Air Flow In Channel Research Articles

0619 To Rely or No to Rely: Understanding the Demographics and Polysomnographic Features of False Negative Home Sleep Apnea Testing

Abstract Introduction The current gold standard for a definitive diagnosis of OSA is an in-center Polysomnography (PSG). Home Sleep Apnea Testing(HSAT) has become an important tool in identifying high-risk populations. One of the limitations of the study is the lack of Electroencephalographic (EEG) data. This prevents the inclusion of Respiratory Effort Related Arousals (RERAs). We attempted to identify the patients whose HSAT showed an REI of less than 5 but are at risk for having sleep apnea based on the presence of airflow and thoraco-abdominal fluctuations. Methods Patients in this study were those that underwent HSAT from September 2016 till June of 2019. The studies reviewed and interpreted by board certified Sleep Specialists. Studies were done using nox-T3 sleep monitor and Nomad portable Home Sleep Testing type III devices-Both are type 3 Portable Monitors. Only those patients whose REI in their HSAT less than 5 were included in this study. All these patients had multiple airflow fluctuations in their HSAT that raised the suspicion for the presence of RERAs. None of these patients had significant hypoxemia in the HSAT.Airflow fluctuations were defined by the presence of fluctuations in the signal in the airflow channel along with increasing thoracoabdominal channels. Those patients with REI of less than 5 and without airflow fluctuations were excluded from the study. Results A total of 178 patients were recommended to undergo an in-center polysomnogram. Of those, 92 patients completed their polysomnogram with 59 patients ending up with a diagnosis of sleep apnea while 33 did not suggesting a false negative rate of 64.13%. Of those who were positive, 39 were females while 20 were males. Both groups did not differ significantly. Females had a median BMI of 32.9(28.19 for males), a median ESS of 11(8 in males) and a median RDI of 14.8(13.25). Conclusion Our study shows that both Home Sleep apnea testing can have a high proportion of false-negative results in patients exhibiting thoraco-abdominal and airflow fluctuations. The interpreting physicians should understand the limitations of the HSAT and should have a low threshold to recommend an in-center polysomnogram. Support None.

Polyacrylonitrile/polyimide composite sub-micro fibrous membranes for precise filtration of PM0.26 pollutants

Particulate matter (PM) pollution has enormously threatened ecosystem and public health. Among various air filtration medium, fibrous ones are very attracting and promising, with an array of advantages such as high specific surface area, and good internal connectivity. Even so, the large-scale fabrication of fibrous filtration materials still remains challenging. Here, three-dimensional polyacrylonitrile/polyimide (PAN/PI) composite sub-micro fibrous membranes were fabricated facilely via free surface electrospinning for precise filtration of PM0.26 pollutants, where the waste PI short fibers were utilized as raw material. The resultant composite fibrous membranes, featuring thin fiber diameter (~150 nm), low areal density (<0.8 g m−2), large porosity, and highly tortuous airflow channels with uniform poresize distribution, possessed excellent mechanical property with tensile strength of 4.95 MPa (twice that of pristine PAN), high thermal durability as well as remarkable filtration performance for ultrafine NaCl aerosol particles (≤0.26 µm) even after multiple filtration tests at high airflow velocity of 14.1 cm s−1. The deepened aperture channels inside three-dimensional sub-micro fibrous membranes are tortuous enough for capturing ultrafine PMs from the airstream mainly via diffusion, interception, and impaction mechanisms, and the reported large-scale fabrication of cost-effective homogeneous PAN/PI fibrous filter media is promising for industrial production and commercial applications.

Thermal and flow performance of tilted oval tubes with novel fin designs

We studied the thermal and flow performance of tube heat exchangers with novel fin designs for tube tilt angles of 0°, 20°, 30° and 40° to the horizontal. The novel fin designs target to enhance the conduction heat transfer within the fin and the convective heat transfer along the fin surface simultaneously. Tubes with three different fin designs, the circular plain fin (CPF), the circular integrated pin fin (CIPF) and the serrated integrated pin fin (SIPF), were additively manufactured by selective laser melting and experimentally investigated in an air flow channel for Reynolds number between 1800 and 7800. We analysed the performance evaluation criterion, the volumetric heat flux density and the global performance criterion. It was found, that the SIPF achieves highest performance evaluation criterion and the CPF performs worst. Thus, the SIPF is recommended, when the required surface area, the material cost and the weight of the finned tube heat exchanger are relevant. Highest heat transfer per volume heat exchanger and temperature difference was achieved for the CIPF at highest tube tilt angle. The value of the global performance criterion strongly depends on the fin design and the tube tilt angle. For the horizontal orientation the CPF reaches highest global performance and for the 40∘ tube tilt angle the CIPF gives best performance. From the experimental data we derived appropriate heat transfer correlations for Reynolds number, Prandtl number, tube tilt angle and fin designs.

