https://doi.org/10.6110/KJACR.2025.37.6.259

Dae-Gyun Lee ; Ju-Hyung Park ; Junsu Park ; Junghoon Yoo ; Hangjoo Shin ; Young-Hoon Noh ; Sungho Choi ; Seungchang Kang ; Jongwon Choi

Nitrogen oxides (NOx) are significant pollutants generated in large quantities during production processes of domestic smelting facilities, arising primarily from fossil fuel combustion. Due to their harmful environmental and health impacts, NOx emissions are subject to stringent global regulations. The selective catalytic reduction (SCR) method using ammonia is widely employed for NOx mitigation. However, this approach is economically challenging due to its high consumption of ammonia, reliance on costly metal oxide catalysts, and necessity of maintaining elevated operating temperatures. Additionally, the predominant component of NOx, nitric oxide (NO), exhibits low solubility in water, resulting in limited reduction efficiency. To address these limitations, research has increasingly focused on pre-oxidizing NO into nitrogen dioxide (NO2) to enhance its solubility and facilitate removal via wet absorption techniques. In this study, the actual performance of NOx emissions from smelting facilities was analyzed under various conditions, considering the type of oxidizing agent, temperature, and concentration. Oxidation rates were systematically measured. Experiments combining oxidation and absorption were conducted to evaluate the efficiency of NOx removal. This research aims to provide insights into optimizing NOx reduction strategies for smelting processes.

https://doi.org/10.6110/KJACR.2025.37.6.269

Young Wook Kim ; Mi Jin Jeong ; Woo Jin Go ; Jeong Se Suh

High temperature exhaust gas is a major cause of environmental pollution and waste of thermal energy. To solve these problems, this study aimed to design a lamella recuperator that could effectively recover waste heat generated from high temperature processes and maximize waste heat utilization. Heat exchanger efficiency and pressure drop between inlet and outlet were selected as performance indicators of the lamella recuperator. Study results showed that, at all flue gas mass flow rates, an increase in air flow caused the pressure drop between the air inlet and outlet to rise, while the pressure drop of the high temperature gas decreased. Furthermore, as the air temperature increased, the pressure drop of both air and gas increased across all gas temperatures, while heat exchanger efficiency decreased. Therefore, it is concluded that optimizing the mass flow rate and temperature conditions of air and high temperature gas is crucial for enhancing the performance of the lamella recuperator.

https://doi.org/10.6110/KJACR.2025.37.6.278

Chanuk Lee ; Minho Kim ; Ahmin Jang ; Insoo Oh ; Beungyong Park ; Yujin Nam ; Sung Lok Do

The Government of the Republic of Korea has implemented various policies targeting public office buildings to reduce peak electricity load and overall energy use in cooling. During periods of energy and power crises, sequential operation strategies for a cooling system are recommended to lower peak electricity demand in buildings. However, current sequential operations are typically implemented through cooling system shutdowns or arbitrary indoor temperature increases to reduce peak cooling electricity load. This study evaluated the effectiveness of different sequential cooling system operation strategies in public office buildings by analyzing their impact on peak cooling energy load and indoor thermal environment. Through simulation-based analysis, two main control approaches, traditional on/off control and set-back temperature control, were compared. Results demonstrated that while on/off control scenarios achieved a 64% reduction in peak cooling electricity load, these scenarios caused significant thermal discomfort and cooling load spikes upon system restart. In contrast, set-back control scenarios maintained indoor temperatures within the set-point range and reduced peak cooling electricity load by 8.7% while maintaining PMV values within approximately +0.5 compared to the common operation case. The set-back control strategy also prevented sudden cooling load increases observed in the on/off scenarios, offering a more balanced approach to energy management and occupant comfort in public office buildings.

https://doi.org/10.6110/KJACR.2025.37.6.288

Geun-Soo Song ; Ji-Seok Yang ; Kun-Hyung Lee ; Kyung-Hoon Yoo

This paper presents transient responses in one hour of indoor temperature and relative humidity according to various simultaneous feedback control schemes for a semiconductor manufacturing electric cleanroom. The MIMO (multi-input-multi-output) feedback was used to control schemes include on/off switching, proportional-integral-derivative (PID), artificial neural network (ANN), and model predictive control (MPC) controllers. Simultaneous feedback control block diagrams for the electric cleanroom were created using the MATLAB/Simulink platform. Simulation results showed that all of the present MIMO feedback control schemes were able to control the indoor temperature and relative humidity to stably settle to set points. In the present electric cleanroom, the ANN controller for the water spraying nozzle humidifier and the PID controller for the DCC were strictly the most water- and energy-saving, respectively. The present ANN and MPC controllers are artificial intelligence-type controllers. They showed almost zero levels of overshooting of indoor relative humidity and temperature compared to 3.6%RH and 3.3℃ by the PID controller. They also provided output responses that soft-landed more quickly and smoothly to target set points, respectively.

https://doi.org/10.6110/KJACR.2025.37.6.300

Joon Ahn ; Dong-Seon Kim ; Sumin Kim ; Hyun Jung Kim ; Yujin Nam ; Young-Jin Baik ; Kwang Ho Lee ; Jae-Weon Jeong ; Jinkyun Cho ; Honghyun Cho

This article offers a comprehensive overview of the latest research findings in the realms of heating, cooling, ventilation, sanitation, and building and plant indoor environments through a thorough examination of articles published in the Korean Journal of Air-Conditioning and Refrigeration Engineering over the course of 2024. Below is a summary of papers reviewed. (1) A total of 21 papers were published in 2024 on building mechanical systems and environmental engineering, marking a slight increase from the previous year. Research was largely centered on empirical studies, including system control, regulatory improvements following the enforcement of the Mechanical Equipment Act, and energy performance analysis. (2) Similarly, 21 papers were published in the building environment field, maintaining a level comparable to that of the previous year. Topics were categorized into indoor environment, building energy, and others, covering areas such as green remodeling technology selection, natural ventilation and stack effect analysis, and evacuation simulations. (3) In the refrigeration sector, the number of publications remained steady over the past three years, with eight papers released in 2024. The focus was on practical and efficiency-oriented research, including control optimization for variable-speed systems, performance improvement of key components, and energy-saving analyses of heat pump systems applicable in industrial settings. (4) Heat transfer and fluid flow research saw ten publications in 2024, reflecting a slight decline. While studies related to phase change and condensation using eco-friendly refrigerants became more prominent, application-oriented topics showed a noticeable decrease, with greater emphasis placed on experimental and quantitative investigations of heat transfer characteristics.