论文部分内容阅读
十一、使用逆流式热交换器,打算用1200℃的烟气3600Nm~3/h把2500Nm~3/h的空气从200℃加热到800℃。试问这时需要的传热面积及在交换器出口的烟气温度是多少? 假定空气侧的平均对流传热系数是15kcal/m~2h℃,烟气侧的平均对流传热系数及辐射传热系数各为13kcal/m~2h℃及17kcal/m~2h℃;热交换器的传热面是平面,其厚度为2cm,传热面的导热系数为1.2kcal/m~2h℃再假定烟气及空气的平均定压比热分别为0.33kcal/Nm~3℃及0.30kcal/Nm~3℃。(第11
Eleven, the use of counter-current heat exchanger, intends to use 1200 flue gas 3600Nm ~ 3 / h 2500Nm ~ 3 / h of air heated from 200 ℃ to 800 ℃. What is the required heat transfer area and the flue gas temperature at the outlet of the exchanger? Assuming that the average convective heat transfer coefficient on the air side is 15 kcal / m ~ 2h ° C, the average convective heat transfer coefficient on the flue gas side and the radiative heat transfer The coefficients are respectively 13kcal / m ~ 2h and 17kcal / m ~ 2h; the heat exchanger surface is flat, the thickness is 2cm, the thermal conductivity of the heat transfer surface is 1.2kcal / m ~ 2h ℃ and then assume the flue gas And the average specific heat of air is 0.33kcal / Nm ~ 3 ℃ and 0.30kcal / Nm ~ 3 ℃ respectively. (number 11