Plate Spacing Research Articles

Investigation of local heat transfer from a flat plate impinged by an inclined circular jet

Experiments are performed to study the influence of an oblique jet on convective heat transfer to a vertical heated plate. The local heat transfer coefficient is investigated parametrically for Reynolds numbers ranging from 10000 to 75000 and jet to plate spacing of 3–20 d for different inclinations of a jet in the range of 15°–75°. The experiments are carried out on a flat rectangular surface of 600 × 300 × 0.1 mm3, hit by a jet of 11.5 mm diameter, with air as the working fluid. The infrared technique is used to examine the temperature contours over the entire section of the test plate. The present investigation deals with the effect of inclination on cooling at different locations over the plate locally in all directions from the point of impingement. The effect of Reynolds number and jet to plate spacing due to inclined jet at different orientations on the longitudinal, lateral, and intercardinal axial location is studied. The study also focuses on the heat transfer phenomenon happening on the far side of the test plate. The correlation analysis is performed on the current experimental data. The local Nusselt number correlations for the inclined jet are suggested that predict the present experimental results as a function of the geometrical and flow parameters.

Effect of metal foam thickness on the conduction and convection heat transfer for a flat plate with metal foam impinged by multiple jets

ABSTRACT The influence of metal foam thickness on the convection and conduction heat transfer is studied by measuring the local heat transfer of a smooth flat plate, attached and detached metal foamed flat plate under multiple jet impingement conditions. 27 jets of 3 mm diameter are introduced from a jet plate. These jets impinge on a thin stainless steel foil that serves as a targeted plate. The pitch of the jets is 4d in both the spanwise and streamwise directions. The spent fluid is exiting in all directions. The influence of metal foam thickness is investigated for an open-cell aluminum foam with 4, 8, and 12 mm thickness. The porosity of aluminum metal foam is 0.92. The pore density (pores per inch) is 20 PPI. The local heat transfer is measured using infrared thermography and a thin metal foil technique. A smooth flat plate impinged by multiple jets serves as a reference case. The evaluation of the convection and conduction heat transfer offered by the metal foamed flat plate is obtained with the help of the detached foam configuration. The jet diameter-based Reynolds number ranges from 2500 to 15000. The range of the jet to plate spacing covered is 3d to 6d. Depending on the metal foam thickness, the metal foamed flat plate offers additional hydraulic resistance to the jet flow and conduction effect. The additional hydraulic resistance attenuates the convective heat transfer and is represented by attenuation factor (α). For metal foam having 4, 8, and 12 mm thickness, the attenuation factor is around 1.11, 0.99, and 0.64, respectively. The conduction effect offered by metal foam is responsible for the enhancement of the heat transfer. The conduction effect is represented as an enhancement factor (E). For metal foam having 4, 8, and 12 mm thickness, the enhancement factor is around 1.51, 1.58, and 2.32, respectively. The conduction effect presented in the metal foamed flat plate dominates over the attenuation in the convective heat transfer. The overall enhancement offered by 4, 8, and 12 mm metal foamed flat plate is around 1.67, 1.56, and 1.48, respectively.

Ball milling Fe3O4@biochar cathode coupling persulfate for the removal of sulfadiazine from water: Effectiveness and mechanisms

This study used biochar as the substrate of the electrodes, and a simple synthetic process (ball milling) was adopted to prepare the Fe3O4 @biochar cathode enhanced coupled system of electrochemistry-potassium persulfate to achieve the efficient removal of sulfadiazine. Studies showed that the cracking temperature of biochar and the iron-to-carbon mass ratio determined the catalytic performance of cathodes. In addition, ball milling increased the surface functional groups of biochar and promoted the dispersion of Fe3O4 on biochar, leading to increased active sites on the Fe3O4 @biochar cathode surface. It was found that SDZ and TOC removal rates reached 95.3% and 86.9% in the coupled system of electrochemical-persulfate with SDZ concentration of 10 mg/L, initial pH0 of 7, PDS concentration of 4 mM, current density of 30 mA/cm2, and electrode plate spacing of 4 cm. Also, this system showed excellent removal of sulfadiazine in actual water bodies. The quenching experiments and electron paramagnetic resonance spectra revealed that free radicals and non-radicals were involved in removing sulfadiazine, with free radicals (SO4•−) being the dominant pathway. Four main degradation pathways were proposed based on the intermediates of sulfadiazine. In conclusion, Fe3O4 @biochar cathode enhanced coupled system of electrochemical-persulfate could be regarded as an efficient cleaning technology to provide a method for the removal of intractable organic pollutants.

