Theoretical and Experimental Research on CO_2 Electrical Heating Pool Boiling Heat Transfer Outside a Horizontal Tube

摘要

Numerical simulation on electrical heating pool boiling heat transfer with CO_2 as refrigerant outside a horizontal tube is carried. A voltage-controlled heating method has been used in the experiment, with the advantages of good stability and adjustability of the experimental heat flux density. After a series of preliminary calculation and pre-work, numerical simulation is carried based on a software FLUENT. Bubble behaviors are observed, the distribution regularity of volume fraction of vapor is obtained and compared with the experimental results. The results show that numerical simulation and experimental results are in good agreement. Furthermore, by changing the heat flux density, the comparison of velocity on center location of experimental tube is analyzed. Varying pattern is satisfying. Evidently, for velocity, the simulation values are relatively higher and the data locate in the range of 1.40～1.52 times higher than the experimental data. This paper makes useful exploration of CO_2 pool boiling heat transfer and the design of evaporator.