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Abhat, A. (1978). Performance studies of a finned heat pipe latent thermal energy storage system. The international solar Energy Society Congress, New Delhi, India.
Abstract
Performance studies of a modular heat pipe heat exchanger concept for use in a latent thermal energy storage system for solar heating application a have been undertaken. The thermal analysis provides the influence of various geometric and thermal parameters on the storage charging time and temperature gradients for heat flow into markedly different storage subsystems. Additionally, experiments are performed with a small 6l test model filled with a paraffin. Results indicate the capability of the heat exchanger concept to operate within small temperature swings (10k) for realistic heat input rates. Comparisons between data and prediction for the test model showed adequate agreement.
Abhat, A., S. Aboul-Enein, et al. (1980). Heat-Of-Fusion Storage Systems For Solar Heating Applications. Thermal Storage Of Solar Energy. C. Den Ouden. Holland, The Hague, Martinus Nijoff Publishers: 157-171.
Biswas, D. (1977). "Thermal energy storage using Sodium Sulfate Decahydrate and Water." Solar Energy 9: 99-100.
Bourdeau, L. E. (1980). Study of two passive solar systems containing phase change material for thermal storage. The 5th National Passive Solar Conference.
Abstract
Two passive storage collector walls using calcium chloride hexahydrate have been tested at Los Alamos during the 1980 winter season. Results are presented, along with a sensitivity study on yearly performances obtained from a validated simulation model. Advantages provided by such a material against classical storage materials are emphasised.
Buddhi, D., J. Kishor, et al. (1987). An experimental study of a solar collector cum storage system with phase change material. Energy Options For The 90's NSES 87.
Abstract
A solar collector cum storage system with a latent heat storage material viz stearic acid was designed and tested under varying conditions of design parameters. The system performance remains unsatisfactory requiring more detailed investigation of optimum design and the corresponding techno-economic evaluation.
Buddhi, D., N. K. Bansal, et al. (1988). "Solar thermal storage systems using phase change materials." International Journal Of Energy Research 12: 547-555.
Abstract
Using Fourier series expansion of the involving temperatures and the forcing parameters i.e. the solar radiation and the ambient temperature, an iterative procedure has been developed to solve the heat transfer problem with moving boundaries. Calculations specific to a typical summer and winter day in Delhi have been presented for a numerical application of the developed analysis. Experiments have been performed to validate the development theoretical analysis. A good agreement is seen between theoretical and experimental results with in the domain of the applicability of theory.
Crane, R. A. and B. G (1991). "Evaluation of thermal energy storage devices for advanced solar dynamic systems." Journal of Solar Energy Engineering 113: 138-145.
Abstract
The work described herein addresses the thermal performance of three concepts for thermal energy storage as applied to solar dynamic applications. It is recognized that designs providing large thermal gradients or large temperature swings during orbit are susceptible to early mechanical failure. Concepts incorporating heat pipe technology may encounter operational limitations over sufficiently large ranges. By reviewing the thermal performance of basic designs the relative merits of the basic concepts are to be compared. In addition, the effect of thermal enhancement and metal utilization as applied to each design provides a partial characterisation of the performance improvements to be achieved by developing these technologies.
De Jong, A. G. and C. J. Hoogendoorn (1980). Improvement Of Heat Transport In Paraffins For Latent Heat Storage Systems. Thermal Storage Of Solar Energy. C. Den Ouden. Holland, Martinus Nijoff Publishers.
Edie, D. D. and S. S. Melsheimer (1976). An immiscible fluid-heat of fusion energy storage system. Sharing The Sun Solar Technology In The Seventies A Joint Conference Of The American Section Of The International Solar Energy Society and The Solar Energy Society Of Canada Inc, Winnipeg, The American Section Of The International Solar Energy Society.
Abstract
Preliminary studies of a novel heat of fusion energy storage system have been conducted. This system uses direct contact heat transfer between an aqueous crystallising solution and an immiscible heat transfer fluid. The phase change solution is permanently contained in an insulated storage tank. A heat transfer fluid (which is immiscible in the phase change solution) is circulated through the solution and transfers heat either to or from the solution. By eliminating permanent heat exchange surfaces, this immiscible fluid system avoids the phase stratification problem, which has negated the potential storage efficiency of many previous heat of fusion systems. The target energy density for this heat storage system design is 3.5 x 10(8) joules per cubic meter. The estimated cost for storage of 1.0 x 10(9) joules is $1,100.