Stress-Electromagnetic Radiation (EMR) Numerical Model and EMR Evolution Law of Composite Coal-Rock under Load.

There is a close relationship between the electromagnetic radiation (EMR) evolution and the stress state during loading of composite coal-rock. In this research, the coal-rock EMR generation mechanism was studied and the stress-EMR numerical model was established. Finite element simulation and experiments were then used to verify their correctness, and EMR characteristics, evolution law, and the corresponding relationship between EMR and coal-rock state were studied in depth. The results show that the deformation cycle of "load compression-deformation release-load compression" occurs at coal-rock internal fractures, which together with friction make the formation of coal-rock alternating weak current sources, resulting in the EMR. In addition, the fracture structure is similar to capacitors with time-varying electric quantity and plate spacing. When the fracture is loaded, it will generate approximately sinusoidal EMR pulses whose amplitude is positively correlated with the degree of coal-rock damage. EMR will be exponentially attenuated and distorted at the medium junction when propagating, which does not affect signal characteristics. Meanwhile, EMR quality within 1.0-2.5 mm outside coal-rock is high, whose change is almost synchronous with source. EMR evolution has stages during loading, whose characteristics are different in each stress stage: In compaction and elastic stages, EMR remains stable for most of the time except for the abrupt change of 1-3 mV/m at the junction. In the yield, coal-rock transitions from elastic to plastic, and both EMR and stress increase rapidly as fracture expands. In the fracture stage, EMR maintains high and produces a peak that is synchronous with the stress. After fracture, they drop and recover to stability. The research results will help improve the basic theory of coal and rock dynamic disasters and provide support for its prediction with multi-information fusion, which will help reduce the adverse impact of coal mine disasters on people's lives and property.

Arc-shaped flutter-driven wind speed sensor based on triboelectric nanogenerator for unmanned aerial vehicle

At present, it is significant for unmanned aerial vehicle (UAV) to sense the external information in the interference environment. Therefore, an arc-shaped flutter-driven wind speed sensor based on triboelectric nanogenerator (AW-TENG) for UAV is proposed in this work. The arc structure of AW-TENG, which adopts contact separation mode through air vibration, is designed according to the working principle and simulation. Then the three influencing factors of plate spacing, radian and radian direction are carried out to determine its optimal structure. The performance of the optimal structure is verified: the voltage frequency that AW-TENG can reach in the wind speed range of 6–20 m/s is 50–200 Hz, the sensitivity is 9.88 Hz/(m s−1) and the goodness of fit R2 = 0.998. Meanwhile, the voltage range that AW-TENG can reach is about 30–55 V, the generated current range is about 8–28 μA. Finally, the application experiment of the wireless wind speed transmission of the UAV with AW-TENG is carried out. The experiment proves that TENG has the ability to apply the wind speed sensor for UAV, and provides experimental support for the wind speed monitoring of the overall structural unit of UAV in the future.

Bragg Resonance-based Wave Elimination Device for Offshore Floating Wind Platforms

This project provides an efficient and effective wave dissipation solution for the real needs of various large oceanic floating platforms, and achieves the power generation gain of the wave energy utilization equipment with the help of the local point of aggregation wave sub-effect. The device uses special shaped plates laid in an array to adjust the unit plate spacing and shaped plate attitude in the form of Bragg resonance with the surface wave wavelength fitting, which makes the surface waves reflect strongly in the peripheral area of the floating platform, while weakening the wave energy intensity of the surface waves in the central area of the beacon. In order to change the form of wave energy distribution in the local sea area, and at the same time play the effect of wave elimination in the core area of the platform and wave energy focusing in the outer power generation point.

