潜热的计算方法一、计算方法蒸发量用重量M(Kg)来标度供热量Q J)由温升热与气化潜热两部分组成1.温升热量Q1 (J)：温升热与蒸发介质的热容和蒸发介质的温升成正比，即：Q=CxMxAT； AT=T2-T1 热容 C： J/Kg.°C这是个非常简单的公式，用于计算温升热量，液体的饱和压力随温度的提高而上 升至液体表面上方压力时开始蒸发2•蒸发潜热Q2 (J)为：Q2=MxAH△H：液体的蒸发焓(汽化热)J/Kg3•总供热量Q=Q1+Q2二例子现在需要用蒸汽来加热水，已经蒸汽的参数为0.8mpa, 300C，水量为12t/h, 水温为57C,现在将蒸汽直接通过水混合将来水加热到62C,请问需要多少蒸 汽呢？ 是否是按照等焓来计算呢放出热量为：蒸汽变成100C水的冷凝潜热热量加上100C的冷凝水变为62C 水放出的热量之和设需要蒸汽D千克/ho吸收的热量为：12吨水从57C升到62C吸收的热量.数值取值为：水的比热按照C=1千卡/千克C计0.8mpa，300C蒸汽的冷凝潜热约为r=330千卡/千克，1吨蒸汽生成1吨凝液 凝液温度为100C，不考虑损失Q 吸收=Cm(t2-t1)=1x12000x(62-57) = 60000 千卡/hQ冷凝放热=Dr=330DQ 冷凝水降温放热=CD(T2-T1)=1xDx(100-62)=38 DQ吸收=Q冷凝放热+ Q冷凝水降温放热330 D+38 D = 60000 = 163kg/h因此，需要该品位蒸汽0.163T/H,水量加热后上升到12.136t/h损失就按5-1 0%考虑了。
例子21 吨水变成水蒸气是多少立方假设水的起始温度为 20 度；加热成为 140 度的水蒸汽（假设为饱和水蒸汽而不 是过热水蒸汽）1 ，简略计算：常压下水的汽化热为 540 千卡/公斤；需要的热量：（140-20）*1000=120000 千卡，再加上汽化热540000 千卡，共计 660000 千卡现在，煤的燃烧值为6000大卡/公斤，所以，需要烧煤660000/6000=110公斤2，较精确的计算： 由常温（假设是20度）升温到100度的水，可以近似地用比热为1（千卡/公斤.度）来计算所需热量；汽化后的水蒸汽由100度升温到 140度所需热量，要从 水蒸汽的焓熵图（h-s图）上查到它的热焓差来计算；最后再加上汽化热；三部分 的总和除以煤的热值就行了3，精确的计算： 通过焓熵软件查20度的水和140度的水蒸汽的焓值,利用焓值差计算所需热量， 再除以煤的热值就行了经查得数据并计算，得到下列结果：焓值差=589.411-83.736=505.675 千焦尔/公斤505675/4.182千卡/公斤=120917 千卡/吨540000+120917=660917660917/6000=110.1528答案：需煤110.1528公斤。
三、概念 对于饱和蒸汽和过热蒸汽，在同等压力下，过热蒸汽的温度比饱和蒸汽的要高 水在一定压力下，加热至沸腾即开始气化，也就逐渐变为蒸汽，这时蒸汽的温度 也就等于饱和温度这种状态的蒸汽就称为饱和蒸汽饱和蒸汽含有水和蒸汽 如果把饱和蒸汽继续进行加热，其温度将会升高，并超过该压力下的饱和温度 这种超过饱和温度的蒸汽就称为过热蒸汽饱和蒸汽温度和压力成一一对应关 系，而过热蒸汽则不存在这种对应关系过热蒸汽有其本身的应用领域，如用在 发电机组的透平，通过喷嘴至电机，推动电机转动但是过热蒸汽很少用于工业 制程的热量传递过程，这是因为过热蒸汽在冷凝释放蒸发焓之前必须先冷却到饱 和温度，很显然，与饱和蒸汽的蒸发焓相比，过热蒸汽冷却到饱和温度释放的热 量是很小的，从而会降低工艺制程设备的性能潜热 r=530kcal/kg 饱和水蒸气表温度(°C绝对压强蒸汽的密焓蒸汽(kcal/kg)汽化热(kgf/cm)2 )(kPa)度(kg/m 3 )液体(kcal/kg)(kJ/kg)(kJ/kg )(kcal/kg)(kJ/kg)00.00620.60820.00484005952491.15952491.150.00890.87310.006805.020.94597.32500.8592.32479.86100.01251.22620.0094010.041.87599.62510.4598.62468.53150.01741.70680.0128315.062.80602.02520.5587.02457.7200.02382.33460.0171920.083.74604.32530.1584.32446.3250.03233.16840.0230425.0104.67606.62539.7581.62435.0300.04334.24740.0303630.0125.60608.92549.3578.92423.7350.05735.62070.0396035.0146.54611.22559.0576.22412.4400.07527.37660.0511440.0167.47613.52568.6573.52401.1450.09779.58370.0654345.0188.41615.72577.8570.72389.4500.125812.3400.083050.0209.34618.02587.4568.02378.1550.160515.7430.104355.0230.27620.22596.7565.22366.4600.203119.9230.130160.0251.21622.52606.3562.52355.1650.255025.0140.161165.0272.14.624.72615.5559.72343.4700.317731.1640.197970.0293.08626.82624.3556.82331.2750.39338.5510.241675.0314.01629.02633.5554.02319.5800.48347.3790.292980.0334.94631.12642.3551.22307.8850.59057.8750.353185.0355.88633.22651.1548.22295.2900.71570.1360.422990.0376.81635.32659.9545.32283.1950.86284.5560.503995.0397.75637.42668.7542.42270.91001.033101.330.5970100.0418.68639.42677.0539.42258.41051.232120.850.7036105.1440.03641.32685.0536.32245.41101.461143.310.8254110.1460.97643.32693.4533.12232.01151.724169.110.9635115.2482.32645.22701.3530.02219.01202.025198.641.1199120.3503.67647.02708.9526.72205.21252.367232.191.296125.4525.02648.82716.4523.52291.81302.755270.25 1.494130.5546.38650.62723.9520.12177.61353.192313.11 1.715135.6567.73652.32731.0516.72163.31403.685361.47 1.962140.7589.08653.92737.7513.22148.71454.238415.72 2.238145.9610.85655.52744.4509.72134.01504.855476.24 2.543151.0632.21657.02750.7506.02118.51606.303618.28 3.252161.4675.75659.92762.9498.52087.11708.080792.59 4.113171.8719.29662.42773.3490.62054.018010.231003.5 5.145182.3763.25664.62782.5482.32019.319012.801255.6 6.378192.9807.64666.42790.1473.51982.420015.851554.77 7.840203.5852.01667.72795.5464.21943.521019.551917.729.567214.3897.23668.62799.3454.41902.522023.662320.88 11.60225.1942.45669.02801.0443.91858.523028.532798.59 13.98236.1988.50668.82800.1432.71811.624034.133347.91 16.76247.11034.56668.02796.8420.81761.825040.553977.67 20.01258.31081.45664.02790.1408.11708.626047.854693.75 23.82269.61128.76664.22780.9394.51651.727056.115503.99 28.27281.11176.91661.22768.3380.11591.428065.426417.24 33.47292.71225.48657.32752.0364.61526.529075.887443.29 39.60304.41274.46652.6。