Heat-exchanger design and switching-frequency effects on the performance of a continuous type solar adsorption chiller

A transient one-dimensional model, capable of describing the performance of a newly-introduced adsorption chiller with continuous operation, is developed. Since the cycle time and the switching frequency have a great influence on chiller performance, a non-dimensional switching frequency is introduc...

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Bibliographic Details
Published in:Applied energy 2008-12, Vol.85 (12), p.1237-1250
Main Authors: Voyiatzis, Evangelos, Palyvos, J.A., Markatos, Nikolaos-Christos
Format: Article
Language:English
Subjects:
Air conditioning. Ventilation
Applied sciences
Devices using thermal energy
Dimensionless numbers
Energy
Energy. Thermal use of fuels
Exact sciences and technology
Heat exchanger
Heat exchangers (included heat transformers, condensers, cooling towers)
Heating, air conditioning and ventilation
Silica gel
Solar adsorption chiller
Solar adsorption chiller Solar air-conditioning Switching frequency Dimensionless numbers Heat exchanger Silica gel
Solar air-conditioning
Switching frequency
Techniques, equipment. Control. Metering
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Summary:A transient one-dimensional model, capable of describing the performance of a newly-introduced adsorption chiller with continuous operation, is developed. Since the cycle time and the switching frequency have a great influence on chiller performance, a non-dimensional switching frequency is introduced and a systematic parametric study is carried out in order to determine regions of optimal operation. An optimization based on the thermodynamic efficiency yields a lower switching frequency than an optimization based on the maximum cooling capacity. In addition, the effect of the heat-exchanger design parameters on system performance is explored. An increase of either the bed’s Fourier number or the thermofluid’s Nusselt number has a positive effect on both COP and cooling capacity. An improvement of system performance can also be achieved by decreasing either the thermofluid’s Fourier number or the bed’s Biot number. Finally, the effect of space velocity of the thermofluid exhibits the most interesting behavior; an increase of the space velocity has a positive effect on cooling capacity and a negative effect on COP.
ISSN:0306-2619
1872-9118
DOI:10.1016/j.apenergy.2008.03.005