Identifying the dominant mode of moisture transport during drying of unsaturated soils

Diffusion of capillary water and water vapor during moisture loss in an unsaturated soil is impeded by the chemical and geometrical interactions between water molecules/vapor and the soil structure. A reduction in moisture content contracts the diffuse and adsorbed water layers in the partly saturated soil and disturbs the connected capillary network for flow of liquid water. With further drying, the dry soil layer expands and moisture is predominantly lost as vapor through continuous air-flow channels. The water-filled capillary network and air-filled channels are moisture conduits during different stages of soil drying. It is important to identify zones of dominant moisture transport and to select appropriate tortuosity equations for correct prediction of moisture flux. Laboratory experiments were performed to determine moisture flux from compacted soil specimens at environmental relative humidity of 33, 76 and 97% respectively. Analysis of the resultant τ - θ (tortuosity - volumetric water content) relations, illustrated the existence of a critical water content (θcr), that delineates the dominant zones of capillary liquid flow and vapor diffusion. At critical water content, the pore-size occupied by the capillary water is governed by the generated soil suction. Generalized equations are proposed to predict tortuosity factor in zones of dominant capillary liquid flow and vapor transport over a wide range of relative humidity (33 to 97%).

Helium leak detection methods using temperatures of a canister bottom and air at an inlet

The aging management of spent nuclear fuel has received increasing attention worldwide. The loss of containment by stress corrosion cracking (SCC) on the canister surface of the concrete cask has been concerned. However, a detector of a helium leak from the canister has not been installed. In light of further improvement of the safety, the containment of the concrete cask should be monitored on a steady basis as well as the metal cask. For development of the detector, we experimentally confirmed that when the internal pressure of the canister decreased, the temperature of the upper part of the canister decreased and the temperature of the bottom of the canister increased. Based on this phenomenon, we had proposed a method using the temperature difference between the top and bottom of the canister for leak detection. This method requires the temperatures at two points on the canister surface; however, it would be difficult to install a temperature sensor on the canister bottom in the case of an air flow channel with a complicated shape. Thus, we have been investigating an easier technique that the leak could be detected by temperature information only at one of the two points on the canister. A method using ambient temperature at the top of the canister has already been developed, and this paper introduced new detection methods using the temperatures of the bottom of the canister and air at its inlet.

Thermal performance of integrated collector storage solar air heater with evacuated tube and lap joint-type flat micro-heat pipe arrays

To alleviate the problem of global warming and the energy crisis, this study proposed an integrated collector storage solar air heater that uses evacuated tubes as solar absorbers and paraffin as thermal storage material. In the proposed unit, lap joint-type flat micro-heat pipe arrays serve as heat conductors that transmit the solar energy absorbed by the evacuated tubes to the thermal storage tank or transfer the heat stored in the tank to the air flow channel. Outdoor experiments were carried out to obtain the thermal performance of the proposed device during charging and discharging. The effects of weather conditions, supply air flow rates, and inlet temperature on the thermal response of the integrated collector storage solar air heater were reported. The thermal storage efficiency during the experiment period ranged from 56.1% to 67.5% when the mean outdoor temperature ranged from −5.7 °C to 36.2 °C. The mean thermal extraction power and thermal released efficiency reached 1268.8 W and 98.5%, respectively. The results of the energy conversion process analysis and mathematical fitting showed that the mean charging efficiency was linear with the normalized temperature difference. The mean outlet temperature and mean extraction power were linear with the inlet temperature and exponential with the air flow rate. A conceptual design of an air heating system using the integrated collector storage solar air heater for a 9.9 m2 building was presented. The benefit pre-evaluation revealed that the system can reduce carbon emissions by approximately 5.8 tons over its life cycle.

