Fin Surface Research Articles

Trochopus martydeveneyi n. sp. (Monogenea) infecting the pectoral fins of the southern African endemic Cape gurnard, Chelidonichthys capensis in Table Bay, and the proposal of Trochopus lawleri n. sp. for T. hobo from Australia.

Trochopus martydeveneyi n. sp., a large, elegant species is described from the dorsal surface of the pectoral fins of captive Cape gurnard, Chelidonichthys capensis (Cuvier), at Two Oceans Aquarium, Cape Town, originally collected from Table Bay, South Africa in 2007. The host microhabitat for T. martydeveneyi n. sp. is uncharacteristic for Trochopus species, which are generally known from the gills, and less so from the skin of the body of their hosts. This new species is unique among the known Trochopus species, possessing a large, dark-staining gland on each of the two testes, presumably to produce the contents of the spermatophore plug that is visible in the vagina of two specimens. Two separate individual specimens of T. martydeveneyi n. sp. also presented with unilateral testicular atrophy, which is apparently rare in the Monogenea but considered a natural occurrence. Egg hatching and larval haptoral morphology are also provided. Trochopus lawleri n. sp. is proposed for Trochopus hobo sensu Lawler and Hargis (1968) from the gills of Chelidonichthys kumu (Cuvier) off Australia, and the monotypic Trochopella Euzet & Trilles, 1962 is synonymised with Trochopus Diesing, 1850. The generic diagnosis is revised for Trochopus to incorporate new data, and information previously excluded.

A New Technique to Qualify Rotary Electro-Mechanical Actuator for Tactical Class of Missile System

A novel technique has been adopted to establish the functionality and to qualify the Rotary Electro-Mechanical Actuator (REMA) system developed for a typical tactical class of weapon system in addition to the conventional method of checking the functionality through On-Board Computer in-loop simulation, Actuator in-loop simulation and Hardware in-loop simulation. The REMA along with full scale fin surface subjected to wind tunnel tests at the actual flight Mach number and flight dynamic pressure conditions. Flight hardware of REMA and fin assembly has been used in the tests so as to derive direct conclusions without applying any corrections to the measured results. This technique revealed the capability of the actuator, the dynamic functionality of its components such as gear systems, bearings and structural integrity of the whole actuator under the flight aerodynamic load on the full scale fin surface and vibration environments. The test conducted is being the most critical condition and the REMA and fin combination performed the intended commands as predictable and survived without any structural dis-integrity qualifies for further flight use. Subsequently flight tests were conducted and found the performance of REMA was as anticipated. Based on these results, recommendation made that it is mandatory that the all the actuation systems developed for fin actuation in missiles has to undergo the wind tunnel tests and qualify further actual use. The details of wind tunnel tests and the results of typical REMA with full scale fin are presented in this paper.

Comparative analysis of transient thermal behaviour and efficiency in longitudinal metal porous fin with combined heat and mass transfer under dehumidification conditions

This investigation explores the transient thermal characteristics of longitudinal porous fins made of Aluminium (Al) and Copper (Cu), exposed to a dynamic moist airstream under dehumidification conditions. Heat and mass transfer processes are initiated when the fin surface temperature falls below the dew point temperature of the surrounding air, driven by differences in temperature and humidity ratios. Heat transfer within the porous structure is modelled using temperature-dependent convective coefficients and Darcy’s flow model, with the governing nonlinear partial differential equation transformed into dimensionless form and solved using the Finite Difference Method (FDM) to analyse the fin thermal profile and efficiency over time. These results reveal that Cu fin due to their superior thermal conductivity exhibit higher temperature profile and efficiency compared to Al fin across all pertinent parameters. A key finding is the significant impact of Relative Humidity (RH) on the thermal behaviour of the fin: as RH increases by 400%, the temperature distribution from base to tip decreases by 138% in Al due to its higher specific heat capacity, which enables it to absorb more latent heat and 85% in Cu, where the superior thermal conductivity allows for faster heat dissipation. As Darcy number (Da) decreases by 99%, the temperature distribution along the fin from base to tip increases by 0.058% in Al due to its lower thermal conductivity and 0.041% in Cu, where its higher thermal conductivity enables more efficient heat dispersion. These insights are pivotal for advancing fin design and optimization, facilitating improved thermal management in industrial applications under transient and dehumidifying conditions.

