文档介绍：摘要摘要节约能源、提高能源利用率是保证我国经济健康增长的必要条件。近年来, 各地普遍出现的用电紧张,某些地区液化石油气价格大幅增长,成品油多次提价,都反映了目前我国的经济增长模式还是以低效的利用能源为代价,节约能源和提高能源利用率刻不容缓。本文以燃气热水器为研究对象,以提高热水器的能效水平为目的,旨在开发高效、节能、环保的冷凝式燃气热水器产品。本文设计了一种烟气导流装置连接冷凝换热器和显热换热器,从而解决了冷凝式热水器的结构布置和冷凝水收集的问题。随后,以天然气和液化石油气为例,计算出烟气的物性参数,进而分析烟气露点温度、热水器排烟温度、空气过量系数以及气种之间的关系。然后对所丌发的两种冷凝换热器进行试验研究。对热水器的性能研究表明,在额定工况下,冷凝式热水器的热效率可达 %,并研究了热水器变负荷、分级负荷与效率、CO体积分数等量的关系。随后,对凝结传热过程进行了分析,根据试验数据,利用传热计算方程式,拟合出Nu数和Re、Ln、Pr的准则关系式。最后,利用PHOENICS软件对烟气在翅片间的传热过程进行了数值模拟,利用流体力学和传热学原理对模拟结果进行分析,提出了对换热器设计的进一步改进建议。关键词:冷凝换热,热效率,热负荷,数值模拟 Abstract Abstract Energy saving andefficiency elevation are bothimportant fordomestic economic the recent years,many incidents such as lack ofelectricity inlarge area ofthecountry,abnormal price increase of LPG and oil,etc,have shown that there’s something wrong with domestic economic development demonstrates thatwe should attach more importance toenergy saving andefficiency. To improve thermal efficiency mon water heaters,thispaper mainly focused on high efficiency,energy saved and environment benefit product ofcondensing water heater. Inthispaper,a device toguide gas—fired exhaust was designed tosolve problems of disposal ofCWH’s new heat exchanger and theformal construction,as well as condensing water that,exhaust properties firedfrom both natural gas and LPG were calculated,for theanalysis ofexhaust dew point temperature,outlet temperature ofwater heater,exceed coefficient ofairand effect ofdifferent inletgas. Experiment on thetwo condensing heatexchanger disclosed that theheatefficiency during rating condition can beimproved up %.Heat input during different level was alSO discussed which revealed thelaw of恤ermal fraction of carbon monoxide in these ,according to theexperiment data,a numeric equation ofNu,Re,Ln and Prwas elicitedby thecalculation result of a number ofthermal was used tosimulate thethermal process of the exhaust between