Towards a general procedure for dynamic model development

1990 ◽  
Vol 12 (4) ◽  
pp. 174-177 ◽  
Author(s):  
A.M. Foss
Author(s):  
Moritz Buchholz ◽  
Johannes Haus ◽  
Fritz Polt ◽  
Swantje Pietsch ◽  
Michael Schönherr ◽  
...  

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
Glen Hay ◽  
John Nighswander

A project team was given the task of evaluating various technology options for design of a small-scale gas-to-liquids (GTL) process operated remotely at or near an individual gas source. For this study, small-scale plants were considered those producing between 100 and 500 barrels per day of liquid fuels. In addition, being remote enforced limitations on utility sources available to the plant site such as water and grid power. A secondary goal was development of a dynamic model of the plant to use in operator training. To accomplish these objectives, the authors investigated the suitability of a process-simulation application. The conceptual design of the GTL unit included many different possibilities, such as front-end design, back-end design, heat integration, and recycling of materials. Complications associated with plant start-up and shutdown, utilities, process reliability, and economics were included in the decision-making process. The authors present selective results from a steady-state model and sensitivity studies. Considerations for the development of the dynamic model included both a fully rigorous dynamic model and a pseudo-dynamic steady-state-based model; results of the latter model are provided. The study concluded that an industrial steady-state simulation tool provided sufficient flexibility to complete the material and energy-balance calculations, sensitivity analyses, and pseudo-dynamic modeling. This study yielded significant insights into the importance of model assumptions and their impact on the overall process viability. The pseudo-dynamic model also provided insight for improving the process control design. During the work completed the authors determined that the object-oriented structure adopted for the model enabled an efficient, rapid model development.


Author(s):  
Pengfei Li ◽  
Yaoyu Li ◽  
John E. Seem

For the heating, ventilating, and air conditioning (HVAC) systems for commercial buildings, the cooling coils in air handling units (AHU) account for a significant fraction of total building energy consumption and have a major impact on comfort conditions and maintenance costs. Development of cost-effective advanced control strategies will enhance the performance and efficiency of AHU. The control design process can be greatly facilitated with simulation on high-fidelity dynamic model prior to experimental validation and implementation. This paper presents a dynamic model for an air-side economizer. The model development was based on Dymola and AirConditioning Library with some revision on heat exchanger modeling. For chilled-water cooling coil modeling, the major challenges include the variation of coil surface conditions under flow rate changes and partially-dry-partially-wet operations. This study proposes a dynamic coil model that is capable of predicting cooling performances under fully dry, partially-dry-partially-wet, and fully wet conditions. Validation with experimental data from a benchmark study was conducted under both dry and wet surface conditions. The model predicted the experimental results quite well for both transient and steady-state behaviors. In addition, other moist air components, such as dampers, fans, ducts and room, were developed. Such transient model will lay a more quality foundation for controller validation at the simulation phase.


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