Investigation into bearing performance of concrete expanded-plates piles: Field test and numerical modelling

Concrete expanded-plates (CEP) piles usually exhibit a higher bearing capacity due to the effect of plates. However, the full-scale field test and the simulation regarding the influence of plate parameters on the bearing performance of CEP piles have not been studied thoroughly. In order to promote the application of the novel, efficient and economic pile in road and railway foundations in practice, this study investigates the loading performance of CEP piles based on a field test and numerical simulation model. The field loading test on the bearing performance of CEP and straight piles is firstly performed to investigate the bearing capacities of two types of piles. A 3D simulation model of CEP pile subjected to vertical loads is then developed using the finite difference software FLAC 3D. The load-settlement curves and bearing capacities of piles obtained from the model are validated against the field test results. The bearing behaviours of CEP and straight piles are investigated and compared. In addition, the influence of plate positions, numbers, dimensions and spacing on the bearing performance of CEP piles has been studied. The novel insight from this study incites an original and better understanding of the bearing performance of CEP piles under vertical loads in engineering foundations.

Multi‐objective optimization of drainage‐plates in wave‐plate mist eliminators using experiment and data‐driven modelling for lower water loss and energy requirement

AbstractWave‐plate mist eliminators are widely employed as gas–liquid separation devices to prevent the liquid escaping from thermal power plants or other cooling towers. In this study, the wave‐plate mist eliminator with drainage plates was numerically analyzed and the effects between geometrical variables on two objectives, namely, pressure drop (ΔP) and separation efficiency (η), were revealed. Plate spacing, width, and length, as well as the relative position of the drainage plate, were thoroughly investigated. A combined strategy was developed for multi‐objective optimization of the wave‐plate mist eliminator by integrating computational fluid dynamics (CFD) simulation, response surface methodology (RSM), non‐dominated sorting genetic algorithm‐II (NSGA‐II), and a technique for order of preference by similarity to ideal solution (TOPSIS) method. The results demonstrated that the relative position of drainage plates has a greater impact on the overall performance, whereas the width of drainage plates has the minimum effect. With the implementation of NSGA‐II and the TOPSIS method, an optimal solution for the design of the mist eliminator was obtained. After comparing with the baseline case, the optimized case presents promising characteristics with high separation efficiency (enhanced by 3.6%~9.06%) and a low energy consumption coefficient (reduced by 72.30% at η = 45%).

Qualitative Classification of Lubricating Oil Wear Particle Morphology Based on Coaxial Capacitive Sensing Network and SVM.

In addition to lubricating and cooling, aero-engine lubricating oil is also a transport medium for wear particles generated by mechanical wear. Online identification of the number and shape of wear particles is an important means to directly determine the wear state of rotating parts, but most of the existing research focuses on the identification and counting of wear particles. In this paper, a qualitative classification method of wear particle morphology based on support vector machine is proposed by using the wear particle capacitance signal obtained by the coaxial capacitive sensing network. Firstly, the coaxial capacitive sensing network simulation model is used to obtain the capacitance signals of different shapes of wear particles entering the detection space of different electrode plates. In addition, a variety of intelligent optimization algorithms are used to optimize the relevant parameters of the support vector machine (SVM) model in order to improve the classification accuracy. By using the processed data and optimized parameters, a SVM-based qualitative classification model for wear particles is established. Finally, the validity of the classification model is verified by real wear particles of different sizes. The simulation and experimental results show that the qualitative classification of different wear particle morphologies can be achieved by using the coaxial capacitive sensing network signal and the SVM model.

Waste coal cinder catalyst enhanced electrocatalytic oxidation and persulfate advanced oxidation for the degradation of sulfadiazine.

Waste coal cinder, a kind of waste cinder discharged from coal combustion of thermal power plants, industrial and civil boilers, and other equipment, was rich in metal oxides with catalytic activity. In this work, waste coal cinder was used to enhance electrochemical coupling peroxymonosulfate (PMS) advanced oxidation degradation of sulfadiazine (SD). The surface morphology, elemental composition, and electrocatalytic activity of waste coal cinder were characterized by various characterization instruments. The results show that compared with simple electrocatalytic oxidation, electrocatalytic oxidation+waste coal cinder and electrocatalytic coupled persulfate oxidation, electrocatalytic oxidation+PMS advanced oxidation+waste coal cinder has the largest removal efficiency (99.95%) and mineralization rates (90.16%) of SD in 90min, indicating that the introduction of waste coal cinder greatly increases the degradation efficiency. •OH and SO4-• were detected during the process of degradation. The optimal degradation process parameters were explored through different voltage, pH, plate spacing, aeration flow rate, potassium peroxymonosulfate sulfate complex salt dose, and Na2SO4 dosage. Cycling experiments show waste coal cinder has good structural stability. Through the analysis of triple quadrupole liquid chromatography-mass spectrometry (LC-MS), we put forward three possible ways of SD degradation. This research will provide a novel vision for water treatment.

