Department of Mechanical engineering

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1921

Browse

Start date: 2020Subject: search.filters.subject.Heat Transfer

Search Results

Now showing 1 - 10 of 48
  • No Thumbnail Available
    Item
    Thermal conductivity enhancement of magnetic nanofluids for energy applications
    (Elsevier, 2023) Parameshwaran, R.
    Nanofluids are a class of fascinating energy transfer fluids that are gaining impetus in many heat transfer applications due to their tremendous potential in augmenting the thermal properties of the base fluids such as water, ethylene glycol, engine oil and so on. From this perspective, this study was aimed at investigating the enhancement of thermal conductivity of distilled water (base fluid) using magnetic nanoparticles. The magnetic nanoparticles were experimented for understanding their surface morphology, crystal structure, chemical stability, thermal conductivity and viscosity using the respective characterization techniques. The scanning electron microscopy results infer that the average size of the agglomerated spherically shaped magnetic nanoparticles was 600.8 nm, however the size of individual particles was observed to be well within 100 nm. The X-ray diffraction pattern showed prominent intense peaks at 29.87°, 35.61° and 63° which have justified the crystalline nature of the nanoparticles. The as-prepared magnetic nanofluids (MNF) when tested for its surface structure has revealed good chemical stability between the base fluid and the magnetic nanoparticles. It is noteworthy that, the thermal conductivity of the MNF was ranging from 0.7666 W/m K to 0.9666 W/m K for the volume fraction of nanoparticles ranging from 0.01 % to 0.1 % and temperature ranging from 35° C to 55 °C. The significance of this work has been justified in terms of achieving enhanced thermal conductivity ranging from 21.3 % to 53.1 % for such low volume fractions of the nanoparticles. Furthermore, the MNF exhibited only marginal variations in viscosity for the specified volume fractions of the nanoparticles. In summary, the as-prepared MNF with these enhanced attributes can be considered to be viable and beneficial for the energy applications.
  • No Thumbnail Available
    Item
    Investigation of flow boiling heat transfer and pressure drop of R134a in a rectangular channel with wavy fin
    (Elsevier, 2020-01) Ranganayakulu, Chennu
    The saturated flow boiling heat transfer and pressure drop studies of R134a were experimentally investigated in a rectangular channel with wavy fin. Experiments were performed at mass flux range 30–50 kg m−2 s−1, heat flux range 11–18 kW m−2 and quality 0.26–0.8. The experimental data were obtained in a brazed test section. In preliminary step, single phase experiments were conducted to find out the j and f data of the wavy fin. In second step, two-phase flow boiling experiments were conducted to estimate the heat transfer and frictional coefficient based on experimental data. The trends of heat transfer and pressure drop with respect to mass flux, heat flux and quality were studied. Two-phase local boiling heat transfer coefficient is correlated in terms of Reynolds number factor F, and Martinelli parameter X. Pressure drop is correlated in terms of two-phase frictional multiplier, and Martinelli parameter, X.
  • No Thumbnail Available
    Item
    Simulation of two-phase nanofluid flow and heat transfer in a 3D diamond shape cavity equipped with square shaped obstacle and decreasing dimensions
    (Authero, 2020-03) Bhattacharyya, Suvanjan
    The present study investigates numerically symmetry simulation of two-phase nanofluid flow and heat transfer in a 3D diamond shape cavity equipped with square-shaped obstacle and decreasing dimensions. The studied material in the present study is assumed with two different emissivity values, ԑ = 0.3 and ԑ = 0.9, due to analyze the effects of emissivity values on radiation heat transfer. Also two different Rayleigh numbers, Ra=106 and 108. The heat transfer fluid is water-based Cu nanofluid which makes a Newtonian nanofluid, but other base fluid is also analyzed. The main aim of present work is to simulate the 3D diamond shape cavity equipped with square-shaped obstacle and decreasing dimensions geometry using symmetry method and also investigate the effects of different Rayleigh numbers, emissivity values and different nanoparticles volume concentrations on thermal and hydraulic characteristics of the model. Base on obtained results, by an increase of nanoparticles volume concentration the temperature gradients and heat transfer characteristics are improved but the streamlines have not a significant change and by an increase of nanoparticles volume concentration the temperature gradients and heat transfer characteristics are improved, but the streamlines have not a significant change. According to results at higher Rayleigh numbers, the heat transfer characteristics are enhanced. Also, it is found that higher Rayleigh numbers and nanoparticles volume concentrations lead to more heat transfer inside the cavity and changes in emissivity coefficients have not a significant effect on heat transfer characteristics and nanofluid flow in the cavity.
