An experimental study on heat transfer in condensing flow inside the tubes with discrete internal grooves

Due to the need to optimize energy consumption in the modern era and increasing energy consumption in different industries, the heat transfer study attracts more attention. Since condensers are one of the most widely used heat exchangers in a variety of applications such as steam power plants, factories, chemical industries, refrigeration systems and air conditioners, the optimization and building lighter and smaller condensers has been the concern of many researchers in recent years. In the present study the condensing heat transfer of R۱۳۴a in the horizontal internal inclined grooved tube was investigated and effect of different geometrical parameters on the heat transfer coefficient was examined experimentally. Nine different grooved tube with different groove’s geometry were investigated as the counter flow test condenser. The inner diameter of test condensers is ۲۰ mm and length of those is ۱۰۰ cm. grooves angle, number of circumferential grooves in the cross section of tube and pitch length of grooves are the geometrical parameters which differ in test tubes. Furthermore the heat transfer was investigated in different mass flux and vapor quality for each test condenser. The mass flux and vapor quality vary from ۱۷ to ۶۰.۵ kg/m۲s and from ۰.۱۵ to ۰.۹ respectively. The experiments reveal that the heat transfer coefficient in condensing flow increases with increase in mass flux and vapor quality in all grooved tubes. Also the heat transfer coefficient increases with increase in number and angle of grooves and it increases with decrease in pitch length of grooves.

Keywords:

Condensing , Inclined , Grooved tube , Heat transfer , R-۱۳۴a