Compact Heat Storage for Solar Heating Systems

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Viktoria Martin ◽  
Fredrik Setterwall
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Average Power ◽  
High Capacity ◽  
High Energy ◽  
Finned Tube ◽  
Hot Water ◽  
High Energy Density ◽  
Power Capacity ◽  
Tube Heat Exchanger

Energy and cost efficient solar hot water systems require some sort of integrated storage, with high energy density and high power capacity for charging and discharging being desirable properties of the storage. This paper presents the results and conclusions from the design, and experimental performance evaluation of high capacity thermal energy storage using so-called phase change materials (PCMs) as the storage media. A 140 l 15 kW  h storage prototype was designed, built, and experimentally evaluated. The storage tank was directly filled with the PCM having its phase change temperature at 58°C. A tube heat exchanger for charging and discharging with water was submerged in the PCM. Results from the experimental evaluation showed that hot water can be provided with a temperature of 40°C for more than 2 h at an average power of 3 kW. The experimental results also show that it is possible to charge the 140 l storage with close to the theoretically calculated value of 15 kW h. Hence, this is a PCM storage solution with a storage capacity of over 100 kW h/m3, and an average power capacity during discharging of over 20 kW/m3. However, it is desirable to increase the heat transfer rate within the prototype. A predesign of using a finned-tube coil instead of an unfinned coil show that by using finned tube, the power capacity for discharging can be at least doubled, if not tripled.

Comparison of Stratification in a Water Tank and a PCM-Water Tank

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
A. Castell ◽  
C. Solé ◽  
M. Medrano ◽  
M. Nogués ◽  
L. F. Cabeza
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Phase Change Materials ◽  
High Energy ◽  
Hot Water ◽  
The Other ◽  
High Energy Density ◽  
Water Tank ◽  
Charging And Discharging Processes ◽  
Thermal Energy Storage Systems

Most of the thermal energy storage systems available on the market use water as a storage medium. The improvement of the storage efficiency results in a higher performance of the whole system, and thermal stratification is commonly used for this purpose. On the other hand, in applications with small temperature changes, phase change materials (PCMs) provide high energy density since the latent heat is much larger than the sensible heat. This is the case of stratified hot water tanks, where the temperature change in the top layer is small as it is held close to the usage temperature. The benefits of using PCMs in a water tank, in terms of energy storage density, have been demonstrated before. The time with available hot water is increased because of the energy stored in the PCMs. The aim of this work is to demonstrate that the use of PCMs in the upper part of a water tank holds or improves the benefit of the stratification phenomenon. Two tanks with the same dimensions were compared during charging and discharging processes. One of them is a traditional water tank and the other is a PCM-water tank (a water tank with a phase change material placed at the top).

Comparison of Stratification in a Water Tank and a PCM-Water Tank

2007 ◽  
Author(s):  
A. Castell ◽  
C. Sole´ ◽  
M. Medrano ◽  
M. Nogue´s ◽  
L. F. Cabeza
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Temperature Change ◽  
High Energy ◽  
Hot Water ◽  
The Other ◽  
High Energy Density ◽  
Water Tank ◽  
Charging And Discharging Processes ◽  
Change Material

Most of the storage systems available on the market use water as storage medium. Enhancing the storage performance is necessary to increase the performance of most systems. The stratification phenomenon is employed to improve the efficiency of storage tanks. Heat at an intermediate temperature, not high enough to heat up the top layer, can still be used to heat the lower, colder layers. There are a lot of parameters to study the stratification in a water tank such as the Mix Number and the Richardson Number among others. The idea studied here was to use these stratification parameters to compare two tanks with the same dimensions during charging and discharging processes. One of them is a traditional water tank and the other is a PCM-water (a water tank with a Phase Change Material). A PCM is good because it has high energy density if there is a small temperature change, since then the latent heat is much larger than the sensible heat. On the other hand, the temperature change in the top layer of a hot water store with stratification is usually small as it is held as close as possible at or above the temperature for usage. In the system studied the Phase Change Material is placed at the top of the tank, therefore the advantages of the stratification still remain. The aim of this work is to demonstrate that the use of PCM in the upper part of a water tank holds or improves the benefit of the stratification phenomenon.