  • No Thumbnail Available
    Item
    Experimental and Numerical Investigation of the Heat Transfer Characteristics of Laminar Flow in a Vertical Circular Tube at Low Reynolds Numbers
    (Springer, 2021-06) Bhattacharyya, Suvanjan
    Laminar flow is very common in practical situations and vertical tubes are used for many industrial applications ranging from cooling of thermal systems such as compact heat exchangers, solar energy collectors, boilers, and nuclear reactor.
  • No Thumbnail Available
    Item
    Research Article Investigation of Counterflow Microchannel Heat Exchanger with Hybrid Nanoparticles and PCM Suspension as a Coolant
    (MDPI, 2021-03) Bhattacharyya, Suvanjan
    A circular tube fitted with novel corrugated spring tape inserts has been investigated. Air was used as the working fluid. A thorough literature review has been done and this geometry has not been studied previously, neither experimentally nor theoretically. A novel experimental investigation of this enhanced geometry can, therefore, be treated as a new substantial contribution in the open literature. Three different spring ratio and depth ratio has been used in this study. Increase in thermal energy transport coefficient is noticed with increase in depth ratio. Corrugated spring tape shows promising results towards heat transfer enhancement. This geometry performs significantly better (60% to 75% increase in heat duty at constant pumping power and 20% to 31% reduction in pumping power at constant heat duty) than simple spring tape. This paper also presented a statistical analysis of the heat transfer and fluid flow by developing an artificial neural network (ANN)- based machine learning (ML) model. The model is evaluated to have an accuracy of 98.00% on unknown test data. These models will help the researchers working in heat transfer enhancementbased experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce. The results of this investigation can be used in designing heat exchangers
  • No Thumbnail Available
    Item
    Computational Investigation on Flow Dynamics and Heat Transfer of Nanofluid in Low Reynolds Number Under Magnetic Field
    (Springer, 2023-04) Bhattacharyya, Suvanjan
    The effect of magnetic field on the heat transfer enhancement and pressure drop is studied numerically. A water based Fe3O4 nanofluid (2 Vol%) is flowing in a 2-dimensional heated channel at low Reynold’s number (Re = 150 - 250) and different magnetic field intensities ranging from 1200 G to 2000 G are applied. The heat sink with dimensions of 40 mm (L) X 4 mm (H) consists of magnets placed at four different locations. The magnetic field is acting as a vortex generator which enhance heat transfer for highly concentrated heat fluxes. The heat transfer enhancement due to the magnetic field at x = 25 mm is studied. Results showed that there is an improvement of maximum 26% in heat transfer using magnetic nano fluid with magnetic field as compared to pure water. This value grows to around 35% when a magnetic field of strength 1200G is applied and even around 200% at magnetic field of strength 4000G as compared to pure water. However, this enhancement comes with an increase of pressure drop and back flow. This can be explained due to formation of vortices due to the turbulence caused by the sudden force of magnetic field. The optimum condition is obtained at magnetic field of strength 2000 G with a heat transfer enhancement of around 70%.
  • No Thumbnail Available
    Item
    Numerical Analysis of Heat Transfer and Pressure Drop in a Square Channel with Novel Centre Hole Inclined Ribs
    (Springer, 2023-04) Bhattacharyya, Suvanjan
    In present simulation analysis, heat transfer, pressure drop and thermal performance factor in a square channel equipped with inclined ribs with central hole is investigated. The study is conducted in turbulent flow regime with Reynolds number ranging from 10000 to 80000. The variable parameters are pitch ratio (y = p/D = 0.5, 1.0 and 1.5), hole ratio (h = d/D = 0.1 and 0.2) and rib angle (θ =30°, 45°, and 60°). ANSYS Fluent 19.0 is used for simulations and governing equation are solved using RANS turbulence model. It is revealed from the investigation that presence of inclined ribs enhance the heat transfer and pressure drop. For the case of inclined ribs with central hole, enhancement is further increased. For all the cases the thermal performance factor remains higher than unity.
