Desiccant cooling systems handle latent loads by sorption dehumidification and sensible loads by over-drying the process air to allow its direct evaporative cooling. In hot and humid climates,such as in Southern Italy, the performed dehumidification may be not enough to enable evaporative cooling of the air. Higher regeneration temperatures are needed to achieve the required humidity ratio reduction, but this limits the use of waste heat or renewable energy as thermal energy source for regeneration. Therefore, other coolingequipment are used in hybrid system, where latent and sensible loads are removed by the desiccant wheel and i.e. a cooling coil,respectively. Advantages of hybrid desiccant cooling systems are: improved indoor air quality thanks to the independent control oftemperature and humidity ratio, lower size and improved energy performance of the cooling unit. In most cases, hybrid systems areequipped with electric-driven chillers, powered by electricity from the grid, cogenerators or renewable technologies (typically PV).Nevertheless, the introduction of a gas engine drivenheat pump seems very interesting, as the compressor of the vapor cycle is directly activated by a natural gas internal combustion engine.This paper examines the benefits of coupling a desiccant dehumidification sub-system to a gas engine-driven vapor compression unit. The former, based on a silica-gel desiccant rotor, is analyzed by means of numerical models, calibrated and validated by means ofexperimental tests in previous works. Data provided by the manufacturer are used for the gas heat pump. An energy and environmental impact comparison with the same hybrid desiccant cooling system, interacting with a microcogenerator is performed. A sensitivityanalysis has been carried out, considering different values of the performance of the electric chiller and of the external electric grid.

ENERGY AND EMISSIONS ANALYSIS OF A HYBRID DESICCANT COOLING SYSTEM WITH A GAS ENGINE DRIVEN HEAT PUMP

Angrisani G.
;
Marrasso E.;Roselli C;Sasso M.
2015

Abstract

Desiccant cooling systems handle latent loads by sorption dehumidification and sensible loads by over-drying the process air to allow its direct evaporative cooling. In hot and humid climates,such as in Southern Italy, the performed dehumidification may be not enough to enable evaporative cooling of the air. Higher regeneration temperatures are needed to achieve the required humidity ratio reduction, but this limits the use of waste heat or renewable energy as thermal energy source for regeneration. Therefore, other coolingequipment are used in hybrid system, where latent and sensible loads are removed by the desiccant wheel and i.e. a cooling coil,respectively. Advantages of hybrid desiccant cooling systems are: improved indoor air quality thanks to the independent control oftemperature and humidity ratio, lower size and improved energy performance of the cooling unit. In most cases, hybrid systems areequipped with electric-driven chillers, powered by electricity from the grid, cogenerators or renewable technologies (typically PV).Nevertheless, the introduction of a gas engine drivenheat pump seems very interesting, as the compressor of the vapor cycle is directly activated by a natural gas internal combustion engine.This paper examines the benefits of coupling a desiccant dehumidification sub-system to a gas engine-driven vapor compression unit. The former, based on a silica-gel desiccant rotor, is analyzed by means of numerical models, calibrated and validated by means ofexperimental tests in previous works. Data provided by the manufacturer are used for the gas heat pump. An energy and environmental impact comparison with the same hybrid desiccant cooling system, interacting with a microcogenerator is performed. A sensitivityanalysis has been carried out, considering different values of the performance of the electric chiller and of the external electric grid.
hybrid desiccant cooling system; gas engine driven heat pump; thermo-economic analysis; numerical models; manufacturer data
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12070/9994
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