Combining pin-fins and superhydrophobic surfaces to enhance the performance of microchannel heat sinks

Electronics cooling and thermal management presents an immense challenge to the electrification of society. From mobile devices to stationary systems, power densification of electronics platforms is putting pressureon thermal systems. This research uniquely combines superhydrophobic surfaces with pin-fin structures to investigate their combined effects on thermal performance and fluid dynamics. We examine the impact of superhydrophobic surfaces on different internal walls for both finned and non-finned microchannels. Three-dimensional finite volume method simulations are used to analyze fluid flow and heat transfer, with surface wettability modeled using a custom user-defined function. The results of the simulations were first validated against experimental data. Thermal-hydraulic performance for finned and non-finned microchannels was studied for both conventional and superhydrophobic surfaces. Superhydrophobic properties on different internal surfaces of the microchannel yielded different outcomes for finned versus non-finned designs. We show that superhydrophobic surfaces are effective in enhancing the performance of finned channels at high Reynolds number (Re). At Re = 500, finned microchannels with superhydrophobic side walls have the same performance factor (η) as a conventional microchannel without fins with a 9.4 °C lower average base surface temperature. Additionally, superhydrophobic side walls increase the pressure drop and Nusselt number by 8.9 % and 6.6 %, respectively, compared to conventional non-superhydrophobic finned surfaces. Conversely, superhydrophobic top and bottom surfaces reduce the pressure drop and Nusselt number by 13 % and 18.5 %, respectively. Our findings reveal that the location and intensity of vortices, influenced by fins, vary with different superhydrophobic surface configurations.

Data Generation and Training of Surrogate Models for Friction Factor and Nusselt Number in Low Reynolds Number Flows Through Pin Fin Geometries

Abstract The design of various biomedical, electronics cooling, and microfluidic devices relies on geometry-specific models and empirical correlations for flow and heat transfer through microscale pin fin geometries. Machine learning (ML) techniques are being used across many branches of science to develop more generalized surrogate models that can predict such transport processes. To collapse the simulation of flow and thermal properties across many different pin fin surfaces into a single predictive tool, the present study develops machine-learning-based surrogate models for the friction factor and Nusselt number (for constant wall temperature conditions) for fully developed low Reynolds number flow across pin fin geometries of differing cross section shape (circular, square, triangular) in aligned or staggered arrangements, oriented at any angle to the incoming flow, and for a range of transverse and longitudinal pitches, with water as the working fluid. The model training data are generated using an automated workflow that allows thousands of numerical simulations to be carried out on across different geometric and flow configurations. A total of ∼14,800 distinct simulation cases, for both friction factor and Nusselt number, are generated while varying the Reynolds number and aforementioned geometric parameters to train and test the machine learning models. The machine learning model architecture takes inputs of both image and vector data, and then outputs a scalar friction factor or Nusselt number. The trained models yield a goodness of fit (R2) value of 0.98 on unseen data.

Porous mesh manifold for enhanced boiling performance

High-performance electronics are continuously demanding cooling of higher heat fluxes. Phase-change cooling, including pool boiling, is a useful approach to address this challenge; however, competition between liquid and vapor flows generally limit the heat fluxes that can be dissipated. A range of strategies to control these flows have been investigated previously, including capillary guides. Here a manifold structure formed from a metallic mesh is investigated to control the disposition of liquid and vapor phases above a pool fed boiling surface enhanced with porous structures. Copper mesh forms defined liquid flow paths, using capillary action to guide and distribute liquid evenly over the heated surface, along with open channels to facilitate vapor escape. The mesh provides a novel structure for liquid guidance that imposes low resistance to liquid flow while occluding a minimal area of heated surface underneath. The manifold performance is characterized in boiling fed by a pool of water above a laser-textured aluminum nitride heat dissipation surface with pin–fin structures having heights of 110 µm and spacing of 30 µm with a heated area of 5mm x 5mm. A maximum heat flux of 490 W/cm2 is reached with the manifold in the pool fed configuration, representing an increase of more than 65% over the porous pin fin surface alone. The maximum stable superheat observed for the manifold of 36K is 14K higher than that for the porous surface without the manifold. The factors limiting performance of the manifold are analyzed. High superheat is attributed to partial flooding of the boiling surface as suggested by the reduction in superheat using external suction. Similar systems and structures for enhanced two-phase cooling are compared.

