Lisa Rueben


Last Name

Rueben

First Name

Lisa

ORCID

0000-0002-6914-4868

Organisational unit

09696 - Bardow, André / Bardow, André

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2021 - 202516
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Publications1 - 10 of 16
  • Störungstheoretische Modellierung der statischen Permittivität: Güte und Grenzen der Anwendbarkeit
    Item type: Other Conference Item
    Rueben, Lisa; Schilling, Johannes; Müller, Simon; et al. (2022)
  • Keine Wärmepumpe ohne Verdichter(modell): Integriertes Design von Kältemitteln und Wärmepumpen
    Item type: Other Conference Item
    Rueben, Lisa; Roskosch, Dennis; Schilling, Johannes; et al. (2021)
    Thermodynamik-Kolloquium 2021. Book of Abstracts
  • Refrigerant Selection for Heat Pumps: the Compressor Makes the Difference
    Item type: Journal Article
    Rueben, Lisa; Roskosch, Dennis; Schilling, Johannes; et al. (2023)
    Energy Technology
    Increasingly stringent regulations and new applications require selecting improved refrigerants for heat pumps. The selected refrigerants should be environmentally friendly and maximize the performance of the heat pump process. Systematic refrigerant selection methods usually model the compressor with onefixed isentropic efficiency identical for all refrigerants. However, compressor studies indicate that the isentropic efficiency may be highly refrigerant-dependent. Herein, the need for a refrigerant-dependent compressor model for refrigerant selection is investigated. For this purpose, a refrigerant-dependent compressor model is combined with an integrated design of refrigerant and heat pump process. To guarantee a comparable nominal heating power among refrigerants, the compressor design is tailored to the refrigerant by expanding the refrigerant-dependent compressor model toward compressor sizing. Integrating compressor design into systematic refrigerant selection is enabled by a computationally efficient model implementation. Accounting for refrigerant-dependent compression substantially changes the resulting refrigerant ranking compared to the widely used assumption of identical isentropic efficiencies forall refrigerants: The best-performing refrigerant is not even identified among the best ten refrigerants when assuming identical isentropic efficiencies.Consequently, compression is identified as the main driver for differences in refrigerant performance. Therefore, integrating refrigerant-dependent compressor models is crucial for systematic refrigerant selection.
  • Temperature control in 5th generation district heating and cooling networks: An MILP-based operation optimization
    Item type: Journal Article
    Wirtz, Marco; Rueben, Lisa; Remmen, Peter; et al. (2021)
    Applied Energy
    In order to realize an energy efficient and emission-free heat and cold supply in urban areas, 5th Generation District Heating and Cooling (5GDHC) networks are a promising technology. In 5GDHC networks, the control of the network temperature is crucial since it affects the efficiency of connected heat pumps and chillers, the heat losses (or gains) of the network, as well as the integration of waste heat or free cooling. Due to the large number of opposing effects, the optimal control of network temperatures is a challenging task. In this paper, a mixed-integer linear program (MILP) is proposed for short-term optimization of the network temperature in 5GDHC systems. The model comprises an air-source heat pump, compression chiller and thermal storage in a central generation unit as well as heat pumps, chillers, electric boilers and thermal storages in buildings. Furthermore, the model considers the thermal inertia of the water mass in the network which functions as additional thermal storage. The optimization model is real-time capable and designed to be deployed in a model-predictive control. In a case study, the optimization approach leads to cost savings in two of three investigated months (by 10 % and 60 % respectively) compared to a reference operation strategy (free floating network temperature).
  • Computer-aided molecular refrigerant design for adsorption chillers based on classical density functional theory and PC-SAFT
    Item type: Journal Article
    Mayer, Fabian; Spiekermann, Lukas; Rueben, Lisa; et al. (2024)
    Computers & Chemical Engineering
