Fluid to fluid modeling of critical heat flux: A compensated distortion model

The characteristics and visualization of critical heat flux of R-134a flowing in a vertical annular geometry with spacer grids

“…Among the efforts to find out a proper fluid-to-fluid scaling law, Ahmad's [7] model is widely used. Based on dimensional analysis according to conventional Pi Theorem, he derived the following non-dimensional parameter groups showing CHF behavior:…”

“…However, the refrigerants such as R-134a and R-152a have been evaluated as an alternative in modeling CHF in water due to its harmlessness on the environment [6,7] because CFC (clorofluorocarbon) family such as R-12, R-22, R-133, and R-144, could deplete the ozone layer. In particular, since the thermophysical properties of R-134a are close to R-12, R-134a is considered to be a new scaling fluid.…”

Experimental study on critical heat flux characteristics of R134a flow boiling in horizontal helically-coiled tubes

“…On the other hand, although water is usually employed for heat transfer in engineering field, low latent heat substance such as Freon is usually used for experiments due to the high pressure and temperature conditions of vapor-water system. Subsequently, the results can be applied to water according to CHF fluid to fluid modeling methods based on similarity theory [3,16,29]. But the CFCs ever used in the past have been banned by Montreal Protocol considering their inherent destruction to ozonosphere.…”

Fluid-to-fluid modeling study on critical heat flux of R134a flow boiling in helically-coiled horizontal tubes

“…For a water-steam two-phase system, however, any experiment is costly and cumbersome because of the harsh conditions of high pressure, high temperature, large power requirement, large facility size, and so on. Instead fluidto-fluid modeling is an alternative method that has been successfully used to predict the CHF [5][6][7][8][9][10][11][12]. R12 and R113 were common refrigerants, but they do not fit to regulations on environmental demand.…”