Comparison of subcooled flow boiling in concentric annuli with bare and finned surfaces

In this study, the hydrodynamic and thermal characteristics of subcooled flow boiling in concentric annuli with inner heating wires, featuring bare and finned surfaces designed for heat transfer enhancement, were experimentally investigated, with a focus on cooling technology for EV charging cables. The bare wire test module consisted of a 300 mm long wire, with a 290 mm long inner heating surface and a diameter of 10 mm. The outer tube was constructed from transparent polycarbonate with a 22 mm diameter, allowing optical access to observe the flow. The finned wire test module has an identical construction, except for the addition of six longitudinally extruded fins with cross-sectional dimensions of 2 × 5 mm2. Experiments and flow visualizations, aided by high speed imaging, were conducted using HFE-7100 as the working fluid at mass velocities, G, 463.7 to 1,309.6 kg/m2s and heat fluxes from 0.90 to 9.93 W/cm2, under inlet pressures between 120 and 240 kPa. The study investigated thermal non-equilibrium phenomena, driven by asymmetric bubble accumulation, and their effects on circumferential temperature distribution, which showed opposing trends between the bare and finned surfaces. An evaluation of previous empirical correlations for predicting subcooled flow boiling heat transfer coefficients was performed, followed by an assessment of fin performance in enhancing heat transfer. A comparative analysis with the bare surface module of the same dimensions confirmed that the longitudinal fins provided superior thermal management, maintaining the surface temperature below the safety threshold, Ts,safe. The longitudinal fins demonstrated a 54.5 % reduction in charging time and a 183.7 % increase in charging current for charging up to 80 % state of charge (SOC) of a 77.4 kWh battery, compared to the bare wire.

Engineering of a Bio-Inspired Tiltable Oscillating Fin Submersible Thruster

Oscillating fins are devices designed to produce thrust through periodic undulating movements. However, these structures lack flexibility and often provide thrust in only one fixed direction. Observation and biological references suggest that the dorsal fin rays of seahorses can tilt longitudinally in the spine direction, changing the thrust direction. This study aims to analyze the dynamic effects of seahorse dorsal fin inclining and design a flexible bionic thruster based on this principle. Computational fluid dynamics analysis hypothesizes that fin inclination controls the net force direction in the vertical plane. A force sensor and pulley system test platform were constructed to examine the influences of wave features and the inclination angle on thrust in both vertical and horizontal directions, with discrete fin surfaces used to eliminate force interference. Force testing and snapshots indicate that wave velocity positively impacts net force magnitude, while fin inclination allows for control over force orientation. This tiltable oscillating fin thruster possesses more degrees of freedom, leading to better flexibility and providing controllable thrust orientation.

Boiling heat transfer of water on smooth and square pin fins surfaces in minichannel

In this investigation, flow boiling heat transfer and hydrodynamic instability using deionized water in a minichannel with smooth and square pin fin surfaces was experimentally examined. The study is aimed to assess local and overall heat transfer coefficients, heat transfer coefficients, pressure drop and Nusselt number across various liquid mass flux ranges (50–93 kg m−2 s−1) and a constant heat flux of 46.91 kW/m2. The minichannel, with a hydraulic diameter of 2.85 mm, features a rectangular shape. Experimental testing was conducted on aluminum surface within a minichannel of dimensions 270 mm in length, 30 mm in width, and 1.5 mm height. The square pin fins are integrated at the base of the boiling surfaces, arranged in staggered form. The results revealed that the boiling heat transfer coefficient on square pin fin surfaces was approximately 88 % higher than that on smooth surfaces. Additionally, a notable increase in local heat transfer coefficient was observed for square pin fin surfaces (i.e., 34.64 kW/m2.K) compared to smooth surfaces (8.09 kW/m2.K) at the same mass flux of 50 kg/m2.s. Besides, the square pin fins surface exhibited a lower and stable pressure drop, particularly near annular flow regimes, compared to the smooth surface. Notably, the highest pressure drop observed was 4.8 kPa for the square pin fins surface, while the smooth surface experienced a higher pressure drop of 6.36 kPa, accompanied by more pronounced pressure fluctuations during annular flow.