Eftekhar, J., A. Haji-Sheikh, et al. (1984). "Heat transfer enhancement in a paraffin wax thermal storage system." Solar Energy Engineering 106.
Abstract
Heat transfer enhancement in a thermal storage system consisting of vertically arranged fins between a heated and cooled horizontal finned-tube arrangement is reported. The high thermal expansion co-efficient and low viscosity of paraffin wax, at temperatures above 50° C, are utilised to induce natural convection in the liquid phase even at small thicknesses. The experimental data on the rate of production of liquid as a function of time and temperature of the hot surface is presented. The photographs of the melted zone indicate a naturally buoyant flow induced in the neighbourhood of the vertical fins causes a rapid melting of the solid wax and a downdraft along cooler solid phase surface. The heat transfer co-efficient at the interface is calculated from experimentally determined instantaneous locations of the moving boundary.
Farid, M. M. (1968). "Solar Energy Storage With Phase Change." Solar Energy Research 4(1): 11-29.
Abstract
A mathematical model recently developed to predict rates of melting and solidification of PCM has been used to study the performance of a solar energy storage unit for domestic purposes. The model assumed one-dimensional heat flow and included the effects of natural convection in melted layer.
In the present work, Computations were carried out for two different paraffin waxes, n-octadene and P-116. having different melting points of 27.7° C and 467.7° C respectively. The results so obtained showed that the rates of melting with convection remained constant during the entire melting period except at the beginning where the conduction mode is predominant. The temperature difference between the heating fluid and the melting mass of the PCM was found to control the rates of melting in the presence of convection in the melted region. However when conduction controls the heat transfer mechanism, the rates of melting and solidification decreased very rapidly to lower values in spite of large temperature differences (Tw-Tf).
In an attempt to overcome the heat transfer problems associated with phase change storage systems, the unit under consideration contains two sections each filled with a PCM having a different melting point. Results obtained also indicate improved overall heat transfer rates to the extent that all the energy collected from a common flat plate type collector got stored at high rate (>0.5 KW/m2) with limited heat transfer area. However heat transfer will remain at relatively low rates during discharge period, which suggests the use of more efficient methods of extracting the heat, such as the use of heat pipes or finned surfaces.
Farouk, B. and S. I. Guceri (1979). Trombe-Michel wall using phase change materials. Proc. 2nd Miami Int. Conf. on Alternative Energy, Miami.
Abstract
A one dimensional numerical model is used to predict the performance of a Trombe-Michel wall suing PCM's. The usefulness of the PCM wall installed in a building for night time home heating is investigated by considering data for Glaubers Salt mixture and SUNOCO P-116 wax. The weather information for a mid-February day along with data for the Solar One house were used for the system simulation. It is observed that if the PCM wall is designed properly, it eliminates some of the undesirable features of the masonry walls with comparable results.
Furbo, S. (1980). Heat Storage With An Incongruently Melting Salt Hydrate As Storage Medium Based On The Extra Water Principle. Thermal Storage Of Solar Energy. C. Den Ouden. Holland, Martinus Nijoff Publishers: 134-145.
Ghoneim, A. A. and S. A. Klein (1989). "The effect of phase change material properties on the performance of solar air based heating systems." Solar Energy 42: 441-447.
Abstract
A large amount of work has been carried out in the use of PCMs in storage systems, which has been triggered by the realisation that PCMs can bring about significant reductions in storage volume over systems suing air as a storage medium. The main determinants of PCM selection is its melting point as this has a major effect on system efficiency. Other factors affect system performance such as
1. Time the storage unit operates in Two-Phase mode. 2. fraction of time storage unit is charged up and the fraction of time the unit is isolated.
PCMs tend to be paraffin waxes or inorganic salts.
Hasnain, S. M. (1998). "Review on sustainable thermal energy storage technologies, part 1: heat storage materials and techniques." Energy Conversion Management 39(11): 1127-1138.
Abstract
This paper reviews the development of available thermal energy storage (TES) technologies and their individual pros and cons for space and water heating applications. Traditionally, available heat has been stored in the form of sensible heat (typically by raising the temperature of water, rocks, etc) for later use. In most of the low temperature applications, water is being used as a storage medium. Latent heat storage on the other hand, is a young and developing technology which has found considerable interest in recent times due to its operational advantages of smaller temperature swing, smaller size and lower weight per unit of storage capacity. It has been demonstrated that, for the development of a latent heat thermal energy storage system, the choice of the phase change material (PCM) plays an important role in addition to heat transfer mechanisms in the PCM. Attempts have also been made to utilise technical grade phase change materials as a storage media and embedded heat exchange tubes/ heat pipes with extended surfaces in order to enhance the heat transfer rate to/from the PCM.
