A roof solar chimney (RSC) is inclined in the roof of a building wherein solar radiation is employed to heat the air the channel. The hot air flows up the channel which can be used to induce flow out of the building i...A roof solar chimney (RSC) is inclined in the roof of a building wherein solar radiation is employed to heat the air the channel. The hot air flows up the channel which can be used to induce flow out of the building in order to ventilate it. In this study, parameters that affect the performance of this natural ventilation system were investigated numerically, namely: inclination angles, channel gaps, solar intensities, vertical chimney attachment heights and channel expanding angles. The two last parameters were new concepts that seem to have never been studied before. All of the mentioned parameters were found to exhibit positive effects on the ventilation. Relative merits of these techniques were compared and discussed.展开更多
Dimensionless variable groups(DGs)of free-fall grain dryer were developed by using the characteristic scaling method and engineering intuition.These DGs were intended for the analyses of drying characteristics and siz...Dimensionless variable groups(DGs)of free-fall grain dryer were developed by using the characteristic scaling method and engineering intuition.These DGs were intended for the analyses of drying characteristics and sizes of this dryer.Experiments of the free-fall rough rice dryer were carried out using different drying chambers(small and medium scales),drying air temperatures(100°C-150°C),and drying air speeds(1-3 m/s).Experimental data were used to study relationships and to validate similarities among these DGs.The results of the study showed the five appropriate dimensionless variables representing and describing the drying mechanism of the free-fall dryer.These DGs could be applied to design and analyze scaling up the dryer.In addition,the dimensionless correlation was established to predict the moisture contents of rough rice while being dried by the free-fall dryer.The predicted values from this correlation were in relatively good agreement with the experimental data under the proposed drying conditions(R2=0.989,MRD=1.82%and RMSE=0.0168).展开更多
文摘A roof solar chimney (RSC) is inclined in the roof of a building wherein solar radiation is employed to heat the air the channel. The hot air flows up the channel which can be used to induce flow out of the building in order to ventilate it. In this study, parameters that affect the performance of this natural ventilation system were investigated numerically, namely: inclination angles, channel gaps, solar intensities, vertical chimney attachment heights and channel expanding angles. The two last parameters were new concepts that seem to have never been studied before. All of the mentioned parameters were found to exhibit positive effects on the ventilation. Relative merits of these techniques were compared and discussed.
基金This research is sponsored by the Royal Golden Jubilee(RGJ)Ph.D.Program of the Thailand Research Fund(TRF).
文摘Dimensionless variable groups(DGs)of free-fall grain dryer were developed by using the characteristic scaling method and engineering intuition.These DGs were intended for the analyses of drying characteristics and sizes of this dryer.Experiments of the free-fall rough rice dryer were carried out using different drying chambers(small and medium scales),drying air temperatures(100°C-150°C),and drying air speeds(1-3 m/s).Experimental data were used to study relationships and to validate similarities among these DGs.The results of the study showed the five appropriate dimensionless variables representing and describing the drying mechanism of the free-fall dryer.These DGs could be applied to design and analyze scaling up the dryer.In addition,the dimensionless correlation was established to predict the moisture contents of rough rice while being dried by the free-fall dryer.The predicted values from this correlation were in relatively good agreement with the experimental data under the proposed drying conditions(R2=0.989,MRD=1.82%and RMSE=0.0168).