Análisis teórico de una chimenea solar con tres canales de flujo de aire

A solar chimney configuration consisting of three air flow channels divided by two metallic plate, placed in the center of the chimney between two acrylic covers, leading to symmetric air flow, is proposed as an alternative for the design of natural ventilation systems for buildings in tropical and subtropical climatic zones The solar chimney dimensions are 2.0 m height, 1.0 m width, and gap between channels of 0.30 m. These dimensions are appropriate for the design of ventilation systems for residential buildings in central México. A Numerical simulation using the global mass and energy balances in steady state was utilized to evaluate the efficacy of the proposed configuration. The temperature profiles, calculated for a typical hot day in a tropical region, reveal that the configuration is more efficient than the single channel chimney, achieving thermal efficiency values near 75%. This solar chimney configuration can be used with better results than the traditional design as an alternative for natural ventilation systems in residential buildings without a significant increase in the cost of the residence investment.

Design of Web-to-Web Spacing for the Reduced Pressure Drop and Effective Depth Filtration.

The study aims at lowering the pressure drop and extending the service life at a given set of filter materials implementing a space between the filter layers. As design factors, the web-to-web space was implemented by inserting either a bulk air gap or porous spacer web between the filter webs. The effect of spacing, either by the air gap or by the spacer web, on the pressure drop reduction was apparent for 4-layer constructions, and the effect was greater at the higher face velocity. The use of spacer web was more effective than the air gap in reducing the pressure drop, because the porous, fluffy spacer web acted as an effective air flow channel between the compact filter layers. The loading capacity was also increased with the spacer web implementation, effectively delaying the clogging point and extending the service life. Employing both experimental investigation and numerical simulation, this study intended to provide a practical design solution to the important problem in the field of air filtration. The results of this study can be used as a practical design guide to reduce pressure drop via depth filtration.

Singing Voice Quality: The Effects of Maxillary Dental Arch and Singing Style

In classical singing techniques, it is common to manipulate the vocal tract to channel airflow to increase voice quality and volume. Technique varies according to the style of the music, the voice type, and range of a given singer. Although these practices are intentional, fixed physiological aspects of a singer's vocal instrument also play an extremely impactful role in determining voice quality. In the present study, the relationship between the dimensions of the maxillary dental arch and voice quality were examined in professional singers. The dimensions of the palate were measured from the maxillary dental casts of 14 female singers. Audio recordings were made for the same participants while singing a sustained /a/ singing vowel, a glissando, the song "Are You Sleeping", and a selected song from their personal repertoire. The dimensions of the palate were measured from maxillary dental casts. From the recordings, two parameters were calculated: (1) the Singing Power Ratio (SPR) and (2) A2 A1 ratio. Higher SPR values indicate a stronger ring in the voice, typical of operatic singing style, while higher A2 A1 ratio values are associated with the belting singing style. Singers with larger frontal palate depth, smaller posterior palate depth, larger frontal palate width, and smaller posterior palate width seem to be more suitable for an operatic singing style. Singers who had larger overall depth and width of the palate measurements produced an increased second harmonic, typical of the belting style. When considering a singer's ability to produce vocalizations successfully, physiological structure is an increasingly important factor. The present study discovered that palate depth and width are associated with statistically significant differences in SPR and A2/A1 parameters. These parameters correlate with two styles of singing, operatic, and belting respectively.

Development of an Electrochemical Oxygen Compressor and Generator for Spacesuit Oxygen Resupply

NASA is sponsoring the development of an electrochemical method of supplying high pressure, high purity oxygen suitable for recharging spacesuit tanks during an exploration mission. The system is referred to as the Electrochemical Oxygen Generator and Compressor (eCOG-C). The method uses a ceramic oxygen transport membrane, with internal process airflow channels, and an electrochemical configuration that electrochemically pumps oxygen from the process air to the external environment. The oxygen transport membrane is placed inside a thermally insulated pressure vessel, allowing the oxygen to accumulate and pressurize. Except for a simple process air blower, the device is solid state. An alternate version of this process has demonstrated the ability to produce high purity (>99.99%) oxygen from ambient air. This version is intended to produce high pressure oxygen, the design goal is >4000 psig delivery pressure. This paper describes the NASA application, and the electrochemical systems found in the ceramic oxygen transport membrane. This project is in an early stage of development, a feasibility assessment has been completed, and the first iteration of prototyping is underway. There are three areas of emphasis in the initial prototyping effort: 1) developing interconnecting seals that join two different wafers with sufficient bond strength to sustainably withstand pressure forces, 2) developing interconnecting seals that join two different wafers with well matched coefficients of thermal expansion (CTE), to minimize thermal stress in the cell stack, 3) developing a ceramic transport membrane wafer with internal process air flow channels. Figure 1

