Session 10D: HVAC Systems

Title: Cabin Thermal Needs: Modeling and Assumption Analysis
Authors: Florent Breque and Maroun Nemer
Abstract:Interest for cabin thermal needs has strongly increased for the past 10 years, particularly due to heating. Indeed, the development of electric and hybrid vehicles put a focus on the HVAC, this high-consuming auxiliary, which can dramatically decrease the vehicle electric range. Thus, this paper presents a detailed transient and mono-zonal model of a car cabin in order to predict the thermal needs. The model is developed using the MODELICA language via the DYMOLA environment. It considers conduction, convection, radiation heat transfers as well as the HVAC and water vapor impacts. The different assumptions of the model are discussed and important considerations usually not discussed are pointed out. The thermal loads are analyzed. Finally, the heating and cooling thermal needs are computed for steady state mode and for convergence mode as well as for varying recirculation ratios. This work is useful to better understand what is behind cabin thermal needs.
Links: Full paper

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Title: Simulative Comparison of Mobile Air-Conditioning Concepts for Mechanical and Electrical Driven Systems
Authors: Arnim von Manstein, Dirk Limperich and Shivakumar Banakar
Abstract:Ever increasing energy demand and the stringent emission norms have resulted in the need for developing more efficient automotive systems. Fuel economy and emission targets are the two important driving factors in the development of an automobile. Efficiency of a Mobile Air-Conditioning system (MAC) has a considerable impact on the fuel economy of an automobile. This study involves simulative comparison of MAC concepts for mechanical & electrical driven systems. System models are developed for MAC concepts using Dymola simulation tool. Drive cycles considered in this study corresponds to the real time driving scenarios and ambient conditions. From this study the conclusions are drawn about the most efficient ways to reach the thermal comfort for the passenger cabin in an automobile.
Links: Full paper

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Title: Duty Cycle for Low Energy Operation of a Personal Conditioning Device
Authors: Rohit Dhumane, Jiazhen Ling, Vikrant Aute and Reinhard Radermacher
Abstract:The Roving Comforter (RoCo) is an innovative personal thermal management technology that provides ultimate personal thermal comfort for individuals in inadequately or even unconditioned environments. It is a miniature heat pump system mounted on a robotic platform capable of autonomously following individuals to deliver comfort by directing hot or cold air through automatically controlled nozzles. This allows buildings to relax their thermostats upto 4 degrees Fahrenheit without sacrificing occupant comfort, leading to energy savings anywhere between 10 to 30% depending on climatic conditions. RoCo, a portable device, operates fully on an onboard battery pack which therefore has to be carefully designed to balance power output, operating time and weight. To address this challenge, a multi-physics model that is capable of simultaneously simulating thermodynamics, electricity and mechanics of RoCo is developed and two duty cycles are analyzed. By observing and analyzing the simulation results, control strategies related to RoCo operation are proposed.
Links: Full paper

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Title: A Platform for the Agent-based Control of HVAC Systems
Authors: Roozbeh Sangi, Felix Bünning, Johannes Fütterer and Dirk Müller
Abstract:The amount of energy used for heating and cooling in the building sector is about one third of the total energy consumed in the world. The finiteness of natural energy resources on the one hand, and the ever-increasing demand for energy in the world on the other hand, necessitate the development of systematic approaches for improving the efficiency of building energy systems as well as minimizing the usage of primary energy resources and the damaging impacts on the environment. Attempts to tackle these problems have led to modern complex energy concepts for buildings, which have consequently initiated a need for new control strategies for them. Multi-agent control, which is known with other names like agent-based control, offers a promising solution to these challenges. To the knowledge of the authors, there are 96 platforms in different programming languages available, which are mostly java-based and mainly used in logistic applications, but there is no platform in the modeling language Modelica, which is widely used for simulation of dynamic systems, especially buildings performance simulation. This lack motivated the authors to develop a platform for agent-based control of HAVC systems. The platform eliminates the dependency of models developed in Modelica on an extra interface, which is usually required to couple the models to the platforms written in any programming languages other than Modelica. This paper presents the structure of the platform and explains how the agents' communications work. The flexibility of the optimization objective is ensured through the definition of readily interchangeable cost functions. The applicability and functionality of the platform are proved by applying the platform in the control of building energy systems examples.
Links: Full paper, Additional material