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Journal ArticleDOI

Experimental investigation of wallboard containing phase change material: Data for validation of numerical modeling

01 May 2009-Energy and Buildings (Elsevier)-Vol. 41, Iss: 5, pp 561-570

Abstract: In construction, the use of phase change materials (PCM) allows the storage/release of energy from the solar radiation and/or internal loads The application of such materials for light weight construction (eg a wood house) makes it possible to improve thermal comfort in summer and reduce heating energy consumption in winter The choice of a PCM depends deeply on the building structure, on the weather and on building use: numerical modeling is indispensable In this paper, an experimental comparative study is described, using cubical test cells with and without PCM composite A set of experimental data is detailed, concerning the air and wall temperatures The results are compared with a numerical modeling and show that hysteresis must be taken into account to predict correctly the heat transfer

Summary (4 min read)

1 Introduction

  • Nowadays, thermal energy storage systems are essential for reducing dependency on fossil fuels and then contributing to a more efficient environmentally benign energy use [1].
  • As demand in thermal comfort of buildings rises increasingly, the energy consumption is correspondingly increasing.
  • As the temperature increases, the material changes phase from solid to liquid.
  • Even if these conditions are more realistic, all of the weather parameters are not known (or measured).
  • From a numerical point of view, having experiments with and without PCM is useful to verify the basic modeling.

2 Description of the test cells MICROBAT

  • Two identical test cells are used to investigate the effects of the PCM wallboards.
  • The design of the test cells is presented part 2.1.
  • The phase change material tested is described part 2.2.
  • The part 2.3 deals with the measurement systems and the probes, the experimental protocol is given part 2.4.

2.1 Design of the cells

  • Two identical test cells are used in the study.
  • Each test cell is a cubical enclosure with an internal dimension of 0.50m .
  • This face is called the active face because of its low thermal inertia and low thermal resistance.
  • It enhances the heat transfer between the exterior and the interior of MICROBAT.
  • The witness box has five normal faces whereas the PCM box contains three PCM faces which are the back face, the right face and the left face.

2.2 Phase change material tested

  • The product tested, ENERGAINr has been achieved by the Dupont de Nemours Society and is constituted of 60% of microencapsulated paraffin within a copolymer.
  • This rate corresponds to 3◦C/h which is an average heating rate in a light weight building during summer season and when solar gains are maximum.
  • The freezing curve (cooling from 34◦C to 1◦C) and the melting curve (heating from 1◦C to 34◦C), also known as Two curves are presented.
  • The physical properties of the composite PCM are: ⋆ peak melting temperature = 22.3◦C, ⋆ peak freezing temperature = 17.8◦C, ⋆ specific heat at the melting peak = 13.4Jg−1K−1, ⋆ specific heat at the freezing peak = 12.9Jg−1K−1, ⋆ solid specific heat = 2.4Jg−1K−1.
  • This curve is typical of the hysteresis loop.

2.3 Instrumentation and measurements

  • All of the temperatures are measured using Pt100 sensors with a calculated resolution of ±0.25◦C.
  • In each test cell the set of probes is: • the internal face temperature, measured at the center of the face, with a probe included in the wall surface, • the active face external temperature, measured at the center of the face, • the air temperature, measured at the center of the cubical air volume.
  • The time step chosen between two series of measurement is 2mn and the duration of each test is about three days.

2.4 Experimental protocol

  • The two MICROBAT test cells are placed into a climatic chamber.
  • The climatic chamber temperature can vary between −10◦C and 40◦C as a function of time.
  • The active face allows to impose the same external temperature for each test cell.
  • Two types of external temperature evolutions are investigated: • a temperature step, heating and cooling, • a sinusoidal temperature evolution.
  • Concerning the heating/cooling temperature step, three cases are tested depending on the slope (SL) i.e. the time needed to reach the constant temperature value: 1hour, 2hours or 3hours.

3 Temperature step

  • The first experiment concerns the temperature steps (heating and cooling) and the present part deals with the results of the cases tested.
  • The part 3.1 deals with general considerations concerning the measurements.
  • The air temperatures is analyzed part 3.2 and the internal face temperature part 3.3.

