Experimental study of falling film evaporation in tube bundles of doubly-enhanced, horizontal tubes

Falling film boiling of refrigerants over nanostructured and roughened tubes: Heat transfer, dryout and critical heat flux

“…This phenomenon of increased HTC at reduced falling film flow rates was captured before in the convective heat transfer of water falling films on Gewa-T 3D micro-enhanced tubes [64] and superhydrophilic and hydrophilic tubes [65]. This was also seen in the falling film boiling of refrigerants on micro-enhanced tubes in R-134a [16,18]. A thinned liquid layer, which resulted in a decrease in evaporative thermal resistance, was considered the likely cause [64,65].…”

“…Typically, falling film dryout occurs in two stages. Firstly, as the refrigerant film flow rate is lowered from a high point at a constant heat flux, a plateau region is seen where heat transfer coefficients (HTCs) remain relatively insensitive to changes [14,15] or slightly decrease [16,17] or slightly increase [18] as film flow rates drop. After this, a critical film Reynolds number is reached where HTCs decrease significantly when film flow rates are decreased further as a result of critical dryout [14][15][16][17].…”

Absorption Kinetics of CO2 in Aqueous Ammonia with High Load and Salinity

“…According to the preliminary experiment, the flow rate of a single liquid column should be kept about 400 mL•min −1 , and the uniform liquid film can be generated on the surface of the column, without static and fractured liquid films. 45 In addition, it can be seen from Figure 4b that there is an obvious linear relationship between the number of liquid columns and K G A. Under the condition of the same number of liquid columns, it is proved that K G A gradually increases with the increase of gas flow (Q) because the k g increases with the increase of Q, which also indicates that all three columns can form a steady liquid film with the same contact area.…”

“…According to the preliminary experiment, the flow rate of a single liquid column should be kept about 400 mL·min –1 , and the uniform liquid film can be generated on the surface of the column, without static and fractured liquid films . In addition, it can be seen from Figure b that there is an obvious linear relationship between the number of liquid columns and K G A .…”

Thermodynamic Performance Study on the Novel Efficient Flow Pattern Global Construction Evaporator

“…The results show that the cooling capacities of the evaporator with inlet restriction is 4.1%-13.3% less than those of the evaporator without inlet restriction. Some studies on the heat transfer and resistance characteristic of evaporators have been conducted in recent years [6][7][8] . Song et al [9] investigated the evaporation heat transfer and pressure drop of R-245fa in a shell and plate heat exchanger.…”