Browsing by Author "Kim, Hyeon-Tae"

Now showing 1 - 4 of 4
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    DETERMINATION OF OVERALL HEAT TRANSFER COEFFICIENT FOR GREENHOUSE ENERGY-SAVING SCREEN USING TRNSYS AND HOTBOX
    (Biosystems Engineering, 2022) Rabiu, Anis; Na, Wook Ho; Akpenpuun, Timothy Denen; Adesanya, Misbaudeen Aderemi; Ogunlowo, Qazeem Opeyemi; Kim, Hyeon-Tae; Lee, Hyun-Woo
    The high energy consumption in the greenhouse during the winter season necessitates the development of various thermal screens for energy-saving purposes. However, there is limited data on the precise properties of thermal screens, while little research has investigated a methodological approach for measuring the screen's energy-saving capacity for greenhouse energy efficiency. This research aims to determine the thermophysical, radiative, and aerodynamic properties of selected commercial greenhouse thermal screens. The transient system simulation (TRNSYS) model was used to simulate the heat flux and derive the thermal retention qualities of the thermal screens through their measured properties. The model was validated by comparing the simulated and experimental heat transfer coefficients, expressed as the overall heat transfer coefficient (U-value), thereby determining the thermal retention of the screens. In addition, the simulated U-value was compared to the experimental U-value in material permeability to investigate the influence of screen porosity on heat loss. The statistical analysis t-test was conducted to compare the U-values obtained from the simulation and the experimental hotbox. The simulated Uvalues (for computed permeability) indicated that samples M1 and M3 exhibited the lowest U-value of 4.4 W m 2 K 1, while white polyester, Luxous, PH-super, PH-66, M2, Clima45 (0), and New-Lux showed higher U-values of 82%, 105%, 161%, 123%, 41%, 102%, and 118%,Uvalde respectively. Because of their low material porosity, M1, M2, and M3 samples showed better greenhouse thermal retention over others. Conclusively, the permeability features of the greenhouse energy screen materials have a substantial impact on their U-values.
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    DYNAMIC NEURAL NETWORK MODELING OF THERMAL ENVIRONMENTS OF TWO ADJACENT SINGLE-SPAN GREENHOUSES WITH DIFFERENT THERMAL CURTAIN POSITIONS
    (2024) Akpenpuun, Timothy Denen; Ogunlowo, Qazeem Opeyemi; Na, Wook-Ho; Dutta, Prabhat; Rabiu, Anis; Adesanya, Misbaudeen Aderemi; Nariman, Mohammadreza; Zakir, Ezatullah; Kim, Hyeon-Tae; Lee, Hyun-Woo
    In order to produce marketable yield, scientific methodologies must be used to forecast the greenhouse microclimate, which is affected by the surrounding macroclimate and crop management techniques. The MATLAB tool NARX was used in this study to predict the strawberry yield, indoor air temperature, relative humidity, and vapor pressure deficit using input parameters such as indoor air temperature, relative humidity, solar radiation, indoor roof temperature, and indoor relative humidity. The data were normalized to improve the accuracy of the model, which was developed using the Levenberg–Marquardt backpropagation algorithm. The accuracy of the models was determined using various evaluation metrics, such as the coefficient of determination, mean square error, root mean square error, mean absolute deviation, and Nash–Sutcliffe efficiency coefficient. The results showed that the models had a high level of accuracy, with no significant difference between the experimental and predicted values. The VPD model was found to be the most important as it influences crop metabolic activities and its accuracy can be used as an indoor climate control parameter.
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    ENERGY- AND YIELD-BASED PERFORMANCE EVALUATION OF A PHASE CHANGE MATERIAL–INTEGRATED SINGLE-SPAN DOUBLE-LAYERED WITH A THERMAL SCREEN GREENHOUSE
    (Thermal Science and Engineering Progress, 2024-01) Ogunlowo, Qazeem Opeyemi; Akpenpun, Timothy Denen; Na, Wook Ho; Adesanya, Misbaudeen Aderemi; Rabiu, Anis; Dutta, Prabhat; Kim, Hyeon-Tae; Lee, Hyun- Woo
    Greenhouse technology emerged to ensure the optimum yield of the host crop —a prerequisite to achieving Sustainable Development Goals 7 and 2. To achieve this, supplemental energy is needed under extreme weather conditions at about half the operational cost. Researchers have focused and succeeded in reducing the energy demand using numerical methods with little focus on the impact of these methods on crop yield. A novel greenhouse system—phase change material–integrated single-span double-layered strawberry greenhouse with a thermal screen—is introduced herein. Furthermore, how the energy management method affects the yield of the host crop is explored. Moreover, the energy-saving potential and yield enhancement achieved by integrating PCMs and other passive thermal-management systems in a specific agricultural setting is investigated. TRNSYS 18 software is used to evaluate the effect of three passive variables on two performance indices. The passive variables are location: Daegu (DG), Seoul, and Jeju Island (JE); orientation: 90◦ (E-W), 45◦ (NE-SW), and 0◦ (NS); and PCM type: “No-fill”, water, and Paraffin (ParC13–C24). The effect of thermal screen control was also studied on the localized optium configuration. Finally, economic analysis was conducted to ascertain the most sustainable configuration. The performance indices are the heating demand and strawberry yield. The results show that the location, orientation, and PCM usage inside the greenhouse greatly affect the greenhouse’s heating demand and crop yield. The configuration selected must be in such a way that the indoor nighttime temperature does not exceed 2 ◦C above the minimum nighttime optimum value of the host crop.
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    SIMULATION OF GREENHOUSE ENERGY AND STRAWBERRY (Seolhyang sp.) YIELD USING TRNSYS DVBES: A BASE CASE
    (2023) Ogunlowo, Qazeem Opeyemi; Akpenpuun, Timothy Denen; Na, Wook Ho; Adesanya, Misbaudeen Aderemi; Rabiu, Anis; Dutta, Prabhat; Kim, Hyeon-Tae; Lee, Hyun-Woo
    This research establishes a base case scenario encompassing the energy behavior of the greenhouse and its direct influence on the yield of strawberries (Seolhyang sp.) to evaluate the performance of the greenhouse energy demand and its effect on crop yield. The objective is to develop a ventilated discretized volume building energy simulation (DVBES) that predicts energy demand, temperature, and relative humidity (RH) of a greenhouse and develop a predictive strawberry yield model that predicts the strawberry yield. This study used two single-span double-layer experimental greenhouses with different features. Experimentation was conducted in the winter season of 2021–2022 and 2022–2023. Hourly temperature, RH, and daily fuel consumption were used to validate the DVBES model. Weekly temperature, RH, solar radiation (SR), and yield were used to validate the strawberry yield model. The results show high prediction accuracy with minor errors. For a single-span double-layer greenhouse at E–W (90◦) orientation, the total energy demand and strawberry yield were 113.861 MJ.m􀀀 2 and 0.466 kg.plant􀀀 1.season􀀀 1, respectively. The findings serve as a foundation for further research on optimizing energy consumption in greenhouse environments. This research contributes to advancing knowledge in sustainable agriculture and facilitates the transition toward a greener and more resource-conscious future.