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About this book

This book investigates the adsorption dynamics of water, methanol, ethanol, and ammonia vapor on loose and consolidated adsorbent beds, as well as the impact of this aspect on the overall performance of adsorption systems for heat transformation. In particular, it presents the results of kinetic measurements made using the large temperature jump (LTJ) method, the most efficient way to study adsorption dynamics under realistic operating conditions for adsorptive heat transformers. The information provided is especially beneficial for all those working on the development of novel adsorbent materials and advanced adsorbers for heating and cooling applications.

Today, technologies and systems based on adsorption heat transformation (AHT) processes offer a fascinating option for meeting the growing worldwide demand for air conditioning and space heating. Nevertheless, considerable efforts must still be made in order to enhance performance so as to effectively compete with commonly used electrical compression and absorption machines. For this purpose, intelligent design for adsorption units should above all focus on finding a convenient choice of adsorbent material by means of a comprehensive analysis that takes into account both thermodynamic and dynamic aspects. While the thermodynamic properties of the AHT cycle have been studied extensively, the dynamic optimization of AHT adsorbers is still an open issue. Several efforts have recently been made in order to analyze AHT dynamics, which greatly influence overall AHT performance.

Table of Contents


Chapter 1. Adsorptive Heat Transformation and Storage: Thermodynamic and Kinetic Aspects

At present, the majority of thermodynamic cycles of heat engines are high-temperature cycles that are realized by internal combustion engines, steam and gas turbines, etc. (Cengel, Boles in Thermodynamics: an engineering approach, 4th edn. McGray-Hill Inc., New York, 2002). Traditional heat engine cycles are mainly based on burning of organic fuel that may result in dramatic increase of CO2 emissions and global warming. The world community has realized the gravity of these problems and taken initiatives to alleviate or reverse this situation. Fulfilment of these initiatives requires, first of all, the replacement of fossil fuels with renewable energy sources (e.g. the sun, wind, ambient heat, natural water basins, soil, air). These new heat sources have significantly lower temperature potential than that achieved by burning of fossil fuels which opens a niche for applying adsorption technologies for heat transformation and storage (Pons et al in Int J Refrig 22:5–17, 1999).

Alessio Sapienza, Andrea Frazzica, Angelo Freni, Yuri Aristov

Chapter 2. Measurement of Adsorption Dynamics: An Overview

Analysis of the Ad-HEx dynamic behaviour is of pivotal importance in development of advanced adsorber concepts, enabling reduction of weight and volume of the real adsorption heat pump/chiller unit, as well as its energy density enhancement.

Alessio Sapienza, Andrea Frazzica, Angelo Freni, Yuri Aristov

Chapter 3. Experimental Findings: Main Factors Affecting the Adsorptive Temperature-Driven Cycle Dynamics

In Chap. 2, the two main methods to study the sorption dynamics for AHT cycles were widely described: (i) the Large Pressure Jump (LPJ) method, in which adsorption is initiated by a jump of pressure over the sample, is the most adequate for pressure-driven AHT cycles; (ii) the Large Temperature Jump (LTJ) method, in which adsorption is enabled by a temperature swing of a heat exchanger wall that is in contact with the adsorbent under an almost isobaric ad/desorption stage, is the proper choice for temperature-driven AHT cycles (see Chaps. 1 and 2). In this chapter, the main factors affecting the sorption dynamics will be highlighted for temperature-driven AHT cycles by the analysis of results achieved by the two versions (namely V-LTJ and G-LTJ) of the LTJ method.

Alessio Sapienza, Andrea Frazzica, Angelo Freni, Yuri Aristov

Chapter 4. Optimization of an “Adsorbent/Heat Exchanger” Unit

Despite significant progress, the AHT technology as yet remains unfinished and expensive, so that there is still a big room for its improvement [1, 2]. This concerns, first of all, enhancement of the AHT dynamics, like the ad/desorption rate and finally the specific power that is the main figure of merit of the AHT dynamic performance. Therefore, further R&D activity is necessary to realize the potential economic and ecological advantages of the AHT technology [3]. The optimization of the AHT dynamic performance is a multi-purpose task that includes, first of all, the improvement of the “adsorbent–heat exchanger” unit.

Alessio Sapienza, Andrea Frazzica, Angelo Freni, Yuri Aristov
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