Hochschule Bremen - University of Applied Sciences

Hochschule Bremen

Application of nanofluids in thermal energy storage systems

Beitrag auf Tagung

Natur und Technik

Julius Robert Mayer - Institut für Energietechnik

Smolen, Slawomir, Prof. Dr.-Ing.
Cieslinski, Janusz T., Prof. Dr.-Ing.


Name(n), Titel
Application of nanofluids in thermal energy storage systems

Weitere Informationen zur Veranstaltung
11th Annual International Symposium on Environment,
Athens Institute for Education and Research (ATINER), Greece, May 2016

Athens, Greece

May 2016

The shortage of fossil fuels and environmental considerations - first of all reduction of carbon dioxide emission, motivated the researchers to use alternative energy source such as solar energy. However, the temporal difference of solar energy and energy needs made necessary the development of storage system. Therefore, the storage of thermal energy has become an important aspect of energy management.
There are three main physical ways for thermal energy storage:
sensible heat, phase change reactions and thermochemical reactions. Storage based on chemical reactions has much higher thermal capacity than sensible heat but are not yet widely commercially viable. Large volume sensible heat systems are promising technologies with low heat losses and attractive prices.
The medium applied in thermal energy storage is a fluids or phase change material (PCM). In general, the thermal conductivity of these materials is poor leading to a slow charging and discharging rate. The charging and discharging rate can be enhanced by applying the heat transfer enhancement methods. The literature shows numerous methods to enhance the thermal conductivity of the materials used in thermal energy storage systems varying from metal ring and metal matrix insertion, encapsulation, and many others. The novel concept is application of nanoparticles in base fluid to obtain so called nanofluids. The thermal response tests shows the addition of nanoparticles remarkably decreases the supercooling degree of base liquids, advances the beginning freezing time and reduces the total freezing time.
This study aims to evaluate the potential of water-Al2O3 nanofluids as a sensible heat storage material in free convection systems.
The test chamber consisted of a cubical vessel made of stainless steel with inside dimensions of 150 mm x 150 mm x 250 mm. Commercially available stainless steel tubes having 10 mm OD and 0.6 mm wall thickness were used to fabricate the test heater. The effective length of a tube was 100 mm. The ends of primary heater are soldered to short cooper cylindrical ends to minimize any additional electrical resistance. The test specimens were heated by using the tubes themselves as resistance heaters. The power supply can be adjusted by an electrical transformer. A K-type thermocouple was used to measure temperature inside the tube.
In the present study Al2O3 nanoparticles were used while distilled, deionized water was applied as a base fluid. Ultrasonic vibration was used for 4 h in order to stabilize the dispersion of the nanoparticles. Alumina nanoparticles were tested at the concentration of 0.01% by weight. Silica (SiO2) nanoparticles, of spherical form have diameter from 5 nm to 250 nm; their mean diameter was estimated to be 47 nm according to the manufacturer (Sigma-Aldrich Co.).



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