The design and performance evaluation of a high-efficient flexible solar air heater based on transparent spacer fabric composite

In this paper, a novel flexible solar air heater (FSAH) has been rationally designed and fully investigated by practical experiments. The main part of the FSAH is an integrated flexible warp-knitted spacer fabric composite, in which spacer filaments are coated with solar energy absorbing materials by the air spraying method. In this system, flexible spacer fabric composite not only works as a solar thermal energy harvesting layer, but also provides airflow channels for energy transmission. By comparison test, it is found that the outlet temperature and thermal efficiency of FSAH were improved by introducing nano-black carbon particles as solar energy absorbing materials coated on the surface of spacer filaments. An analysis of net energy gain and effective efficiency was then carried out and the best thermohydraulic performance of the as-fabricated FSAH was found at the mass flow velocity of 0.037 kg m−2 s−1. The optimization experiments demonstrated that with the increase of heater length, the outlet temperature and energy gain of FSAH increased, while their thermal efficiency and effective efficiency decreased. Furthermore, to reduce the heat losses from the top layer to the surrounding ambient, another layer of transparent spacer fabric composite was assembled with the FSAH as a thermal insulation layer and its thermal efficiency and effective efficiency were found to be increased by 20%.

Influence of the location of discrete macro-encapsulated thermal energy storage on the performance of a double pass solar plate collector system

In this work, an outdoor experimental analysis is conducted to determine the impact on the useful heat gain when discrete cylindrical energy storage units are directly integrated into the solar collector. The collector has a double-pass airflow channel pathway, and the storage is intended to serve only for a short-term. The location of storage inside the collector is always a major concern. This study seeks to determine whether the thermodynamic performance of the system is effective by the location of cylindrical energy storage (paraffin wax) capsules on the upper or the lower airflow channel pathway. The obtained results suggest that due to asymmetric channel depth, the thermodynamic performance of the collector was not greatly influenced by the placement of capsules, unlike with symmetric channel depths. The amount of useful heat gain when storage was placed in the upper (Case A) and lower (Case B) airflow pathways was 0.35 kW and 0.4 kW. For Case A and Case B, the average collector thermal efficiency was 62.9% and 73.7%, and the exergy efficiency was 44.3% and 47.5%. The energy payback time for the collector based on energy calculations is nine months, and that on exergy analysis is 34 months and 20 days.

Determination of the aerosol disperse composition by a laser particle analyzer with Gaussian distribution of the light beam intensity

Optical devices for detection and sizing of aerosol microparticles (aerosol particle counters) employ the fact that the scattering efficiency, and accordingly, the scattering signal amplitude grows with the particle’s size. This principle implies that all the analyzed particles “feel” the same optical field intensity. However, frequently the light beam intensity in the measured volume depends on the coordinates, and identical particles produce different scattering signals depending on their trajectory with respect to the light beam axis. In such situations, typical for laser light sources, the unambiguous relation between the particle size and the scattering signal amplitude is destroyed. However, the original particle-size distribution can be retrieved via a special mathematical processing, provided that statistical parameters of the particles’ trajectories are known, as well as the spatial inhomgeneity of illumination. We develop the mathematical model describing formation of the scattering signals’ set. It leads to an integral equation involving the probability densities of: (i) the scattering signal amplitude, A, distribution P(A); (ii) the particle radius, a, distribution W(a) in the original aerosol; the particle-trajectories’ spatial distribution n(x) with respect to the light beam axis x = 0; and the spatial distribution of the light intensity I(x) within the measuring volume. For the practical case of Gaussian I(x) and rectangular n(x), the equation can be reduced to the known Abel equation, which enables to retrieve W(a) from the experimentally measured P(A) via the exact analytical expression. However, in many practical situations a numerical approximate approach may be more efficient. To this end, we describe in detail a simplified numerical procedure that enables to find the numbers of particles whose sizes lie within a few fixed intervals. Additionally, we show that a proper choice of such intervals can eliminate the harmful influence of the non-monotonic calibration curve of the aerosol counter. The algorithms and procedures are illustrated by numerical examples with a set of polystyrene particles whose sizes are distributed log-normally within the range 0.3 mm to 5 mm, analyzed by the aerosol counter that employs a semiconductor-laser beam of the wavelength 0.85 mm and radius 0.1 mm crossing the 1-mm air flow channel.

