Analysis Of Pressure Drop Research Articles

Heat transfer and pressure drop analysis of a microchannel heat sink using nanofluids for energy applications

Abstract The present research aims to enhance heat transfer in straight and wavy profile heat sinks using the same length and hydraulic diameter with different microchannel geometries (triangular, rectangular, trapezoidal, semi-circular, and circular) for uses in electronics, inkjet printing, high heat flux cooling of lasers, and other domains. The nanofluid employed is water/aluminum oxide (water/Al2O3), and the flow regime is laminar. The range of Reynolds number (Re) in this study was 220 ≤ Re ≤ 550, and the concentrations of nanoparticle Al2O3 with Heavy Water (2H2O) were 1.2 % volume. This investigation uses 3-dimensional Computational Fluid Dynamics (CFD) simulation software to investigate the heat transfer characteristics of several cross-sectioned microchannels. The numerical investigation utilizes the finite volume approach, and the CFD analysis is validated with accessible literature with different wavy profiles. According to the CFD simulation results, the microchannel with a circular cross-section has the highest heat transfer performance (up to 18 %) among the other cross-sections. The circular cross-section microchannel seemed to have the most significant increase in coolant temperature (by 9–22 %). The analysis outcomes prove that the microchannel with a circular cross-section has the highest performance for heat transfer; the triangular channel has the lowest performance under the same geometric parameters and boundary conditions. So, it is suggested that a circular microchannel can be used for a heat-carrying capacity of 150 W/cm2, a hydraulic diameter of 500 µm, and a Reynolds number equal to 500.

A comparative investigation on heat transfer performance of novel nanoaerosols in pipe flow: Experimental results

This paper describes the experimental analysis of aerosol heat transfer coefficient (AHTC), pressure drop, and friction factor of SiO2, TiO2, and MgO nanoaerosol in the pipe flow with the volumetric flow rate of 30 lpm, 40 lpm, and 50 lpm. The SiO2, TiO2, and MgO nanoparticles are characterized by using the field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) analysis. The SiO2, TiO2, and MgO nanoparticles are dispersed in the air at the particle volume concentrations of 0.5 %, 1.0 %, and 5.0 %, respectively. The thermo-physical characteristics of nanoaerosols are determined using empirical correlations. The variation in temperature, pressure, and flow rates are measured by using the thermocouples, pressure gauges, and flow meters installed in the experimental setup. The temperature readings are recorded by using the data acquisition system. The experimental results indicate the enhancement of forced convective AHTC with the increase in the nanoparticle volume concentration and the volumetric flow rate of the nanoaerosol. At volumetric flow rates of 30 lpm, 40 lpm, and 50 lpm, respectively, increasing the particle volume fraction from 0.5 % to 5.0 % improves the average heat transfer coefficient by 92 %, 84 %, and 91 % for SiO2 nanoaerosol, 72 %, 50 %, and 37 % for TiO2 nanoaerosol, and 50 %, 67 %, and 72 % for MgO nanoaerosol. The pressure drop of the nanoaerosol increases by 2, 2.33, and 3 times, respectively, and the friction factor decreases by 27.99, 15.99, and 11.1 times for SiO2, TiO2, and MgO nanoaerosol by increasing the flow rate from 30 lpm to 50 lpm. For the SiO2, TiO2, and MgO nanoaerosols, increasing the particle volume concentration from 0.5 % to 5.0 % increases the pressure drop by 6, 7.66, and 10 times, respectively, and the friction factor by 32.03, 19.08, and 5.67 times. By considering all of these factors, it is concluded that the performance evaluation criteria are lowest for 0.5 % TiO2 and highest for 5.0 % MgO. The significant finding of this research is that the AHTC increases with the increase in the particle volume concentration and volumetric flow rate. Whereas, the friction factor decreases with the increase in the volumetric flow rates.

