Experimental Study On The Outside Of Tube Heat-Trasfer Performance Of Horizontal Tube Falling Film Evaporator

The falling film horizontal-tube evaporator, it is characterized by phase changing on both side of the tube wall and film waving on the evaporation surface, have won widespread acceptance in evaporation and heat-trasfer for its distinct advantage:high heat-transfer efficiency and excellent performance at low-temperature and operational stability.When water was used as the medium, experiment was on condition of the single tube and the testing tube was blinding tube , the sprinkling density ?,heat flux q, difference in temperature of evaporation At and temperature of evaporation t_s were studied on film coefficient of heat-trasfer of the falling film horizontal-tube evaporator .The result showed that: whenO. 27 kg/m. s ≤?≤0. 49 kg/m. s ,the film coefficient of heat-trasfer was increased along with accretion of ?;whenl. 29kW/m~2≤q≤5. 08 kW/m~2, the film coefficient of heat-trasfer was increased along with accretion of q;when △t was 8°C,10°C,12°C and 14°C on the difenite temperature of evaporation and the sprinkling density, the film coefficient of heat-trasfer was increased along with accretion of At;when t_s was 100℃ ,96℃ ,93℃, 90℃, and 85℃ on the difenite difference in temperature of evaporation and the sprinkling density, the film coefficient of heat-trasfer was minished along with accretion of t_s.The experimental formulas of the heat-trasfer coefficient on the horizontal tube were fitted by the experiment data. The error between the predicated heat-transfer coefficient and the experiment value was basically under 10%.Theory of evaporation and heat was applied, theory of falling film becoming full falling film was analyzed, and theoretic formula of critical falling film was educed.