Effect of pin fins on heat transfer during condensation in minichannel heat exchanger

In this study, condensation heat transfer of water vapor in a minichannel heat exchanger on smooth and pin fins surfaces was investigated experimentally. The experimental study was carried out to evaluate heat transfer coefficient, overall heat transfer coefficient, and Nusselt number over different ranges of vapor mass flux from 0.0064 to 0.0368 kg m−2 s−1 and cold-water flow rate range between 0.0013 kg s−1 to 0.0057 kg s−1. The minichannel has a rectangular shape with a hydraulic diameter of 1.3 mm. The experimental testing is carried out on aluminum surface with a channel that has a length of 270, width of 30 mm, and height of 1.3 mm. The pin fins surface is on the bottom of the condensing channel and the fins are circular and have diameter, height, and spacing of 1 mm, and are in-inline arrangement. It is found that condensation heat transfer coefficient on pin fins surface is about 15 % higher than that on smooth surface. It is found that the condensation heat transfer coefficient increases significantly with increasing the vapor mass flux. In addition, the effect of increasing the cold fluid flow rate is lower than that of the hot vapor flow rate, but it becomes more significant for higher vapor flux.

Improved Subthreshold Characteristics of Epi-Silicon FinFET via Fin Surface Passivation Technologies

As demand for advanced integrated circuits (ICs) continues to grow, fin field-effect transistors (FinFETs) have remained highly influential in the IC market because of their mature fabrication process and powerful driving capabilities. However, the ion bombardment that occurs during the reactive ion etching (RIE) process used to form the fin structure increases the fin’s surface roughness and results in a high interfacial state density (D it ), which hinders further improvement in the subthreshold swing (SS) of FinFETs. To overcome this issue, this study proposes two oxidative trimming methods for use on the fin structures to improve their interface quality. It is found that conventional thermal oxidation and low-temperature oxidation processes reduced the channel D it by 73.31% vs 71.17%, respectively. Furthermore, the corresponding SS values of the device improved to 72.76 and 71.72 mV dec−1, respectively. The technical solutions proposed in this paper represent a promising approach for performance optimization of FinFETs and other advanced devices.

Anti-Frosting and Defrosting Fins with Hierarchical Interlocking Structure for Enhancing Energy Utilization Efficiency of Heat Exchanger.

Air conditioners, being an indispensable component of contemporary living, consume a significant amount of electricity every year. The accumulation of frost, dust, and water on the fins surface hinders the efficiency of the heat exchange process, thereby reducing the effectiveness of the air conditioning system. To address these limitations, this paper proposes a large-scale and cost-effective method combining compression molding, chemical etching, and spray coating to fabricate aluminum fins (HMNA) with hierarchical interlocking structures. The HMNA exhibits outstanding durability, passive and active anti-icing, anti-frosting and defrosting, and self-cleaning capabilities associated with the robust super-hydrophobicity. The hierarchical interlocking structure effectively enhances the physical and environmental durability of the HMNA. Most significantly, the frost time of the HMNA fins assembled heat exchanger is significantly delayed by ≈700% compared to the traditional Al fins heat exchanger, while the frost layer thickness is reduced by ≈75%. This greatly reduces the frequency with which the defrosting cycle is started, thus effectively improving the efficiency of the air conditioning system. The proposed method for economical and mass production of the HMNA fins can be an excellent candidate for the development of low energy consumption air conditioning system.

