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Session: System Design and Optimization I
Session starts: Monday 07 October, 11:10
Presentation starts: 11:10
Room: Ruys & Rijckenvorsel Zaal

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Guofu Chen (ASME)

Abstract:
The design and the actual performance of a geothermal air-cooled power plant utilizing a supercritical refrigerant of R134a as the working fluid are discussed. A supercritical Organic Rankine Cycle (“ORC”) in many cases outperforms a sub-critical cycle, from the net kilowatt (kW) generated point of view. Additionally, the plant configuration is simpler to design and easier to operate. An additional advantage of using non-flammable working fluid in the cycle, such as R134a, eliminates the risk of fires. During the design stage, a preliminary process flow diagram is established based on the standard process engineering practices in HYSYS, a simulation software from ASPENTECH. Based on the preliminary process requirement, the components of the cycle, including the shell and tube heat exchanger(s), expansion turbine, air-cooled condenser, and working fluid feed pump are sized and selected. A true simulation model is built to analyze the off design performance of a “virtual plant”. Given the geothermal heat source information and the ambient conditions, the power output is maximized and committed to the customer (Model 1 with geometries). After the plant is successfully commissioned, by measuring the flow rate, temperature and pressure, a plant reality model is built to reflect the actual plant operating conditions (Model 2 without geometries). Normally the process conditions of Model 2 are different from Model 1. To validate Model 1, developed in the design stage, the process conditions of Model 2 are extracted and input into Model 1, thus Model 3 with actual process conditions and actual geometries is established. Model 2 is the reality, while Model 3 is used to predict the reality with actual process conditions and actual equipment selection. By comparing these two models, Model 3 accurately predicts the gross power and net power generated at various operating conditions.