Thermal conductivity enhancement in a latent heat storage system

This paper presents an analysis of the storage/release of thermal heat during melting and solidification of paraffin wax PCM (phase change material) with different composite of materials. In this composite material, the paraffin wax is characterized by high phase change latent heat and serves as the heat capacity promoter. Since the low thermal conductivity of PCM makes charging and discharging those system challenging on enhance the heat transfer and latent heat storage. In different geometric design used to enhance the heat transfer for addition of fins, use of straight tube, shell tube and encapsulation in this configuration mostly used for thermal storage system. Finally this paper discusses about heat transfer enhancement study using PCM at there different geometry and composites materials in an heat exchanger.

This heat transfer text provides a comprehensive treatment of the fundamental aspects of conduction, convection, and radiation. Emphasis is placed on careful and complete theoretical developments, and numerous solved example problems and design problems are included to illustrate practical applications of fundamental principles. The appendices provide properties of materials, tables of mathematical functions, author index, and subject index. (LCL)

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Solar Energy, 1999

Commercial acceptance and the economics of solar thermal technologies are tied to the design and development of efficient, cost-effective thermal storage systems. Thermal storage units that utilize latent heat storage materials have received greater attention in the recent years because of their large heat storage capacity and their isothermal behavior during the charging and discharging processes. One major issue that needs to be addressed is that most phase-change materials (PCM) with high energy storage density have an unacceptably low thermal conductivity and hence heat transfer enhancement techniques are required for any latent heat thermal storage (LHTS) applications. In the present paper the various heat transfer enhancement methods for LHTS systems are discussed. Three different experiments to augment heat transfer were conducted and the findings are reported.

A large amount of heat is generated during the operation of electronic gadgets. Efficient thermal management is crucial for their safe operation and reliability. Phase change materials serve the role to maintain almost constant temperature during the phase change process by absorbing the generated heat. Therefore, the present experimental investigation is performed to single out the thermal performance of nickel foam-based heat sink embedded with RT-44HC paraffin as phase change material (PCM). Nickel foam is used for a high heat transfer area with a minimum reduction in the latent heat of a composite PCM. Results revealed that at the end of the charging process, the heat sink base temperature is reduced by 18.6% when a PCM volume fraction of 0.6 was added to the nickel foam. Furthermore, as the PCM fraction increased, the base temperature decreased further. An 11.6% additional decrease in temperature of the PCM was observed for volume fraction increment from 0.6 to 0.8. The effective thermal conductivity of the composite PCM was noticed to be enhanced by six times as that of a pristine PCM. The discharging process of the composite PCM was delayed compared with that of nickel foam without PCM. However, the sink temperature lies within the safe limits for the composite PCM. The latent heat of the composite PCM was diminished by 23% when effective thermal conductivity was enhanced. Thus, a nickel foam-PCM based heat sink is an efficient source to maintain the electronics temperature within the safe limits.