Holographic deflection imaging measurement of electric charge on aerosol particles

We propose a simple noninvasive technique called holographic deflection imaging (HDI) to measure electric charge on individual aerosol particles. Particles in many flows such as atmospheric turbulence can carry electric charges, which add forces that compete with turbulence and affect particle dynamics. To measure particle charges, we devised a novel technique for polydispersed particles with bipolar charge distributions. The technique uses common optical hardware and a novel particle sizing algorithm for polydispersed size distributions. A charged particle sample is introduced into a vertical channel air flow and a horizontal electric field. For each particle, In-line digital holography is used to simultaneously track particle positions over successive holograms and decode size information from hologram interference fringes. This enables measurement of the electric-force-induced horizontal component of terminal velocity and the particle size. From velocity and size, particle charge is calculated using a force balance, assuming Stokes drag on spherical particles. Two experiments were conducted, one to validate HDI measurements of a bipolarly charged particle sample against an electrometer, and the other to demonstrate particle size effect on triboelectric charging of aerosols in a fan-driven isotropic turbulence chamber. The HDI setup was configured for each experiment, and measurement uncertainty was estimated. Experiment 1 found good agreement (< 5%) in mean charge between measurements by HDI and the electrometer. Experiment 2 found nearly symmetric bipolar charge distributions, which broadened with increasing particle surface area, as expected for triboelectric charging by the symmetrically installed fans.

Stokes-layer formation under absence of moving parts—A novel oscillatory plasma actuator design for turbulent drag reduction

A novel plasma actuator concept is proposed to mimic the effect of spanwise wall oscillations without mechanically moving parts, where four groups of electrodes and three independently operated high-voltage power supplies maintain a pulsatile dielectric barrier discharge (DBD) array. Time-resolved planar velocity fields are obtained with high-speed particle image velocimetry (PIV) in proximity of the discharge zones for quiescent ambient conditions. Resulting flow topologies and wall-normal velocity profiles indicate the Stokes-layer-like flow formation, which is elevated above the wall due to the no-slip condition. The underlying body forces are derived from the PIV data to provide further insight into cause-effect relations between pulsatile discharge and oscillatory flow. The momentum transfer domain is found to be only interrupted with the width of the exposed electrode, which is an important step toward homogeneous virtual wall oscillations. A comparison with earlier studies by Gatti et al. [“Experimental assessment of spanwise-oscillating dielectric electroactive surfaces for turbulent drag reduction in an air channel flow,” Exp. Fluids 56, 110 (2015)] leads to the hypothesis that DBD-based turbulent drag reduction might be a competing alternative to conventional active and passive shear-layer formation strategies, where the adjustability of both oscillation frequency and velocity amplitude might cover a wide range of Reynolds numbers.

Pemanfaatan Potensi Energi Aliran Kanal Kalisolo I pada Pusat Pengembangan Sumber Daya Manusia Minyak dan Gas Bumi

Energy needs to improve services and operations in every office are needed, as well as infrastructure for oil and gas PPSDM infrastructure; Office, laboratory, housing and processing facilities are reported. Along with operational costs that increase in terms of energy costs, which include electricity, air and fuel oil. Oil and Gas PPSDM can request operational costs. The utilization of this energy can simultaneously participate in government programs to develop new renewable energy, as well as a pilot project for the community to use waste energy. To fulfill the need for clean water in Oil and Gas PPSDM, which on average every meeting requires water of 3,250 m3, using air from Bengawan Solo, which is processed in the air treatment section, by pumping and channeling it through the traffic channel to processing tanks. The air flow in this canal requires energy as a power plant. In this research, the installation of Kalisolo 1 Oil and Gas PPSDM Channel was installed for Hydrokinetic Power Plant (PLTHk) and / or Micro Hydro Power Plant (PLTMH) using the Open Flume Turbine. After measuring the object and analyzing it, on object I with a cross-sectional area of ​​1 mx 0.35 m, velocity of channel air flow 0.8 m / s, the power potential of 89.6 W. was obtained in object II with a cross-sectional area of ​​0, 4 mx 0.4 m, canal water flow velocity 0.4 m / s, obtained power potential of 5.12 W, if using MHP. While using the Micro Hydro Power Plant (PLTMH) using the Open Flume Turbine, taking into account the 2 m water head, on my object it can produce electric power of 494,424 W or 0.5 kW, and if the air head is 1 m, power can be generated electricity is 247,212 Watt or 0.25 kW, with generator efficiency 0.9 and turbine efficiency of 0.9, while in object II the Turbine Flume PLTMH cannot be regulated, because it is difficult to design head water.

