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1
An Energy Rating Methodology for Long Term Performance Evaluation of Renewable Energy Systems

Muhammad Wakil Shahzad,Kyaw Thu,YounCheol Park,Seung Jin Oh,Kim Choon Ng 한국에너지기후변화학회 2013 에너지기후변화학회지 Vol.8 No.2
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This paper describes a simple methodology for determining the long term performance of renewable energy systems (solar, photovoltaics, wind turbines, etc) that is important for project evaluation. Overall efficiency of solar collector hot water plants, photovoltaics and wind turbines are examined by using a ratio of output of useful effects to energy input. Long-term efficiency of class A solar collectors is typically higher ≥ 50%in thermal energy whilst the silicon-based photovoltaics has only <10% efficiency in electricity: In these mentioned cases, the useful output differ in form, obscuring the comparison of one renewable system to the other.The thermal or electricity rating proposed here enable one to make a performance comparison across a host of renewable energy systems. Based on the long term performance rating, itwill assist engineers and managers topredict accurately the payback periods of renewable energy plants as well as the annual carbon emissions.
2
An improved indirect evaporative cooler experimental investigation

Shahzad, Muhammad Wakil,Burhan, Muhammad,Ybyraiymkul, Doskhan,Oh, Seung Jin,Ng, Kim Choon ELSEVIER 2019 Applied Energy Vol. No.
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Abstract Air conditioning has enhanced the work efficiency and improved life style by maintaining comfortable environment. The growing demand of air conditioning has negative impact on energy and environment. In 2015, air conditioning consumed 6% of total global electricity produced and it is expected to increase to 20% by 2050. The leveling-off conventional chiller’s efficiency at 0.85 ± 0.03 kW/Rton due to pairing of dehumidification and cooling processes in one machine is not only the major reason of high energy consumption but also the key limitation in efficiency improvement. The de-coupling of dehumidification and cooling processes can be one of the solution to achieve the quantum jump in the performance, 0.6 ± 0.03 kW/Rton, by improving individual processes. We proposed an improved indirect evaporative cooler system for sensible cooling that can be combined with dehumidification processes to achieve sustainable cooling goals. The experimentation on 800 mm long and 280 mm wide generic cell showed that it can produce temperature differential up to 10 °C with small area of heat transfer. It was showed that the proposed vertical heat exchanger configuration with multi point injection of working air is the best configuration of the indirect evaporative cooler, achieving coefficient of performance level of 78 for cooling alone. We expect that overall coefficient of performance level of 7–8 is achievable by incorporating efficient dehumidification processes. We also presented detailed design parameters that can be used as a reference for commercial system design. Highlights <UL> <LI> Decoupling of latent and sensible load in cooling is the key for sustainability. </LI> <LI> The indirect evaporative cooler integrated with dehumidification is one of the solution. </LI> <LI> Improved IEC with three major modification can achieve COP up to 78 for cooling only. </LI> <LI> The dehumidification system COP around 4–5 can help to achieve overall COP of 7–8. </LI> <LI> The proposed multi injection vertical heat exchanger design has the best performance. </LI> </UL>
3
Approaches to energy efficiency in air conditioning: A comparative study on purge configurations for indirect evaporative cooling

Oh, Seung Jin,Shahzad, Muhammad Wakil,Burhan, Muhammad,Chun, Wongee,Kian Jon, Chua,KumJa, M.,Ng, Kim Choon Elsevier 2019 ENERGY Vol.168 No.-
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Abstract This paper presents a mathematical model to enable a more in-depth understanding of the combined heat and mass transfer processes of a counter-flow indirect evaporative cooler operating in semi-arid regions. A series of simulation was conducted to compare the performances between a single-purge and four-purge configurations. Furthermore, the effect of several parameters on the performance of the single-purge configuration was investigated under the baseline condition. The developed model was validated against experimental data from literature to within 2% discrepancy. Key results revealed that the single-purge configuration produced higher cooling capacity (around 20% higher), as well as higher dew-point effectiveness under the same operating conditions. A parametric study was also made on the single-purge configuration. The results revealed that lower product air temperature and higher dew-point effectiveness were achieved with longer channel length and larger purge ratio. However, the maximum cooling capacity approached its maximum with longer channel length and 35% purge ratio.