After Cancūn - G21, WTO, and Multilateralism

Imtiaz Hussain 서울대학교 국제학연구소 2004 Journal of International and Area Studies Vol.11 No.2

  Why did the Canc?n WTO meeting collapse? What is expected next? A content analysis finds G21 at the interface of 1) less developed countries (LDCs) protesting the uneven playing field; 2) longstanding substantive fissures; 3) increasing unilateralism by developed countries (DCs); and 4) farm protection haunting multilateralism. US competitive liberalization emerges most coherently from the WTO wreckage (Feinberg 2003). Based on discrimination and asymmetrical reciprocity, it aggressively targets the European Union (EU), seeks LDC bandwagoning, discourages regime reconstruction (Krasner 1982), defies neorealist/neoliberalist/constructivist tendencies (Waltz 1979; Keohane 1989; Hopf 1998), and predicts future trade turbulence (Rosenau 1997).

Numerical and experimental heat transfer analyses of a novel concentric tube absorber under non-uniform solar flux condition

Imtiaz Hussain, M.,Lee, Gwi Hyun Pergamon 2017 RENEWABLE ENERGY Vol.103 No.-

<P><B>Abstract</B></P> <P>The thermal performance of a novel concentric tube absorber for a conical solar collector (CSC) under forced convection was investigated by numerical and experimental analyses. In this system, the CSC assembly is mounted on dual axis tracking platform that can accurately track the sun position to get maximum concentrated solar radiation over the entire circumference of the absorber. Due to conical-shape reflector, the non-uniformity of the solar flux distribution along the absorber length is high; therefore, the non-uniform concentrated solar flux was applied to the absorber surface as boundary condition in Fluent software. To evaluate the heat transfer characteristics and performance of the system, heat loss and gain factors were derived from the novel concentric tube absorber while varying the flow rate. The concentric tube absorber of the CSC system was developed and analyzed with different operational parameters. The double-tube design provides the uniformly distributed flow and temperature symmetricity along the absorber length. The predicted results of the CSC system were in good agreement with the measured results.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A numerical thermal analysis of a concentric tube absorber was performed. </LI> <LI> Non-uniform solar flux was applied by dividing the absorber into different parts. </LI> <LI> CSC with dual axis tracker got concentrated flux on whole absorber circumference. </LI> <LI> The numerical model of the absorber was validated with experimental results. </LI> </UL> </P>

Advances in solar thermal harvesting technology based on surface solar absorption collectors: A review

Imtiaz Hussain, M.,Mé,né,zo, Christophe,Kim, Jun-Tae Elsevier 2018 Solar energy materials and solar cells Vol.187 No.-

<P><B>Abstract</B></P> <P>This study presents a critical review of the major research and development work that has advanced surface solar absorption technology and also discusses the applications of this technology in the last 15 years. In a surface solar absorption collector (SSAC), solar radiation is first absorbed on the surface of the collector and then transferred to the circulating fluid. This article reviews a wide range of studies on different SSAC systems with the aim of identifying research gaps to prepare this technology for commercial availability. Moreover, qualitative and quantitative research information on non-concentrating and concentrating SSACs was collected and evaluated in the context of a performance-based assessment, environmental issues, and sustainability concerns. The performance of these collectors mainly relies on the receiver design and thermal storage tanks with different heat transfer fluids. For high concentration collectors, there is an urgent need for new heat transfer and storage fluids to withstand elevated temperatures to minimize the flow instability. A review of the literature suggests that ongoing high quality research on this technology, especially on medium and high concentration collectors, will soon overcome the existing problems bringing this technology into temperature ranges that will make it commercially available. Finally, the scientific challenges and opportunities relevant to this technology are also discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Various types of surface solar absorption systems have been critically discussed. </LI> <LI> Report trends of research and development of the technology advancements. </LI> <LI> Recently developed application advancements have been highlighted. </LI> <LI> Based on literature reviewed, opportunities and challenges have been proposed. </LI> </UL> </P>

Performance and economic analyses of linear and spot Fresnel lens solar collectors used for greenhouse heating in South Korea

Imtiaz Hussain, M.,Ali, Asma,Lee, Gwi Hyun Elsevier 2015 ENERGY Vol.90 No.2

<P><B>Abstract</B></P> <P>This paper compares the thermal performance characteristics of LFL and SFL (linear and spot Fresnel lens, respectively) solar collectors for heating identical greenhouses in Chuncheon, South Korea. LFL and SFL collectors with similar storage capacities and Fresnel lens surface areas were tested under the same weather and operating conditions. Both systems were equipped with a dual-axis solar tracker for tracking the sun position and a circulating pump for forced convective heat transfer. Economic analyses of the solar collectors were performed by considering the current interest rate, inflation rate, and electricity prices in South Korea. The available energy per unit area and thermal efficiency were higher for the SFL than for the LFL collector. The discounted payback period decreased and electricity savings increased when the storage capacity was increased with either collector. All results indicate that SFL collector performance was about 7–12% higher than that of LFL collector. It is also noticed that changing the inlet flow rate of the greenhouse heat exchanger may be a good solution for obtaining the seed germination temperatures needed for different crops.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SFL collector has more available energy per unit area compared to LFL collector. </LI> <LI> Useful energy gain for both collectors varied with varying storage capacities. </LI> <LI> The fraction of heat supplied by SFL for greenhouse heating was higher than LFL. </LI> <LI> SFL collector has lower discounted payback period compared to LFL collector. </LI> </UL> </P>

