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Water-calorimetric measurement on large samples of PCM
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
2005 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178Article in journal (Other academic) Submitted
Place, publisher, year, edition, pages
2005.
Keyword [en]
Phase-change material, PCM, Water calorimeter, Durability, Thermal storage capacity, TSC
National Category
Construction Management
Identifiers
URN: urn:nbn:se:kth:diva-7483OAI: oai:DiVA.org:kth-7483DiVA: diva2:12520
Note
QS 20120316Available from: 2005-10-14 Created: 2005-10-14 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Testing large samples of PCM in water calorimeter and PCM used in room applications by night-air cooling
Open this publication in new window or tab >>Testing large samples of PCM in water calorimeter and PCM used in room applications by night-air cooling
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The latent-heat-storage capacity in Phase-Change Materials can be used for storing or releasing energy within a small temperature interval. Upon the phase transition taking place in a narrow temperature span, the material takes up or releases more energy compared to sensible heat storage. For an ideal phase-change material, the transition temperature is a single value, but for the most common phase-change materials on the market, used in building applications, the transition temperature is distributed within a temperature range of several degrees.

Integration of phase-change materials in building applications can be effected in several ways, for example by impregnating phase-change materials into porous building materials like concrete, wallboards, bricks or complements of the building structure. Integrating storages filled with phase-change materials makes other implementations, for instance accumulating tanks or envelopes as presented in this thesis, in an air heat exchanger. An appropriate phasetransition temperature of the supposed application is critical to the functionality of the material. For example, in cooling applications, the transition temperature of the material should be a few degrees lower than the requested comfort temperature in the building, and the opposite for heating applications.

In order to assess the thermal properties and the durability of the material, a watercalorimetric equipment was developed and employed in an accelerated testing programme. The heat capacity of the material and in particular possible change in the heat capacity over time, after thermal cycling of the material, were measured. In the thermal cycling of the material from solid to liquid phase, the temperature rise and required energy supply were recorded. The testing programme was undertaken according to control procedures and documents. In order to be able to utilize the heat-storage capacity in the best way, it is necessary to gain knowledge about thermal properties of the material, especially the long-term behaviour of the material and the deterioration rates of the thermal properties.

A semi-full-scale air heat exchanger based on phase-change material was developed and tested under real temperature conditions during the summer of 2004. The test results were used to compare and verify computer simulations made on a similar plant. The air heat exchanger utilises the ambient diurnal temperature swing to charge and discharge the phasechange material. The material tested in the calorimeter and in the air heat exchanger has an estimated phase-change temperature of about 24 °C.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. viii, 29 p.
Keyword
phase-change material, PCM, water calorimeter, air heat exchanger, durability, thermal properties, heat capacity
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-495 (URN)91-7178-160-9 (ISBN)
Presentation
2005-10-25, Hörsalen BMG/ITB-Brynäs, Södra Sjötullsgatan 3, Gävle, 10:00
Opponent
Supervisors
Note
QC 20101123Available from: 2005-11-22 Created: 2005-11-22 Last updated: 2010-11-23Bibliographically approved
2. Service life estimations in the design of a PCM based night cooling system
Open this publication in new window or tab >>Service life estimations in the design of a PCM based night cooling system
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The use of Phase Change Material, PCM, to change the thermal inertia of lightweight buildings is investigated in the CRAFT project C-TIDE. It is a joint project with Italian and Swedish partners, representing both industry and research. PCMs are materials where the phase change enthalpy can be used for thermal storage. The Swedish application is a night ventilation system where cold night air is used to solidify the PCM. The PCM is melted in the day with warm indoor air and thereby the indoor air is cooled. The system is intended for light weight buildings with an overproduction of heat during daytime. In the thesis, the results of experiments and numerical simulations of the application are presented. The theoretical background in order design the heat exchanger and applying the installation in thermal simulation software is presented. An extensive program is set up, in order to develop test methods and carry tests to evaluate the performance over time of the PCM. Testing procedures are set up according to ISO standards concerning service life testing. The tests are focused on the change over time of the Thermal Storage Capacity (TSC) in different temperature spans. Measurements are carried out on large samples with a water bath calorimeter. The service life estimation of a material is based on the performance of one or more critical properties over time. When the performances of these properties are below the performance requirements, the material has reached its service life. The critical properties of the PCM are evaluated by simulation of the application. The performance requirements of the material are set up according to general requirements of PCM and requirements according to building legislation. The critical properties of a PCM are the transition temperature, the melting temperature range and the TSC in the operative temperature interval. The critical property of the application is its energy efficiency.

The results of the study show that the night cooling system will lower the indoor air temperature during daytime. It also shows that the tested PCM does not have a clear phase change, but an increased specific heat in the operative temperature interval. Increasing the amount of material, used in the application, can compensate this. Finally, the tested PCM is thermally stable and the service life of the product is within the range of the design lives of the building services. It is essential to for all designers to know the performance over time of the properties of PCMs. Therefore it is desirable that standardized testing methods of PCM are established and standardized classification systems of PCMs are developed.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xvi, 80 p.
National Category
Construction Management
Identifiers
urn:nbn:se:kth:diva-449 (URN)91-7178-141-2 (ISBN)
Public defence
2005-10-20, Gävle Konserthus, 10:00
Opponent
Supervisors
Note
QC 20101020Available from: 2005-10-14 Created: 2005-10-14 Last updated: 2010-10-20Bibliographically approved

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