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实验研究了不同热流密度不同液膜流量下,R134a在垂直布置的七根水平强化管外的降膜蒸发传热特性。结果表明:相同热流密度下在液膜流量较小阶段,管外传热系数随着液膜流量增加而明显增加;随着液膜流量的进一步增大,管1~3的管外传热系数保持不变,管4~7的管外传热系数先增大后减小。同时发现,液膜流量为0.159 kg·m~(-1)·s~(-1)时,随着热流密度的增大所有管的传热性能先增大后减小,并且转折点出现在较小的热流密度下;液膜流量为0.29 kg·m~(-1)·s~(-1)时,管1性能一直增强,管2~4的传热系数随热流密度增大先增大后减小,管5~7的传热系数一直减小,并且管1~4转折点出现在较大热流密度下。
Experimental study of different heat flux at different liquid film flow rate, R134a in the vertical arrangement of the seven horizontal enhanced tube falling film evaporation heat transfer characteristics. The results show that with the same heat flux, the heat transfer coefficient outside the tube increases with the increase of the liquid film flow rate at the smaller liquid flow rate. With the further increase of liquid film flow, the heat transfer coefficient outside the tube 1 ~ 3 Remain unchanged, tube 4 ~ 7 tube heat transfer coefficient increases and then decreases. At the same time, it was found that the heat transfer performance of all tubes first increased and then decreased with the increase of heat flux when the liquid film flow rate was 0.159 kg · m -1 · s -1, The performance of tube 1 is enhanced with the flow rate of 0.29 kg · m -1 · s -1 and the heat transfer coefficient of tubes 2 ~ 4 increases with the increase of heat flux After the decrease, the heat transfer coefficient of tubes 5 ~ 7 decreased all the time, and the turning points of tubes 1 ~ 4 appeared at larger heat flux density.