  • No Thumbnail Available
    Item
    Flow and Heat Transfer Over a Moving Surface Due to Impinging Annular Jets
    (Springer, 2023-04) Bhattacharyya, Suvanjan
    In the present paper, fluid flow and heat transfer over a moving surface owing to an array of impinging annular jets at a constant temperature have been numerically studied at a Reynolds number of 5000. The flow field was resolved using the transition SST model with highly refined mesh. In the direction of the surface movement, a periodic element from a jet-bank design was chosen. Different nondimensional surface velocities were considered from zero (stationary surface) to two times of inlet jet velocity. It is observed that both the flow field and thermal performance of the jet is strongly affected by the surface motion. The initial symmetric distribution alters when the surface motion increases up to a particular degree of surface velocity, and the average heat transfer decreases. When surface motion exceeds this threshold, net heat transmission increases which leads to the more uniform and enhance heat transfer for high surface velocity cases.
  • No Thumbnail Available
    Item
    Thermo-Hydraulic Characteristics of a Stepped Micro-Channel Under Pulsating Inlet Flow Condition
    (Springer, 2023-04) Bhattacharyya, Suvanjan
    Present work constitutes of numerical analysis of fluid flow as well as heat transfer for a flow through a corrugated micro-channel. Water, which has a Pr = 7, is apprehended to be the fluid flowing through the corrugated channel. A sinusoidal pulsation was introduced at the inlet to regulate the inlet velocity as well as incoming volume flow rate towards the channel. A commercial code ANSYS FLUENT 19.2 was used for the inspection purpose. The flow is apprehended to be laminar and a laminar flow model was employed accordingly. The solution is carried out employing a finite volume based method. Isothermal wall boundary condition was engaged for the case, to realize the fluid flow and thermal performance of the proposed geometry. Reynolds number (Re) ranging from 1–100 was engaged for the analysis purpose. Also, a wide range of amplitude (A) of the pulsation and the frequency (f) which is represented by dimensionless Strouhal number (St), was taken on. Nusselt number, friction factor are reported characteristics to assess the overall thermal performance of the enhanced geometry.
  • No Thumbnail Available
    Item
    Editorial for the Special Issue “Heat Transfer Enhancement and Fluid Flow Features Due to the Addition of Nanoparticles in Engineering Applications"
    (MDPI, 2023-02) Bhattacharyya, Suvanjan
    This Special Issue titled “Heat Transfer Enhancement and Fluid Flow Features Due to the Addition of Nanoparticles in Engineering Applications” comprises nine original research articles devoted to recent advances, as well as up-to-date progress, in all areas of heat transfer due to the addition of different types of nanoparticles in engineering and its influence on emerging technologies. The application of nanofluids which are fluids including suspended solid particles with diameters below 100 nm has clearly increased since the past two decades. Nanofluids are considered as potential working fluids to improve heat transfer characteristics compared with conventional fluids due to the high thermal conductivity of the suspended particles. Furthermore, they are ideally suited for practical applications in distinct domains due to their remarkable characteristics. Thermal systems are one of the most important parts of various industries, which have always been researched due to their cooling abilities and improved efficiency. Because of the wide applications of natural convection in cooling industrial tools, this challenging topic has gathered the attention of many researchers. Natural convection has wide applications in various industries and technologies such as growing crystals, cooling microchips, oil extraction, solar collectors, voltage increase transformers, etc. The optimization of heat transfer devices for reaching higher levels of efficiency requires the miniaturization of devices and increased heat transfer per unit surface at the same time. In tandem, this Special Issue highlights the techniques for enhancing convective heat transfer, including passive techniques such as treated surfaces, rough surfaces, extended surfaces, displaced enhancement devices, swirl flow devices, coiled tubes, surface tension devices, and additives for fluids such as nanoparticles.