Hokoi, S. and T. Kuroki (1997). Application of phase change material to passive solar heating. Second International Conference Buildings and the Environment: 585-592.
Abstract
The effect of a phase change material (PCM in mitigating changes in room air temperature is investigated by examining the room and floor temperatures during winter, with a PCM installed in the floor to absorb solar radiation. In the numerical analysis, the phase change process is investigated by making use of the apparent heat capacity, which includes latent heat, although it is usually formulated as a moving boundary problem. For effective use of the PCM, the selection of the melting point was found to be important. It is shown that the optimum value of the melting point for suppression of room temperature change is the average sol-air-temperature, which is the equivalent average room temperature taking into account the effect of solar radiation absorbed on the surface of the PCM. The average room temperature can be calculated accurately by the steady -state method of calculation, which requires only the heat loss factor of the room (the over-all thermal conductance) and the average values of weather conditions . Thus it is independent of the melting point of the PCM and also of whether the PCM is used or not. The value of the average room temperature thus obtained also allows the optimum value of the melting point to be determined in advance. Furthermore, an approximate method of thermal calculation is proposed, which allows calculation of how far the change of room air temperature can be mitigated by a PCM.
IP, K. C. W. (1998). Solar thermal storage with phase change materials in domestic buildings. CIB World Congress, Gavle, Sweden: 1265-1272.
Abstract
This paper summarises the investigation and analysis of a solar space heating system incorporating phase change materials for use in domestic buildings in the UK. Encapsulated phase change material modules designed to absorb heat from water pipes are used for the thermal storage of solar energy. By choosing a suitable phase change material to take advantage of the latent heat absorbed during phase of the material from solid form to liquid form, a large quantity of daytime solar energy can be stored and used for space heating at a later time. Conventional roof mounted flat plate solar panels have been selected for solar collection and the thermal energy is transferred to the phase change material through a series of pipes under the floor.
A dynamic modular simulation program is sued to study the performance of the proposed space heating system. Components which simulate the two dimensional heat transfer and the phase change process are established. Seven system configurations are analysed and their performances and energy savings are evaluated.
Results indicate the performance of the proposed system is affected by the attainment of phase change temperature in the phase change material. The generation of this phase change temperature is related to the area and efficiency of the solar pane, the temperature gradient along the length of pipe and the heat transfer characteristics of the equipment. The proposed system, which uses commonly available commercial materials and equipment, demonstrated to be viable. The results show the thermal effectiveness of phase change material and significant amount of energy saving can be achieved.
Jotshi, C. K., D. Y. Goswami, et al. (1992). Solar thermal energy storage in phase change materials. Proceedings of Solar 92: The 1992 AM. Solar Energy Society Annual Conference: 174-179.
Abstract
This paper describes the thermo physical properties and thermal behaviour of the phase change materials (PCMs) that have been identified as potential materials for solar thermal energy storage applications. PCMs that undergo solid-liquid and solid-solid phase transformation have been described. PCMs which include salt hydrates, paraffins, non-paraffins, eutectics of inorganic and/or organic compounds, and polyalcohols are discussed. The containment requirement for these PCMs are also described in this paper.
Kapur, J. C. (1978). A passive integrated unit for the collection, thermal storage in fusion materials and distribution of solar energy for home heating and other applications. Proceedings Of The International Solar Energy Society Congress, New Delhi, India.
Kauffmann, K. W. and H. G. Lorsch (1976). Thermal energy storage with saturated aqueous solutions. Sharing The Sun Solar Technology In The Seventies A Joint Conference Of The American Section Of The International Solar Energy Society and The Solar Energy Society Of Canada Inc, Winnipeg, The American Section Of The International Solar Energy Society.
Abstract
A method of thermal energy storage at temperature of O° C to 12° Cis being developed for application to solar space heating, water heating and air conditioning. The method uses saturated aqueous solutions of salts which dissolve endothermically and have large coefficients of solubility with temperature. Latent heat of crystallisation is continuously released on cooling and absorbed on heating, resulting in specific heat capacities up to 480% of the specific heat of water. Over a 10° C range of temperature. storage densities can be achieved which are in the same range as those of latent heat of fusion materials. Since the solutions are pumpable, systems employing them do not require the expensive container/heat exchangers characteristic of latent heat devices using phase change materials. Total costs for a 10(8) joule storage device are 1/4 to 1/2 the cost of devices using sodium thiosulfate pentahydrate or 50% water - ethylene glycol.
