Solar systems have the main purpose of replacing fossil fuel based systems so as to attain a primary energy saving. In this context, the recourse to solar-assisted air conditioning systems in buildings represents a suitable choice not only to reduce the final energy consumptions but also to enlarge the utilization field of solar thermal energy. On the other hand, different technical solutions can be profitably employed. Among these, desiccant cooling systems (DEC) represent an interesting option to be investigated. Aim of this work is to assess the potential of solar-assisted air conditioning systems based on a desiccant cooling cycle which regenerating heat is supplied by low temperature solar thermal collectors. In the present study a comparative analysis, based on an energy saving approach by comparison with an electrically driven vapour compression heat pump (assumed as reference convectional cooling and heating machine), has been carried out. In order to assess the energy performance of the solar-assisted desiccant cooling system, different plant configurations have been investigated by means of suitable TRNSYS simulation models. The analysis has been performed for a typical residential building (a terraced house) located in Palermo, whose heating and cooling loads have been estimated by means of EnergyPlus simulation program and used in TRNSYS as input file. Concerning DEC system, both recirculation and ventilation modes have been examined. The regeneration heat has been supplied by a water heater solar system powered by evacuated tubular collectors and assisted by an in line air-heater. An apposite control strategy, based on both the control of inlet humidity and the following of regeneration temperature, has been implemented. For all the considered configurations, thermal COP (evaluated as the ratio between the cooling capacity and the regeneration heat), consumed primary energy and solar fractions (evaluated on monthly and annual basis) have been calculated. From the results obtained, a techno-economic comparison, relevant to other thermally driven air conditioning systems (single and double effect absorption chillers using water/LiBr, advanced cycles using ammonia/water and adsorption chillers), has been carried out. This in order to assess the energy and the cost effectiveness of DEC systems compared with other solar-assisted technologies. The obtained results show the capacity of these systems to reduce significantly the primary energy consumption. On the other hand, some open questions remain: the cost-effectiveness compared to reference conventional heating/cooling systems and the assessment of how the electrical energy consumption (due to high air flow rates and large pressure drops) could affects (affect) the overall primary energy saving.
Energy performance assessment of solar-assisted desiccant cooling system
CARDINALE, Nicola;
2009-01-01
Abstract
Solar systems have the main purpose of replacing fossil fuel based systems so as to attain a primary energy saving. In this context, the recourse to solar-assisted air conditioning systems in buildings represents a suitable choice not only to reduce the final energy consumptions but also to enlarge the utilization field of solar thermal energy. On the other hand, different technical solutions can be profitably employed. Among these, desiccant cooling systems (DEC) represent an interesting option to be investigated. Aim of this work is to assess the potential of solar-assisted air conditioning systems based on a desiccant cooling cycle which regenerating heat is supplied by low temperature solar thermal collectors. In the present study a comparative analysis, based on an energy saving approach by comparison with an electrically driven vapour compression heat pump (assumed as reference convectional cooling and heating machine), has been carried out. In order to assess the energy performance of the solar-assisted desiccant cooling system, different plant configurations have been investigated by means of suitable TRNSYS simulation models. The analysis has been performed for a typical residential building (a terraced house) located in Palermo, whose heating and cooling loads have been estimated by means of EnergyPlus simulation program and used in TRNSYS as input file. Concerning DEC system, both recirculation and ventilation modes have been examined. The regeneration heat has been supplied by a water heater solar system powered by evacuated tubular collectors and assisted by an in line air-heater. An apposite control strategy, based on both the control of inlet humidity and the following of regeneration temperature, has been implemented. For all the considered configurations, thermal COP (evaluated as the ratio between the cooling capacity and the regeneration heat), consumed primary energy and solar fractions (evaluated on monthly and annual basis) have been calculated. From the results obtained, a techno-economic comparison, relevant to other thermally driven air conditioning systems (single and double effect absorption chillers using water/LiBr, advanced cycles using ammonia/water and adsorption chillers), has been carried out. This in order to assess the energy and the cost effectiveness of DEC systems compared with other solar-assisted technologies. The obtained results show the capacity of these systems to reduce significantly the primary energy consumption. On the other hand, some open questions remain: the cost-effectiveness compared to reference conventional heating/cooling systems and the assessment of how the electrical energy consumption (due to high air flow rates and large pressure drops) could affects (affect) the overall primary energy saving.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