Roughness mass transfer function for an electro-chemical column with inserted heptagonal plate as turbulence promoter

Experiments have been done to evaluate the effect of a coaxially arranged entry area heptagonal plate as a turbulence promoter on mass transfer rates in electrolyte induced convection flow. The goal of this research is to determine mass transfer rates at the electrochemical cell's outside wall. The measured limiting currents technique was used to calculate mass transfer coefficients. This research examines the effects of several characteristics such as plate side (SP), plate number (NP), and plate spacing (H). The mass transfer coefficient increases as the velocity, side of the plate (SP), and number of plates (NP) increase, but decreases as the spacing between plates (H) grow. The correlation achieved is.g(h+)=2227.3(Re+)-0.70264SPd1.6255L/NPd-0.12198Hd-0.17904Sc0.38927

Noise optimization of multi-stage orifice plates based on RBF neural network response surface and adaptive NSGA-II

In the multi-stage orifice plates (MSOP) design of the pipeline system of the nuclear power plant, since the multi-parameter coupling and matching technology has not been broken through, the high noise cannot be effectively suppressed under large flow rate and high pressure drop conditions. This paper proposes an optimization method for the low noise design of the MSOP based on the RBF neural network response surface and the adaptive NSGA-II algorithm. Cavitation and flow velocity are proposed as the characteristic parameter for evaluating the noise. The relationship between coupling parameters such as diameter ratio, plates thickness, and plates spacing is clarified by correlation analysis. The method increased the minimum pressure by 28.57% and reduced the maximum velocity by 11.49% under the constraints of the high pressure drop, structure size and flow rate. The results prove that this method can effectively realize the design of the MSOP with low noise.

Investigation on mechanical behavior of steel angle frame reinforced concrete beams under torsion

SummarySteel angle frame reinforced concrete (SARC) beam is a kind of composite beam with encased steel angle frame. The torsion tests were carried out on six SARC beams and one reinforced concrete (RC) beam to investigate their torsional behavior. Test variables include space between steel plates, angle of steel plates, concrete cover depth, and concrete strength. The results showed that the reduction of space between steel plates causes specimens to crack in advance, but improves torsional behavior after cracking markedly. The energy dissipation coefficient reduces as concrete cover depth increases. Damage index can be effectively reduced by increasing concrete strength, reducing plates spacing, and increasing concrete cover depth. The overall torsional behavior of SARC beam can be improved by reducing the spacing between the plates, adopting staggered vertical and oblique steel plates, and increasing concrete strength, but the effect is adverse when concrete cover depth increases. Moreover, the space between steel plates should be greater than 100 mm, and concrete cover depth should be less than 35 mm for maximizing the torsional strength of steel angle frame. Considering the positive roles of steel angle frame and oblique steel plates, the calculation methods of cracking and ultimate torsional moment were proposed. This study can provide a theoretical basis for the engineering application of SARC beams subjected to torsion.

Facile Synthesis of n-Fe3O4/ACF Functional Cathode for Efficient Dye Degradation through Heterogeneous E-Fenton Process

In order to put forward an efficient and eco-friendly approach to degrade dye-containing industrial effluents, an n-Fe3O4/ACF nanocomposite was synthesized using the facile precipitation method and applied as a functional cathode for a heterogeneous electro-Fenton (E-Fenton) process. In particular, optimal initial pH value, current density, pole plate spacing, and electrode area were confirmed through systematical experiments as 5.73, 30 mA/cm2, 3 cm, and 2 × 2 cm2, respectively. Under such optimal reaction conditions, 98% of the methylene blue (MB) was degraded by n-Fe3O4/ACF after 2 h of E-Fenton treatment. In addition, n-Fe3O4/ACF could still decolor about 90% of the methylene blue (MB) for five rounds with some reductions in efficiency. Furthermore, results of electrochemical impedance spectroscopy and heterogeneous E-Fenton performance tests indicated that the loading of metal material Fe3O4 could enhance the overall electron transport capacity, which could accelerate the whole degradation processes. Moreover, the rich pores and large specific surface area of n-Fe3O4/ACF provided many active sites, which could greatly improve the efficiency of O2 reduction, promote the generation of H2O2, and shorten the reaction length between •OH and the pollutant groups.