scholarly journals Triglycerides as Novel Phase-Change Materials: A Review and Assessment of Their Thermal Properties

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5572
Author(s):  
Rebecca Ravotti ◽  
Jörg Worlitschek ◽  
Colin R. Pulham ◽  
Anastasia Stamatiou
Keyword(s):  
Thermal Properties ◽  
Phase Change ◽  
Phase Change Materials ◽  
Waste Heat ◽  
High Energy ◽  
High Energy Density ◽  
Melting Points ◽  
Latent Heat Storage ◽  
Chemical Structures ◽  
Energy Technologies

Latent Heat Storage (LHS) with Phase-Change Materials (PCMs) represents a high energy density storage technology which could be applied in a variety of applications such as waste heat recovery and integration of renewable energy technologies in energy systems. To increase the sustainability of these storage solutions, PCMs have to be developed with particular regard to bio-origin and biodegradability. Triglycerides represent an interesting class of esters as the main constituents of animal and vegetable fats, with attractive thermal properties. In order to be used as PCMs, the thermal behaviour of triglycerides has to be fully understood, as in some cases they have been reported to show polymorphism and supercooling. This study assesses the suitability of triglycerides as PCMs by reviewing the literature published so far on their behaviour and properties. In particular, melting points, enthalpies of fusion, polymorphism, thermal conductivities, heat capacities and thermal cycling stabilities are considered, with a focus on LHS and thermal energy storage applications. In addition, the efforts conducted regarding modelling and the prediction of melting points and enthalpies based on chemical structures are summarized and assessed.

scholarly journals Evaluating a prototype compact thermal energy storage tank using paraffin-based phase change material for domestic hot water production

2019 ◽  
Vol 116 ◽  
pp. 00016
Author(s):  
George Dogkas ◽  
John Konstantaras ◽  
Maria K. Koukou ◽  
Vassilis N. Stathopoulos ◽  
Luis Coelho ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Storage System ◽  
Energy Storage System ◽  
Hot Water ◽  
Domestic Hot Water ◽  
Tube Heat Exchanger

A full-scale thermal energy storage system using phase change materials (PCM) is experimentally investigated for solar and geothermal applications. The system consists of a rectangular tank filled with PCM and a staggered fin tube heat exchanger (HE). The system is designed for the production of Domestic Hot Water (DHW) based on the EU Commission Regulation No 814/2013 [1] requirements. The characteristics that are studied are the stored energy density of the system, the heat transfer rate through the HE during the charging and discharging processes, the adequacy of produced hot water amount and the storage efficiency of the tank. The results of the experiments confirmed the potential of the system to meet several prerequisites of a DHW installation and in addition to make the operation of the coupled solar collector or ground heat pump efficient.

scholarly journals Solvothermal method as a green chemistry solution for micro-encapsulation of phase change materials for high temperature thermal energy storage

2018 ◽  
Vol 5 ◽  
pp. 4 ◽  
Author(s):  
Albert Ioan Tudor ◽  
Adrian Mihail Motoc ◽  
Cristina Florentina Ciobota ◽  
Dan. Nastase Ciobota ◽  
Radu Robert Piticescu ◽  
...  
Keyword(s):  
High Temperature ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Solvothermal Method ◽  
High Energy ◽  
High Energy Density ◽  
Latent Heat Storage

Thermal energy storage systems using phase change materials (PCMs) as latent heat storage are one of the main challenges at European level in improving the performances and efficiency of concentrated solar power energy generation due to their high energy density. PCM with high working temperatures in the temperature range 300–500 °C are required for these purposes. However their use is still limited due to the problems raised by the corrosion of the majority of high temperature PCMs and lower thermal transfer properties. Micro-encapsulation was proposed as one method to overcome these problems. Different micro-encapsulation methods proposed in the literature are presented and discussed. An original process for the micro-encapsulation of potassium nitrate as PCM in inorganic zinc oxide shells based on a solvothermal method followed by spray drying to produce microcapsules with controlled phase composition and distribution is proposed and their transformation temperatures and enthalpies measured by differential scanning calorimetry are presented.

