亚/跨临界状态下不同组分燃油液滴蒸发特性分析

Analysis of evaporation characteristics for different fuel oil droplets in sub/transcritical state

亚/跨临界状态对不同燃油液滴的蒸发规律有很大影响,通过搭建高温定容液滴蒸发测量装置,测量了处于不同临界状态的C_(12)H_(26)、C_(14)H_(30)、柴油和生物柴油液滴的液滴寿命、液滴直径、液滴蒸发速率等参数,分析了4种不同组分液滴的蒸发过程、蒸发特性.结果表明:与亚临界状态(温度为573 K)相比,4种液滴处于跨临界状态(温度为973 K)时,蒸发速率分别增加了1.25、1.03、0.71、0.51 mm^(2)·s^(-1),单组分液滴的蒸发速率高于多组分液滴;液滴寿命降幅较大,分别降低了86%、89%、93%、89%;跨临界状态时,生物柴油液滴蒸发的膨胀阶段较短,液滴直径d的平方不随时间线性减小,不符合d^(2)定律;C_(12)H_(26)、C_(14)H_(30)、柴油液滴不存在膨胀阶段,液滴直径d的平方随时间线性减小,符合d^(2)定律.

The sub/transcritical state has great influence on the evaporation rules of different fuel droplets.By building a high-temperature constant-volume droplet evaporation measurement device,droplet life,droplet diameter,droplet evaporation rate and other parameters of C_(12)H_(26),C_(14)H_(30),diesel and biodiesel droplets in different critical states were measured.The results show that compared to the subcritical state with temperature of 573 K,when the four droplets are in the transcritical state with temperature of 973 K,the evaporation rates are increased by 1.25,1.03,0.71 and 0.51 mm^(2)·s^(-1),respectively.The evaporation rate of single-component droplets is higher than that of multi-component droplets.The droplet lifetimes are greatly reduced by 86%,89%,93%and 89%,respectively.In the transcritical state,the expansion stage of biodiesel droplet evaporation is short,and the square of droplet diameter is decreased nonlinearly with time,which is not consistent with d^(2) law.C_(12)H_(26),C_(14)H_(30)and diesel droplets do not have expansion stage,and the square of droplet diameter is decreased linearly with time,which is conformed to d^(2) law.