Electrochemical oxidation degradation of fungicide 5-chloro-2-methyl-4-isothiazoline-3-one (CMIT) in brine of reverse osmosis by a novel Ti/CB@MXene anode

The electrochemical oxidation purification of reverse osmosis concentrated brine was sustainable water purification technology; however, anode oxidation efficiency and capacity limit its development. According to MXene’s high surface area and structure characterization, a novel Ti/ carbon black (CB) @MXene anode was prepared for the first time for electrochemical oxidation degradation of 5-chloro-2-methyl-4-isothiazoline-3-one (CMIT) in reverse osmosis brine, even though MXene was studied more widely in sulfate radical based AOP and photocatalysis. This anode showed slippy surface and high oxygen evolution potential (2.84 V), suggesting it is hard to be fouled and eliminated the side reaction effect. According to the anode fabrication parameters optimization, the best mass ratio of Ti3C2Tx and CB was 1:1, showing the highest oxygen evolution potential. The reaction parameters including current density and plate spacing were optimized as 5.625 mA/cm2 and 1.0 cm, where the best CMIT degradation efficiency was 89.86 %. This performance was better than DSA and similar with BDD anode, however its stability needs to be improved. The indirect oxidation dominated CMIT degradation as 99.69 % and •OH formation rate was 13.81 L·mol−1·s−1, which was approximately 5.04 fold higher than that of traditional Ti anode. Three possible degradation pathways of CMIT were proposed, as below: electron rich sulfur in SN bond was oxidized to form sulfoxide structure, chlorine was replaced by •OH, olefin double bond was attacked by •OH. The formed intermediates showed less ecotoxicity. The Ti/CB@MXene anode showed better potential in electrochemical oxidation treatment of reverse osmosis brine.

Treatment of membrane concentrated landfill leachate by a heterogeneous electro-Fenton process with an iron-loaded needle coke cathode

Mature membrane concentrated landfill leachate is one of the most recalcitrant wastewaters due to its high pollutant concentration, poor biodegradability, and stable organic structure. In this study, a heterogeneous electro-Fenton system was constructed using a Fe-loaded needle coke composite electrode as a cathode to treat the membrane concentrated landfill leachate from a local closed landfill. The reaction conditions were evaluated and optimized by the response surface method based on Box-Behnken design. A second-order polynomial model with COD removal rate as the response and initial pH, plate spacing, and applied voltage as independent variables were established. After treatment by the heterogeneous electro-Fenton process with the needle coke composite cathode under the optimal conditions of applied voltage 10 V, initial pH 3.6, and the plate spacing 1.4 cm, the COD and color removal rates of the membrane concentrate were up to 71.9% and 99.8%, respectively, and the biodegradability was significantly improved with the BOD5/COD increasing from 0.003 to 0.379. Various spectral analyses of the wastewater before and after electro-Fenton treatment with the needle coke composite cathode demonstrated that most of the macromolecular organic pollutants in the landfill leachate concentrate including aromatic compounds, simple aromatic protein compounds, soluble microbial by-products, and humic acid were significantly degraded. As a result, the electro-Fenton technique with the needle coke composite cathodes is one of the cost-effective options for treating membrane concentrated landfill leachate.

Experimental and LES study of unconfined jet impingement on a smooth flat heated plate with slots of different widths

ABSTRACT The present work focuses on the experimental and large-eddy simulation (LES) investigation of fluid flow and heat transfer due to the impingement of an unconfined turbulent slot jet on a smooth flat plate. Three LES sub-grid scale models are validated with the experimental observations for first time in terms effect of slot widths. A detailed parametric study is conducted considering nozzle to plate spacing ratio from 4 to 12, non-dimensional slot width from 0.015 to 0.035, and Reynolds number range from 4000 to 12000. The results show an appreciable change in the stagnation point and along the wall jet Nusselt numbers with the change in Reynolds number, nozzle-to-plate spacing and non-dimensional slot width. No significant effect of nozzle to plate spacing is observed along the wall jet Nusselt number beyond the streamwise location at 0.2. The local Nusselt number increases with an increase in Reynolds number while it decreases with an increase in nondimensional slot width. Comparison of various LES sub-grid models with RANS (k-ω SST) turbulence model is performed. The results show that turbulent kinetic energy plays a major role in enhancing the heat transfer rate. Dissipation of the turbulent kinetic energy increases with an increase in nozzle to plate spacing and non-dimensional slot width. Further, a correlation is proposed for the stagnation point and wall jet region Nusselt numbers in terms of effect of slots width, Reynolds number and non-dimensional nozzle to plate spacing.

