zeolite catalyst, utilizing a packed bed reactor modelled through ANSYS thermal transient software. The simulations were conducted at various temperatures, specifically 523 K, 623 K, and 823 K, with a consistent heating rate of 800 K/hour over 120 minutes. Our findings reveal that zeolite significantly outperforms mahogany wood in thermal efficiency, demonstrating faster, more uniform, and stable heating across the reactor volume. In contrast, mahogany biomass experiences delays in reaching optimal temperatures, particularly at lower settings. The disparity in thermal performance between the two materials becomes more pronounced with increasing temperatures. These results underscore the effectiveness of zeolite catalysts in not only expediting the attainment of pyrolysis temperatures but also improving heating efficiency and uniformity. This study positions zeolite as a promising catalyst for enhancing the performance and sustainability of biomass pyrolysis reactors, offering valuable insights for optimizing industrial applications.

Abstract: This paper presents a numerical investigation to evaluate thermal-hydraulic performance of double forward facing step. The combined analysis of double forward-facing step geometries and wavy-wall amplitude, which has never been done previously, is what makes this study groundbreaking. With the help of the double-step construction and the undulating upper wall, this special arrangement seeks to improve the thermal-hydraulic performance.The effect of varying wavy amplitude and the relative double step height was evaluated under different turbulent flow conditions. The turbulent flow and energy was modelled by contiuity full Navier-Stockesand energy equations. The effect of turbulent was modelled by k- Ɛ model. The finite volume method based on a simple algorithm was adoped to the discretise the flow and energy models. ANSYS Fluent was used to obtain the target results. The obtained results show that the increasing the amplitude value and the relative step height has a noticeable effect on intensification of average Nusselt number and overall performance with a moderate increase in friction losses. The findings reported that the steps height ratio (H_r= 2.6) provides the best overall performance for all the tested Reynolds numbers.The maximum performance was 1.63 (163%) at Re=10000 for Am=0.03 m.

Abstract: This study presents the modelling of heat loss and mass transfer through the walls, using Ubakus program, of a block of flats built in 1978 and thermally rehabilitated after 1990. The objective of the study is to present the thermal and mass transfer parameters before and after thermal rehabilitation. Thus, the benefits obtained after the rehabilitation consist in improving the comfort and health conditions for the residents, as well as reducing the expenses for heating/cooling the house and for renovating the degradation caused by humidity in the walls.

Abstract: Li-ion batteries generate significant heat during operation, which leads to an increase in temperature and, consequently, a reduction in the battery's efficiency and lifespan. In this study, different cooling methods are simulated for the thermal management of the battery. The cooling using air and liquids is investigated with laminar flow at varying velocities. Results indicated that the use of water/glycol is more effective than air and mineral oil.

Abstract: The precision in temperature estimation plays a pivotal role in the design and operational efficiency of CubeSats. This study leverages the capabilities of COMSOL MULTIPHYSICS to model the thermal behavior of a 1U CubeSat, with a focus on evaluating the impact of orientation and beta angle on heat transfer dynamics and the resultant temperature distribution throughout the satellite. By conducting an extensive range of simulations that explore beta angles from 0° to 90° across four distinct satellite orientations, this research uncovers critical insights into the heat transfer mechanisms within the CubeSat framework. These findings illuminate the substantial influence of orientation and beta angle on the satellite's thermal state, highlighting the necessity of incorporating these factors into any comprehensive thermal analysis of spacecraft. The outcomes of this investigation not only contribute to a deeper understanding of CubeSat thermal management but also underscore the importance of meticulous design and analysis practices to optimize satellite performance in the challenging space environment.

Abstract: This work presents a numerical study of natural convection heat transfer in a cavity filled with an ionanofluid. The governing equations are solved using the finite volume method and the SIMPLEC algorithm. This study aims to analyze the effects of key parameters influencing the flow structure and heat transfer, including the Rayleigh number (Ra), the volume fraction (𝜑), the inclination angle, and the type of base fluid.The results indicate that increasing the volume fraction (𝜑) enhances heat transfer and underscores the superiority of ionic fluids over water as a base fluid. Additionally, heat transfer reaches its maximum at a specific inclination angle.