Fog-flow mercury condensing pressure drop correlation
Pressure drops of mercury vapor flowing and condensing inside tubes
MERCURY VAPOR↗
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Results for “PRESSURE DROP”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A correlation of subcooled-boiling pressure drop for low-pressure water flowing in tubes with constant heat flux
One dimensional flow model to correlate subcooled boiling pressure drop in circular tubes with constant heat flux
Stone, J. R.↗
Heat transfer and pressure drop in laterally perforated-finned heat sinks across different flow regimes
Not Available
Shaeri, Mohammad Reza↗
Pressure Drop Across Finned Cylinders Enclosed in a Jacket
The pressure drop across finned cylinders in a jacket for a range of air speeds from approximately 13 to 230 miles per hour has been investigated. Tests were made to determine the effect on the pressure drop of changes in fin space, fin width, jacket entrance and exit areas, skirt-approach radius, and the use of fillets and a separator plate at the rear of the cylinder. The pressure drop across the cylinder increased as the fin space decreased, the increase being very rapid at fin spaces smaller than approximately 0.20 inch. Fin width had little effect on the pressure drop for the range of widths tested. The pressure drop across the cylinder was nearly halved by increasing the skirt-approach radius from 3/4 inch to 1-1/4 inches, but fillets and a separator plate at the rear of the cylinder had little effect on the pressure drop. The pressure drop across a cylinder with tapered fins was greater than that for a cylinder having rectangular fins with the same effective fin spacing.
Rollin, Vern G↗
Grid pressure drop prediction in a fuel assembly
In fuel assembly, spacer grids have strong effects on pressure drop and other thermal-hydraulic behaviors. Considering the design and safety operation of a reactor, it is important to predict pressure drop accurately in the fuel assembly. For a mixed core, a reactor with mixed fuel designs in the reactor core, undesired cross flow were often caused by differences in pressure drop among neighboring bundles. The pressure drop is often estimated for designs of new reactor core fuel assemblies. In the past, due to complex flow conditions in fuel assembly, the pressure drop of a fuel assembly relied greatly on costly and time-consuming full length thermal hydraulic tests. Some empirical pressure drop correlations and CFD methodology were applied, however, only limited to a single gird span. Without considering pressure drop in the entire fuel assembly it is quite difficult to optimize the fuel assembly design. Most experimental fuel assemblies consist of mixing vane grids (MVG) and simple support grids (SSG). The MVG's were the main tested spacer grids in the reactor and SSG's were used only in experimental study to support the fuel assembly. In fuel reactor core, the fuel assembly heats the coolant, which could turn the single-phase water system into a two-phase flow system and eventually lead to critical heat flux (CHF). Because of the complexity of phase change, it is very difficult to predict pressure drop in rod bundles with two-phase flow. In this paper, a new method to predict the pressure drop in the fuel assembly is proposed and verified by experimental data.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
KC-135 zero-gravity two phase flow pressure drop - Experiments and modeling
A methodology for correcting raw pressure-drop data on the influence of acceleration on the instrumentation in two-phase flow thermal management systems is described. Such systems are now being considered as an alternative to conventional single-phase systems in future space missions because of the potential to reduce overall system mass, size, and pumping power requirements. Corrected pressure-drop measurements are presented and compared with predictions of two-phase flow pressure-drop models. A set of flow and acceleration conditions is defined for which the frictional pressure drop does not increase upon entry into 0-'g' pressure drop.
Lambert, Anne↗
Experimental Investigation of Oscillatory Flow Pressure and Pressure Drop Through Complex Geometries
A series of experiments have been performed to investigate the oscillatory flow pressure and pressure drop through complex geometries. These experiments were conducted at the CSU-SLRE facility which is a horizontally opposed, two-piston, single-acting engine with a split crankshaft driving mechanism. Flow through a rectangular duct, with no insert (obstruction), was studied first. Then four different inserts were examined: Abrupt, Manifold, Diverging Short and Diverging Long. The inserts were mounted in the center of the rectangular duct to represent different type of geometries that could be encountered in Stirling machines. The pressure and pressure drop of the oscillating flow was studied for: 1) different inserts, 2) different phase angle between the two pistons of the engine (zero, 90 lead, 180, and 90 lag), and 3) for different piston frequencies (5, 10, 15, and 20 Hz). It was found that the pressure drop of the oscillatory flow increases with increasing Reynolds number. The pressure drop was shown to be mainly due to the gas inertia for the case of oscillatory flow through a rectangular duct with no insert. On the other hand, for the cases with different inserts into the rectangular duct, the pressure drop has three sources: inertia, friction, and local losses. The friction pressure drop is only a small fraction of the total pressure drop. It was also shown that the dimensionless pressure drop decreases with increasing kinetic Reynolds number.