Experimental study on the pressure drop and thickness variation of carbon black particle layer during oxidation on DPF channels

Investigating the evolution of pressure drop and particle layer thickness during oxidation is crucial for comprehending the regeneration performance of diesel particulate filters (DPFs) and optimizing the regeneration process. In this study, a visualized single-channel test bench was employed to actively regenerate carbon black particle layers on DPF channels. Online measurements and dynamic analysis of pressure drop and particle layer thickness were conducted to examine their behaviors. The results demonstrated that the particle layer regeneration process can be categorized into three stages. In the first stage, the pressure drop gradually decreased while the thickness continued to increase. In the second stage, the pressure drop reduction rate significantly accelerated with increasing deposition thickness (particularly between 112 μm and 147 μm), while the particle layer continued to thicken due to thermal expansion, reaching a peak of 193 μm before declining. For layers thicker than 273 μm, continuous thickening was observed. In the third stage, the pressure drop reached its minimum value, and the rate of thickness decrease became relatively high. Notably, a time delay was observed between the rapid decline in thickness and the steep decrease in pressure drop, which increased with the thickness of the particle layer. At a deposition thickness of 404 μm, the particle layer became suspended on the filter wall during the heating process, creating a gap .

Analysis of Flow and Pressure Drop on Tube Side of Spiral Tube Heat Exchanger under Sloshing Conditions

The utilization of the spiral tube heat exchanger (SHE) has become increasingly prevalent in large-scale liquefaction processes. However, the flow pattern and frictional pressure drop of two-phase flow in the spiral tube have been scarcely studied, particularly under offshore sloshing conditions. An experimental system had been developed to explore the flow pattern and frictional pressure drop characteristics of mixed hydrocarbon fluid in a spiral tube. Moreover, these have been developed in order to examine the effects of sloshing style (roll, pitch, heave), sloshing period (5–15 s), sloshing amplitude (5–15° or 50–150 mm), mass flux (200–800 kg/(m2·s)), vapor quality (0–1), and saturation pressure (2–4 MPa) on the frictional pressure drop of methane/ethane mixture in the spiral tube. The results indicated that sloshing conditions reduce the frictional pressure drop, thereby enhancing fluid flow. A correlation was established to predict the sloshing factor of frictional pressure drop, and the MARD under verification conditions was 6.04%. Furthermore, three flow pattern boundaries were proposed based on We* as an indicator.

P44: Toward 3D-Printed Microfluidic Artificial Lungs with Complex, Biomimetic Geometries

