蒸発器性能に及ぼす冷凍機油の影響:第4報曲がり管内の流動様式と圧力損失について

概要

論文の詳細を見る
Compact heat exchager of serpentine type is mainly made of many straight and curved pipe, namely180°U-bend. In spite of the fact that almost half of heat transfer area is occupied by the curved section, up to now thermal and hydraulic characteritics of this section have been predicted assuming a straight tube. The existance of violent secondary flow and vortex, the flow direction circulating downward or upward, might be an important factor to determine the evaporator performance.In consideration to the above, in order to make clear the fundamental thermal and hydrauric characteristic, a study on two-phase refrigerant (R12) including lubrication oil (Suniso 5GS) effect on these in return bend (U-bend) have been made.The experiment was performed using a copper U-bend tube having an inner diameter of 8.7mm, thickness of 2mm and radius of curveture of 35.0mm. The total length of test section was 1965mm consisting of 655mm in upstream and downstream straight sections and 655mm in curved section.To confirm the uniform heat flux and uniform change of quality (0.1) at each heating section, seat-hed and flexible heater was wrapped around the outside of the test section. To observe the two phase flow regime, the transparent U-bend glass tube was used, instead of copper tube.The experment comporised systematic variation of mass velocity (100-250 kg/m2·s), mass concentration of lubrication oil (0-9%) and thermal equilibrium vapor quality (0.1-1.2). During the experiment, temperature of outside wall and pressure drop were measured and flow pattern was observed. As the results, the flow disturbance at the downstream of U-bend was violent at the wavy and stratified flow regime and the strong effect of lubrication oil was observed. The local pressure drop at the bend was five times lager than at straight tube. This factor was increased with increasing oil concentration. Finally, the emprical correlation to predict the pressure drop was developed.
公益社団法人　日本冷凍空調学会の論文

蒸発器性能に及ぼす冷凍機油の影響:第4報曲がり管内の流動様式と圧力損失について

スポンサーリンク

概要

著者

関連論文

スポンサーリンク

蒸発器性能に及ぼす冷凍機油の影響:第4報 曲がり管内の流動様式と圧力損失について

スポンサーリンク

概要

著者

関連論文

スポンサーリンク

蒸発器性能に及ぼす冷凍機油の影響:第4報曲がり管内の流動様式と圧力損失について