Binder-free granulated zeolite Y was post-synthetically modified to improve its low-temperature heat storage performance. Procedures such as treatment with EDTA, treatment with HCl, and ion exchange (Mg2 +) with acid treatment were used, all in order to reduce the desorption temperature and optimize the storage density. All modified samples showed a decrease in the desorption temperature from 10 to 30 °C compared to the unmodified zeolite. Only the desorption temperature of the ion-exchanged and acid-treated sample was increased. We carefully studied the effect of various treatments on the structural properties of materials, including the formation of structural defects. The energy storage density of our materials was compared with one of the currently used adsorbents (zeolite X) and an increase of up to 50% was determined.
COBISS.SI-ID: 6387482
The efficiency of sorption-based heat storage technologies is governed by the performance of the applied sorbents. Thus, sorbents with high water sorption capacity and regeneration temperature from 80 to 150 °C are required. Incorporation of hygroscopic salt such as calcium chloride into porous materials is a logical strategy for increasing the water sorption capacity. This work reports the study on the development of composites with PHTS (plugged hexagonal templated silicate) matrix with an average pore size of 5.7 nm and different amounts of calcium chloride (4, 10, 20 wt.%) for solar thermal energy storage. These composites were prepared by wetness incipient impregnation method. Structural properties were determined by X-ray diffraction (XRD), nitrogen physisorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). CaCl2 was confined in micro- and mesopores of the matrix. The resulting CaCl2-PHTS materials were used for water sorption at 40 °C, showing an increase of maximal water uptake with higher amount of calcium chloride from 0.78 g/g to 2.44 g/g of the dry composite. A small reduction in water uptake was observed after 20 cycles of sorption/desorption between temperatures of 140 °C and 40 °C, indicating good cycling stability of these composites under the working conditions.
COBISS.SI-ID: 39873541
Hydrophilic porous materials are recognized as very promising materials for water-sorption-based energy storage and transformation. In this study, a porous, zeolite-like aluminophosphate with LTA (Linde Type A) topology is inspected as an energy-storage material. According to sorption and calorimetric tests, the aluminophosphate outperforms all other zeolite-like and metal-organic porous materials tested so far. It adsorbs water in an extremely narrow relative-pressure interval (0.10 ( p/p0 ( 0.15) and exhibits superior water uptake (0.42 g g-1) and energy-storage capacity (527 kW h m-3). It also shows remarkable cycling stability; after 40 cycles of adsorption/desorption its capacity drops by less than 2%. Desorption temperature for this material, which is one of crucial parameters in applications, is lower from desorption temperatures of other tested materials by 10–15 °C. On the microscopic scale, sorption mechanism in AlPO4-LTA is elucidated by X-ray diffraction, nuclear magnetic resonance measurements, and first-principles calculations.
COBISS.SI-ID: 6070810
The main goal of this research was to develop the adsorption thermal storage device for domestic heating system charged by solar collectors and to indicate a new way of storing energy. Main characteristic of the storage system is to retain the energy for a longer period (seasonal storage), as long as the adsorbent and adsorbat are separated. In this research the influence of several parameters on the adsorption heat storage system is performed such as: the quantity of the stored heat, the inlet and the outlet water temperatures, the water mass flow and the saturation of the adsorbent. Adsorbent silica gel HX-13 (sodium aluminosilicate Na2O Al2O3 * 2SiO2) in the form of granule was used. According to the results the conclusion can be made that the low adsorption heat storage is a consequence of low hydrophilic characteristic of the used adsorbent and therefore additional research is needed.
COBISS.SI-ID: 15757339
Actual national and international energy strategies generally encourage the use of renewable energy sources. Thermal energy storage (TES) offers various opportunities in the design of renewable energy systems. Thermochemical heat storage has gained popularity among researches because of higher energy density and lower heat loss compared to sensible and latent heat storage. On the other side solar energy has been recognized as one of the renewable energy sources with the most potential. This paper reviews thermochemical heat storage technologies and systems with emphasis on systems involving solar energy utilization in buildings. The studies are reviewed based on used storage materials, system configuration as well as models to predict and optimize system performance.
COBISS.SI-ID: 15839515