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Abstract Thermal energy storage systems for both heat and cold are necessary for many industrial processes. High energy density and high power capacity are desirable properties of the storage. The use of latent heat increases the energy density of the storage tank with high temperature control close to the melting point. Tube in PCM tank is a very promising system that provides high packing factor. This work presents an experimental study of a PCM tank for cold storage applications. Two different configurations and different flow rates of the heat transfer fluid were studied. The effectiveness of the PCM storage system was defined as that of a heat exchanger. The results showed that the heat exchange effectiveness of the system did not vary with time, decreased with increasing flow rate and increased with increasing heat transfer area. The effectiveness was experimentally determined to only be a function of the ratio m ˙ /A. This equation was found to be adequately be used to design a PCM storage system, and a case study is presented. It was shown that the tube in tank design together with a low temperature PCM is suitable as a thermal storage facility for cold storage.

Abstract Life Cycle Assessment (LCA) has been conducted for seven experimental cubicles located in Puigverd de Lleida (Spain). The objective of this experimental set-up is to test different constructive solutions in order to point out the most sustainable solution with lower energy demand during the operational phase. Therefore, different building, insulation and Phase Change Materials (PCMs) have been tested under controlled temperature conditions to examine the thermal performance of the whole system. Although some of these materials are able to reduce the energy demand and consequently the environmental impact during the operational phase, they still have high embodied energy that can cause high environmental impact during the manufacturing phase. Therefore the LCA study in this paper focuses on assessing the impact of the embodied energy needed during the manufacturing and disposal phase by highlighting and comparing the effect of using different building materials, insulating materials, and phase change materials.

Central solar heating plants with seasonal storage (CSHPSS) are among the most promising technologies to save energy in the industrial and residential-commercial building sectors. This work introduces a systematic approach to optimize these systems according to economic and environmental criteria. Our method, which combines the TRNSYS 17 simulation software with life cycle assessment and multi-objective optimization, identifies optimal CSHPSS designs for any climatic condition and heating demand profile considering economic and environmental criteria simultaneously. The capabilities of this approach are illustrated through its application to a case study of a CSHPSS located in Barcelona (Spain), which satisfies a heating demand for a neighborhood of 1120 dwellings. Numerical results show that the CSHPSS plant leads to significant environmental and economic improvements compared to the use of a conventional natural gas heating system. Our tool can guide engineers and architects in the transition towards a more sustainable residential sector.

Aquaculture has become an important sector of animal food production thanks to a fast and continuous growth over the last few decades. Both marine and fresh water fish can be reared in fish farms, and there are species that are mainly produced by aquaculture rather than capture. As most of the reared fish species are sensible to water temperature and its fluctuations, having the control of this parameter in fish farms becomes an important issue that has to be taken into account. In this paper, three different fish farms are studied by simulating the water temperature when a thermal energy storage (TES) system using phase change materials (PCMs) is implemented. The effect and the estimated amounts of PCM required in each particular case are also analyzed. The results show that appreciable effects can be obtained, especially when the TES unit is used in combination with auxiliary sources of energy, such as solar collectors.

Abstract Transport and storage of low temperature sensitive products is an issue worldwide due to changes of the lifestyle and population increase. In the recent years, thermal energy storage (TES) using phase change materials (PCMs) is being highly studied and developed for cold storage applications. Furthermore, the PCM are normally encapsulated in containers and added in the available systems, usually in food processes. Therefore safety constraints as the compatibility of the PCM with other materials have to take into account. Hence the main goal of the paper is to study the corrosion effect of different metals and polymer materials in contact with some PCM used in low temperature applications. Results show that copper and carbon steel must be avoided as PCM containers, and aluminium is not recommended; stainless steel 316 is recommended when in contact with the tested PCM. Moreover, PP, PS, PET, and HDPE are not affected by a process of degradation and are also compatible with the PCM studied.

Today, green roofs are a building system which provides interesting benefits over traditional roof solutions. The most important advantages are the reduction of surface runoff in cities, improvement of the urban climate, biodiversity support, improvement of the durability of roofing materials, and, especially, energy savings. This paper has the aim of studying the performance of green roofs as a passive system for energy savings, within a wider objective of seeking constructive solutions suitable for sustainable and environmentally friendly architecture. This idea is tested at an experimental installation available at the University of Lleida, with several cubicles testing the energy performance of different construction solutions. This work raises the possibility of using recycled rubber from tires as a drainage layer in green roofs, substituting the porous stone materials currently used (such as expanded clay, expanded shale, pumice, and natural puzolana). This solution would reduce the consumption of these natural materials, which also require large amounts of energy in its transformation process to obtain their properties. Moreover it would provide a solution to the problem of waste rubber from the tires, known as rubber crumbs. Since the purpose of the drainage layer is the optimum balance between air and water in the green roof system, first the ability for draining of recycled rubber granules was studied and was compared with the offered by stone materials. The new solution using rubber crumbs is also studied to test if it would keep the same insulating properties that the green roof with stone materials presented in previous studies. Early results show that this extensive green roof system can be a good passive energy savings tool in Continental Mediterranean climate in summer, and that rubber crumbs can be an interesting substitute for stone materials used as drainage layer in this type of green roofs.

Abstract The use of night cooling ventilation in addition of phase change materials (PCMs) is a very powerful strategy for reducing the cooling demand of buildings. Nevertheless, there are inherent drawbacks in the way things have been doing so far: (a) The limited area of contact between PCM and the air; (b) the very low convective heat transfer coefficients which prevents the use of significant amounts of PCM and (c) the very low utilization factor of the cool stored due to the large phase shift between the time when cool is stored and time when it is required by the building. In this paper, we present innovative solutions using PCM to overcome the above situation. Compared with existing solutions, innovative solutions proposed, increase the contact area between PCM and air by a factor of approximately 3.6, increase the convective heat transfer coefficient significantly, and improve the utilization factor due to the inclusion of active control systems which allow the cold stored be actually used when required.

Thermal energy storage (TES) using phase change materials (PCM) can be used for load shaving or peak load shifting when coupled to a heating, ventilation, and air-conditioning (HVAC) system such as heat pump. In these systems the PCM is embedded in packages or used in bulk, so the compatibility of the encapsulation materials and the PCM is a key factor to ensure long operational life of the system. Although corrosion caused by salts is known from the chemical industry, when these salts are used as PCM no corrosion data is available, since the salts are used without being in water solution. Producing new corrosion data is essential for PCM utilisation in new applications. In this study the corrosion rate of two metals and two metal alloys when they are in contact with different salt hydrate PCM is evaluated; in total eleven PCM, being four of them commercial PCM, are tested. Since they are PCM to be used for heating and cooling applications they are classified in two different groups to present the corrosion study. Results present the recommendation of using each PCM with the different metals and metal alloys according to the obtained corrosion rate and visual observation of the samples.