Experimental study of cascading adsorption cycles
Abstract
A lot of speculation exists on the possibilities of cascading cycles while very few experimental data are available. Herein, experiments on a cascading adsorptive heat pump are reported. The cascading cycle consits of a two adsorber zeolite—water high temperature stage and an intermittent active carbon—methanol low temperature stage. Driving heat is supplied by a boiler to zeolite adsorbers while active carbon adsorber is heated by heat recovered from zeolite adsorber under adsorption. Evaporators from both basic cycles operate at the same temperature and contibute to the evaporating load. Experimental cooling COP is found to be 1.06, much more than the COP of an intermittent cycle (≈0.5) and more than the COP of a two adsorber zeolite water cycle (≈0.75). Despite of the discontinuous operation of the cycle, evaporating rate is nearly constant (≈2.35 kW or 37W per kg of adsorbent). An analysis of the results shows that the components which limit the power of the unit are the evaporators and basically water evaporator. The COP of this cascading cycle is very sensitive to the evaporating temperature lift. If the temperature lift is higher than 45°C, a two adsorber zeolite water cycle has to be preffered. This cycle seems to be well adapted to air conditioning as long as the evaporation temperature lift is less than 45°C.
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Experimental validation of an organic rankine-vapor compression cooling cycle using low GWP refrigerant R1234ze(E)
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Solar cooling research and technology
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