Optimal operation of adsorption chillers: First implementation and experimental evaluation of a nonlinear model-predictive-control strategy

Bau, Uwe; Baumgärtner, Nils; Seiler, Jan; Lanzerath, Franz; Kirches, Christian

doi:10.1016/j.applthermaleng.2018.07.078

Cited by 13 publications

(7 citation statements)

References 34 publications

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“…The heat and mass transfer strongly affect the kinetics of the adsorption chiller process and are generally very complex due to various interrelated transport mechanisms. [ 49 ] Here, we summarize the heat and mass transfer according to numerical simulations of adsorption chillers [ 50,51 ] to: 1) heat transfer in the adsorber; 2) mass transfer from and into the adsorbent; 3) heat transfer during condensation; and 4) heat transfer during evaporation. In the following, we discuss the effect of ethanol on these heat and mass transfer processes.…”

Section: Discussion On Ethanol's Impact On Performancementioning

confidence: 99%

Water and Ethanol as Refrigerant Mixture Enabling Adsorption Cooling below 0 °C

et al. 2023

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Adsorption chillers can avoid two types of greenhouse gas emissions from conventional cooling technologies: energy‐related emissions by utilizing waste heat and refrigerant leakage‐related emissions by employing the natural refrigerant water. However, water restricts the minimal cooling temperature to its freezing point. To overcome this limitation, herein, a boiling antifreeze in adsorption chillers is proposed. For this purpose, a databank of over 12 000 molecules for suitable antifreezes is screened and ethanol is derived as the best candidate. Employing ethanol as antifreeze, the experimental feasibility in a lab‐scale adsorption chiller is demonstrated: ethanol can prevent freezing at a cooling temperature of –5 °C and, thus, extend the operating range of the adsorption chiller. Thereby, the favorable properties of water can be partially retained. Furthermore, water–ethanol mixtures to pure water at a cooling temperature of 10 °C are compared: maximal coefficient of performance (COP) and specific cooling power (SCP) decrease by 45% and 42%, respectively, when 14 mol% ethanol is used instead of pure water. Herein, the influence of ethanol on the adsorbed mass and heat transfer during evaporation are crucial. In summary, boiling antifreezes can extend the operating range of water‐based adsorption chillers below 0 °C.

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Section: Discussion On Ethanol's Impact On Performancementioning

confidence: 99%

Water and Ethanol as Refrigerant Mixture Enabling Adsorption Cooling below 0 °C

et al. 2023

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“…Binary control functions v v v enter nonlinearly and in a non-convex way in Eqs. (2,3,5). Hence, the problem is an NP-hard non-convex MINLP, cf.…”

Section: Solution Approachmentioning

confidence: 99%

“…It has already been used in various studies with different building energy system components and configurations, e.g 1 Institute of Engineering Design, Mechatronics and Electromobility (IKME), Hannover University of Applied Sciences and Arts, Hannover, Germany {dimitri.bitner|artyom.burda|martin.grotjahn}@hs-hannover.de 2 Institute for Mathematical Optimization, Technische Universität Carolo-Wilhelmina zu Braunschweig, Germany. {c.kirches|f.bestehorn}@tu-bs.de in [2], where an NMPC-based controller showed a potential increase in the specific cooling power by 31.1% for absorption chillers, or [3], where the application to domestic micro-grid results in energy savings in the magnitude of 10%. A predictive controller was implemented as a real building temperature management system in [4] and achieved more than 17% savings compared to the conventional control.…”

Section: Introductionmentioning

confidence: 99%

Mixed-Integer Real-Time Control of a Building Energy Supply System

Burda¹,

Bitner²,

Bestehorn

et al. 2023

IEEE Control Syst. Lett.

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We present a methodology based on mixed-integer nonlinear model predictive control for a real-time building energy management system in application to a single-family house with a combined heat and power (CHP) unit. The developed strategy successfully deals with the switching behavior of the system components as well as minimum admissible operating time constraints by use of a special switch-cost-aware rounding procedure. The quality of the presented solution is evaluated in comparison to the globally optimal dynamic programming method and conventional rule-based control strategy. Based on a real-world scenario, we show that our approach is more than real-time capable while maintaining high correspondence with the globally optimal solution. We achieve an average optimality gap of 2.5% compared to 20% for a conventional control approach, and are faster and more scalable than a dynamic programming approach.

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“…* While we focus on the optimal switching of an ACM within this work, it should be noted that MPC can also yield large potential for optimization of the internal processes of an ACM. 32 F I G U R E 1 System components in the cellar of the building: (1) control cabinet, (2) low temperature storage, (3) adsorption cooling machine, (4) high temperature storage, (5) pump P ssc , (6) pump P psc , (7) The temperature at the inlets and outlets of the ACM and the current flows in each circuit are measured, as well as the temperatures at the inlets and outlets of the RTHX and the outlet temperature of the RT.…”

Section: Adsorption Cooling Machinementioning

confidence: 99%

Experimental operation of a solar‐driven climate system with thermal energy storages using mixed‐integer nonlinear model predictive control

Bürger

Bull

Sawant

et al. 2021

Optim Control Appl Methods

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This work presents the results of experimental operation of a solar-driven climate system using mixed-integer nonlinear model predictive control (MPC).The system is installed in a university building and consists of two solar thermal collector fields, an adsorption cooling machine with different operation modes, a stratified hot water storage with multiple inlets and outlets as well as a cold water storage. The system and the applied modeling approach is described and a parallelized algorithm for mixed-integer nonlinear MPC and a corresponding implementation for the system are presented. Finally, we show and discuss the results of experimental operation of the system and highlight the advantages of the mixed-integer nonlinear MPC application. K E Y W O R D Sexperimental study, mixed-integer nonlinear programming, model predictive control, renewable energy systems, solar thermal climate systemsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Optimal operation of adsorption chillers: First implementation and experimental evaluation of a nonlinear model-predictive-control strategy

Cited by 13 publications

References 34 publications

Water and Ethanol as Refrigerant Mixture Enabling Adsorption Cooling below 0 °C

Water and Ethanol as Refrigerant Mixture Enabling Adsorption Cooling below 0 °C

Mixed-Integer Real-Time Control of a Building Energy Supply System

Experimental operation of a solar‐driven climate system with thermal energy storages using mixed‐integer nonlinear model predictive control

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