International Journal of Heat and Mass Transfer, 1994

Composite(s) or layered material(s)/anisotropic media Papers addressing heat contact in composite construction, thermal expansion issues, thermal cracks, multi-layered models, influences due to various heat loads and boundary effects, thermal calculations in composite wall(s) and anisotropic media, effective thermal conductivity approximations, multilayered media, graphite fiber/polymer matrix composites, transverse thermal diffusivity evaluations, thermal resistance in multi-layer composites appear in refs. [18A-39A]. Injluence of laser/pulse heat and thermal propagation The effect(s) due to sudden laser impact on materials, pulse heat loading situations and thermal shock(s) are addressed in this subcategory. Of mention are also publications involving thermal wave propagation problems under the influence of a hyperbolic heat conduction mode. Tbe papers in this subcategory are identified in refs. [40A-53A]. Conduction in arbitrary geometries and complex configurations In this subcategory, papers dealing with simplified models for homogeneous cylinders, temperature distribution in journal bearings and spherical ridges and troughs in a plane are addressed. These are identified in refs. [54A-56A]. Models/methods and approaches and numerical studies This subcategory continues to attract a wide range of interest in the development of accurate models, and modeling/analysis approaches including numerical studies for a variety of physical situations involving heat transfer due to conduction. Finite difference, finite element, boundary element methods and the like have been employed for a wide range of research investigations. These appear in refs. [57A-8lA]. Thermo-mechanical problems The influence of temperature effects on materials and components in particular, thermal-stresses and thermally induced stress waves are addressed in this subcategory. Both linear and nonlinear thermal-stress issues are addressed including theoretical/numerical and experimental studies. These papers are identified in refs. [82A-145A]. Inverse heat conduction Inverse heat conduction aspects including development of methods, substitution of multi-dimensional problems, prediction under the influence of heat sources and various types of boundary conditions, regularized solutions, explicitly sometimes, numerical approximations and simulations appear in refs. [146A-148A]. Miscellaneous conduction studies Various types of miscellaneous heat conduction problems have been studied in literature and appear in refs. [149A-178A]. Special applications Specialized applications involving heat conduction via theoretical, numerical/approximate method sand/or experimental investigations are addressed in refs. [179A-209A]. Electronic packaging Various theoretical, experimental and numerical studies dealing with thermal heat transfer characteristics, influence of heat sources, contact issues, prediction of temperature field and the like in microelectronic packaging appear in refs. [210A-232A]. BOUNDARY LAYERS AND EXTERNAL FLOWS The research on boundary layer and external flows during 1992 has been categorized as follows: flows influenced externally, flows with special geometrir Heat transfer-a review of 1992 literature 1287 effects, compressible and high-speed flows, analysis and modeling techniques, unsteady flow effects, films and interfacial effects, flows with special fluid types, and conjugate heat transfer situations. Unsteady eflects External effects Several papers documented the effects of an imposed streamwise pressure gradient [lB, 3B, lOB, IJB-lSB]. Some included the effects of acceleration on the stabiiity of the boundary layer indicating conditions of transition and reiaminarization. One addressed the effect of agitation. Other effects discussed were variations of the thermal boundary condition, raising of the external (free stream) disturbance level, imposition of longitudinal vortex arrays, and application of sonic disturbances [2B, 4B-9B, llB, 12B] Heat transfer-a review of 1992 literature 1289 periodically perturbed flow and heat transfer due to electrohydrodynamical forcing was treated in refrigerant 113. Transient flow was examined in the presence of twisted oval tubes and for time-varying temperature field in a thick-walled pipe [88C-97C]. Multi-phase jlow in ducts Multi-phase flow in ducts was examined in over a wide range of physical situations. Solid-gas two-phase flow was considered in the following studies: submicron particle flow in a cooled laminar tube considering convection, diffusion, and thermophoresis; gas-particle flow of nonisothermal turbulent swirling flow was studied in a cylindrical channel; and mixtures of combustible and non-combustible particles in gas were studied. Gas (typically air) and liquid flow was examined in the presence of wave motion; the interfacial heat transfer was investigated. A new correlation was presented for the air-water flow in horizontal rectangular channels. Air-water flow was also treated in the stratified arrangement found in certain rod bundles. Polydisperse aerosols in cooled laminar flow was studied theoretically and experimentally. Three-phase flow of water (ice-steamliquid) was examined and compared to single-phase flow. A three-phase system of air-water-sand was also studied in the presence of a tube bundle [98C-109C]. Non-Newtonian jlow in ducts Non-Newtonian fluid flow in ducts was a particularly active research area during the year. Power law tluids in concentric annular ducts were examined, where both the heat transfer and pressure drop were considered. Viscous dissipation effects on heat transfer to power law fluids was studied in arbitrary duct cross sections. Non-Newtonian flow was investigated in a variety of geometries including: axisymmetric sudden expansion (with applications to extruston processes and capillary rheometry); flow in a rectangular duct (viscoelastic, inelastic, and polymerizable fluids were considered); Couette flow in an annuli with moving outer cylinder (power law fluids); and viscoelastic fluid flow in a screw-wall channel. A second law analysis of non-Newtonian forced convection was also presented [l lOC-12OC]. Miscellaneous duct jlow A handful of studies did not fit well into the categories highlighted above. These investigations included cryogenic applications (e.g. liquid helium), high-speed gas flows, and fluidized bed channel flow [121C-128C].

Materials Today: Proceedings, 2016

An Experimental study on latent heat storage system (LHS) using Erythritol as a phase change material (PCM) has been carried out to analyze the thermal characteristics. The study is part of testing aimed at observation of PCM to store solar energy to melt paraffin wax for candle making. The trial inspected the effect of inlet temperatures (T h) of heat transfer fluid (HTF) on the thermal behaviour of the LHS system. The outcome revealed that the suitable inlet temperature (T h) for charging the system is 143° C. The trial plan also examined the temperature gradient in the axial directions during charging to help predict heat transfer in the system during phase change of Erythritol. Time bound temperature curves were used to analyse the results. An LHS was fabricated of shell and tube (bundle) type heat exchanger for this study. Thermocouples connected to a data logger were used to measure the temperature of the PCM along the direction of flow.

International Journal of …, 2006

The present paper is intended to encompass the English language heat transfer papers published in 2003, including some translations of foreign language papers. This survey, although extensive cannot include every paper; some selection is necessary. Many papers reviewed herein relate to the science of heat transfer, including numerical, analytical and experimental works. Others relate to applications where heat transfer plays a major role not only in man-made devices, but in natural systems as well. The papers are grouped into categories and then into sub-fields within these categories. We restrict ourselves to papers published in reviewed archival journals. Besides reviewing the journal articles in the body of this paper, we also mention important conferences and meetings on heat transfer and related fields, major awards presented in 2003, and books on heat transfer published during the year.

This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

Solar Energy, 1999

Commercial acceptance and the economics of solar thermal technologies are tied to the design and development of efficient, cost-effective thermal storage systems. Thermal storage units that utilize latent heat storage materials have received greater attention in the recent years because of their large heat storage capacity and their isothermal behavior during the charging and discharging processes. One major issue that needs to be addressed is that most phase-change materials (PCM) with high energy storage density have an unacceptably low thermal conductivity and hence heat transfer enhancement techniques are required for any latent heat thermal storage (LHTS) applications. In the present paper the various heat transfer enhancement methods for LHTS systems are discussed. Three different experiments to augment heat transfer were conducted and the findings are reported.