Determining the optimum cyclic operation of adsorption chillers by a direct method for periodic optimal control

• Published in: International journal of refrigeration Vol. 34; no. 4; pp. 902 - 913
• Main Authors: Gräber, Manuel, Kirches, Christian, Bock, Hans Georg, Schlöder, Johannes P., Tegethoff, Wilhelm, Köhler, Jürgen
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2011; Elsevier
• Subjects: Adsorption; Air conditioning. Ventilation; Applied sciences; Control; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat transfer; Heating, air conditioning and ventilation; Optimisation; Optimization; Refrigerating engineering; Refrigerating engineering. Cryogenics. Food conservation; Régulation; Simulation; System; Système; Techniques, equipment. Control. Metering; Techniques. Materials; Theoretical studies. Data and constants. Metering; Control; Adsorption; Simulation; Régulation; Système; Optimisation; System; Optimization; Air conditioning; Refrigeration installation; Chiller; Flow rate; Cooling; Operating conditions; Heat source; Computation time; Regulation(control); Optimal control; Air temperature; Waste heat; Dynamic model; Refrigeration; Room temperature; Heat transfer
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2010.12.021

Adsorption refrigeration systems provide a sustainable possibility to reduce the environmental impact of refrigeration and air-conditioning as they allow for sources of otherwise unused excess waste heat to be reused for cooling purposes. Adsorptive cooling is a discontinuously operated cycling process, and it is well known that the determination of an optimal cycling time yielding maximum cooling power is a key to the design of an efficient mode of operation. The optimal cycle time however strongly depends on operating conditions such as ambient air temperature, available heat source temperature, desired target cooling temperature, and achievable volume flow rates of the secondary heat transfer circuits. In this contribution, we apply a direct method for periodic optimal control to optimize two-bed adsorption chillers. We present a first principles dynamic model of the underlying thermal process. We show that direct methods for periodic optimal control allow for quick and reliable computation of optimal cycle times for a given set of parameters. Contrary to pre-existing methods, fast computation times and guaranteed optimality of the solutions computed by our approach makes it viable to extensively study the simulated optimal cyclic operation of two-bed adsorption chillers under a wide range of varying conditions.