Application of efficient pre‐treatment by physical fields for improving the taste and flavor of processed chicken enzymatic hydrolysate

In the condiment industry, people usually use enzymatic hydrolyzate to improve the umami of the product, and there are few reports on the umami intensity of the enzymatic hydrolysate. To explore the differences in taste and flavor of the samples pretreated with different physical fields, the chicken was pretreated by ultrasound (US, 600 W, 30 min), infrared radiation (IR, 90°C, 30 min), and radio frequency (RF, 120 mm, 30 min), respectively, and followed by a two-step enzymatic hydrolysis. Results revealed that the chicken enzymatic hydrolyzate after RF pretreatment (120 mm, 30 min) had the best overall taste and stronger umami. The sample treated with 90°C IR has a richer flavor, while there were no significant changes in taste of the 600 W ultrasound treatment group compared with the “control.” Therefore, RF pretreatment (120 mm, 30 min) is more suitable for industrial to produce low cost and high umami chicken enzymatic hydrolyzates. Practical applications In the condiment food industry, people usually use umami-rich enzymatic hydrolysates to improve the umami taste of products. The 120 mm plate spacing radio frequency pretreatment proposed in this study for 30 min before enzymolysis can significantly improve the taste characteristics of the chicken enzymolysate, significantly enhance its saltness and umami, and make the overall taste more harmonious. It provides a certain theoretical basis for the industrial production of low-cost umami-enhancing enzymatic hydrolysis products.

Experimental and Numerical Investigation of Plastic–Concrete Waterproof Walls of an Underground Granary Subject to Combined Bending Moment and Water Pressure

To investigate the mechanical properties of plastic–concrete silo walls in practice, the mechanical properties and failure mechanism under the combined bending moment and water pressure were analyzed through the uniform loading test, water pressure test, and numerical analysis. The influence of the connecting plate spacing, radius, and the waterproof plate thickness on the water pressure-bearing capacity were analyzed. The test results show that the chemical adhesive force exists between the waterproof plate and concrete and can resist 20 kPa. The displacement and strain of the waterproof plate increases significantly with the increment in water pressure. When the water pressure reached 85 kPa, the specimen was damaged due to shear failure. The established numerical model was validated by the test results. The numerical analysis results show that the specimen failure mainly depends on the bolt strength when the thickness of the waterproof plate is greater than 14 mm or the radius of the connecting plate is greater than 60 mm. The relation between the design parameters and the water pressure-bearing capacity was proposed. Compared with the waterproof plate thickness, the connecting plate spacing and radius have greater influence on the water pressure-bearing capacity.

Effect of plate distance on light conversion efficiency of a Synechocystis culture grown outdoors in a multiplate photobioreactor

In this work, the performance of a vertical multiplate photobioreactor is analyzed and presented. The photobioreactor consisted of 20 vertical plates (1 m2 each) connected by manifolds and a working volume of 1300 L. The total area occupied (footprint) was 10 m2, while the illuminated area was 40 m2, therefore the ratio of illuminated area to volume ratio was about 30 m−1. The performance of the photobioreactor was evaluated using a culture of Synechocystis PCC 6803, circulated by a centrifuge pump. The results showed that the amount of light captured by the photobioreactor at a plate spacing of 0.5 m was 90.2 % of the light incident on the horizontal surface, while at a plate spacing of 1.0 m, 50.3 % was captured. The corresponding biomass yield, calculated based on the ground area occupied by the reactor, was 26.0 g m−2 day−1 and 7.2 g m−2 day−1, when the plates were spaced at 0.5 m and 1.0 m respectively. Therefore, the light conversion efficiency calculated based on the ground area was significantly higher in the configuration with a plate spacing of 0.5 m, reaching 5.43 % based on PAR (photosynthetically active radiation), and 2.44 % based on solar radiation, giving a value 3.7 higher than when the plates were spaced 1.0 m apart. It was concluded that the light conversion efficiency might be further improved by reducing the plate spacing while also reducing the culture light path.