查看更多>>摘要：On the plateau,symmetrical(WDS)and asymmetrical(WLS)dressing habits have been developed to adapt to the extreme climate of the plateau,which is characterized by large temperature variations.Few studies have investigated the impact of these dressing styles on the heat loss and thermal comfort of the Xizang people.To better characterize these impacts,models representing local heat loss of human are developed,and human heat loss experiments are conducted on the plateau.The results showed that the WLS increased the total heat loss of the participants by a range between 7.2％and 25.7％compared to the WDS;however,WLS narrowed the range of localized heat loss and reset the distribution of heat loss intensity.Adopting the WLS,the localized convection and radiation heat loss reported in the right sleeve was higher than that of the WDS by a range of 3.1 to 12.5 W/m2 and 5.2 to 22.5 W/m2,respectively.Also,the results of thermal neutral temperature of the participants increased by 2 ℃ when the WLS was utilized.Focusing on the distribution of heat loss to achieve localized insulation through clothing thermal regulation is an effective strategy to achieve human thermal comfort and energy savings.
查看更多>>摘要：In response to the growing necessity for rapid simulation techniques for long-term building energy forecasting,this study establishes a'reference day'method.This method significantly alleviates computational load in intricate simulation tasks by minimizing the redundancy of meteorological data.By employing a selected number of reference days to represent the meteorological profile over an extended period,we can estimate the total long-term energy consumption of buildings.The Finkelstein-Schafer statistic is utilized to identify these reference days.To evaluate the effectiveness of this proposed methodology,we analyzed sixteen prototype buildings—comprising two residential and fourteen commercial structures—and thirty years of meteorological data from Denver,USA.The findings indicate that the reference day approach effectively identifies days with representative weather conditions,enabling accurate energy consumption predictions while considerably reducing computational demands.Our case study suggests that selecting nine reference days strikes a good balance between predictive accuracy and computational efficiency over a long time span,even a 25-year period.In such a period,the margin of average error for predicting electricity and gas consumption was remarkably low,at-0.7％and-3.0％,respectively.It is important to note that the building's operational schedule can significantly influence energy consumption.Hence,different sets of reference days should be designated for varied building operation categories.In summary,considering the high computational costs and lengthy durations of work associated with standard building simulations,our proposed reference day method could play a pivotal role in rapid energy consumption assessments.The efficacy and applicability of this method warrant further investigation.
查看更多>>摘要：Beyond the design of the system components,the potential application of thermoelectric(TE)systems is influenced by various factors in the control process.To understand the effects of these control factors on TE system performance in buildings,computational models for a TE window frame are established.In this work,two different numerical methodologies are applied to calculate the desired operating current and temperature distributions within the airflows and on the surfaces of the Peltier cells.The simulation results obtained from these methodologies are cross-validated and compared with relevant experimental results from existing studies.The mathematical model iterates the outgoing airflow temperature at non-object sides after determining the object-side temperature under a certain heat load.Additionally,alongside the number of activated Peltier cells and airflow rate,a new factor,termed the distribution of power strength,is considered in the analysis.The results indicate that homogeneous power strength across each Peltier cell yields favorable outcomes in both heating and cooling modes.The coefficient of performance(COP)increases with the activation of more Peltier cells under a constant heat load,while begins to decline beyond a certain threshold.Moreover,the COP is enhanced with a relatively higher airflow rate by strengthening the heat transfer to relieve the temperature difference between both sides.Consequently,based on the result analysis,we propose an optimization strategy for TE systems.This strategy aims to optimize operating currents,the number of working Peltier cells,and operating airflow rates,particularly when working conditions fluctuate.
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