Thermo-hydraulic performance enhancement of convex-concave natural convection solar air heaters

Conventional natural convection flat plate solar air heater (SAH) suffers from low heat transfer characteristics. Putting extended surfaces in the air flow channel to augment thermal performance actually hinders the buoyancy driven flow, and thereby reducing the hydraulic performance due to high frictional losses. The objective of the present study is to enhance thermo-hydraulic performance by incorporating convex and concave flow channel with chimney effect. The curved SAH has been investigated using an experimentally validated computational fluid dynamic model for different curvature angles in the range of 25–50°. The results show significant increase in Nusselt number per unit pressure drop (NuP), heat transfer enhancement factor, temperature enhancement ratio and effectiveness, in comparison to conventional flat SAH. The convex and concave designs are respectively 43% and 31% thermally, and 7% and 6% by NuP, higher than conventional flat natural convection SAH. Two different independent correlations derived for Nusselt number for different geometries were found to be in excellent agreement with the data. The designs and data presented in the study would help scientific community and solar based industries in developing efficient natural convection SAH.

Summer study on thermal performance of an exhausting airflow window in evaporatively-cooled buildings

By using exhaust mode ventilated windows in buildings cooled by evaporative cooler, the air flow channel of the window can play the role of natural relief air path. Thereby, the cooling potential of the relief air can be recovered and used to improve the thermal performance of the ventilated window. This paper investigates the thermal performance of an exhausting ventilated window in a typical evaporatively-cooled space. In this study, a zonal model has been used for simulation. The numerical approach was validated with reported experimental data and good agreement was shown. Results showed that the heat gain and the maximum daily temperature of the interior glass pane of the proposed ventilated window are less than those of the conventional double-glazed window. Providing natural relief through ventilated window can cause extra pressure drop and consequently reducing cooling capacity. This may also disturb the occupant's comfort due to noise issue. Hence, the impacts of window aspect ratio and thickness of the air flow channel have been investigated as effective factors on pressure drop and sound power level. Eventually, a step by step procedure has been proposed for determining the geometric parameters of the ventilated window for practical use in evaporatively-cooled buildings.

Prediction of Noise Transmission Loss and Acoustic Comfort Assessment of a Ventilated Window using Statistical Energy Analysis

In this paper, a novel analytical method was developed based on statistical energy analysis framework to evaluate sound transmission loss through ventilated windows. The proposed method was compared to numerical and analytical models available in the literature. Results showed the success and advantage of the proposed model in predicting the acoustic performance of the ventilated window and the proposed method proved itself as a low-cost and high-accurate method. Considering the slit-like effect of the inlet and outlet of the ventilated window and channel attenuation is the distinct feature of the proposed method compared to the existing analytical models. This paper also discussed the effectiveness of the ventilated window in the provision of indoor acoustic comfort according to the different types of the outdoor traffic noise spectra and sound transmission loss. The results showed the acceptance of the indoor noise level made by the ventilated window. To recognize how the effective factors improve the acoustic performance of the ventilated window, the effect of window aspect ratio, channel thickness and opening size on Sound Transmission Class (STC) were studied. The results revealed that the ventilated window with higher aspect ratio and wider airflow channel has a higher STC while widening the opening size reduces the sound insulation.

Effective efficiency distribution characteristics in protruded/dimpled-arc plate solar thermal collector

Protruded or dimpled-arc absorbers help in accelerating the heat transfer through the rectangular air flow channels while keeping the friction factor at lowest possible value. In the present study, the effective efficiency distribution for protruded/dimpled-arc absorbers in a solar thermal collector is studied taking into account the thermal energy gain and the required pumping power for air flow as simultaneous considerations. The mathematical model used for computation has been validated and the effective efficiency characteristics have been presented as a function of flow Reynolds number. Further, the optimization of process parameters has been carried out and the design procedure for selection of optimal set of design parameters for desired value of temperature rise is discussed. The investigation concludes that the relative height and pitch affect the effective reattachment of the distributed flow whereas the arc angle due to presence of vortex legs generation by dimple/protrusion affects laminar sub-layer and thereby the performance attributes. Highest effective efficiency of 72% for protruded-arc absorber for protrusion height ratio of 0.36, protrusion pitch ratio of 12 and arc angle of 60° has been achieved while maximum of 69.7% for dimpled-arc absorber is achieved on dimple height ratio of 0.3, dimple pitch ratio of 10 and arc angle of 60°.