3.1 General considerations

  • The box without PCM is strongly insulated but with a relatively low thermal inertia.
  • The figure 7 shows the measured temperatures for the internal faces and air in the test cell without PCM for the case SL = 1hour.
  • Except for the active face, the other faces temperatures and the air temperature are nearly identical.
  • The temperature gradient in the box does not affect the heat transfer, and particularly the convection heat transfer.
  • This conclusion is valid for all the cases tested and then only air temperature is presented in the following paragraphs of the article.

3.2.1 Heating step

  • The air temperature measured for the three kinds of heating steps and for the two test cells is presented in figure 8.
  • The air temperature for the box without PCM is close to the exterior temperature with a little time lag due to the low thermal inertia of the box.
  • The air temperature evolution of the witness box is nearly exponential.
  • 21◦C, the air temperature is increasing linearly with a slope SL1 , (2) for 21◦C . θ(t) .
  • The table 3 summarizes the τ values for the heating step cases.

3.2.2 Cooling step

  • The air temperature measured for the three kinds of cooling steps and for the two test cells is presented in figure 9.
  • For the box with PCM, the temperature evolution is composed of three stages: (1) for θ(t) & 19◦C, the air temperature is decreasing linearly with a slope SLc, (2) for 15◦C . θ(t) .
  • This flat part of the curve lasts about 1h.
  • The PCM composite is composed of microencapsulated paraffin spheres included in a copolymer matrix.
  • As the solidification proceeds, the melt volume decreases with a simultaneous decrease in the magnitude of natural convection within the melt and the process is therefore much longer [14].

3.3 Test cell with PCM: temperature evolution

  • The phase change material included in the wallboards stores/releases energy transferred from the air volume mainly by convection.
  • Then, the wall surfaces temperatures are an important feature in the phase change phenomenon.
  • The figures 10 and 11 present the internal faces temperature , for the cell with PCM, and for the heating and cooling steps.
  • For all the cases tested, the three PCM walls have the same surface temperature.
  • For all of the cases tested, the temperature difference between the six faces of the cell never exceeds 5◦C.

3.4 Discussion

  • Of course, the presence of PCM allows to delay the box air temperature increase or decrease (as long as the temperature varies within the phase change range).
  • The analysis of the time lag defined paragraph 3.2.1 shows that the more the thermal excitation is rapid, the more the PCM is efficient.
  • In buildings, rapid thermal excitation can be solar spot or internal load.
  • For the PCM used in wallboards, hysteresis exists and has clearly been exhibited in paragraph 2.2.
  • This phenomenon has been few studied in literature and never been taken into account in numerical modeling as well as in experimental analysis.

4 External sinusoidal temperature evolution

  • The response of the MICROBAT to an external temperature step allows to characterize the time lag due to PCM wallboards.
  • In order to characterize the phase difference and the decrement factor due to PCM, an external sinusoidal temperature evolution is used, case which is closer to the real building configuration.
  • The phase difference ζ is defined as the time difference between outdoor temperature maximum and indoor temperature maximum.
  • The decrement factor f is defined as the ratio between indoor temperature amplitude and outdoor temperature amplitude.
  • For the walls with PCM, the temperature curve has two breaks of slope: one at about 19◦C and one at about 22◦C.

5 Numerical modeling

  • In the previous section, experimental data are described so that in the present section numerical modeling can be held.
  • Then, the numerical results are presented in paragraph 5.2.
  • The paragraph 5.3 is a discussion concerning the numerical modeling.

5.1 Presentation of the numerical modeling

  • The first modeling step consists in decomposing the test cell (or the building) in elementary objects: air zones, walls,...
  • In order to solve numerically the problem, a finite-difference method is used: the continuous information contained in the exact solution of the differential equation are replaced by discrete temperature values.
  • Only the longwave radiation exchanges are considered in the present modeling.
  • The internal exchanges occur between the internal surfaces of the walls.
  • The software MATLAB is used for all the simulations.

