Department of Mechanical engineering

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

Browse

Subject: search.filters.subject.Pool boiling

Search Results

Now showing 1 - 8 of 8
  • No Thumbnail Available
    Item
    Synergistic effect of binary surfactant mixture for enhanced boiling heat transfer
    (Elsevier, 2025-07) Verma, Saket
    Surfactants are ubiquitous in our everyday life ranging from household applications to various industrial applications. One such critical application is boiling, wherein, aqueous solution of surfactant is used to enhance the heat transfer coefficient (HTC) compared to pure water. However, this accompanies with the degradation in critical heat flux (CHF). While the binary mixture of surfactants has been widely investigated for its use in numerous applications, such as, corrosion inhibition, foaming, anti-toxicity, and oil and petrochemical industry, among others, its potential to enhance the boiling heat transfer performance, HTC and CHF simultaneously, remains unexplored. In this work, we investigate pool boiling heat transfer performance of aqueous solutions of individual surfactants, namely, SDS (sodium dodecyl sulfate) and DTAB (dodecyl trimethyl ammonium bromide), and their binary mixtures at various mixing ratios. Upon boiling of aqueous solution of individual surfactant, CHF significantly deteriorates. Formation of vapor foam surrounds the heater surface, due to the strong foamability, to impede the supply of fresh liquid from the bulk, leading to the deterioration in CHF. We show that the adverse effect on CHF can be mitigated with binary surfactant mixture. The adsorption dynamics at the liquid–vapor and solid–liquid interfaces are altered favorably, which reduce the foamability and enhance the wettability. Consequently, binary mixtures exhibit not only better CHF than individual surfactant solutions but also demonstrate higher HTC (%) and CHF (%), at suitable mixing ratios and concentration, in comparison to pure water. These findings highlight the potential of binary surfactant mixtures as boiling fluids and opens new area of research for other possible combination of surfactants and ionic liquids for enhanced boiling heat transfer performance.
  • No Thumbnail Available
    Item
    An experimental investigation on the pool boiling heat transfer of R-134A on microporous cu-mwcnt composite surfaces
    (MDPI, 2024-01) Belgamwar, Sachin U.
    Multiwalled carbon nanotubes (MWCNTs) exhibit outstanding physical properties, including high thermal conductivity, excellent mechanical strength, and low electrical resistivity, which make them suitable candidates for a variety of applications. The work presented in this paper focuses on the pool boiling performance of refrigerant R-134a on microporous Cu-MWCNT composite surface layers. A two-stage electrodeposition technique was used to fabricate Cu-MWCNT composite coatings. In order to achieve variation in the surface properties of the Cu-MWCNT composite surface layer, electrodeposition was carried out at various bath temperatures (25 °C, 30 °C, 35 °C, and 40 °C). All surfaces coated with the Cu-MWCNT composite demonstrated superior boiling performance compared to the uncoated surface. Heat transfer coefficient (HTC) values for Cu-MWCNT composite surface layers, prepared at bath temperatures of 25 °C, 30 °C, 35 °C, and 40 °C, exhibited improvements of up to 1.75, 1.88, 2.06, and 2.22, respectively, in comparison to the plain Cu surface.
  • No Thumbnail Available
    Item
    Heat transfer from horizontal tubes in pool boiling: influence of three-dimensional heat conduction in the wall of the evaporator tube—a finite element analysis
    (Springer, 2005-10) Ranganayakulu, Chennu
    In pool boiling, the electrically heated tube releases the energy non-uniformly to the liquid, due to different surface roughness and flowing liquid. The heat transfer coefficient therefore varies with axial and azimuthal position on the tube. Hence a finite element analysis has been carried out on a horizontal 1in. copper tube for evaporation in pool boiling for three-dimensional conduction heat transfer. A test tube has been made with different surface structures, tested and analysed for heat conduction effects. It has been observed that significant amount of heat flows in azimuthal and axial directions in addition to the heat flow in radial direction.
  • No Thumbnail Available
    Item
    Experimental Investigation of Pool BHT Performance of R-141b on Micro/Nano-Porous Copper Coating Prepared by a Two-stage Electrodeposition Method
    (IEI Conferences, 2021) Belgamwar, Sachin U.
