Determination of the enthalpy of PCM as a function of temperature using a heat-flux DSC—A study of different measurement procedures and their accuracy
TL;DR: In this paper, the authors investigate different methods for differential scanning calorimetry (hf-DSC) analysis, namely the dynamic method and the step method, and test their accuracy in the determination of the enthalpy-temperature relationship of PCM.
Abstract: Thermal energy storage by latent heat allows storing high amounts of energy working in narrow margins of
temperature. The use of phase change material (PCM) for the latent heat storage has been studied in different
applications and it has been commercialized in containers to transport blood, products sensible to temperature, to
decrease their energy demand. The use of PCM in cooling and refrigeration has been attracting a lot of interest lately,
but for all applications, the properties of these materials need to be known with sufficient accuracy. Regarding heat
storage, it is necessary to know the enthalpy as a function of temperature. The most widely used calorimeter is the heatflux
differential scanning calorimetry (hf-DSC). The objective of this study is to investigate different methods for hf-
DSC analysis, namely the dynamic method and the step method, and to test their accuracy in the determination of
enthalpy–temperature relationship of PCM. For the dynamic method, a strong influence of heating/cooling rate was
observed. For the step method, the resulting enthalpy–temperature relationship is independent of heating/cooling rate.
Commercial PCM RT27 was chosen as sample material to avoid subcooling and kinetic effects in the test
measurements. The approach introduced in this study can be used to carry out similar investigations for other classes of
PCM and/or other DSC instruments.
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TL;DR: In this article, the enthalpy change of phase change materials (PCMs) is measured with high precision using differential scanning calorimetry (DSC) and T-history method.
Abstract: Phase change materials (PCMs) are thermal storage materials with a high storage density for small temperature range applications. In the design of latent heat storage systems, the enthalpy change of the PCM has to be known as a function of temperature with high precision. During dynamic measurements, the sample is not in thermal equilibrium, and therefore the measured value is not the equilibrium value. The influence of non-equilibrium on the measurement results can be quantified by doing measurements during heating and cooling with any measurement instrument. Measurements carried out by differential scanning calorimetry (DSC) and by the T-history method are presented and discussed. To characterize encapsulated PCM objects, measurements on the whole objects should be carried out. A measurement setup for this purpose is also presented. The obtained precision meets typical application requirements, and good agreement between results obtained with the different methods is demonstrated.
260 citations
TL;DR: In this paper, the latent heat thermal energy storage properties of micro/nano encapsulated paraffin eutectic mixtures (PEMs) with polymethylmethacrylate (PMMA) shell were investigated.
192 citations
TL;DR: In this article, an innovative phase change material (nano-PCM) was developed with PCM supported by expanded graphite (interconnected) nanosheets, which are highly conductive and allow enhanced thermal storage and energy distribution.
184 citations
TL;DR: In this paper, a collection of similar methods previous to T-history are exposed and different proposals based on improving the original T- history method are discussed and reviewed, and the goal of this paper is moving towards a consensus to achieve this goal.
Abstract: Phase change materials (PCM) are able to store thermal energy when becoming liquid and to release it when solidifying Latent heat storage has gained importance due the applications towards increasing energy efficiency in several systems Thus, a correct and accurate thermal characterization of these materials should be achieved Among all possible thermal analysis methods to determine PCM thermophysical properties, the T-history method presents certain advantages The T-history method is known to be suitable to obtain fusion enthalpy, specific heat and thermal conductivity for large phase change materials samples On the other hand, no experimental T-history equipment is commercially available yet Therefore, the goal of this paper is moving towards a consensus To achieve this goal, a collection of similar methods previous to T-history are exposed and different proposals based on improving the original T-history method are discussed and reviewed
160 citations
TL;DR: In this paper, a set of Round Robin Tests (RRTs) was proposed to determine phase change enthalpy, thermal conductivity in solid and liquid phases, viscosity and density in function of temperature.
132 citations
Cites methods from "Determination of the enthalpy of PC..."
...[19] studied the different methods for heatflux DSC analysis to investigate their accuracy in the determination of enthalpy in function of PCM temperature....
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References
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TL;DR: In this paper, a review of the history of thermal energy storage with solid-liquid phase change has been carried out and three aspects have been the focus of this review: materials, heat transfer and applications.
4,019 citations
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29 Apr 2002
TL;DR: In this paper, the authors present an overview of thermal energy storage systems and their application in the context of thermal engineering, including thermal transfer with phase change in simple and complex geometries.
Abstract: List of Contributors.Acknowledgements.Preface.General Introductory Aspects for Thermal Engineering. Energy Storage Systems. Thermal Energy Storage (TES) Methods. Thermal Energy Storage and Environmental Impact. Thermal Energy Storage and Energy Savings. Heat Transfer and Stratification in Sensible Heat Storage Systems. Modeling of Latent Heat Storage Systems. Heat Transfer with Phase Change in Simple and Complex Geometries. Thermodynamic Optimization of Thermal Energy Storage Systems. Energy and Exergy Analyses of Thermal Energy Storage Systems. Thermal Energy Storage Case Studies.Appendix A -- Conversion Factors.Appendix B -- Thermophysical Properties.Appendix C -- Glossary.Subject Index.
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TL;DR: In this article, phase change materials (PCMs) are used to capture solar energy directly and increase human comfort by decreasing the frequency of internal air temperature swings and maintaining the temperature closer to the desired temperature for a longer period of time.
1,274 citations
Book•
16 Sep 1993
TL;DR: In this article, the authors discuss the design and optimum use of thermal analysis instrumentation for materials' property measurement and discuss potential pitfalls and the fitting of experimental results to theoretical models.
Abstract: Discussing the design and optimum use of thermal analysis instrumentation for materials' property measurement, this work details how the instruments work, what they measure, potential pitfalls and the fitting of experimental results to theoretical models. It presents a tutorial on writing computer programs for data manipulation, advanced thermoanal
322 citations
TL;DR: In this article, the phase diagram of the binary system of tetradecane and hexadecANE has been used to obtain information of the phase transition processes for cool storage applications.
218 citations