30%, if the double effect ACM is implemented. This can even be more optimal, if the thermal losses of the parabolic trough collector do not rise so much with higher absorber temperatures, e.g. when evacuated receivers would be used. Energy Supply Concept for Cooling and Heat Resulting from the market investigation and the simulations of energy flows, the decision in the project fell for a double effect ACM from Broad and a parabolic trough collector array. Due to the necessities of the absorption cooling machine, the solar collector field has to run at 150°C inlet and 180°C outlet temperature. The ongoing planning of the solar field foresees a collector area of at least 100 m2 of collector aperture area (depending on the decision of the investor) on the hotel roof , delivering pressurised water to a short term storage tank (Figure 4). The tank supplies pressurised water of 180°C to a steam generator producing saturated steam at 4.5 bar (148°C), which feeds an already existing steam distribution. Excessive solar heat so supplies other consumers. With a nominal cooling capacity of 116 kW the ACM provides part of the climatisation of the hotel rooms. Most of the cooling demand will be met by existing compression refrigerators. The laundry is the main steam consumer running a 20 hour shift in the main season. Laundry steam demand changes from 300 to 700 kg/hr, in average it is about 240 kW. Collector are:a "'- )_ __.,_ )_ ___,_ )__ ) He.ı (hot waler) Storage tank D Qc:; Steam Hotel complex man � ifold Steam ::> □ c::> '"2>a□ bsorptıon chıller Ex�tingsteam boiler ci Figure 4 Thermal energy flows in absorption air conditioning system operated through solar energy and supply with steam boiler Development of the Parabolic Trough Collector The main fields of parabolic trough collectors for process heat have been manufactured by lndustrial Solar Technology. The price of their collectors is momentarily elevated for Turkish buyers, due to the high exchange rate for US Dollars in Turkey. No other collector was available though. Therefore the development of a new parabolic trough has been started by Solitem, which will be produced in Turkey, first aiming on the Turkish market and later on the European market. The low production costs in Turkey will most likely permit significantly reduced collector costs in the long term. The collector is being developed for the low temperature range up to 200°c (Figure 5). MAKALE / ARTICLE Development Model of Collector The modules measure 1.8m by 5.3 m and are tracked in one axis. The reflector (aluminium mirrors of Alanod) with a rim angle of 60° concentrates the radiation onto an absorber of 38 mm, resulting in a concentration of 47. Thermal losses are reduced by a glass tube surrounding the absorber, but no vacuum is used. To minimise shading, the modules structure is put partly behind the reflector. A torsion tube provides the necessary stiffness for the collector. Conclusions A double effect absorption ehiller offers the advantage of using solar energy efficiently. Parabolic trough collectors will be installed on the hotel roof in a Turkish project to supply ehiller and other consumers with steam at 4.5 bar through a Space heating, laundry, food preparation steam generator. As the simulations only can give first indications of the system performance, solar field and ehiller will be measured thoroughly. Air conditioning in the current energy situation in Turkey, steam production by the parabolic trough collector system is expected to replace steam from LPG fireci steam boilers with economic conditions. Hotel energy costs can be minimised by shifting solar steam from laundry to absorption ehiller or vice versa, depending on the prices of electricity and LPG respectively. The concept seems to be appropriate for many consumers in the Mediterranean area. The company Solitem plans to realise more installations of this kind, provided a successful outcome of the project. Acknowledgements The authors thank the Ministerium für Wirtschaft und Mittelstand, Energie und Verkehr des Landes NRW, Germany, for supporting this work within the framework of the Landesinitiative Zukunftsenergien. References [1] Bergquam, Brezner, Hewett. Comparison of Flat Plate and Parabolic Trough Collectors in a Solar HVAC Application. in: AICHE Annual meeting in Los Angeles, CA, Nov 16-21, 1997 [2] Zunft. Solar-driven sorption cooling in arid regions. Proceedings Eurosun Conference, Bologna, ltaly, 2002, to be published [3] Krüger, Hoffschmidt, Hennecke, Pitz-Paal, Rietbrock, Fend. Results !rom Parabolic Trough Collectors tor Process Heat at the DLR Cologne. in: Proceedings of the 10th lnternational Symposium on Solar Thermal Concentrating Technologies, Sydney; 8-1 O March, 2000 ECOGENERATION WORLD 53
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