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http://dx.doi.org/10.6110/KJACR.2014.26.12.579

State Equation Modeling and the Optimum Control of a Variable-Speed Refrigeration System  

Lee, Dan-Bi (Graduate School of Refrigeration and Air-conditioning Engineering Pukyong National University)
Jeong, Seok-Kwon (Department of Refrigeration and Air-conditioning Engineering, Pukyong National University)
Jung, Young-Mi (Department of Refrigeration and Air-conditioning Engineering, Pukyong National University)
Publication Information
Korean Journal of Air-Conditioning and Refrigeration Engineering / v.26, no.12, 2014 , pp. 579-587 More about this Journal
Abstract
This paper deals with precise analytical state equation modeling of a variable speed refrigeration system (VSRS) for optimum control in state space. The VSRS is described as multi-input and multi-output (MIMO) system, which has two controlled variables and two control inputs. First, the Navier-Stokes equation and mass flow rate were applied to each component of the basic refrigeration cycle to build a dynamic model. The dynamic model, represented by a differential equation, was transformed into the state equation formula. Next, a full-order state observer was built to estimate all of the state variables to compose an optimum control system. Then, an optimum controller was designed to minimize an evaluation function that has input energy and control error. Finally, simulations and experiments were conducted to verify the validity of the proposed modeling and designed optimum controller to regulate target temperature and superheat in a 1RT oil cooler system. The results show that the proposed method, state equation modeling and optimum control, is efficient to ensure optimal control performance of the VSRS.
Keywords
Variable speed refrigeration system; Optimum control; Multi-input multioutput system; State equation; Full order state observer;
Citations & Related Records
Times Cited By KSCI : 6  (Citation Analysis)
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1 Lee, S. W., Yeom, H. K., and Park, K. J., 2009, Performance of hot gas bypass type oil cooler system, Journal of Korean Society for Precision Engineering, Vol. 26, No. 3, pp. 73-80.
2 Byun, J. Y. and Jeong, S. K., 2010, Design of PI and feedforward controller for precise temperature control of oil cooler system, Journal of the Korean Society for Power System Engineering, Vol. 14, No. 6, pp. 89-95.   과학기술학회마을
3 Jeong, S. K. and Kim, S. H., 2011, Optimum controller design of a water cooler for machine tools based on the state space model, Korean Journal of Air-conditioning and Refrigeration Engineering, Vol. 23, No. 12, pp. 782-790.   과학기술학회마을   DOI   ScienceOn
4 Jeong, S. K., Lee, D. B., and Hong, K. H., 2014, Comparison of system performance on hot-gas bypass and variable speed compressor in an oil cooler for machine tools, Journal of Mechanical Science and Technology, Vol. 28, No. 2, pp. 721-727.   과학기술학회마을   DOI
5 Jeong, S. K. and Hong, K. H., 2013, Optimal PI controller design for refrigeration system considering disturbance, Korean Journal of Air-conditioning and Refrigeration Engineering, Vol. 25, No. 2, pp. 85-93.   과학기술학회마을   DOI
6 Lee, D. B., 2013, State equation modeling for the optimum control of the refrigeration cycle, MS thesis, Pukyong National University, Busan, Korea.
7 Rajat, S., Andrew, G. A., and Clark, W. B., 2004, Dynamic modeling and control of multi-evaporator airconditioning systems, ASHRAE Transactions Research, pp. 109-119.
8 Fumio, M., Dynamic characteristics and control of refrigeration cycle, Refrigeration of Japan, Vol. 78, No. 906, pp. 282-290.
9 William, S. Levine, 1995, The control handbook, IEEE Press, Vol. 1, p. 597, pp. 607-612.
10 Lenardo, C. S., Christian, J. L. H., and Alexandre, T. N., 2009, A model-driven multivariable controller for vapor compression refrigeration systems, International Journal of Refrigeration, Vol. 32, pp. 1672-1682.   DOI   ScienceOn
11 Kang, C. G., Park, J. H., Park, J. K., 2010, Modern control engineering, 5th Edition, Kyobo, pp. 893.
12 Li, H. and Jeong, S. K., 2007, Design and analysis of Fuzzy control in a variable speed refrigeration system, International Journal of Air-Conditioning and Refrigeration Engineering, Vol. 15, No. 2, pp. 61-69.
13 Li, H., Jeong, S. K., and You, S. S., 2009, Feedforward control of capacity and superheat for a variable speed refrigeration system, Applied Thermal Engineering, Vol. 29, pp. 1067-1074.   DOI   ScienceOn
14 Beak, S. M., Moon, C. G., Kim, E. P., Jeong, S. K., and Yoon, J. I., 2011, The characteristic study of capacity control of an industrial cooler using an inverter compressor with varying the ambient temperatures, Journal of the Korean Society of Marine Engineering, Vol. 35, No. 2, pp. 238-243.   DOI
15 Li, H., You, S. S., Yoon, J. I., and Jeong, S. K., 2008, An empirical model for independent control of variable speed refrigeration system, Applied Thermal Engineering, Vol. 28, pp. 1918-1924.   DOI   ScienceOn