Purpose: Current hollow-fiber oxygenators used in Extracorporeal Membrane Oxygenation have suboptimal gas exchange performance and hemocompatibility. Microfluidic artificial lungs (µALs) promise smaller feature sizes, improving gas exchange efficiency, and biomimetic flow paths, improving blood compatibility. For the first time, we leverage the geometric freedom of 3D-printing technology to demonstrate µALs with truly 3D, biomimetic branching capillaries and gas-side designs to increase gas exchange surface area. Methods: Two µAL designs were generated in Solidworks and printed on an Asiga MAX X27 UV printer. The first was a “simple branching” µAL (Fig 1A) with quadfurcating, biomimetic branching for blood distribution. The second was a “hatched” µAL (Fig 1B) employing a gas phase with strategically placed supports to maximize gas exchange surface area while maintaining structural stability. These changes are only to the gas, and so the blood-phase is unchanged. Dyed water was used to visualize internal structures (Fig 1D). Geometric analysis and proven models were used to calculate theoretical shear rate and rated flow. Computational Fluid Dynamics (CFD) was used to visualize flow (Fig 1E,F). Experimental pressure drop vs water flow rates were measured (Fig 2). Results: Through geometric analysis (Table 1), branching distribution technique provides more uniform shear stress (0.95-1.34 dyn/cm2) compared to a non-branching “open-plenum” control (0.09-1.27 dyn/cm2). The hatched µAL has a 3.18 mL/min rated flow, 1.7x greater than the 1.84 mL/min rated flow of the non-hatched branching µAL. As a result of the higher rated flow, it also has higher theoretical shear of 1.64-2.31 dyn/cm2 (at rated flow) despite identical blood-side geometry. The branching lung demonstrated a pressure drop up to 12 mmHg at flows up to 5 mL/min (Fig 2). These are significantly larger than analytically predicted values (extrapolated 7 mmHg vs 0.233 mmHg at 3.2 mL/min), prompting investigation into resolution of internal capillaries and effects of surface roughness on pressure drop. Conclusion: We have demonstrated the first 3D-printed branching biomimetic µAL formed from a gas permeable material, with gas-side geometries to improve gas exchange efficiency. These geometries are expected to translate to greater blood flows enabling creation of future animal and human-scale µALs. Table 1. Theoretical calculations. All uALs have 256 8.5mm long 216x324 µm blood and gas channels, with 54 µm-thick membranes. They differ in their effective gas exchange area, and blood distribution method, resulting in differing rated flows, shears, and pressure drops. The Branching uAL employs a branching distribution, resulting in a much tighter shear stress range. The GasHatch uAL employs both a branching distribution, and a blood-gas geometric-synchronization, with 100% rather than 58% of the gas-exchange capillary face being used for gas exchange. Values for a theoretical “control” lung (not fabricated; contains an open plenum/ non-branching distribution region) are displayed for comparison. Flow velocity and shear stresses are calculated separately for capillary and distribution areas.Figure 1. Blood flows are indicated using red arrows, and gas flows are indicated using blue arrows. (A) Design of simple (non-hatched) branched μAL. (B) Close-up of the hatched μAL capillaries and gas channels, showing how gas-side supports are only in regions not adjacent to capillaries and therefore not reducing gas exchange surface area. (C) Hatched μAL with the gas phase filled with blue dye for visualization. (D) Non-hatched branching μAL with blood phase filled with blue dye, and gas phase filled with red dye. (E) CFD visualization of flow velocities in the branching blood distribution network; (F) CFD analysis of pressure drop in the biomimetic blood distribution channels.Figure 2. Pressure drop of branching µALs (water; n=3)

Flow Pattern Study and Pressure Drop Prediction of Two-Phase Boiling Process in Different Surface Wettability Microchannel.

An experimental study of two-phase flow pressure drop using R-134a is conducted on three types of different surface wettability microchannels with superhydrophilic (contact angle of 0°), hydrophilic (contact angle of 43°) and common (contact angle of 70°, unmodified) surfaces, all with a hydraulic diameter of 0.805 mm. Experiments were conducted using a mass flux of 713-1629 kg/m2s and a heat flux of 7.0-35.1 kW/m2. Firstly, the bubble behavior during the two-phase boiling process in the superhydrophilic and common surface microchannel is studied. Through a large number of flow pattern diagrams under different working conditions, it is found that the bubble behavior shows different degrees of order in microchannels with different surface wettability. The experimental results show that the hydrophilic surface modification of microchannel is an effective method to enhance heat transfer and reduce friction pressure drop. Through the data analysis of friction pressure drop and C parameter, it is found that the three most important parameters affecting the two-phase friction pressure drop are mass flux, vapor quality, and surface wettability. Based on flow patterns and pressure drop characteristics obtained from the experiments, a new parameter, named flow order degree, is proposed to account for the overall effects of mass flux, vapor quality, and surface wettability on two-phase frictional pressure drop in microchannels, and a newly developed correlation based on the separated flow model is presented. In the superhydrophilic microchannel, the mean absolute error of the new correlation is 19.8%, which is considerably less than the error of the previous models.

