Performance analysis of solar still using 10-E, sustainability, and heat transfer analysis: Exploring synergistic effects of PCM quantity and ultrasonic fogger

The mechanical behavior of welds is sensitive to the close coupling between heat transfer, microstructure evolution and thermal stress analysis. Since the temperature field computed from a heat transfer analysis can be considered to drive the mechanics of the welding process, the first step is to solve the energy equation usually with FEM. The research issue is decoupling the physics of the arc and weld pool from the energy equation. This is done by modeling the heating effect of the arc. Although the effects of microstructure and stress-strain evolution on heat transfer are not large, the effect of temperature on the microstructure and thermal stress is dominant. In addition, the coupling between microstructure and thermal stress can be strong and subtle. The microstructure evolution is modeled with algebraic equations for thermodynamics and ordinary differential equations for kinetics. The thermal stress analysis involves large strains and large rotations. The most popular constitutive equation has been elasto-plastic. Phase transformations such as the austenite to martensite transformation, can dominate the stress analysis. Since realistic welding problems tend to be truly three dimensional with complex geometry, transient and nonlinear, numerical methods have advantages. However, the computational demands have limited the size of welds that can be analyzed. In the past five years considerable progress has been made in developing numerical methods to solve this coupled problem with increasing speed and accuracy. Major gains have been made with better mesh grading and more efficient solvers. In addition, software engineering has played a major role in managing the complexity of software.

The pipeline support is a complex component structure in liquefied natural gas (LNG) loading arm. In order to study the impact of ultra-low temperature conditions on the mechanical performance of pipeline brackets, the heat transfer analysis and thermal stress calculation of the pipeline support of the LNG loading arm are carried out under low-temperature conditions in this paper. Based on the principle of steady-state heat transfer, the finite element method is used to study the sensitivity of ambient temperature to heat transfer results of pipe support, the results show that the heat dissipated by the duct support is proportional to the temperature difference. The temperature field distribution of the pipe-bundle rib on the duct support under ice-free and ice-covered conditions is analyzed, and two different paths are selected to study the temperature distribution law of the structure, and the conclusion that the ice has the effect of cooling is drawn. Finally, based on the temperature field distribution results obtained by the heat transfer analysis, the low-temperature stress analysis of the pipe support is carried out. According to the thermal stress results, the corresponding improvement measures are proposed. It provides some guidance for the structural design of the loading arm.

In this study, the performance of a thermo siphon type radiator made of copper for LED lighting system was evaluated by using an inverse heat transfer method. Heating experiments and finite element heat transfer analysis were conducted for three different cases. The data obtained from experiments were compared with the analysis results. Based on the data obtained from experiments, the inverse heat transfer method was used in order to evaluate the heat transfer coefficient. First, the heat transfer analysis was conducted for non-vacuum state, without the refrigerant. The evaluated heat transfer coefficient on the radiator surface was 40W/<TEX>$m^2^{\circ}C$</TEX>. Second, the heat transfer analysis was conducted for non-vacuum state, with the refrigerant, resulting in the heat transfer coefficient of 95W/<TEX>$m^2^{\circ}C$</TEX>. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/<TEX>$m^2^{\circ}C$</TEX>. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the third case, the evaluated heat transfer coefficients were 140W/<TEX>$m^2^{\circ}C$</TEX> for the radiator body, 5W/<TEX>$m^2^{\circ}C$</TEX>. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant for the rising position of radiator pipe, 35W/<TEX>$m^2^{\circ}C$</TEX>. Third, the heat transfer analysis was conducted for vacuum state, with refrigerant. For the highest position of radiator pipe, and 120W/<TEX>$m^2^{\circ}C$</TEX> for the downturn position of radiator pipe. As a result of inverse heat transfer analysis, it was confirmed that the thermal performance of the current radiator was best in the case of the vacuum state using the refrigerant.

Analysis of heat transfer in oscillating flow through a channel filled with metal foam using computational fluid dynamics

Thermal modeling of a packed bed thermal energy storage system during charging

This study is concerned with the analyses of heat transfer through an exhaust valve considering the real unsteady effects during the cycle of an internal combustion engine and to identify the factors and parameters affecting the heat transfer. The valve is segmented into several zones to facilitate incorporating the boundary conditions and evaluating the heat transfer coefficient and the adiabatic wall temperature based on the finite element method. The unsteady simulations were carried out using ANSYS-APDL for the proposed thermal model. The effect of lubricating oil and the contact resistance between guide and engine block and the thermal contact between exhaust valve and seat are included, as well as the differential displacement of both the guide and engine block walls due to high working temperature. The averaged values of heat transfer coefficient and adiabatic wall temperature used in the boundary conditions are shown to underestimate the temperature maps. The cyclic boundary conditions required more run time to reach the steady state and allowed better monitoring of the thermal process. The thermal contact resistance has the main contribution in the zone of valve-seat, whereas the resistance of oil film between the guide and stem valve is shown to affect mainly heat transfer coefficient. The obtained maps of temperature reveal the locations of maximum temperatures in the exhaust valve.

A new approach to the analysis of variable property heat transfer for turbulent flow is presented. The mathematical model developed herein is based on the principle of surface renewal and involves the use of an integral technique. The proposed expressions for heat transfer account for both variable conductivity and variable viscosity and are applicable to heating and cooling. The theoretical predictions are in good agreement with available experimental heat transfer data for moderate Prandtl number fluids.