Constructal design of cross‐flow heat exchanger with concave/convex fins

AbstractA contractual design of cross‐flow heat exchanger with concave/convex fins under fixed pressure drop is presented in this paper. An array of heated concave and convex fins are placed in a fixed area, and they are cooled by incoming cross flow, which is moving towards the fins due to constant pressure drop. The distances from fin to fin, the fin base, and the fin surface curvature (concave and convex) are free to morph and are constrained by the fin length and the height of cross flow. Bejan's number ranges from 105 to 107. The ratio of fin base‐to‐fin length is changed from 0.1 to 0.3. The dimensionless mass, momentum, and energy equations for two‐dimensional, steady, and incompressible flow are solved based on the finite volume numerical method. Also, the scale analysis method is used to compare heat transfer densities from concave and convex fins. The numerical results showed that the maximal convective heat transfer density for convex fins is higher than that of the concave fins for all Bejan numbers. The augmentations in the maximal heat transfer density are 2.1% at Be = 105, 4% at Be = 106, and 12.5% at Be = 107. Also, this is confirmed by the scale analysis method.

Local heat transfer measurements of the fin on the blade crown by infrared thermography

Current research on heat transfer of the labyrinth surface mainly focuses on the whole structure made of the same material, but the heat conduction from the tip to the root will affect the measurement of the heat transfer coefficient. To minimize the influence of heat conduction, copper strips are embedded on the surface of the fin made of bakelite. The inverse heat transfer problem is solved using the temperatures collected by an infrared thermal imager to determine the local convective heat transfer coefficient. The error of the lumped parameter method is smaller compared to the differential solution. Constant heat flux experiments are used to validate the experimental results, and numerical analysis is performed to analyze the heat transfer mechanism. The flow field, the Nu number distribution, and fitting correlations of the fins are obtained. By comparing and analyzing the heat transfer coefficients obtained by the three methods, it is found that the lumped parameter method can eliminate the influence of heat conduction on the surface. Taking the lumped parameter method as a reference, the errors of stable heat flow and numerical calculation were 21 % and 4.7 %, respectively. Due to the influence of the vortex direction, the Nu number distribution along the height of the windward surface of the second fin is different from the others. The Nu number distribution along the x-direction on the top surface of the fin is similar to the tip of the windward surface. Along the flow direction, the average Nu number on the top surface of the first fin is 1.2 times that of the second one.

Dynamic phase change materials with extended surfaces

Phase change materials (PCMs) present opportunities for efficient thermal management due to their high latent heat of melting. However, a fundamental challenge for PCM cooling is the presence of a growing liquid layer of relatively low thermal conductivity melted PCM that limits heat transfer. Dynamic phase change material (dynPCM) uses an applied pressure to pump away the melt layer and achieve a thin liquid layer, ensuring high heat transfer for extended periods. This paper investigates heat transfer during dynPCM cooling when the heated surface has extended features made from high thermal conductivity copper (Cu). Using experiments and finite element simulations, we investigate the heat transfer performance of dynPCM paraffin wax on finned Cu surfaces. A total of 102 transient temperature measurements characterize the performance of dynPCM with extended surfaces and compare the performance with other cooling methods including hybrid PCM and air cooling. The study examines the effects of fin geometry, applied power (20–65 W), and pressure (0.97–12.5 kPa). For dynPCM on a finned surface and a heating power of 65 W, the thermal conductance is 0.45 W/cm2-K, compared to 0.22 W/cm2-K for dynPCM on a flat surface and 0.10 W/cm2-K for hybrid PCM. The heat transfer is highest at the fin tips where the melt layer is thinnest, providing valuable design guidelines for future high performance dynPCM cooling technologies.

