Below are two abstracts for projects he is presenting at ASME 2012 International Mechanical Engineering Congress & Exposition, November 9-15, Houston, Texas. (See Track 6, Section 6-9-2 ‘Distributed Generation and CCHP’)APPLICATION OF AN ADVANCED SIMULATION MODEL TO A MICRO-CHP ORC-BASED SYSTEM FOR ULTRA-LOW GRADE HEAT RECOVERY
Davide Ziviani, Asfaw Beyene¹, and Mauro Venturini²This paper presents the results of the application of an advanced thermodynamic model developed by the authors for the simulation of Organic Rankine Cycles (ORCs). The model allows ORC simulation both for steady and transient analysis. The expander, selected to be a scroll expander, is modeled in detail by decomposing the behavior of the fluid stream into several steps. The heat source is coupled with the system through a plate heat exchanger, which is modeled using an iterative sub-heat exchanger modeling approach.
The considered ORC system uses solar thermal energy for ultra-low grade heat recovery. The simulation model is used to investigate the influence of ORC characteristic parameters related to the working medium, hot reservoir and component efficiencies for the purpose of optimizing the ORC system efficiency and power output. Moreover, dynamic response of the ORC is also evaluated for two scenarios, i.e. (i) supplying electricity for a typical residential user and (ii) being driven by a hot reservoir. Finally, the simulation model is used to evaluate ORC capability to meet electric, thermal and cooling loads of a single residential building, for typical temperatures of the hot water exiting from a solar collector.
DEVELOPMENT AND VALIDATION OF AN ADVANCED SIMULATION MODEL FOR ORC-BASED SYSTEMS
Davide Ziviani, Asfaw Beyene¹, and Mauro Venturini²Low-grade heat recovery from solar or geothermal energy may be an eco-friendly resource for electric and thermal energy recovery. The Organic Rankine Cycle (ORC) is one of the main candidates to exploit low-temperature heat sources, otherwise difficult to access using conventional power generation systems.
In this paper, an advanced thermodynamic model of an ORC is developed, with the final aim to optimize ORC conversion efficiency, especially for micro-CHP applications. First, a thorough review of issues related to ORC system modeling is presented by analyzing the state-of-the-art experience and advancements. Subsequently, an advanced simulation model is developed, by taking advantage of all the key characteristics of the models presented in the literature. The simulation model is developed in Matlab®/AMESim® environment, which allows system modeling both for steady and transient analysis. The heat source is coupled with the system through a plate heat exchanger, which is modeled using an iterative sub-heat exchanger modeling approach. A scroll expander, modeled in detail by decomposing the behavior of the fluid stream into several steps, is used to extract the useful work.
Finally, model predictions for the evaporator and the expander are validated against both numerical and experimental data published in literature. The simulation model of the entire ORC system is also validated against literature data taken on a test bench.
- ¹ San Diego State University, 5500 Campanile Drive, San Diego, CA (USA)
- ² University of Ferrara, Via Giuseppe Saragat 1, Ferrara (Italy)
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