Integrated System Model of District Cooling for Energy Consumption Optimization

The successful modeling of a multi-plant district cooling (DC) system presents several challenges in integrating system level requirements with engineering analysis for verification and optimization. Currently, the ability to predict the behavior and performance parameters such as chilled water temperature difference, annual energy consumption, and central chiller plant coefficient of performance (COP) of the dynamic system is limited. Effective modeling and efficient simulation are required when it comes to complex physical systems. This paper presents an integrated model that combines system architecture with physical modeling to represent and simulate a multi-plant district cooling system (DCS). We refer to this model as model-based systems engineering (MBSE) model of the DC system. A systems modeling language (SysML) model is created to develop a multi-domain architecture of the DC system that will satisfy stakeholder needs and requirements. This model is capable of executing behavior and parametric aspects (or “views”) of the system. A closed-loop of information flow was developed to map SysML constructs with their respective Modelica models to support the integration of simulated experiments with SysML construct. The integrated MBSE model is successfully implemented and the results show that the IPLV.SI value of the chiller model was 6.4157, which is in the acceptable range. Based on the initial conditions provided by the actual plant, the simulation results show that the chilled water temperature predictions by Modelica as 4.8℃ verify the corresponding stakeholders’ requirements captured in the SysML model

A Frontier Based Eco-Efficiency Assessment of Electric Vehicles: The Case of European Union Countries Using Mixed and Renewable Sources of Energy

Electric vehicles (EVs) are seen as a promising solution for creating more efficient and sustainable transportation systems. European Union (EU) members show a strong interest in implementing EVs, and the governments support the concept by offering facilities to the buyers. Although electric vehicles can be operated with nonpolluting fuels, such as natural gas, fuel cells are more efficient. Creating electricity can affect the environment and the economy. Three environmental features (consumption of water, GHG emissions, and energy consumption, plus GDP's contribution to EU gross domestic product) were analyzed for 28 EU member states to measure electric vehicle efficiency. In one of the DEA models, an input-oriented method was employed to compute the efficiency scores. The k-means clustering algorithm defined the high, medium, and low-efficiency groups. Even more so, the total efficiency scores in this study show that using solar energy outperforms mixed-source energy sources was found to be more efficient

System requirements and optimization of multi-chillers district cooling plants

District cooling systems (DCS) are particularly important in the Middle East due to higher overall temperatures on most days of the year. The design, operation, and control of a new DCS should consider the abundant stakeholders and system requirements transformation using the system engineering processes. Integrating these requirements at an early stage in the system model is essential, specifically, the regulation on energy efficiency or system reliability; without such integration, the system may miss some important aspects and lead to higher energy consumption, lower reliability, higher system cost, greater CO2 emissions and may not satisfy cooling demand of the stakeholders. In this paper, a framework for DCS analysis is proposed by considering inputs, process (core), and outputs. The framework considers the structure and behavior of the DCS system to enhance system design and operation. The core of the framework uses a mathematical model in mixed-integer linear programming (MILP) to optimize the overall DCS cost by integrating the system and stakeholders' requirements. The results obtained from the application of the framework show that addressing the requirements reduces cost and increases energy efficiency, and when the cooling demand is variable, it might be better to have multiple capacities for chillers and chiller storage. The paper is helpful for the decision-makers to understand the impact of requirements and their management in the design, operation, and control of multi-chiller DCS in relief with the cost and energy efficiency. 2022 Elsevier LtdThis publication was made possible by the NPRP award [ NPRP 10-0129-170280 ] from the Qatar National Research Fund (a member of The Qatar Foundation ). The statements made herein are solely the responsibility of the authors.Scopus2-s2.0-8512462610

Operations management of outpatient chemotherapy process: An optimization-oriented comprehensive review

International audienc