Immune response of Rhinogobio ventralis to Ichthyophthirius multifiliis infection: Insights from histopathological and real-time gene expression analyses

Ichthyophthirius multifiliis is a parasite that poses a considerable threat to aquaculture and the ornamental fish industry, but with limited effective treatment options available. This study employed RT-qPCR to detect and analyze the expression changes of partial toll-like receptor (TLR) genes (TLR1 and TLR21), adapter protein and signal transduction molecule genes (MyD88, TRIF, NF-κB, IRAK4, and IRF3), and cytokines (IL-6, IL-8, IL-13, CXC-α and CXCR1), as well as complement C3, in the skin, gill, fin, liver, head kidney and spleen of Rhinogobio ventralis under different infection conditions. Additionally, tissue sections and scanning electron microscopy were utilized to observe the pathological changes in the gills and fins of R. ventralis after infection with I. multifiliis. The expression patterns of TLR-related DEGs (differentially expressed genes) in diseased wild fish were analyzed, revealing upregulation of TLR1, TLR21, MyD88, NF-κB, IRAK4, TRIF, IRF3, IL-6, IL-8, IL-13, CXC-α, CXCR1, and C3 genes in various tissues, indicating that these genes may be involved in the immune response of R. ventralis to I. multifiliis infection. To further analyze the gene expression of sampled from the field, an artificial infection model of R. ventralis was established under laboratory conditions, with additional sampling from the skin and fins. These genes continued to show varying degrees of upregulation, but the results were not entirely consistent with those from Wudongde samples, which may be due to the more complex environment in the wild or differences in the degree of I. multifiliis infection in wild fish. The infection of I. multifiliis caused severe damage to the gills and fins of R. ventralis, characterized by extensive secretions on the gill and fin surfaces, with the presence of attached I. multifiliis trophonts, including damage and loss of gill filaments, swollen gill lamellae, and deformed gill plates, as well as cell proliferation and necrosis of gill epithelial cells. This study sheds light on the role of the TLR signaling pathway in resisting I. multifiliis infection and its associated histopathological changes in R. ventralis, providing valuable insights for the prevention and treatment of I. multifiliis infection in R. ventralis.

Terrestrial locomotion stability of undulating fin amphibious robots: Separated elastic fin rays and asynchronous control

To address the problem of poor postural stability in an undulating fin robot during terrestrial locomotion, this study proposes a novel design featuring separate elastic fin rays with an asynchronous control scheme for bilateral fin surfaces. In this scheme, the robotic fin ray structure and surface driving mode are innovatively designed to mitigate the pitch-angle instability caused by adverse factors, such as integral rigid fin rays and synchronized fin surfaces. Expanding on the ground dynamics model of the robot, this study examined the variation in the pitch angle of the robot body. In this study, an innovative design with separated elastic fin rays was proposed and their feasibility was validated through finite element simulations. In addition, a virtual simulation prototype of the robot was developed to verify the robot body stability under asynchronous fin surface control. The simulation results show that separate elastic fin rays and asynchronous control can effectively improve the postural stability of robots in terrestrial locomotion. In this study, a robot prototype was tested experimentally in various terrestrial environments. The experimental results indicate that equipping the robot with separated elastic fin rays and employing asynchronous motion control significantly enhances the motion postural stability across typical terrain conditions. The maximum pitch angle range can be reduced by 42.7–52.4%, providing new insights for the design of amphibious robots with undulating fins.

Influence of the Presence of Different Signatures on the Heat Transfer Profile of Laminar Flow Inside a Microchannel

Abstract The process of transferring heat and mass involves a high-pressure decline. Hence microchannels are utilized in extremely efficient heat and mass transfer processes, such as in the systems of the lungs and kidneys. Due to their high surface-to-volume ratio and compact volume, microchannels have demonstrated superior thermal performance. In this work, micro-fins of different topologies and arrangements were used inside microchannels for modulating heat transfer from the surface of the fins, in the presence of flowing media. The influx of media was simulated in sinusoidal form, reproducing simplified form of physiological circulatory blood flow. The study was conducted in numerical domain, while heat transfer and mass transfer equations were solved using pardiso solver. Temperature modulation at the fin surfaces was conducted to examine the transient profile of heat transfer, as function of both variable fluid velocity as well as variable feeding heat sources. In case of different input boundary conditions, the effect of heat distributions on fluid flow with respect to spatial distribution of micro-fins within a microchannel was evaluated. Results revealed the difference in heat transfer profiles in microchannels in presence of different sets of fin configurations. It was found that rectangular fins have the highest heat transfer in fluid at all its spatial configurations; while semi-ellipsoidal-shaped fins had shown the least heat transfer profile at same surface area. At the same time, it was also observed that the rate of heat dissipation was faster and limited in semi-ellipsoidal-shaped fins configuration; while the heat transfer rate was found symmetrical and low in presence of rectangular fins. Hence, this article emphasizes the modulation of temperature and velocity variations within the working fluid by emphasizing the thermo-fluid coupling effects in microchannels.