5.2 Numerical results

  • The experimental data are compared with the numerical results obtained from their modeling.
  • The figure 14 shows the comparisons between experiments and modeling for the heating step.
  • The figure (d) shows that the freezing specific heat curve is not adapted for the heating step modeling.
  • The modelings (a), (b) and (c) use the equivalent specific heat obtained with the data of the figure 4 freezing curve.
  • For the three cases, the numerical data are in quite good agreement with experiment, excepted for the flat part of the curve around 19◦C.

5.3 Discussion concerning the numerical modeling

  • The main problem of the PCM modeling is the way to introduce the phase change.
  • The equivalent specific heat has been tested.
  • Unfortunately, the paraffin used is not an eutectic mixture, so hysteresis occurs during the phase change.
  • When simulating heating step or cooling step separately, the numerical data are in good agreement with experiments only if the corresponding specific heat curve is used, e.g. melting curve and cooling curve.
  • The hysteresis phenomenon must the be taken into account correctly in order to predict the PCM composite thermal behavior.

6 Conclusions and outlook

  • The objective of this article is first, providing reliable experimental data that can be used for the validation of numerical modeling and then, studying some features related to the use of phase change material wallboard.
  • The external temperature is the thermal excitation; a heating/cooling step and a sinusoidal evolution are tested.
  • The effects of PCM wallboard are to cause time lag between indoor and outdoor temperature evolutions and to reduce the external temperature amplitude in the cell.
  • The effect of hysteresis phenomenon has been clearly exhibited with the experimental data: the melting process arises at a temperature higher than for the solidification process.
  • Further investigations are needed to have a better numerical description of this special phase change feature.

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Experimental Investigation of Wallboard Containing
Phase Change Material: Data for Validation of
Numerical Modeling
F. Kuznik, J. Virgone
To cite this version:
F. Kuznik, J. Virgone. Experimental Investigation of Wallboard Containing Phase Change Material:
Data for Validation of Numerical Modeling. Energy and Buildings, Elsevier, 2009, 41 (5), pp.561-570.
�10.1016/j.enbuild.2008.11.022�. �hal-00567439�

Experimental Investigation of Wallboard
Containing Phase Change Material: Data for
Validation of Numerical Modeling
F. Kuznik
a,
J. Virgone
b
a
Thermal Sciences Center of Lyon
CNRS, UMR 5008, INSA de Lyon, Universit´e Lyon 1
Bt. Sadi Carnot, 9 rue de la Physique - 69621 Villeurbanne Cedex, France
b
Universit´e de Lyon, Universit´e Lyon 1
DGCB laboratory, URA 1652,ENTPE rue Maurice Audin
69518 Vaulx-en-Velin Cedex, France
Abstract
In construction, the use of Phase Change Materials (PCM) allows the storage/release
of energy from the solar radiation and/or internal loads. The application of such
materials for lightweight construction (e.g. a wood house) makes it possible to im-
prove thermal comfort in summer and reduce heating energy consumption in win-
ter. The choice of a PCM depends deeply on the building structure, on the weather
and on building use: numerical modeling is indispensable. In this paper, an exper-
imental comparative study is described, using cubical test cells with and without
PCM composite. A set of experimental data is detailed, concerning the air and wall
temperatures. The results are compared with a numerical modeling and show that
hysteresis must be taken into account to predict correctly the heat transfer.
Key words: experimental data, PCM composite, phase change material,
Preprint submitted to Energy and Buildings 15 November 2008

wallboard, thermal energy storage, hysteresis.
1 Introduction
Nowadays, thermal energy storage systems are essential for reducing depen-
dency on fossil fuels and then contributing to a more efficient environmentally
benign energy use [1]. As demand in thermal comfort of buildings rises increas-
ingly, the energy consumption is correspondingly increasing. For example, in
France, the energy consumption of buildings has increased by 30% the last
30 years. Housing and tertiary buildings are responsible for the consumption
of approximatively 46% of all energies and approximatively 19% of the total
CO
2
emissions [2].
Thermal energy storage can be accomplished either by using sensible heat
storage or latent heat storage. Sensible heat storage has been used for centuries
by builders to store/release passively thermal energy, but a much larger volume
of material is required to store the same amount of energy in comparison to
latent heat storage. The principle of the phase change material (PCM) use is
simple. As the temperature increases, the material changes phase from solid
to liquid. The reaction being endothermic, the PCM absorbs heat. Similarly,
when the temperature decreases, the material changes phase from liquid to
solid. The reaction being exothermic, the PCM desorbs heat.
The main disadvantage of light weight buildings concerning thermal comfort
and energy consumption is their low thermal energy storage potential in walls.
Corresponding author. Tel.: +33-472-438-461; Fax: +33-472-438-522
Email address: frederic.kuznik@insa-lyon.fr (F. Kuznik).
2

