燃气锅炉的烟气凝结换热

燃气锅炉排放的烟气温度很高且含有一定数量的水蒸汽,在回收烟气余热时,水蒸汽的换热是影响余热回收效率的主要因素之一。利用多孔介质理论对各控制方程进行重新修正;采用标准的k-ε模型和两相界面上凝结换热边界条件,对换热过程进行数值计算。结果表明,有凝结换热发生时,换热能力的计算值与实验值的误差在允许范围内。

The Myth of the High-Efficiency External-Combustion Stirling Engine

The reported discrepancy between theory and experiment for external combustion Stirling engines is explained by the addition of thermal resistance of the combustion gasses to the standard Carnot model. In these cases, the Stirling engine ideal efficiency is not as is normally reported equal to the Carnot cycle efficiency but is significantly lower. A new equation for ideal Stirling engine efficiency when the heat is obtained through external combustion without pre-heating the air, is presented and results for various fuels tabulated. The results show that petrol and diesel, internal combustion engines (Otto cycle) have a higher ideal efficiency than the Stirling engine. When comparing thermoacoustic engines heated by wood, efficiency should not be quoted as a percentage of the Carnot efficiency, but against a figure 48% lower than Carnot. The effect is not seen with electrically heated rigs, solar or nuclear fission heated engines.

思维导图在建筑环境与能源应用工程专业课程教与学中的应用

建筑环境与能源应用工程专业(简称建环专业)是一门多学科交叉的工学学科,在专业课程教与学中,采用思维导图的方法将课程的知识点、重点、难点进行梳理、归纳和总结,构建知识点框架,贯通知识点间的联系,加深学生对课程重点和难点的理解,培养学生的逻辑思维和自主学习能力。