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Heat rejection and primary energy efficiency of solar driven absorption cooling systems / Ursula Eicker in International journal of refrigeration, Vol. 35 N° 3 (Mai 2012) 

Public ISBD [article]  in International journal of refrigeration > Vol. 35 N° 3 (Mai 2012) . - pp. 729–738 Titre : Heat rejection and primary energy efficiency of solar driven absorption cooling systems Titre original : Rejet de chaleur et efficacité de l'énergie primaire des systèmes de refroidissement à absorption faisant appel à l'énergie solaire Type de document : texte imprimé Auteurs : Ursula Eicker, Auteur ; Dirk Pietruschka, Auteur ; Ruben Pesch, Auteur Année de publication : 2012 Article en page(s) : pp. 729–738 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Primary  energy  Absorption  system  Control  Cooling  tower Résumé : Efficient heat rejection is crucial for the overall primary energy balance of sorption systems, as it dominates the auxiliary energy consumption. Low ratios of cooling power to auxiliary electricity of 3.0 or less are still common in sorption system, so that the primary energy efficiency is not always higher than for conventional compression chillers. Whereas dry heat rejection systems require electricity for fan operation, hybrid or wet cooling systems in addition need pumping energy for the cooling water and the water itself. The energy efficiency can be improved for heat rejection to the ground, where only pumping energy is needed for the geothermal heat exchange. Dynamic simulation models were used for a single effect absorption chiller powered by solar thermal collectors via a hot storage tank. The chiller models were coupled to a three dimensional numerical ground heat exchanger model or to cooling tower models. The models were validated with operating data of a 15 kW solar cooling system installed in an office building. Primary energy efficiency ratios were determined for different heat rejection systems and improved control strategies were developed. The installed system primary energy ratios varied between 1.1 and 2.2 for auxiliary heating and between 1.2 and 2.5 for auxiliary cooling depending on the heat rejection and control strategy chosen. The low electrical energy consumption of the geothermal heat rejection saves 30% of auxiliary electricity and results in an electrical coefficient of performance of 13. The maximum primary energy ratios for solar fractions up to 88% are 2.7 for auxiliary heating and 3.2 for auxiliary cooling, i.e. nearly three times higher than for the reference electrical compression system of 1.2. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712000229# [article] Heat rejection and primary energy efficiency of solar driven absorption cooling systems = Rejet de chaleur et efficacité de l'énergie primaire des systèmes de refroidissement à absorption faisant appel à l'énergie solaire [texte imprimé] / Ursula Eicker, Auteur ; Dirk Pietruschka, Auteur ; Ruben Pesch, Auteur . - 2012 . - pp. 729–738. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 35 N° 3 (Mai 2012) . - pp. 729–738 Mots-clés : Primary  energy  Absorption  system  Control  Cooling  tower Résumé : Efficient heat rejection is crucial for the overall primary energy balance of sorption systems, as it dominates the auxiliary energy consumption. Low ratios of cooling power to auxiliary electricity of 3.0 or less are still common in sorption system, so that the primary energy efficiency is not always higher than for conventional compression chillers. Whereas dry heat rejection systems require electricity for fan operation, hybrid or wet cooling systems in addition need pumping energy for the cooling water and the water itself. The energy efficiency can be improved for heat rejection to the ground, where only pumping energy is needed for the geothermal heat exchange. Dynamic simulation models were used for a single effect absorption chiller powered by solar thermal collectors via a hot storage tank. The chiller models were coupled to a three dimensional numerical ground heat exchanger model or to cooling tower models. The models were validated with operating data of a 15 kW solar cooling system installed in an office building. Primary energy efficiency ratios were determined for different heat rejection systems and improved control strategies were developed. The installed system primary energy ratios varied between 1.1 and 2.2 for auxiliary heating and between 1.2 and 2.5 for auxiliary cooling depending on the heat rejection and control strategy chosen. The low electrical energy consumption of the geothermal heat rejection saves 30% of auxiliary electricity and results in an electrical coefficient of performance of 13. The maximum primary energy ratios for solar fractions up to 88% are 2.7 for auxiliary heating and 3.2 for auxiliary cooling, i.e. nearly three times higher than for the reference electrical compression system of 1.2. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712000229#