Experimental Investigation of Heat Transfer Enhancement by Using Different Number of Fins in Circular Tube

2018 ◽  
Vol 6 (3) ◽  
pp. 1-12
Author(s):  
Kamil Abdul Hussien
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cold Water ◽  
Finned Tube ◽  
Hot Water ◽  
Copper Tube ◽  
Smooth Tube ◽  
Tube Heat Exchanger ◽  
Mass Flow Rates ◽  
Flow Heat

Abstract-The present work investigates the enhancement of heat transfer by using different number of circular fins (8, 10, 12, 16, and 20) in double tube counter flow heat exchanger experimentally. The fins are made of copper with dimensions 66 mm OD, 22 mm ID and 1 mm thickness. Each fin has three of 14 mm diameter perforations located at 120o from each to another. The fins are fixed on a straight smooth copper tube of 1 m length, 19.9 mm ID and 22.2 mm OD. The tube is inserted inside the insulated PVC tube of 100 mm ID. The cold water is pumped around the finned copper tube, inside the PVC, at mass flow rates range (0.01019 - 0.0219) kg/s. The Reynold's number of hot water ranges (640 - 1921). The experiment results are obtained using six double tube heat exchanger (1 smooth tube and the other 5 are finned one). The results, illustrated that the heat transfer coefficient proportionally with the number of fin. The results also showed that the enhancement ratio of heat transfer for finned tube is higher than for smooth tube with (9.2, 10.2, 11.1, 12.1 13.1) times for number of fins (8, 10, 12, 16 and 20) respectively.

scholarly journals Thermal Dynamic Behavior in Bi-Zone Habitable Cell with and without Phase Change Materials

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 41
Author(s):  
Hanae El Fakiri ◽  
Lahoucine Ouhsaine ◽  
Abdelmajid El Bouardi
Keyword(s):  
Thermal Behavior ◽  
Thermal Comfort ◽  
Phase Change ◽  
Dynamic Behavior ◽  
Phase Change Materials ◽  
Energy Performance ◽  
High Energy ◽  
Water Heater ◽  
Simplified Modeling

The thermal dynamic behavior of buildings represents an important aspect of the energy efficiency and thermal comfort of the indoor environment. For this, phase change material (PCM) wallboards integrated into building envelopes play an important role in stabilizing the temperature of the human comfort condition. This article provides an assessment of the thermal behavior of a “bi-zone” building cell, which was built based on high-energy performance (HEP) standards and heated by a solar water heater system through a hydronic circuit. The current study is based on studying the dynamic thermal behavior, with and without implantation of PCMs on envelope structure, using a simplified modeling approach. The evolution of the average air temperature was first evaluated as a major indicator of thermal comfort. Then, an evaluation of the thermal behavior’s dynamic profile was carried out in this study, which allowed for the determination of the PCM rate anticipation in the thermal comfort of the building cell.

scholarly journals Influence of Adding Encapsulated Phase Change Materials in Aerial Lime Based Mortars

2013 ◽  
Vol 687 ◽  
pp. 255-261 ◽  
Author(s):  
Sandra Cunha ◽  
José Barroso Aguiar ◽  
Victor Ferreira ◽  
António Tadeu
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Renewable Energy Sources ◽  
High Growth ◽  
High Energy ◽  
High Growth Rate ◽  
Aesthetic Appearance ◽  
Hardened State ◽  
High Energy Consumption

Increasingly in a society with a high growth rate and standards of comfort, the need to minimize the currently high energy consumption by taking advantage of renewable energy sources arises. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing for an increase in the level of thermal comfort and reduction of the use of heating, ventilation and air conditioning (HVAC) equipment, using only the energy supplied by the sun. However, the incorporation of PCM in mortars modifies some of its characteristics. Therefore, the main objective of this study was the characterization of mortars doped with two different phase change materials. Specific properties of different PCM, such as particle size, shape and enthalpy were studied, as well as the properties of the fresh and hardened state of these mortars. Nine different compositions were developed which were initially doped with microcapsules of PCM A and subsequently doped with microcapsules of PCM B. It was possible to observe that the incorporation of phase change materials in mortars causes differences in properties such as compressive strength, flexural strength and shrinkage. After the study of the behaviour of these mortars with the incorporation of two different phase change materials, it was possible to select the composition with a better compromise between its aesthetic appearance, physical and mechanical characteristics.

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