Simulation and Model Validation of a Multi-Concentration Points Concentrated Photovoltaic Thermal System

Hussain, M. Imtiaz,Lee, Gwi Hyun,Kim, Jun-Tae American Scientific Publishers 2018 Journal of nanoelectronics and optoelectronics Vol.13 No.10

Experimental validation of mathematical models of identical aluminum and stainless steel engineered conical solar collectors

Imtiaz Hussain, M.,Lee, Gwi Hyun,Kim, Jun-Tae Elsevier 2017 RENEWABLE ENERGY Vol.112 No.-

<P><B>Abstract</B></P> <P>This paper studies the mathematical modeling of a conical solar collector (CSC) based on different reflector materials and view angles. The optical performance testing using both stainless steel reflector (SSR) and aluminum mirror reflector (AMR) was performed under similar conditions at reflector view angles of 35°, 40°, and 45°, respectively. Main operational parameters related to the thermal/optical efficiencies of the SSR and AMR systems were determined and compared with each other. In addition, the interdependent transient temperature responses of both system components were predicted using Matlab<SUP>®</SUP> ordinary differential equation (ODE) solvers. For the purpose of model validation, simulation results from both systems were compared with experimental data. Results showed that the highest efficiencies and maximum water temperatures were achieved at reflector view angle of 45°, but these values were significantly higher in AMR system than SSR system for all of the aforementioned cases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Performance comparison of identical solar systems having different reflectors. </LI> <LI> Mathematical modeling was performed using MATLAB ordinary equation solvers. </LI> <LI> Measured and predicted results showed satisfactory agreement for both systems. </LI> <LI> Aluminum reflector system has more thermal output than the stainless steel system. </LI> </UL> </P>

Conventional fluid- and nanofluid-based photovoltaic thermal (PV/T) systems: a techno-economic and environmental analysis

Hussain, M. Imtiaz,Kim, Jun-Tae Taylor Francis 2018 International journal of green energy Vol.15 No.11

Performance Comparison and Model Validation of a Conical Solar Reflector and a Linear Fresnel Concentrator

Imtiaz Hussain, M.,Hyun Lee, Gwi ASME International 2016 Journal of Solar Energy Engineering Vol.138 No.6

Thermal performance comparison of line- and point-focus solar concentrating systems: Experimental and numerical analyses

Imtiaz Hussain, M.,Lee, G.H. Association for Applied Solar Energy ; Elsevier Sc 2016 SOLAR ENERGY -PHOENIX ARIZONA THEN NEW YORK- Vol.133 No.-

The purpose of this study was to analyze and compare the thermal performances of a line-focus and a point-focus solar concentrators (LFSC and PFSC, respectively) under similar operating and weather conditions in South Korea. Both concentrator systems had Fresnel lenses of the same surface area. To reduce heat loss, absorber pipes of the LFSC and PFSC systems were covered with borosilicate glass tube and foamed polyethylene insulation, respectively. Collector temperature (inlet and outlet temperature differential), collected energy, and thermal efficiency over experimental test time were calculated while the solar radiation, volumetric flow rate, and inlet temperature of the thermal fluid were varied. Good harmony was observed between the experimental and predicted results. Calibration of the both models reduced the deviation between the experimental and predicted temperature results compared to the uncalibrated models. Although both solar collectors showed similar trends in the variations of the average efficiency and total collected energy, these parameters were about 7% and 8% higher, respectively, in the PFSC compared to the LFSC. Overall, the results indicate that the PFSC performs slightly better than the LFSC in terms of the thermal efficiency, total collected energy, and heat loss.

Utilization of Solar Energy in Agricultural Machinery Engineering: A Review

Hussain, M. Imtiaz,Lee, Gwi Hyun Korean Society for Agricultural Machinery 2015 바이오시스템공학 Vol.40 No.3

Background: Various solar energy collecting systems have been developed and analyzed for agricultural applications. They include solar thermal and electric devices such as solar crop dryers, solar water pumps, solar greenhouse heating, ventilation for livestock, solar aeration pumps, solar electricity, and many more. Purpose: This review provides the current status of research and development in the field as well as the solar energy systems that are currently in use in the agriculture sector across the globe. Review: Solar energy is the largest and cheapest energy resource on earth; one hour of solar radiation exceeds the complete global energy consumption in one year. The potential annual total solar radiation in South Korea is $3.58-5.4 kWh/m^2/day$. The available solar energy is sufficient for agricultural applications across the entire country. Conclusion: The scope of solar energy utilization in agricultural machinery engineering in South Korea and in other countries is promising.