Zeolite/aluminum composite adsorbents for application in adsorption refrigeration

Abstract

SUMMARYThermally driven adsorption refrigerators, which transform available low-temperature waste heat (from processes, engines, solar radiation, district heat) into useful cooling energy, are a very promising and green technology to reduce the demand for primary energy. To improve their refrigeration performance, new zeolite/aluminum composite adsorbents with optimized sorption and heat transfer properties were prepared following the partial support transformation technique. A direct and binderless contact between the closed zeolite layer and the metal could be established which enables best thermal diffusivity. It is shown by measurements of thermal sorption capacities and kinetics on planar samples and on coated heat exchangers that this causes best sorption performance combined with high mechanical stability.

A New Adsorbent Composite Material Based on Metal Fiber Technology and Its Application in Adsorption Heat Exchangers

“…In situ crystallization of SAPO-34 on aluminum supports has been reported by Bauer, Herrmann, Mittelbach, and Schwieger [23] and in US 8,053,032 B2 [24]. This process can also be described as a consumptive crystallization, since the Al support is partially transformed into the micro-porous adsorbent material SAPO-34.…”

“…In some cases, direct crystallization leads to a much more compact adsorbent layer (with a density close to the single-crystal density) than is achievable through a coating process. Different materials such as aluminum [23,24], copper [25], stainless steel [26], or graphite [27] can be used as a substrate.…”

“…An overview on recent developments in the field of coated adsorption heat exchangers and their characterization can be found in [33]. In this paper, we present a novel composite material of aluminum fibers coated by a silico-alumino-phosphate (SAPO-34) with a chabasite structure using a partial support transformation (PST) method as described by Bauer, Herrmann, Mittelbach, and Schwieger [23]. SAPO-34 has been shown to be a suitable adsorbent for heat transformation of low grade heat (<100 °C) [34][35][36][37].…”

Advanced Measurement and Simulation Procedure for the Identification of Heat and Mass Transfer Parameters in Dynamic Adsorption Experiments

“…The data for a fibrous structures directly crystallized with SAPO-34 (fibrous structure called '2_Fib' in the paper) as studied by Füldner [19], Füldner et al [20], Wittstadt et al [9] and Velte et al [21] can be found in Table 1. The directly-crystallized SAPO-34 has a chabazite (CHA) structure with a three-dimensional pore structure and a micro pore size of 3.8 Å [7]. More information about this adsorbent and the partial support transformation synthesis technique was published earlier by Bauer et al [7].…”

“…In the last few years, various designs were presented. They can be grouped into three main classes: adsorbent in the form of granules (loose grains configuration) [2,3], binder-based coatings [4][5][6] or adsorbent in form of compact layers, which are directly crystallized on a metal surface [7][8][9][10][11][12].…”