Ibrahim, Mounir B.↗
EVALUATION OF PRESSURE DROP CORRELATIONS FOR THE WIRE-WRAPPED ROD BUNDLES
The accurate prediction of pressure drop in the fuel rod bundle is of importance for the design and thermal-hydraulic analysis of nuclear reactor system. Due to very complex geometry of wire-wrapped fuel rod bundle geometry for the Sodium Fast Reactor (SFR), a simple method using hydraulic (equivalent) diameter is not sufficient to predict the pressure drop of rod bundle accurately. For several decades, many experimental works have been performed to develop an accurate correlation for wire-wrapped fuel bundle friction factor. In these works, the friction factor correlation of wire-wrapped fuel bundle has been developed as a function of Reynolds number of the flow and the design parameters such as fuel pin diameter, wire diameter, rod pitch, and wire lead length. The Cheng and Todreas correlations are well-known and used in many subchannel analysis code, such as CADET, TRIO-U, MATRA-LMW, SE2-ANL, etc. Novendstern model, Rehme model, Baxi and Dalle Donne model are also well-known and widely referred. Computational Fluid Dynamics is another typical approach to predict the pressure drop of wire-wrapped fuel rod bundle, but it requires the model validation because the accuracy of pressure drop prediction by the CFD simulation depends on what turbulence model is employed. The present work aims at evaluating the existing pressure drop correlations for the wire-wrapped fuel rod bundle and evaluating the pressure drop of 217-pin rod bundle by the CFD analysis.
99 GENERAL AND MISCELLANEOUS↗
Pronghorn Porous Media Model Validation with Pressure Drop Measurements
The verification and validation (V&V) of Pronghorn is imperative to assert its accuracy when predicting the fluid velocity, temperature, and pressure in high temperature gas-cooled reactors. Pronghorn is a coarse-mesh, intermediate-fidelity, and multidimensional thermal-hydraulics (TH) code developed by the Idaho National Laboratory (INL). New pebble bed experiments are used to observe the details of the fluid motion and pressure drop in the porous bed under the reactor normal operation. This paper focuses on the validation of the Pronghorn compressible and incompressible Navier-Stokes equations using the pressure drop measurements performed at the engineering-scale pebble bed facility at the Texas A&M university (TAMU). Various pressure drop correlations and porosity functions are implemented in both Pronghorn and STAR-CCM+ to compare the pressure drop due to the combined viscous and inertial resistances in the porous bed. The correlations accounting for the near-wall effect are also utilized to observe if the pressure drop estimates can be improved. Pronghorn porous media models predict the pressure drop well relative to the STAR-CCM+ simulation results and 1D correlations, and both the finite element method (FEM) and finite volume method (FVM) perform accurately. Pronghorn models are also validated with the experimental measurements given the different Reynolds number ranges and specific aspect ratios. The likelihood of the statistical significance between the pressure drop measurements and specific correlations or simulations is low provided that the overlap of their confidence intervals is more than the half of a single arm. Several validation metrics are reasonable in regard to the similar studies from other literature. The precise average pebble bed porosity estimation has much impact on the pressure drop, and the Foumeny and Montillet (dense packing) models carry out the accurate pressure drop prediction by considering the near-wall effect.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Condensation heat transfer and pressure drop of low-pressure hydrocarbons and synthetic refrigerants
Not Available
Garimella, Srinivas (ORCID:0000000256974096)↗
Two-phase pressure drop of ammonia in small diameter horizontal tubes
Data for pressure drop in adiabatic two-phase ammonia flows in small diameter horizontal tubes are presented. The data has direct application to the sizing of the flow-through radiator tubes in the Space Station Freedom heat rejection system. The data are compared to existing correlations for pressure drop and are found to be significantly lower than the most commonly used correlations. However, several of the less commonly used correlations predict the data accurately. Alternate pressure drop prediction methods are explored and a recommendation is made for a method to accurately predict the pressure drop in two-phase ammonia flows in small horizontal tubes.
Ungar, Eugene K.↗
Pressure drop in a prototypical 3D magnetohydrodynamic flow across contraction of a fusion blanket manifold
Predicting 3D magnetohydrodynamic (MHD) pressure losses associated with liquid metal flows in complex geometry ducts is required to design breeding blankets for fusion reactors. Of such components, manifolds exhibit major pressure losses. Recent correlations [T. Rhodeset al. Magnetohydrodynamic pressure drop and flow balancing of liquid metal flow in a prototypic fusion blanket manifold. Phys. Fluids. 2018; 30: 057101.] demonstrate promise for predicting pressure drops in electrically insulated inlet manifolds. In the present work, the extend to which these correlations can be applied to outlet manifolds, which feature sudden contractions, is investigated in both viscous-electromagnetic (VE) and inertial-electromagnetic (IE) regimes for Reynolds numbers 50 < Re < 1500, Hartmann numbers 2500 < Ha < 5475, and expansion/contraction ratio 10. Numerical computations have shown that the MHD pressure drops in the eutectic lead-lithium (PbLi) flows in contractions are almost identical to those in the flows featuring expansion with slightly higher magnitudes in the contraction cases. The small discripancy in the MHD pressure drop between contractions and expansions (<8%) suggests that the earlier obtained correlations for the 3D MHD pressure drop in a duct flow with a sudden expansion can also be applied to flows with a sudden contraction.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Compressibility Effects on Heat Transfer and Pressure Drop in Smooth Cylindrical Tubes
An analysis is made to simplify pressure-drop calculations for nonadiabatic and adiabatic friction flow of air in smooth cylindrical tubes when the density changes due to heat transfer and pressure drop are appreciable. Solutions of the equation of motion are obtained by the use of Reynolds' analogy between heat transfer and skin friction. Charts of the solutions are presented for making pressure-drop calculations. A technique of using the charts to determine the position of a normal shock in a tube is described.