Obviously, they tend to large temperature fluctuations due to external cooling
or heating loads. Using PCM material in such building walls can decrease the
temperature fluctuations, particularly in case of solar radiations loads. It is
then a potential method for reducing energy consumption in passively designed
buildings. This tendency is confirmed by numerous papers. For a review, see
in [3].
When selecting a PCM, the average room temperature should be close to the
melting/freezing range of the material. Moreover, the day fluctuations should
allow the material phase change. Then many factors influence the choice of
the PCM: weather, building structure and thermophysical properties,... Nu-
merical simulation must then be used to achieve the practical application of
this technology. In order to validate a PCM numerical model, experimental
data are essential.
The table 1 summarizes, not exhaustively, some experimental studies con-
cerning measurements held in a room with walls containing PCM wallboards.
Most of these experiments were carried out in outdoor conditions. Even if these
conditions are more realistic, all of the weather parameters are not known (or
measured). These studies cannot then be used to validate a numerical model
requiring all of the experimental conditions. Concerning the number of the
test cells, few studies use two identical cells with and without PCM. From a
numerical point of view, having experiments with and without PCM is useful
to verify the basic modeling.
The part 2 of this article presents the two identical test cells called MICRO-
BAT and the PCM tested. Two kinds of external temperature evolutions are
tested: heating and cooling steps with various slopes and sinusoidal temper-
3

ature evolution with 24h period. The part 3 deals with the results of the
temperature steps. The sinusoidal external temperature results are presented
in the next part of the paper. The part 5 is dedicated to the numerical mod-
eling of the experiments: the main assumptions of the model are presented,
then the simulations are compared with experimental data and finally, the
numerical modeling is discussed.
2 Description of the test cells MICROBAT
Two identical test cells are used to investigate the effects of the PCM wall-
boards. The design of the test cells is presented part 2.1. The phase change
material tested is described part 2.2. The part 2.3 deals with the measurement
systems and the probes, the experimental protocol is given part 2.4.
2.1 Design of the cells
Two identical test cells are used in the study. Each test cell is a cubical enclo-
sure with an internal dimension of 0.50m (figure 1). The skeleton of MICRO-
BAT is made of polish aluminium and is not painted in order to minimize the
shortwave radiative heat transfer with the surroundings.
The front face of MICROBAT is an aluminium plate of 2mm thickness. This
face is called the active face because of its low thermal inertia and low thermal
resistance. It enhances the heat transfer between the exterior and the interior
of MICROBAT. The other faces of the test cells are of two types:
= the normal face (figure 2), mainly composed of insulating material in order
4

Citations
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Journal ArticleDOI
Dan Zhou1, Changying Zhao2, Yuan Tian1Institutions (2)
Abstract: Thermal energy storage with phase change materials (PCMs) offers a high thermal storage density with a moderate temperature variation, and has attracted growing attention due to its important role in achieving energy conservation in buildings with thermal comfort. Various methods have been investigated by previous researchers to incorporate PCMs into the building structures, and it has been found that with the help of PCMs the indoor temperature fluctuations can be reduced significantly whilst maintaining desirable thermal comfort. This paper summarises previous works on latent thermal energy storage in building applications, covering PCMs, the impregnation methods, current building applications and their thermal performance analyses, as well as numerical simulation of buildings with PCMs. Over 100 references are included in this paper.

1,336 citations


Cites background or methods from "Experimental investigation of wallb..."

