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Your search keyword '"Kwak, Kyoung Hyun"' showing total 20 results
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20 results on '"Kwak, Kyoung Hyun"'

1. Hierarchical Climate Control Strategy for Electric Vehicles with Door-Opening Consideration

Author

Nam, Sanghyeon, Lee, Hyejin, Kim, Youngki, Kwak, Kyoung hyun, and Han, Kyoungseok

Subjects
Electrical Engineering and Systems Science - Systems and Control
Abstract

This study proposes a novel climate control strategy for electric vehicles (EVs) by addressing door-opening interruptions, an overlooked aspect in EV thermal management. We create and validate an EV simulation model that incorporates door-opening scenarios. Three controllers are compared using the simulation model: (i) a hierarchical non-linear model predictive control (NMPC) with a unique coolant dividing layer and a component for cabin air inflow regulation based on door-opening signals; (ii) a single MPC controller; and (iii) a rule-based controller. The hierarchical controller outperforms, reducing door-opening temperature drops by 46.96% and 51.33% compared to single layer MPC and rule-based methods in the relevant section. Additionally, our strategy minimizes the maximum temperature gaps between the sections during recovery by 86.4% and 78.7%, surpassing single layer MPC and rule-based approaches, respectively. We believe that this result opens up future possibilities for incorporating the thermal comfort of passengers across all sections within the vehicle., Comment: This paper, intended for presentation at the IEEE Intelligent Vehicles Symposium (IV) 2024, comprises six pages and includes eight figures

Published
2024

11. Energy‐efficient cabin climate control of electric vehicles using linear time‐varying model predictive control.

Author

Chen, Youyi, Kwak, Kyoung Hyun, Kim, Jaewoong, Kim, Youngki, and Jung, Dewey

Subjects
ENVIRONMENTAL engineering, PREDICTION models, TEMPERATURE control, COST functions, REAL-time programming
Abstract

A cabin climate control system, often referred to as a heating, ventilation, and air conditioning (HVAC) system, is one of the largest auxiliary loads of an electric vehicle (EV), and the real‐time optimal control of HVAC brings a significant energy‐saving potential. In this article, a linear‐time‐varying (LTV) model predictive control (MPC)‐based approach is presented for energy‐efficient cabin climate control of EVs. A modification is made to the cost function in the considered MPC problem to simplify the Hessian matrix in utilizing quadratic programming for real‐time computation. A rigorous parametric study is conducted to determine optimal weighting factors that work robustly under various operating conditions. Then, the performance of the proposed LTV‐MPC controller is compared against a rule‐based (RB) controller and a nonlinear economic MPC (NEMPC) benchmark. Compared with the RB controller benchmark, the LTV‐MPC reaches the target cabin temperature at least 69 s faster with 3.2% to 15% less HVAC system energy consumption, and the averaged cabin temperature difference is 0.7°C at most. Compared with the NEMPC, the LTV‐MPC controller can achieve comparable performance in temperature regulation and energy consumption with fast computation time: the maximum differences in temperature and energy consumption are 0.4°C and 2.6%, respectively, and the computational time is reduced 72.4% on average with the LTV‐MPC. [ABSTRACT FROM AUTHOR]

Published
2023
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19. Enhanced spray and evaporation model with multi-fuel mixtures for direct injection internal combustion engines.

Author

Kwak, Kyoung Hyun, Jung, Dohoy, and Borgnakke, Claus

Abstract

A spray and evaporation model has been developed and embedded in a quasi-dimensional multi-zone direct injection internal combustion engine simulation framework. The model accounts for the behavior of the spray zone and fuel evaporation including sub-models for spray breakup, improved zone velocity estimations with transient fuel injection, spray penetration and tracking of evaporated fuel components. Each sub-model deals with multi-component fuel surrogates to simulate the real fuel effects. To enhance sensitivity of the model to the fuel components, additional thermophysical properties to the traditional spray model are incorporated. The ideal gas and the ideal solution are assumed in the model to retain computational efficiency. Finally, the model was validated against experiments and compared with other numerical methods. The ability of the new model to treat a multi-component fuel provides an improvement in the simulations of modern direct injection internal combustion engine when used with alternative fuels. [ABSTRACT FROM PUBLISHER]

Published
2014
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20. Fuel Sensitive Combustion Model Based On Quasi-Dimensional Multi-Zone Approach For Direct Injection Compression Ignition Engines.

Author

Kwak, Kyoung Hyun

Subjects
Diesel Engine, Quasi-dimensional Multi-zone Simulation, Alternative Fuels, Ignition Delay, Multi-component Evaporation, Spray Model
Abstract

This study describes a development of fuel sensitive quasi-dimensional multi-zone model for a direct injection compression ignition (DICI) engine. The objective is to develop fuel sensitive sub models of the DICI combustion process and integrate them into a thermodynamic engine cycle simulation. The proposed spray and evaporation models comprise the sub-models including fuel sensitive spray breakup, improved zone velocity estimations with transient fuel injection, spray penetration and tracking of evaporated fuel components. On these foundations, ignition delay models are formulated with two different descriptions based on the origin of the charge properties in a DICI engine. The global ignition delay model is based on the global combustion chamber charge properties while the local ignition delay model includes variations in properties of each spray zones. The Cetane number is used to describe a fuel effect for both models. Then, the premixed combustion model is reformulated to calculate a proper burn rate profile with respect to equivalence ratio and scale the profile with diluted air. While the developed models are validated and evaluated by comparing the predictions with experimental data, some of important conclusions have been made. In the spray formation model, the degree of viscosity and surface tension effect on the spray formation and air entrainment is much more pronounced with DME fuel. For the fuels closer to the conventional DF2, the effect of those properties is minimal. The evaporation model includes the behavior of evaporation at high pressure. The rate of evaporation is usually suppressed with higher pressure but at lower temperature than typical engine-like conditions, the effect is inverted. This effect might be significant for the low temperature combustion. Of the two proposed ignition delay models the local model has a slightly better accuracy compared to the global model. The results demonstrate the improvements that can be obtained when additional fuel specific properties are included in the spray ignition model. Although the proposed fuel sensitive combustion model calculates fuel effect to the combustion, the effect of ignition delay to the overall result of engine cycle simulation was much more dominant with given fuels in this study.

Published
2014

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