Experimental and numerical studies on moisture adsorption/desorption characteristics across the circular fin tube desiccant coated heat exchanger

To improve the energy transfer abilities, enhance the quality of air, and curtail the growth of microorganisms, the desiccant coated heat exchangers are a capable substitute compared to conventional heat exchangers due to their capability of decoupling the sensible and latent loads and utilizing low-grade thermal energy. The concept of desiccant coated heat exchangers (DCHE) can be employed in various heat exchange/transport systems like heat pumps, atmospheric water harvesters, adsorption chillers, and air conditioners. Thus, in this research work, a circular fin tube desiccant coated heat exchanger (DCCHE) has been proposed and designed and a dynamic numerical model is established for simulating the combined heat and mass transport occurring across the adsorption/desorption process of a DCCHE employing finite element approach. The moisture and temperature distribution and flow of fluid are considered in the transient numerical model covering several domains such as water flow, air flow, and the coated desiccant. The desiccant material utilized in the current analysis is silica gel. The validation study showed good agreement, and the maximum error between the experimental result and simulated model for the humidity ratio of air and temperature of outlet air were observed to be ± 8 % and ± 7 %, respectively. A parametric analysis is carried out to assess the effect of varying the different input parameters on DCCHE’s performance. The field emission scanning electron microscopy results concluded that a uniform coating is formed on the circular fin surface. The experimental examination on the sorption kinetics of the silica gel showed that the moisture uptake capability was 0.34 g/g. Moreover, the proposed circular fin tube desiccant coated heat exchanger has been compared with the conventional plate type fin tube DCHE to assess its performance in terms of thermal coefficient of performance and specific dehumidification energy.

Experimental performance evaluation of air-based photovoltaic–thermal collector with rectangular turbulators and longitudinal fins

An air-based photovoltaic–thermal collector (PVTC) simultaneously generates electricity and heats air using energy from incident solar radiation. Its simple design ensures low initial costs and easier maintenance. However, its thermal efficiency is limited by the low heat conductivity of air. To address this shortcoming, considerable research has focused on enhancing either the heat transfer area or the heat transfer coefficient. However, only one of these two methods has typically been utilized, and information regarding PVTCs that incorporate both technologies is lacking. Thus, a novel air-based PVTC featuring longitudinal fins and rectangular turbulators is proposed herein. In this PVTC, the fins enlarge the heat transfer area, while the turbulators improve the heat transfer coefficient by creating turbulence near the fin surface. The proposed PTVC (PTVC-LFRT) was experimentally evaluated under real-world weather conditions and also compared with two other PVTC configurations: one with a smooth air channel (PTVC-SMAC) and one with only fins (PTVC-LF) to reveal the potential thermal and electrical gains achievable with the proposed design. As a result, PVTC-LFRT achieved an electrical efficiency of 17.06 %, whereas PVTC-SMAC and PTVC-LF recorded corresponding values of 16.55 % and 16.8 %, respectively. Moreover, PVTC-LFRT exhibited a thermal efficiency of 38.93 %, while PVTC-SMAC and PVTC-LF achieved thermal efficiencies of 22.68 % and 33.56 %, respectively. Finally, the total daily energy output of PVTC-LFRT from incident solar radiation was 42.73 % and 11.2 % higher than those of PVTC-SMAC and PVTC-LF, respectively. These findings verify that incorporating fins with turbulators into a PVTC effectively enhances its electrical and thermal efficiency. Consequently, the feasibility of the proposed system could be confirmed, and its promotion is considered worthwhile.