  • ...[60,61] Copolymer Paraffin wax 60% [44] CSM panel with brick RT27; SP 25 A 8 ---[62] Gypsum board MPCM 28D 23%, 30% 40% [63] Aluminium Paraffin A22; Paraffin A26 ---[64] Honeycomb panel Mixture of Tetradecane and Octadecane ---[65] Concrete (Regular block; Autoclaved block) Butyl stearate (Autoclaved block) Unicere 55 (Autoclaved block) Unicere 55 (Regular block) 5....

    [...]

  • ...Kuznik and Virgone [61] also tested two identical test cells under two kinds of external temperature evolutions, heating and cooling steps with various slopes and sinusoidal temperature evolution with 24h period....

    [...]


Journal ArticleDOI
Abstract: The present paper is the first comprehensive review of the integration of phase change materials in building walls. Many considerations are discussed in this paper including physical considerations about building envelope and phase change material, phase change material integration and thermophysical property measurements and various experimental and numerical studies concerning the integration. Even if the integrated phase change material have a good potential for reducing energy demand, further investigations are needed to really assess their use.

749 citations


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Abstract: This paper aims to explore how and where phase change materials (PCMs) are used in passive latent heat thermal energy storage (LHTES) systems, and to present an overview of how these construction solutions are related to building's energy performance. A survey on research trends are firstly presented followed by the discussion of some physical and theoretical considerations about the building and the potential of integrating PCMs in construction elements. The different types of PCMs and main criteria that govern their selection are reviewed, as well as the main methods to measure PCMs’ thermal properties, and the techniques to incorporate PCMs into building elements. The numerical modeling of heat transfer with phase-change and heat transfer enhanced techniques are discussed, followed by a review of several passive LHTES systems with PCMs. Studies on dynamic simulation of energy in buildings (DSEB) incorporating PCMs are reviewed, mainly those supported by EnergyPlus, ESP-r and TRNSYS software tools. Lifecycle assessments, both environmental and economic are discussed. This review shows that passive construction solutions with PCMs provide the potential for reducing energy consumption for heating and cooling due to the load reduction/shifting, and for increasing indoor thermal comfort due to the reduced indoor temperature fluctuations.

687 citations


Journal ArticleDOI
Shazim Ali Memon1Institutions (1)
Abstract: The building sector is the dominant energy consumer with a total 30% share of the overall energy consumption and accounts for one-third of the greenhouse gas emissions around the world. Moreover, in recent years the energy demands for buildings have increased very rapidly due to increase in the growth rate of population and improvement in living standards of people. Furthermore, fossil fuels will continue to dominate the world's primary energy by 2030. Thus, the increase in energy demand, shortage of fossil fuels and environmental concerns has provided impetus to the development of sustainable building and renewable energy resources. Thermal energy storage is an efficient method for applying to building envelopes to improve the energy efficiency of buildings. This, in turn, reduces the environmental impact related to energy usage. The combination of construction materials and PCM is an efficient way to increase the thermal energy storage capacity of construction elements. Therefore, an extensive review on the incorporation of PCM into construction materials and elements by direct incorporation, immersion, encapsulation, shape-stabilization and form-stable composite PCMs is presented. For the first time, the differentiation between shape-stabilized and form-stable composite PCM has been made. Moreover, various construction materials such as diatomite, expanded perlite and graphite, etc. which are used as supports for form-stable composite PCM along with their worldwide availability are extensively discussed. One of the main aims of this review paper is to focus on the test methods which are used to determine the chemical compatibility, thermal properties, thermal stability and thermal conductivity of the PCM. Hence, the details related to calibration, sample preparation, test cell and analysis of test results are comprehensively covered. Finally, because of the renewed interest in integration of PCM in wallboards and concrete, an up-to-date review with focus on PCM enhanced wallboard and concrete for building applications is added.

396 citations


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Abstract: Thermal energy storage systems (TES), using phase change material (PCM) in buildings, are widely investigated technologies and a fast developing research area. Therefore, there is a need for regular and consistent reviews of the published studies. This review is focused on PCM technologies developed to serve the building industry. Various PCM technologies tailored for building applications are studied with respect to technological potential to improve indoor environment, increase thermal inertia and decrease energy use for building operation. What is more, in this review special attention is paid to discussion and identification of proper methods to correctly determine the thermal properties of PCM materials and their composites and as well procedures to determine their energy storage and saving potential. The purpose of the paper is to highlight promising technologies for PCM application in buildings with focus on room application and to indicate in which applications the potential is less significant.

