Experimental Study Of Pressure Drop Research Articles

Enhanced thermal-hydraulic performance in tubes of reciprocating scraped surface heat exchangers

An experimental study of pressure drop and heat transfer in tubes of reciprocating scraped surface heat exchangers is presented. Inside the tube, a concentric rod which mounts an array of equally-spaced semi-circular blades is fitted. The reciprocating motion of the rod induces the continuous scraping of the inner tube wall, enhancing heat transfer through the removal of the thermal boundary layer, the promotion of mixing of the bulk flow and the mitigation of fouling. Using propylene-glycol as working fluid, friction factor results in isothermal conditions are obtained for 15<Reh<1500 and velocity ratios 0<ω<2. Early transition to turbulence for Reh<150 is detected. Pressure drop augmentations of the order of 20, with respect to the smooth tube, are found in laminar regime for ω=2. In the turbulent flow regime, this pressure drop increase rises up to 400 times. In laminar regime, results for ω=0.1 lead to heat transfer augmentation of 30 % compared with the smooth tube. When increasing from ω=0.1 to ω=1, the Nusselt number is doubled. However, when increasing from ω=0.1 to ω=2 the Nusselt number is only increased by 2.8 times. The beneficial influence of higher scraping amplitudes on heat transfer have been demonstrated, as well as their negligible impact on the friction characteristics.

Experimental study of pressure drop in porous structures created on the basis of Kelvin cells

In this work, we carried out the experimental studies of the pressure drop in porous structures created on the basis of Kelvin cells. The cross sections of the struts of porous structures had the following geometries: circle, triangle, and spinner. The equivalent diameter of the struts was 5, 10, 15, and 20% of 3 mm, where 3 mm is the length of the edge of the cube into which the cell is inscribed. At the same time, several models of porous structures had narrowing in the struts. Experimental studies were carried out at the following air flow velocities: 0.25; 0.5; 0.75; 1 and 1.25 m/s. The research results showed that with an equivalent strut diameter of 5, 10, and 15% of the length of the edge of the cube in which the cell is inscribed, the largest pressure drop at all studied air flow velocities is observed in porous structures with a circular cross section of the struts, without narrowing. With an equivalent strut diameter of 10, 15, 20% of the length of the cube edge, the smallest pressure drop is shown by cells with a circular cross section of the struts, with a narrowing. With an equivalent strut diameter of 20%, the structure with strut geometry in the form of a spinner showed the highest pressure drop. Thus, the geometry of struts of porous structures has a significant effect on the value of the pressure drop.

Experimental study of pressure drop during water–ethanol condensation in a vertical plate heat exchanger

Experimental study of pressure drop during water–ethanol condensation in a vertical plate heat exchanger

Parametric Experimental Study of Pressure Drop of Two-Phase Oil (D130)-Water Flow in 4" Diameter Pipe

The flow of two immiscible liquids oil and water in pipes has been a challenging research topic since several decades. Oil and water are often produced and transported together in pipelines over long distances. In oil and chemical industries, knowledge of the frictional pressure loss (FPD) of oil-water flows in pipes is necessary to specify the size of the pump required to pump the emulsions. The present parametric study reports pressure drops measurements of oil (D130)-water flow in a 4? diameter stainless steel pipe at different flow conditions. Experiments were carried out for different water cuts (WC: 0-100%) and for different inclination angles (including 0°, 15°, and 30°). Oil-water flow rates were varied from 4000 to 8000 barrels-per-day in steps of 2000. For a given flow rate, the FPD has been found to increase (for all angles) from WC = 0 - 60%, and thereafter FPD decreases, this could be due phase inversion. For a given WC = 40%, the FPD has been found to increase with angle and flow rate. It has been noticed that inclination angle has appreciable effect on FPD. Also, it has been found that the FPD decreases for WC = 0 - 40% for 0° case. With further increase in WC, FPD increases, this may be due to phase inversion.

Experimental Study of Pressure Drop after the Circle Grids Fractal Orifice

Flow rate measurements are among the most important operations in modern industries dealing with increasingly expensive fluids such as petroleum, biodiesel and natural gas. The accuracy of flow meters depends mainly on their position in a pipe network and their operating conditions. Another important in designing piping system is a pressure drop across the flow measurement devices. Here, we investigate the pressure drop after the circle grids fractal orifices using a digital differential pressure manometer at different stations downstream a turbulent flow pipe then a direct comparison has been made with the pressure drop measured from regular orifices with the same flow area. Our results showed that the circle grid fractal orifices have a significant effect on pressure drop downstream the flow which is to be lower than that from ordinary orifices of the same flow area. This result could be important from point of view of losses consideration with the same flow control area. The experimental results using the circle grid fractal orifices show that these types of orifices can sense the pressure drop across them accurately with minimum losses than the regular ones.

An experimental study of pressure drop and friction factor for laminar and transition opposing mixed convection in entrance region of rectangular duct

The laminar and transition opposing mixed convection was experimentally investigated when the air flow was in the entrance region through a rectangular duct. The pressure drops were measured under different air flowrates, convective heat fluxes and inclination angles, with the maximum value less than 6.0 Pa. The friction factors were calculated and analyzed under different Reynolds numbers, Grashof numbers and inclination angles. The results indicated that the pressure drops increased with the mean air velocity, and the friction factors showed different characteristics when the Reynolds numbers were larger or smaller than 1500. Finally, the correlations of friction factors were fitted considering the influences of Reynolds number, Grashof number, inclination angle and length to diameter ratio, which fitted the experimental data with the deviations less than ±10.0%.