4D-Flow MRI Characterization of Pulmonary Flow in Repaired Tetralogy of Fallot

Patients with Tetralogy of Fallot (TOF) have multiple surgical sequelae altering the pulmonary flow hemodynamics. Repaired TOF (rTOF) adults frequently develop pulmonary regurgitation impacting the blood flow pressure, right ventricle load, and pulmonary hemodynamics. We aimed to evaluate the pulmonary flow hemodynamics using 4D-flow magnetic resonance imaging (MRI) for characterizing altered blood flow, viscous energy loss (EL), wall shear stress (WSS), pressure drop (PD), and ventricular flow analysis (VFA) in rTOF patients. We hypothesized that 4D-flow based parameters can identify pulmonary blood flow alterations. A total of 17 rTOF patients (age: 29 ± 10 years, 35% women) and 20 controls (age: 36 ± 12 years, 25% women) were scanned using a dedicated cardiac MRI protocol. Peak velocity and regurgitant fraction were significantly higher for rTOF patients (p < 0.001). WSS was consistently elevated along the PA in the rTOF (p ≤ 0.05). The rTOF average circumferential WSS was higher than axial WSS at the main pulmonary artery (p ≤ 0.001). PD and EL were consistently higher in the rTOF as compared with controls (p < 0.05). For VFA, delayed ejection increased and retained inflow decreased in rTOF patients (p < 0.001). To conclude, this study demonstrated that 4D-flow MRI pulmonary flow in the rTOF can exhibit altered peak velocity, valvular regurgitation, WSS, EL, PD, and VFA.

Study on the structural design and performance of magnetorheological (MR) valve with hybrid supply magnetic source and double annular channels

Valve plays an important role in achieving precise position control for the hydraulic lift system. In order to improve the performance of hydraulic lift in precise motion, this paper proposes an MR valve with hybrid supply magnetic source and double annular channels. In addition, a structural model was established to perform pressure drop analysis. According to its working principle, it is proposed that this MR valve has two channels that work separately. There are three working modes in which the two channels work together, and the pressure drop of the MR valve can be calculated in different ways. Therefore, the MR valve with hybrid supply magnetic source and double annular channel performance test system is constructed, and the magnetic field inside the valve is simulated by performing magnetic field finite element analysis. Finally, a test bench of vehicle maintenance elevators is built to analyze whether the MR valve with hybrid supply magnetic source and double annular channels can achieve accurate control on the vehicle maintenance elevators. According to the experimental and simulation results, the pressure drop of the MR valve with hybrid supply magnetic source and double annular channels is affected by the current and channel operating mode, while the load makes little difference to the pressure drop. The worse the rising response time performance increases with increasing current, but the response time performance decreases without being affected by current. When a current greater than 1.5A is applied to the coil, the response time of the lifting platform is basically maintained at 6 s with the increase of current. The position accuracy is ±1 mm for the experimental platform of the vehicle maintenance lift table based on the MR valve with hybrid supply magnetic source and double annular channel hydraulic system.

Pressure drop analysis of subsurface irrigation dripper system and its flow rate uniformity

Recently, water scarcity has become a serious social problem caused by global climate change. In agricultural water usage, subsurface irrigation techniques can be an alternative method to save water and improve the productivity and quality of crops. The technique supplies water by burying an irrigation hose 30 cm underground rather than placing it on the ground (topsoil), effectively preventing evaporation loss at the soil surface. In this study, we numerically calculated the pressure drop using a dripper installed inside an underground irrigation hose developed in Korea. The pumping load of the domestic product was evaluated in terms of momentum loss and compared with the most widely used Netafim products. The lower the pressure drop in the dripper, the higher the performance of the irrigation system in terms of stable water supply. Using computational fluid dynamics and experiments, we provide a meaningful evaluation of the domestic product in the irrigation system.

Experimental Investigation and CFD Analysis of Pressure Drop in an ORC Boiler for a WHRS Implementation

Waste heat dissipated in the exhaust system of a combustion engine represents a major source of energy to be recovered and converted into useful work. The Waste Heat Recovery System (WHRS) based in an Organic Rankine Cycle (ORC) is an approach for recovering energy from heat sources, achieving a significant reduction in fuel consumption and, as a result, exhaust emissions. This paper studies pressure drop in an ORC shell-and-tubes boiler for a WHRS implementation experimentally and with computational simulations based on a 1-dimensional heat transfer model coupled with 3D calculations. An experimental database is developed, using ethanol in a pressure range of 10-15 absolute bar as working fluid, with mass fluxes inside the tubes in the range of 349.31 kg/s-m2 and 523.97 kg/s-m2, and inlet temperatures in the range of 60 °C and 80 °C. Thus, the friction factor of different regions of the boiler were estimated using both CFD simulations, experimental data, and bibliographic correlations. Simulations of operating points and the results of the experimental test bench showed good agreement in pressure drop results, with a mean absolute error of 15.47%, without a significant increment in the computational cost.

