Experimental Investigation of Minimum Film Boiling Temperature for Vertical Cylinders at Elevated Pressure

Abstract

The minimum film boiling temperature, Tmin, is of particular interest to nuclear safety. Many thermal-hydraulics codes depend on an accurate estimation of Tmin to determine the appropriate heat transfer regime. Heat transfer coefficients increase considerably when the surface temperature decreases below Tmin. This paper presents the results of an experimental investigation of Tmin for vertical cylinders at elevated pressure. While several previous studies have investigated Tmin under various conditions, relatively few have generated experimental data at pressures above atmospheric. As a result, correlations for Tmin often predict unrealistic values at high pressure. The present investigation has generated an experimental database examining the effects of pressure, material, subcooling, surface roughness, and oxidation on Tmin. The experimental apparatus and test specimens are described in addition to the evaluation procedure. Tmin results are reported in this paper for Type 316 stainless steel, Type 1018 carbon steel, and Zircaloy-4. Pressure was varied from 0.101 MPa to 3.0 MPa, and liquid subcooling was ranged up to 30 °C. Zircaloy-4 samples with a thick oxide layer were also tested. The results show that Tmin increases with pressure, liquid subcooling, surface roughness, and surface oxidation. Tmin is a strong function of pressure at low pressure, but asymptotically approaches a constant value as pressure increases. Tmin is also a function of surface material properties, with Zircaloy-4 being found to have the highest minimum film boiling temperature compared to carbon steel and stainless steel. For Zircaloy-4, an oxide layer was found to significantly increase Tmin.

Prediction of the Minimum Film Boiling Temperature of Quenching Vertical Rods in Water Using Random Forest Machine Learning Algorithm

“…The disagreement between the experimental and predicted data could be due to the other effects such as surface conditions and vapor film collapse mode. Peterson and Bajorek (2002) concluded that T min has a strong, positive relationship with pressure at pressures below 1.0 MPa. Therefore, Berenson's correlation predicts T min accurately at lower system pressures compared to Henry's correlation which does not adequately account for a pressure effect on T min .…”

“…Thus, investigating the T min point is essential in areas such as metal heat treating, nuclear engineering industry, in a hypothetical large break lossof-coolant accident (LOCA), evaporators and compressors in the air conditioning systems, refrigeration systems, chemical processes, and oil systems (Pettersson et al, 2009;Ramesh and Prabhu, 2015). T min has been widely studied in terms of various parameters such as substrate material (Peterson and Bajorek, 2002), surface conditions and oxidation (Sinha, 2003;Lee et al, 2014), system pressure (Henry, 1974;Sakurai et al, 1984), flow condition (Groeneveld and Stewart, 1982;Carbajo, 1985), initial surface temperature (Kang et al, 2018), rod diameter (Sakurai et al, 1987;Jun-young et al, 2018), liquid subcooling (Adler, 1979;Freud et al, 2009), vapor-liquid contact angle (Ebrahim et al, 2018), surface roughness and microstructure (Peterson and Bajorek, 2002;Carey, 2020), and alternative quenching fluids (Shoji et al, 1990;Lee and Kim, 2017).…”

“…The proposed empirical equations were exclusively in terms of the system pressure, which is considered a restriction since T min is a function of different parameters. Later, Peterson and Bajorek (2002) developed another correlation for T min which was an extension of Berenson's (1961) and Henry's (1974) correlations, taking into account the heat transfer surface properties, liquid subcooling temperature (T sub ), and surface roughness. The mean absolute error (MAE) and the root mean square error (RMSE) were estimated to be 51.38 and 65.47%, respectively.…”

Carbon-Based Nanofluids and Their Advances towards Heat Transfer Applications—A Review

“…The performance of the pool boiling is evaluated by the enhancement in CHF, HTC, T min , and vapor film thickness. In literature, the effects of the following parameters have been studied: substrate material [ 340 ], surface conditions and oxidation [ 341 , 342 ], system pressure [ 343 , 344 ], initial wall temperature [ 345 ], shape and dimension of the testing specimen [ 346 , 347 ], degrees of liquid subcooling [ 348 , 349 , 350 ], surface wettability and vapor–liquid contact angle [ 351 ], surface roughness and wickability [ 352 ], and type of quenchant such as water, oil, or nanofluids [ 353 , 354 ]. Recently, researchers have been focused on the effects of the later parameter on pool boiling heat transfer performance.…”

Implementation of fiber optic temperature sensors in quenching heat transfer analysis

“…The authors used cladding materials made of stainless steel 316, Zirconium 702, and Inconel 600. Data taken from only three embedded thermocouples resulted in the authors producing a correlation for T min based on one given by Peterson and Bajorek in 2002 [8], shown in Equation (3).…”