Experimental Study of Pressure Drop and Heat Transfer of Heat Exchangers with LASH Baffles

LASH or large-and-small-hole baffle is a new kind of baffle which induces axial flow in the shell-side of heat exchangers. In this paper, pressure drop and heat transfer of heat exchangers with LASH baffles were experimentally studied and compared with those in common heat exchangers with segmental baffle. It is founded that compared with the segmental baffles, pressure drops caused by LASH baffles are greatly decreased. Although the shell-side heat transfer coefficient with the LASH baffles is decreased, more comprehensive performance for heat exchangers with LASH baffles can be achieved.

Turbulent Liquid−Liquid Dispersion in Sulzer SMX Mixer

This paper presents an experimental study of pressure drop of single-phase flow and liquid−liquid dispersion through a Sulzer SMX mixer in the turbulent flow regime. Emulsification experiments are performed with various numbers of mixing elements from 2 to 20 and different flow rates ranging from 204 to 600 L/h. Pressure drop in single phase flow when Re is greater than 800 is modeled using a correlation based on the Blasius approach. The pressure drop is quantified at high Reynolds numbers for a liquid−liquid system. The droplet size distribution evolves along the mixer, and 10 mixing elements are required to reach break-up coalescence equilibrium in the case of emulsification experiments. Finally, assuming Kolmogorov’s theory of isotropic turbulence, a new correlation is established to predict the Sauter mean diameter in this mixing device as a function of the Reynolds and Weber numbers as well as the number of mixing elements.

Effect of Bi-Modal Aerosol Mass Loading on the Pressure Drop for Gas Cleaning Industrial Filters

The typical size distribution of emission particulates is bi-modal in shape with particles in the fine mode (< 2.0 w m) and the coarse mode. An experimental study of pressure drop across industrial gas cleaning filters has been conducted using a particle mixture of fine alumina and coarse Arizona dusts with a rotating aerosol disperser to generate the bi-modal test aerosol. Pressure drop increased linearly with increasing mass loading. The pressure drop was found to be strongly dependent upon the mass ratio of fine to coarse particles. The measured specific resistances of HEPA filters at a given face velocity of 5 cm/s were 1.18 2 10 6 , 5.89 2 10 5 , 4.67 2 10 5 , 2.65 2 10 5 , and 1.18 2 10 5 s -1 for the mass ratio of fine to coarse particles of fine only, 50%:50%, 25%:75%, 10%:90%, and coarse particles only, respectively. The pressure drop across the loaded filter increased with increasing face velocity. The larger the mass ratio of fine to coarse particles and the higher the face velocity are, the fa...

An experimental study of pressure drop in helical pipes

Pressure drops of fully-developed incompressible laminar newtonian flows in helical pipes of constant circular cross-section having a finite pitch are experimentally investigated. For the case of loosely coiled pipes of 0 &lt; η/λ &lt; 41.22, f Re ( f is the Fanning friction factor and Re is the Reynolds number) is found to be proportional to the square root of the flow Dean number, Dn = Re λ ½ . Here λ and η are the normalized curvature ratio and torsion which incorporate both the coil radius and its pitch. In all cases studied, the experimental results for f Re are in excellent agreement with the theoretical prediction of Liu &amp; Masliyah.

High flux boiling in low flow rate, low pressure drop mini-channel and micro-channel heat sinks

Due to the need for practical cooling technologies which could dissipate high heat fluxes, an experimental study of pressure drop and CHF in mini-channel ( D = 2.54 mm) and micro-channel ( D = 510 μm) heat sinks of 1 cm heated length was performed using R-113. Test conditions included inlet subcooling ranging from 10 to 32°C and a range of low flow rates up to a maximum of 95 ml min −1. The tests yielded CHF values for both heat sinks in excess of 200 W cm −2 with the advantage of both low flow rates and low pressure drops ( ΔP < 0.32 bar) as compared to high-flux, single-phase micro-channel heat sinks. Key features of the miniature heat sinks include a lack of inlet subcooling effect on CHF and superheated outlet conditions at the lowest flow rates. A single CHF correlation was developed for both heat sinks. The paper will illustrate the use of the CHF correlation and a generalized model for pressure drop as predictive tools in assessing the merits of different channel sizes in incorporating miniature heat sink technology into high heat flux cooling schemes. Overall, the mini-channel's performance proved superior to the micro-channel due to pressure drops less than 0.01 bar for comparable CHF values as well as the reduced likelihood of clogging and the relative ease in fabricating the mini-channel.

Subcooled boiling pressure drop with water at low pressure

Results are presented for an experimental study of pressure drop with subcooled boiling of water at pressures below 100 p.s.i.a. in horizontal round tubes of diameter less than 0·2 in. Test conditions were comparable to those required for the cooling of high power density systems. A correlation is presented in graphical form which satisfactorily accounts for variations in velocity, pressure, and inlet temperature. The correlation is in good agreement with the limited data reported by other investigators for similar conditions. Application of the data to diagnosis of system stability is noted.

Local Pressure Gradients in Forced Convection Vaporization

An experimental study of pressure drop in forced convection vaporization has been made in a heat transfer loop designed for the investigation of local heat transfer coefficients and local pressure gradients for water flowing vertically upward in an electrically heated tube. Data presented are for ⅛-in. i.d. 347 stainless steel tubes of 15 and 20-in. lengths with mass fluxes of 200 to 700 lb/sec ft2, heat fluxes of 1 to 8 × 105 Btu/hr-ft2, qualities at the exit up to 50% and with pressures ranging from 50 to 400 psia. A correlation of the local pressure gradients as a function of the Martinelli parameter Xtt has been obtained to within ±15% and a design procedure for calculating over-all pressure drop from this correlation is suggested.