THE OPTIMIZATION OF PASSIVE MICROMIXERS WITH THREE-SPLIT RHOMBIC SUB-CHANNELS FOR CHEMICAL ANALYSIS APPLICATION

A rhombic with unbalanced three-split in a passive micromixer is studied. This work aims to optimize micromixers' three-split rhombic design for chemical analysis through mixing index and pressure drop analysis. The optimization was obtained by varying the angle of the rhombic and the ratio of the sub-channel widths, including angles of 30°, 45°, 60°, 90° and widths of 150:100 μm, 200:100 μm, 250:100 μm, and 300:100 μm. The COMSOL Multiphysics was used to simulate the performance based on a three-dimensional Navier-Stokes equation with the working fluid model in the form of water in the advection-diffusion model. A parametric study was carried out to evaluate the effect of the geometric micromixer variable on the mixing performance for the Reynolds range of 10-120. The results show that a micromixer with an unbalanced triangular rhombic the structure with an angle of 30° and width of 200:100 μm on Re 120 achieve mixing efficiency at 0.91 with pressure drop 1700 Pa.

Non-dimensional analysis of experimental pressure drop and energy dissipation measurements in Oscillatory Baffled Reactors

An experimental study is performed to characterize the pressure drop and the power consumption in Oscillatory Baffled Reactors, using dimensionless numbers: the oscillatory Fanning friction factor (fosc) and the Power number (Po), respectively. Two baffle geometries (one-orifice and three orifices) are tested, for different fluids and oscillating amplitudes. The range of oscillatory Reynolds numbers (Reosc) tested is 10–1000. Data reduction based on the statistical fitting and the FFT of the pressure drop and velocity signals is introduced to assess the maximum pressure drop and the phase lag between both signals. The new set of experimental data proves the limitations of the conventional models available in the open literature. fosc and Po provide consistent dimensionless results for the different working fluids tested and their trends are clearly related to different flow behaviours: laminar or chaotic flow. Correlations for fosc and Po as a function of Reosc and dimensionless amplitude are obtained.

Extrusion foaming of linear and branched polypropylenes – input of the thermomechanical analysis of pressure drop in the die

Abstract This paper aims at a better understanding of the polypropylene (PP) physical extrusion foaming process with the objective of obtaining the lowest possible foam density. Two branched PPs were compared to the corresponding linear ones. Their shear and elongation viscosities were measured as well as their crystalline properties. Trials were conducted in a single screw extruder equipped with a gear pump and a static mixer cooler to adjust the melt temperature at the final die. The effect of decreasing this temperature on the PP foamability and on the pressure drop in the die was analyzed. The foam density of branched PPs varies from high to low values while decreasing the foaming temperature. In the same processing conditions, the foam density of linear PPs does not decrease so much, as already evidenced in the literature. The foamability transition coincides with an increase of the pressure drop in the die. The originality of the work lies in the thermomechanical analysis of the polymer flow in the die which allows the identification of the relevant physical phenomena for a good foamability. The comparison of the experimental pressure drops in the die and the computed ones with the identified purely viscous behavior points out the influence of the foaming temperature and of the PP structure. At high foaming temperature the discrepancy between experimental measurements and the computed pressure drops remains limited. It increases when decreasing the foaming temperature, but the mismatch is much more important for branched PPs than for linear ones. This difference is analyzed as a combination of the activation energy of the viscosity, the elongational viscosity in the convergent geometry of the die which is much more important for branched PPs than for linear ones, and the onset of crystallization which occurs at higher temperature for branched PPs than for linear PPs.