Michaels, I. A. (1981). An overview of the USA program for the development of thermal energy storage for solar energy applications. The Hague, TNO and Martinus Nijhoff.
Morrison, D. J. and S. I. Abdel-Khalik (1978). "Effects of phase change energy storage on the performance of air based and liquid-based solar heating systems." Solar Energy 20: 57-67.
Abstract
Models describing the transient behaviour of phase-change energy storage (PCES) units are presented. Simulation techniques are used in conjunction with these models to determine the performance of solar heating systems utilising PCES. Both air-based and liquid based and liquid based systems are investigated. The effects of storage capacity, storage unit heat transfer characteristics, collector area and location on the system performance are investigated and systems utilising sodium sulfate decahydrate and paraffin wax as storage media. Optimum ranges of storage sizes are recommended an the basis of system's thermal performance. Comparison is made between systems utilising PCES and those using sensible heat storage, viz, rock beds in air based systems and water tanks in liquid-based systems. The variation of the solar supplied fraction of load with storage size and collector area is given for systems utilising both types of storage. The effects of location and collector energy and collector area is given for systems utilising both types of storage. The effects of location and collector energy size and collector energy loss coefficient on the relative performance of PCES and sensible heat storage are also investigated.
Rice, R. E. and B. M. Cohen (1978). Phase change thermal storage for a solar total energy system. Proceedings of the Int. Solar Energy Society Congress, New Delhi, India.
Abstract
An analytical and experimental program is being conducted on a one-tenth scale model of a high temperature (584k) phase change thermal energy storage system for installation in the solar total energy test facility of the Sadia Laboratories at Alburquerque, New Mexico, U.S.A. The Thermal storage medium is anhydrous sodium hydroxide with 8% sodium nitrate. The program will produce data on the dynamic response of the system to repeated cycles of charging and discharging simulating those of the test facility. data will be correlated with a mathematical model which will then be used in the design of the full scale system.
Swet, C. J. (1976). New directions in heat storage for buildings. Sharing The Sun Solar Technology In The Seventies A Joint Conference Of The American Section Of The International Solar Energy Society and The Solar Energy Society Of Canada Inc, Winnipeg, The American Section Of The International Solar Energy Society.
Abstract
Many advanced technologies are being explored in order to overcome the limitations on solar heating and cooling of buildings imposed by presently available water and rock bed storage systems. Specific goals include higher energy density, retro-fittability, higher temperatures for improved cooling system performance, yearly averaging storage for 100 percent solar operation, and incorporation into building materials for distributed storage. Some of the more promising sensible and latent heat storage technologies are discussed and tentatively evaluated for the standpoints of utility, technical feasibility, and cost.
Swet, C. J. (1980). Phase change storage in passive solar architecture. The National Passive Solar Conference.
Abstract
Phase change materials (PCM) can be used in many ways for thermal energy storage in passive solar architecture. Candidate materials are sodium sulfate decahydrate (Glauber's salts), calcium chloride hexahydrate, and paraffin wax. Applications include reduced mass and volume, better comfort maintenance, and higher solar collection efficiency. Methods include encapsulation in exposed containers, encasement in building materials, and permeation of building materials. state of the art is reviewed.
Telkes, M. (1977). Solar Energy Storage. Applications Of Solar Energy For Heating and Cooling of Buildings. New York, American Society Of Heating and Air Conditioning Engineers Inc.
Van Galen, E. (1980). Experimental Results Of A Latent Heat Storage System Based On Sodium Acetate Trihydrate In A Stabilising Colloidal Polymer Matrix, Tested As A Component Of A Solar Heating System. Thermal Storage Of Solar Energy. C. Den Ouden. Holland, the Hague, Martinus Nijoff Publishers: 147-155.
Velraj, R., R. V. Seeniraj, et al. Heat transfer enhancement in a latent heat storage system [online]. Solar Energy Online. Available from: http://oxford.elsevier.com [accessed 25 Feb 2000].
Abstract
Commercial acceptance and the economics of solar thermal technologies are tied to the design and development of efficient, cost effective thermal storage system. Thermal storage units that utilise latent heat storage materials have received greater attention in the recent years because of large heat storage capacity and their isothermal behaviour during charging and discharging process. One major issue that needed to be addressed is that most PCM's with high energy density have an unacceptably low thermal conductivity. So the heat transfer enhancement techniques are very much required for any latent heat thermal storage 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.
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