Theoretical study of CO2 hydrogenation to methanol on isolated small Pdx clusters

CO2 hydrogenation to methanol on small size Pdxclusters(x = 7, 9 and 13) has been studied using density functional theory calculations. It has been found that in contrast to metallic Pd system, these small Pdxclusters can interact well with CO2 molecule. CO2 molecule can be adsorbed with a bidendate configuration on the Pdxclusters. The formation of CO2 bidendate adsorption configuration facilitates the first step of CO2 hydrogenation reaction on the clusters. The energy profiles for formate pathway and reverse water gas shift + CO hydrogenation pathways on Pdxclusters are quite similar with Cu(111) surface, except for the first and last hydrogenation steps where the Pdxclusters have lower activation energies. This improvement causing the Pdxclusters to have a tolerable turn over frequencies values. In general, the usage of Pd in the form of small size cluster can improve the catalytic performance of metallic Pd for the CO2 hydrogenation to methanol because small size Pd cluster can act not only as an H2 dissociation center but also as a CO2 hydrogenation center.

Experiment and simulation to determine the optimum orientation of building-integrated photovoltaic on tropical building façades considering annual daylight performance and energy yield

Building-Integrated Photovoltaic(BIPV)on vertical façades is a potential PV application in today’s buildings.The performance of BIPV on façades is significantly influenced by the façade orientation.For tropical cities,the optimum façade orientation,in terms of maximum energy yield and daylight performance,cannot be simply determined,due to relatively symmetrical sun path throughout the day.This study therefore aims to determine the optimum orientation for BIPV on tropical building façades.To achieve the objective,experiment,modelling,and computational simulation are conducted to evaluate the BIPV energy yield and to predict the indoor daylight performance in a scale-model building with a 105Wp monocrystalline silicon PV,facing each cardinal orienta-tion in Bandung,Indonesia.The South orientation yields practically zero ASE_(1000,250),providing the best annual daylight performance,and yielding the most desirable value in four out of five daylight metrics.The greatest annual energy yield is at the North orientation,providing 179-186 kWh(95%prediction interval)per year,but with larger uncertainty compared to that at the South,due to direct sunlight occurrence.Based on three different objective functions,the South orientation is considered optimum for placing the BIPV panel on the prototype façade in the location.

Verification tests of a mirror box type artificial sky without and with building scale model

A mirror box type artificial sky for simulating the ClE standard overcast sky has been designed and constructed, while the verification method has been developed and tested. Ratio between the mirror height above the workplane and the room Length is 60：133 or 0.451, whereas the ratio between the mirror height above the workplane and the room width is 5：9 or 0.556. Taking the ClE standard overcast sky as reference, indoor illuminance ratios at various elevation angles relative to the zenith is found to be more consistent than Luminance ratios. The Largest error of illuminance and Luminance ratios are respectively 10% and 43%, obtained at O elevation angle. Horizontal workplane illuminance values are on average 11,400 lx, with iLLuminance uniformity Uo and UI of respectively 0.92 and 0.86. Based on test results with a building scale model, four out of nine measuring points inside the model have small errors, four have medium error, and one has a large error of 25%. Most of the obtained errors are within the tolerable range of ±21% from the ideal values. Based on the conducted tests, the constructed mirror box type artificial sky is considered appropriate to be utilised for its purpose.