The analysis of pressure drop, spray angle, and sprinkling intensity distribution in the spray stream produced by the water-foam nozzle

Abstract This paper summarises a series of large-scale fire suppression tests conducted to simulate a fire in the big surface and/or surface sprinkling. The subject of this paper is the research on water spraying with the use of the Turbo Jet 2011 water-foam nozzle manufactured by Supon Białystok. The results discuss the pressure losses caused by the flow through the discharge hose, spray angle, and the intensity of surface sprinkling. The greatest stream ranges and the highest maximum values of the sprinkling intensity were obtained at the capacity of 400 l/min, and a solid spray angle. The smallest values were obtained at 200 l/min, a pressure of 5 bar, and a solid spray angle. The actual pressures taking into account the losses in the hose section were calculated. As for the highest firefighting effectiveness of the stream, the authors recommended the following parameters: semi spray angle, 200 l/min, and 2.5 bar.

Investigation on inlet obstruction in transitional flow regime: Heat transfer augmentation and pressure drop analysis

Thermohydraulic characteristics of air as the working medium in a circular heated channel fitted with inlet obstruction (ribbed prism) at the inlet is carried out experimentally for transitional flow regime. The ribbed prism is fabricated using aluminum metal. Three non-dimensional parameters clearance ratio (C = 0.4, 0.5 and 0.6) and pitch ratio (e = 0.12, 0.15 and 0.16) were investigated. The Reynolds number (Nu) varied from 500 to 7036 to cover all the flow regimes. Experiments were conducted at two constant heat fluxes of 0.5 kW/m 2 and 1 kW/m 2 . It was found that start and end of transitional flow regime was influenced by insertion of the inlet obstruction at the inlet of the test section. With placement of prism in the channel, the boundaries of transition changes when compared with the plain channel. It is observed that transition starts early and also end early to the transition limit of plain channel. Heat flux shows significant influence on the onset and termination of the transition. At higher heat flux the transition starts later and terminates later when compared with the lower heat flux conditions. For the case of C = 0.6 and e = 0.16, the transition begins Re = 1648 and ends at Re = 3387 for 1 kw/m 2 heat flux. The transition of 0.5 kW/m 2 of heat flux for C = 0.6 and e = 0.16 begins at Re = 1554 and ends at Re = 3321. Correlations were also developed for predicting the Nusselt number and friction factor and the results are useful to design solar thermal systems and heat exchangers.

Mixing characteristics and pressure drop analysis in a spiral micromixer

In this work, numerical computations are performed to analyze the mixing characteristics and pressure drop in a spiral micromixer. The effects of variation in width and depth of the micromixer are investigated for Reynolds number ( Re) in the range of 0.1 ≤ Re≤100. Results are enumerated in terms of mass contours, streamlines, mixing index and pressure drop. It is observed that the designed spiral micromixer provides a better mixing for both low and high Re values, and moreover, the mixing index remains almost the same with the variation of the depth and width of the mixer for Re > 50. The mixing index first decreases with Re, reaches a minimum value, and thereafter again increases with a further increase in Re in the range of 0.1 ≤ Re≤50. For intermediate Reynolds number, a high mixing index is observed in micromixer having higher depth and lower width. Although the driving pressure force increases with the increase in Reynolds number, it decreases with the increase in width and depth of the micromixer.

Heat transfer, pressure drop, and economic analysis of a tube with a constant temperature equipped with semi-circular and teardrop-shaped turbulators

The effect of using innovative turbulator geometry, such as semi-circular and teardrop-shaped turbulators, on heat transfer and pressure drop has been studied for the first time in this study. To this end, eight different geometries have been considered for turbulator in a tube with constant surface temperature. Then, some tests have been performed for different hot water flow rates (mh˙) in the range of 0.044–0.099 kg/s. Also, the optimization was performed using the thermal enhancement factor (TEF) and the net profit of unit transferred heat load (ηp). These kind of turbulators have a major impact on heat transfer and friction factor, according to the findings. The maximum heat transfer values for semi-circular and teardrop-shaped turbulators were respectively 257% and 298% higher than that of the plain tube. Base on the results, a tube with teardrop-shaped inserts (case C) is the optimum case.