    Adsorption chillers are a promising technology for sustainable cooling. The performance of adsorption chillers is highly influenced by the selection of the refrigerant. Still, systematic selection of refrigerants is challenging because evaluating adsorption properties requires significant experimental or simulation efforts. Thus, refrigerant design options are often limited. Here, we propose a systematic refrigerant design method for adsorption chillers assessing refrigerants based on their process performance. Our method quantifies adsorption isotherms by 1-dimensional classical density functional theory (DFT) based on the PC-SAFT equation of state. The method is used to screen over 1800 refrigerants based on their coefficient of performance (COP). We identify refrigerants with higher COPs than commonly used refrigerants and highlight the advantage of a process-based objective function over material based heuristic selection criteria. Finally, we advance from screening to computer-aided molecular design of the refrigerant, leveraging the efficiency of the DFT model to explore the molecular design space systematically.
  • Computergestützter Entwurf von Kältemitteln für Adsorptionskältemaschinen basierend auf Dichtefunktionaltheorie und PC-SAFT
    Item type: Other Conference Item
    Mayer, Fabian; Spiekermann, Lukas; Rueben, Lisa; et al. (2021)
    Thermodynamik-Kolloquium 2021. Book of Abstracts
  • Permittivity Modeling in Electrolyte PC-SAFT
    Item type: Journal Article
    Rueben, Lisa; Rehner, Philipp; Gross, Joachim; et al. (2024)
    Journal of Chemical & Engineering Data
    Accurately modeling the thermodynamic properties of electrolyte systems is key to designing decarbonized energy and chemical processes. For this purpose, a promising model class are electrolyte equations of state. These electrolyte equations of state require the relative static permittivity as an important input. The permittivity in solution deviates from the solvent permittivity, particularly at high ion concentrations. This deviation necessitates an approach to account for this dielectric decrement. This work presents a model for the dielectric decrement in the electrolyte equation of state ePC-SAFT. For this purpose, we extend ePC-SAFT by integrating our previous model for the relative static permittivity, based on perturbation theory. To account for the dielectric decrement, we obtain ion-specific permittivity parameters by adjusting to experimental mean ionic activity coefficients of water-salt mixtures. With a relative deviation of 4.1% averaged over all studied mixtures, the proposed approach accurately models mean ionic activity coefficients for lithium salts, sodium salts, potassium salts, and hydrogen halides. Moreover, the approach outperforms the common linear mixing approach based on the mole fraction. In this work, ePC-SAFT is implemented in the open-source software framework for equations of state FeOs and can be used as an easy-to-install Python package.
  • Don't compress the compressor (model): Integrated design of refrigerants and heat pumps
    Item type: Other Conference Item
    Rueben, Lisa; Schilling, Johannes; Roskosch, Dennis; et al. (2022)
    Vapor-compression heat pumps are a key technology for decarbonizing our energy systems. Due to more stringent regulations and new applications, selecting efficient and environmentally friendly refrigerants for vapor-compression heat pumps is still an open research question. To evaluate potential refrigerants concerning their actual process performance, systematic refrigerant-selection methods employ process models. These process models should capture all interactions between the refrigerant and the heat pump that significantly influence system performance while still being computationally tractable. However, current refrigerant-selection methods often neglect the compressor's fluid dependency, assuming a constant, fixed compressor efficiency for all refrigerants. In this work, we first show that efficiencies of reciprocating compressors depend strongly on the refrigerant. In contrast, the refrigerants' compressor performance is almost independent of the compressor design. Based on these findings, we propose integrating a refrigerant-dependent compressor model into refrigerant-selection methods. This model allows us to investigate the impact of the compressor model on refrigerant selection. For this purpose, an integrated design method of refrigerants and heat pump processes is combined with a detailed reciprocating compressor model and compared with the widely used assumption of constant compressor efficiency. The integrated design shows that neglecting the dependency of the compressor efficiency on the fluids changes the ranking of refrigerants, leading to suboptimal selections. In particular, the best ten refrigerants differ strongly in performance for a fluid-dependent compressor efficiency. In contrast, the differences in the performance almost disappear when assuming a constant compressor efficiency. The work shows that detailed compressor modeling is crucial in systematic refrigerant selection to identify an optimal combination of refrigerants and heat pump processes.
  • Modeling the dielectric constant of mixed solvents based on perturbation theory
    Item type: Conference Poster
    Rueben, Lisa; Schilling, Johannes; Bardow, André; et al. (2021)
Publications1 - 10 of 16