A novel adsorption module with fiber heat exchangers: Performance analysis based on driving temperature differences

Abstract

A main focus of recent R&D on adsorption modules for thermally driven heat pumps and chillers has been to enhance the volume specific power output while maintaining a reasonable coefficient of performance (COP).An adsorption module using a new type of heat exchanger based on aluminum sintered metal fiber structures brazed on flat fluid channels has been developed. The heat exchangers for adsorber/desorber and evaporator/condenser are identically constructed. The adsorption heat exchanger is coated with a silico-alumino phosphate (SAPO-34) by a partial support transformation direct crystallization (PST) [1]. Both components are placed in a vacuum tight housing using a valve-free configuration. Water is used as adsorptive. The experimental characterization of the module shows a high volume specific power (up to 82 W/litre module for cooling, 320 W/litre for heating). Although no heat is recovered between ad- and desorption cycle, a COP of almost 0.4 is reached for cooling and 1.4 for heating. Driving temperature differences are defined for the analysis of the heat exchanger performance. The evaporator/condenser shows extremely good performance with about 240 W/K specific evaporation power per litre of heat exchanger, while the adsorber is limiting the module performance

Experimentally Measured Thermal Masses of Adsorption Heat Exchangers

“…The first experimental results for directly crystallized fibrous structures showed the potential of this approach to massively increase power density [39]. These findings were confirmed later at the scale of a complete adsorption module including a fiber HX [40]. The fibers had a mean diameter of approximately 130 µm.…”

Novel Adsorption Cycle for High-Efficiency Adsorption Heat Pumps and Chillers: Modeling and Simulation Results

“…In this manner, the heat transfer between the fluid and the heat exchanger is improved considerably. The adsorber design is still under development [19][20][21], particularly regarding the manufacturing process, e.g., the joining technology, the channel layout, as well as the interconnection of the modules. Aluminum fiber structures are sintered on top of the heat exchanger plates, and these structures are assumed to be coated with the adsorbent zeolite Li-Y.…”

Development and Testing of Novel Applications for Adsorption Heat Pumps and Chillers

“…Freni et al [11] report advanced sorbent materials such as new zeolite-like materials (AIPO and SAPO) and composite adsorbents like LiBr-silica and CaCl 2 -silica as very promising for conventional adsorptive heat pumps and chillers. In parallel of the enhancement of the working pairs' performance, studies are carried out on the intensification of the heat and mass transfer [12][13][14]. These recent advances could open new fields of applications for adHP, because of enhanced performances for specific temperature levels.…”