Central Receiver System (CRS) with molten salt (MS) technology represents the most cost effective and leading candidate technology for electricity generation for stand-alone Solar Power Plants. But MS has a high freezing point, and the tube alloy also can not stand long time with high temperature in MS circumstances. Tube freezing, leaking and salt decomposing are very likely to happen during the operation, especially under the unstable and non-uniform solar incidence flux. The conventional heat transfer correlations are not well available to deal with the MS receiver, for the heat flux are inconstant and non-uniform and only heat one side of the receiver tube, and the thermal properties of MS are also changed with temperature. By using a commercial CFD software FLUENT, this paper presents the results and analysis of the heat transfer in MS receiver tube with steady non-uniform heat flux around the circumference. This results will do some help to the 100kW MS receiver design and fabrication in the next step in DAHAN SPT project.

The practice of solar energy usage has reached a remarkable level in recent years. Solar collectors are used to trap solar radiations incident on it and these trapped energy can be used for various applications such as heating the water and space, and other commercial purposes. Flat plate collectors are most widely used for low and medium heating applications. It is the need of the hour to analyse the solar collectors for enhancing the thermal efficiency, heat transfer rate and reduce the size. This paper presented an overview of the performance analysis, heat transfer analysis, transient analysis and energy and exergy study of various solar flat plate collectors. This review paper will be beneficial for the scientists, academicians, energy planners and policymakers to promote the use of solar flat plate collectors for thermal applications for sustainable development and cleaner production.

Development And Implementation Of Interactive/Visual Software For Steady State And Transient Heat Conduction Problems

Heat and mass transfer analysis of falling liquid film over a heated horizontal elliptical tube used in desalination systems are investigated. The heat transfer analysis is based on the energy integral formulation with constant wall temperature. Thermal conditions at free surface of the liquid falling film are assumed to be subcooled and saturated, and the effects of surface tension have been considered. The effects of boiling and ripple at the film free surface have been ignored. Heat transfer zoning is considered as the three distinct regions, namely, the jet impingement region, the thermal developing region, and the fully developed region. Extensive analytical study is performed on the thermal hydraulic behavior of the three above mentioned regions, and correlations for both of the film and thermal boundary layer thicknesses, as well as the local and average heat transfer coefficients, have been derived. The results show that the effects of surface tension on heat transfer coefficient is nearly negligible. Based on the presented results, it can be emphasized that the overall heat transfer coefficient increases by increasing the ellipticity of the tube, implying that the elliptical tubes possess more advantages over circular tubes in desalination systems. Comparisons of the analytical results with the existing experimental data verify the validation of the present study.

Analysis of heat transfer with liquid-vapor phase change in a forced-flow fluid moving through porous media

The low convective coefficient at the condenser part of spreaders and vapor chambers due to film blanket blocking encourages utilizing dropwise condensation (DWC). Challenges exist in the experimental characterization of DWC, which includes dependence on numerous parameters and, more importantly, measurement difficulties due to low driving temperature differences. This highlights the necessity of accurate modeling of this complex process. The widely used macroscale modeling process of DWC, known as classical analytical modeling of DWC, typically combines state-of-the-art droplet size distribution model with a simplified shape-factor-based heat transfer analysis of a single droplet that contains major simplifications, such as conduction only through the bulk liquid, hemispheric droplet shape, and homogeneously distributed temperature over the entire droplet surface. Recent numerical approaches included the effect of the Marangoni convection and implanted realistic thermal boundary conditions on liquid–vapor interface and reported significant errors of classical modeling. Based on a novel dynamic numerical approach that incorporates surface tension, the Marangoni convection, and active mass transfer at the liquid–vapor interface, the droplet growth phenomenon has been modeled in this study. Notable differences of droplet growth and flow field have been observed resulted from dynamic growth modeling of the droplet as more than 70% heat transfer rate underestimation of quasi-steady modeling in 1-mm droplets with a contact angle of 150° is observed. The effect of shape change due to gravity on the heat and mass transfer analyses of individual droplets found to be negligible.

Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

Models are available to predict the fire‐resistance ratings of wood‐frame assemblies protected by gypsum board. These models have been developed to predict the performance of assemblies exposed to a standard fire test in which temperatures increase monotonically. In an ongoing effort to model the fire resistance of light‐frame wood floor assemblies, in this study, a number of improvements over past heat transfer models have been made in an attempt to simulate assembly performance in any arbitrary fire exposure. For this purpose, the heat transfer analysis has been coupled with a mass transfer analysis. The calcination of gypsum board and pyrolysis of wood are now modelled using an Arrhenius expression.In order to evaluate the accuracy of the model, a series of cone calorimeter experiments have been conducted in an effort to generate experimental data under well‐defined boundary conditions. Comparisons between test results and the predictions from a one‐dimensional heat and mass transfer analysis are encouraging with excellent agreement in predicting the point at which gypsum board is fully calcinated. A lack of material property data, particularly the permeability of gypsum board, remains a limiting factor in further improvement of the accuracy of the model. Copyright © 2008 John Wiley &amp; Sons, Ltd.