Solar Cooling Technologies for Southern Climates - A System Comparison – Dirk Pietruschka 1 , Uli Jakob 2 , Ursula Eicker 1 1 Centre of Applied Research Sustainable Energy Technology - zafh.net, Stuttgart University of Applied Sciences, Schellingstrasse 24, D-70174 Stuttgart, Germany, Phone +49 711 8926 2674, dirk.pietruschka@hft-stuttgart.de 2 Solem Consulting, Postfach 2127, D-71370 Weinstadt, Germany Phone +49 174 4130921, uli.jakob@solem-consulting.com Abstract In the present paper different solar thermal cooling systems are compared to a PV driven and a net connected compression chiller in hot and dry southern climate. The cooling systems are considered to be applied to a planned innovative office building in Cairo, Egypt. A single effect absorption chiller with vacuum tube collectors is analysed as well as a double and a triple effect absorption chiller with higher concentrating Fresnel collectors. For the PV driven compression chiller system high efficient mono crystalline PV modules are considered together with a highly efficient compression chiller system with integrated direct dry het rejection. Dynamic system simulations with INSEL are used to analyse the performance of the different cooling systems. To compare the overall performance of the analysed solar cooling systems, the primary energy consumption required to cover the whole cooling load of the building and the resulting primary energy ratio are calculated for each system. 1. Introduction The overall efficiency of solar driven absorption cooling machines (ACM) is mainly influenced by the thermal COP of the absorption chiller and the electricity consumption caused by the heat rejection system, the chiller and all connected system pumps. Single effect absorption chillers reach only quite low thermal COPs which are typically in the region between 0.55 and 0.75. In consequence, large solar collector areas and large heat rejection systems are required to reach high solar fractions and to remove the waste heat. This often cause high electricity consumptions which reduces the primary energy efficiency of the systems [1]. However, the main advantage of single effect absorption and adsorption chillers is the relatively low driving temperature which varies between 65°C and 95°C. Such temperatures can be provided by efficient flat plate or vacuum tube collectors. Double effect absorption chillers reach much higher thermal COPs of 1.3 and above but typically require much higher driving temperatures of around 180°C. To provide such high temperatures higher concentrating solar systems like parabolic trough or Published in: Proceedings of 4th Solar Air Conditioning Conference, Larnaka, Cyprus, 12.-14.10.2011