Andrea Frazzica

Synthesis of SAPO-34/graphite composites for low temperature heat adsorption pumps

Low temperature heat adsorption pumps represent the innovative cooling systems, where cold is generated through adsorption/desorption cycle of water by a suitable adsorbent with good adsorption and high thermal conductive properties. In this work, the hydrothermal synthesis of zeolite SAPO-34 on thermal conductive graphitic supports, aiming at the development of highly performing adsorbent materials, is reported. The synthesis was carried out using as-received and oxidized commercial carbon papers, and graphite plate. Composites were characterized by XRD, SEM and also by a thermogravimetric method, using a Cahn microbalance. The water adsorbing capacity showed typical S-shape trend and the maximum water loading was around 25 wt%, a value close to water adsorption capability of pure SAPO-34. These results are very promising for their application in heat adsorption pumps.

Metal Hydride-Based Composite Materials with Improved Thermal Conductivity and Dimensional Stability Properties

To address the issues of poor thermal conductivity and fragmentation of metal hydride particles undergoing hydriding/dehydriding reactions, a metal hydride-based composite material was developed. The active metal phase was embedded in a silica matrix and a graphite filler was incorporated by ball milling. A set of compact pellet samples at different composition were prepared and tested. Experimental data obtained from the thermal conductivity measurements shown that using powder graphite produced a quite linear increase in the thermal conductivity of the metal hydride – silica composite. Ongoing studies include composition optimization as well as long-term testing upon cycling of such metal hydride composites to evaluate their potentiality in technological hydrogen storage applications.

Adsorption Heat Storage: State of the Art and Future Perspectives

Thermal energy storage (TES) is a key technology to enhance the efficiency of energy systems as well as to increase the share of renewable energies. In this context, the present paper reports a literature review of the recent advancement in the field of adsorption TES systems. After an initial introduction concerning different heat storage technologies, the working principle of the adsorption TES is explained and compared to other technologies. Subsequently, promising features and critical issues at a material, component and system level are deeply analyzed and the ongoing activities to make this technology ready for marketing are introduced.

Adsorption Heat Exchangers

As described in Chap. 1, one of the major adsorber heat exchanger design requirements is the reduction of the ratio between the heat capacity of the adsorber heat exchanger material as well as its heat transfer medium’s holdup and the heat capacity of the applied adsorbent. This results in enhancing the coefficient of performance of the adsorption heat pump and increases the obtainable specific heating or cooling power.

Mechanical Stability of Adsorbent Coatings

An adsorbent material consolidated in form of coating could present poor mechanical stability if a proper binder and/or an optimized binder content are not adopted in the coating formulation. Mechanical stability of the adsorbent coating may be affected by different typologies of mechanical stresses during its lifetime (vibrations, impacts, etc.). For this reason, a single mechanical test is not sufficient to prove completely the overall mechanical stability of the coated layer.

Definition of Performance Indicators for Thermal Energy Storage

With the aim of standardizing the evaluation of thermal storage systems/tanks, this chapter assesses and compares the different performance indicators that can be found in the literature and tries to recommend those which enable a better comparison.

Experimental Methods for the Characterization of Materials for Sorption Storage

The present chapter deals with the main experimental characterizations available to measure the performance of sorbent working pairs used in sorption TES. The experimental methods for the evaluation of equilibrium sorption curves and the models for the sorption equilibrium description are introduced. Furthermore, theoretical and experimental approaches for the heat of sorption evaluation are defined and some examples, reported in the literature, about the thermal storage capacity evaluation of different working pairs are reported.

Experimental Characterization of Sorption Thermal Energy Storage Systems

In the present chapter, the experimental methods employed for the characterisation of sorption TES are discussed. The investigated systems comprise liquid and solid sorption technologies, both for closed and open systems. In particular, the proposed procedure for the closed sorption TES systems is described in details and an example on a lab-scale adsorption TES is reported. Finally, also experimental methodologies applied for components testing, namely, kinetic testing of small-scale adsorbers and characterisation of evaporators, are introduced.

Experimental Characterization of Latent Thermal Energy Storage Systems

In the present chapter, the experimental methods employed for the characterisation of latent TES are discussed. The investigated systems comprise both static and dynamic PCM storage concepts. In particular, experimental approaches applied by different laboratories are discussed in details and examples are provided to confirm the reliability of the proposed methods.

Sorption Thermal Energy Storage

In the present chapter, an introduction about the concept of sorption TES technology is reported. The closed and open configurations are discussed and an overview on the ongoing research and development activities for materials, components and systems is given.