312 citations


References
More filters

Book
29 Apr 2002
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.

1,269 citations


"Experimental investigation of wallb..." refers background in this paper

  • ...Nowadays, thermal energy storage systems are essential for reducing dependency on fossil fuels and then contributing to a more efficient environmentally benign energy use [1]....

    [...]


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Abstract: A comprehensive review of various possible methods for heating and cooling in buildings are discussed in this paper. The thermal performance of various types of systems like PCM trombe wall, PCM wallboards, PCM shutters, PCM building blocks, air-based heating systems, floor heating, ceiling boards, etc., is presented in this paper. All systems have good potential for heating and cooling in building through phase change materials and also very beneficial to reduce the energy demand of the buildings.

839 citations


Journal ArticleDOI
Abstract: This paper studies a new innovative concrete with phase change materials (PCM) on thermal aspects. The final objective is to develop a product which would achieve important energy savings in buildings. The work here presented is the construction and experimental installation of two real size concrete cubicles to study the effect of the inclusion of a PCM with a melting point of 26 °C. The cubicles were constructed in the locality of Puigverd of Lleida (Spain). The results of this study show the energy storage in the walls by encapsulating PCMs and the comparison with conventional concrete without PCMs leading to an improved thermal inertia as well as lower inner temperatures.

641 citations


Additional excerpts

  • ...00m 2 outdoor [9] paraffin / gypsum 2....

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Andreas K. Athienitis1, C. Liu1, D.W. Hawes1, D. Banu1  +1 moreInstitutions (1)
Abstract: An experimental and numerical simulation study is presented of the application of phase change materials (PCM) in building envelope components for thermal storage in a passive solar test-room. Gypsum board impregnated with a phase change material was used. The experimental study was conducted in a full-scale outdoor test-room with the PCM gypsum board as inside wall lining. An explicit finite difference model was developed to simulate the transient heat transfer process in the walls. Reasonable agreement between the simulation and the experimental results was observed. It was shown that the utilization of PCM gypsum board in a passive solar building may reduce the maximum room temperature by about 4 °C during the daytime and can reduce the heating load at night significantly.

367 citations


"Experimental investigation of wallb..." refers background in this paper

  • ...PCM composite Size Number of cells Conditions [4] butyl stearate / gypsum 2....

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Journal ArticleDOI
Yinping Zhang1, Kunping Lin1, Ruizhi Yang1, Hongfa Di1  +1 moreInstitutions (1)
Abstract: Shape-stabilized phase change material (PCM) is a kind of novel PCM. It has the following salient features: large apparent specific heat for phase change temperature region, suitable thermal conductivity, keeping shape stabilized in the phase change process and no need for containers. The preparation for such kind material was investigated and the thermophysical properties of various samples developed by us were measured. Several applications of such material in energy efficient buildings (e.g., in electric under floor space heating system, in wallboard or floor to absorb solar energy to narrow the temperature swing of a day in winter) were studied. Some models of analyzing the thermal performance of the systems were developed, which were validated with our experiments. The following conclusions are obtained: (1) The applications of the novel PCM we put forward are of promising perspectives in different climate regions; (2) By using different paraffin, the melting temperature of shape-stabilized PCM can be adjusted; (3) The optimal composition of paraffin in shape-stabilized PCM is about 80%; (4) The heat of fusion of it is in the range of 62-138 kJ/kg; (5) For PCM floor or wallboard to absorb solar energy to narrow the temperature swing in a day in winter, the suitable melting temperature of PCM should be a little bit higher than the average indoor air temperature of the room without PCM for the period of sunshine; (7) For the electric under-floor space heating system, the optimal melting temperature can be determined by simulation; (8) PCM layer used in the aforementioned application should not be thicker than 2 cm; (9) For given conditions, the numerical models developed by us can provide the prediction and optimal design for the applications of shape-stabilized PCM in buildings.

259 citations


Additional excerpts

  • ...00m 2 outdoor [10] paraffin / polyethylene 3....

    [...]


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201915
201812
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