AIR FLOW - TUBES, CYLINDRICAL↗
Analysis of maximum pressure drop for a flat-base spouted fluid bed
For design purposes of the blower power requirements during startup of a spouting bed process, knowledge of the maximum pressure drop across a spouting bed at the onset of spouting is required. A survey of the literature for this information lead to only a few correlations which required information from a spouting bed test to be applicable. Therefore, an experimental investigation of this pressure drop and its associated superficial gas velocity in a flat based spouted bed operating with and without fluidization has been conducted. Measurements were performed using a 10 cm cylindrical bed with different static bed heights and two Geldard group B particles (Al2O3 and HDPE). The results show that the taller static bed height creates a larger maximum pressure drop across the bed, as expected. The maximum pressure drop also increases with increasing fluidized gas velocity. In conclusion, the evolution of maximum pressure drop and its velocity were evaluated and a correlation for the maximum pressure drop and its corresponding velocity for spouted and spouted fluid beds were obtained.
42 ENGINEERING↗
Effect of External Pressure Drop on Loop Heat Pipe Operating Temperature
This paper discusses the effect of the pressure drop on the operating temperature in a loop heat pipe (LHP). Because the evaporator and the compensation chamber (CC) both contain two-phase fluid, a thermodynamic constraint exists between the temperature difference and the pressure drop for these two components. As the pressure drop increases, so will the temperature difference. The temperature difference in turn causes an increase of the heat leak from the evaporator to the CC, resulting in a higher CC temperature. Furthermore, the heat leak strongly depends on the vapor void fraction inside the evaporator core. Tests were conducted by installing a valve on the vapor line so as to vary the pressure drop, and by charging the LHP with various amounts of fluid. Test results verify that the LHP operating temperature increases with an increasing differential pressure, and the temperature increase is a strong function of the fluid inventory in the loop.
Jentung, Ku↗
An experimental study and prediction of a two-phase pressure drop in microgravity
Experimental two-phase pressure drop results obtained in normal gravity and in nearly zero-gravity aboard a NASA-JSC reduced-gravity KC-135 aircraft are used to evaluate several empirically based correlations and flow-regime dependent models. Pressure drops in reduced gravity and those in normal gravity are shown to be related to flow pattern models for each. Two annular flow models are developed which are found to accurately predict the reduced-gravity data.
Chen, I. Y.↗
Evaluation and optimization of flow boiling frictional pressure drop correlations using the data from traditional and next-generation refrigerants in a micro-fin tube
This study presents an experimental evaluation and optimization of flow boiling frictional pressure drop correlations for conventional and next-generation refrigerants in a horizontal micro-fin tube, with particular emphasis on the newly emerging refrigerant blends R-454C and R-455A, for which pressure-drop data in enhanced tubes remain limited. Experiments were conducted with R-410A, R-454C, R-455A, R-134a, R-1234yf, and R-1234ze(E) in a copper micro-fin tube with an inner diameter of 8.468 mm, over mass fluxes ranging from 100 to 300 kg/(m²·s) depending on the refrigerant, and evaporation temperatures of 7, 12, and 14 °C. Frictional pressure gradients were determined from measured total pressure drops after subtracting acceleration pressure drop, and the resulting database was used to assess four existing models: Kuo and Wang (1996), Cavallini et al. (1997), Goto et al. (2001), and Diani et al. (2014). The measured frictional pressure gradient increased with vapor quality and mass flux for all refrigerants and increased further at lower evaporation temperatures, with the overall trend strongly related to liquid viscosity. Among the four correlations, the Goto et al. (2001) model provided the best overall agreement with the measured data before optimization. To further improve prediction accuracy, the Kuo and Wang (1996) and Goto et al. (2001) models were optimized using the complete experimental database. After optimization, both models reduced the overall mean absolute deviation to below 15%, while the optimized Goto et al. (2001) model maintained the best and most consistent overall performance. The results provide new pressure-drop data for next-generation refrigerants and demonstrate that parameter optimization can significantly enhance the applicability of existing micro-fin-tube correlations.
Hu, Yifeng [ORNL] (ORCID:0000000242875185)↗