The developing flow characteristics of water - ethylene glycol mixture based Fe3O4 nanofluids in eccentric annular ducts in low temperature applications

• The effect of nanofluids’ lower viscosity values on heat transfer was investigated. • Annular flow propagation of water-ethylene glycol based Fe 3 O 4 nanofluid was studied. • Maximum heat transfer enhancement was obtained for highest concentration. • Addition of the nanoparticles resulted in delay to reach steady-state conditions. • The performance evaluation criteria, pressure drop and exergy analysis were studied. Natural circulation loops with double pipe heat exchangers at heating and cooling ends have a potential to be used in the refrigeration systems as an alternative to suction line heat exchangers. The heat transfer capability of such natural circulation loops depends on the geometrical parameters as well as thermophysical properties of the working fluid. This study aims to investigate the effect of water-ethylene glycol mixture based Fe 3 O 4 nanofluids (0.01, 0.05 and 0.1 vol.%) on the annular flow propagation and heat transfer in the annuli of double pipe heat exchanger at low pressure side of the refrigeration cycle. In addition to increased non-dimensional velocity values due to the lower viscosity and higher non-dimensional temperature values with expanded temperature gradient, improved heat transfer by nanofluids shows that they can be used as secondary heat transfer fluids at low-pressure side in refrigeration systems. Although the maximum transferred (13.6% improvement compared to base fluid) heat observed for the highest concentration, the nanofluids with smallest concentration has the minimum pressure drop value (25% reduction compared to base fluid) and the highest performance evaluation criteria (PEC) value (PEC = 1.08) with tiny increase in exergy destruction (1.45% compared to base fluid).

Pressure drop analysis for organic Rankine cycle power generation system using low-grade heat sources

Pressure drops are unavoidable when testing or applying power generation systems. Similar to any other system, the organic Rankine cycle (ORC) power generation system also experiences pressure drops. This study focused on analyzing the pressure drop in the plate heat exchanger of the evaporator, the condenser, and the piping to minimize the occurrence of a decrease in the system performance. Three scenarios, organic fluids R141b (scenario 1), R245fa (scenario 2), and R227ea (scenario 3), are used to determine the working fluid with the lowest pressure drop at a heat source with a temperature of 95 °C. The analysis was performed with data from an ORC system that had been installed in a laboratory. Pressure drop calculation was divided into cold and hot sides because of the presence of two fluid flows in the evaporator and condenser. Each side was divided into two zones because of a phase change in the evaporator and the condenser. The pressure drops from the plate and through the port were calculated in the evaporator and the condenser, and the pressure drop in the piping system completed the analysis. The analysis results showed that the total pressure drop in the evaporator and condenser for scenarios 1, 2, and 3 are 0.268 bar, 0.173 bar, and 0.134 bar, respectively. In addition, the total pressure drop in the piping system is 0.069 bar, 0.075 bar, and 0.081 bar for scenarios 1, 2, and 3. Therefore, scenario 3 had the lowest total pressure drop than other scenarios.

Heat transfer, pressure drop, and exergy analyses of a shot-peened tube in the tube heat exchanger using Al2O3 nanofluids for solar thermal applications

The effects of shot peening on the heat transfer, exergy analysis, and pressure drop in the heat exchanger were studied. Nanofluids were produced at different volume concentrations of 0.15, 0.3, and 0.45% of alumina oxide (Al2O3) nanomaterials well dispersed in solar glycol/water (80:20 by volume) as a base fluid. The outcomes point out that nanofluids (0.15, 0.3, and 0.45%) can enhance the Nusselt number by 8.098, 16.81, and 26.98%, compared with SG/H2O mixture respectively when compared with the SG-H2O blend with an impelling penalty of 1.47 folds. A higher enhancement in the CHTC of 56.32% was attained using 0.45 vol% of Al2O3 nanofluids at 0.08 kg/s. TEF of 1.118 is attained for the 0.45 vol% nanofluid inside the surface-modified (shot peening) heat exchanger. The maximal exergy efficiency was found to be 30.82% for 0.45 vol% of SG-H2O-based nanofluids and nanofluid MFR of 0.08 kg/s.