    Pool boiling heat transfer (BHT) of R-141b on po-rous Cu coated heating surface was experimentally studied. Porous Cu coating was fabricated on a plain Cu heating sur-face through a two-stage electrodeposition method. Surface characterization of Cu coating confirmed the successful syn-thesis of micro/nano-porous Cu coating. Experimental re-sults showed that the Cu coated heating surface introduced a significant enhancement in heat transfer coefficient (HTC) and a great reduction in wall superheat compared to the plain Cu surface. The maximum enhancement in HTC for the Cu coated heating surface was approximately 53% compared to the uncoated heating surface. This is believed to have re-sulted from the increase in active surface area, nucleation site density and cavitation activity owing to the microporous structure of Cu coating. Obtained results showed that the mi-croporous Cu coated heating surface could be employed in modern heat transfer applications.
  • No Thumbnail Available
    Item
    Pool boiling of R-134a on ZnO nanostructured surfaces: and heat transfer
    (CRC Press, 2023) Belgamwar, Sachin U.
    An experimental study was carried out to investigate the pool boiling performance of R-134a onZnO nanostructured heating surfaces. ZnO nanostructured heating surfaces were fabricated by the thermal evaporation technique followed by heat treatment. Nanostructured ZnO thin films were applied on the bare aluminum heating substrate, furthermore pool boiling performance was carried out with R-134a. Experimental data were recorded at heat fluxes ranging from 9.37 to 72.23 kW/m2k. It was found that with a rise in the thickness of nanostructured ZnO thin film, the wall superheat was decreased and the maximum decrement in wall superheat was observed for nanostructure ZnO thin film with 300 nm thickness. It was also observed that the heat transfer coefficient (HTC) of the ZnO nanostructured surfaces increased with the rise in thickness of coating. The highest value of HTC for ZnO-300 surface was61% greater than the bare Al heating surface.
  • No Thumbnail Available
    Item
    Experimental investigation of pool boiling heat transfer performance of refrigerant R-134a on differently roughened copper surfaces
    (Elsevier, 2021) Belgamwar, Sachin U.
    Pool boiling heat transfer of refrigerant R-134a at saturation temperature of 5 °C was investigated experimentally on copper. The effect of surface roughness was studied at various average roughness (Ra) values ranging from 0.130 to 0.274 µm. All experimental samples were vertically oriented, and experiments were carried out at varying heat flux ranges between 10 and 70 kW/m2. The investigations are carried out to calculate the boiling heat transfer coefficient (h), wall superheat (ΔT) and heat flux (q) for different roughness of heat transfer surfaces. The obtained results revealed that the Cu surface with Ra = 0.274 µm showed outstanding heat transfer performance compared to other Cu surfaces. The overall boiling performances enhanced with an increase in roughness value of the heat transfer surface owing to the increased number of cavities.
  • No Thumbnail Available
    Item
    Experimental Study of Pool Boiling Enhancement Using a Two-Step Electrodeposited Cu–GNPs Nanocomposite Porous Surface With R-134a
    (ASME, 2021-09) Belgamwar, Sachin U.
    The fabrication of porous metallic composite coating on the heating surface to improve pool boiling heat transfer (BHT) performance has received significant attention in recent years. In this work, Cu–GNPs nanocomposite coatings, which were prepared on a copper substrate using various current densities through a two-step electrodeposition technique, were used as heating surfaces to study the pool BHT performance of refrigerant R-134a. The surface morphology, elemental composition, thickness, surface roughness, and porosity of prepared Cu–GNPs nanocomposite coatings are studied and presented in detail. All Cu–GNPs nanocomposite coated surfaces exhibited improved boiling performance compared to the plain Cu surface. The heat transfer coefficient (HTC) values for Cu–GNPs nanocomposite coated Cu surfaces prepared at 0.1, 0.2, 0.3, and 0.4 A/cm2 were improved up to 1.48, 1.67, 1.82, and 1.97, respectively, compared with the plain Cu surface. The enhancement in the HTC is mainly associated with the increase in surface roughness, active nucleation site density, and micro/nanoporosity of the heating surface.
  • No Thumbnail Available
    Item
    A review on the effects of porous coating surfaces on boiling heat transfer
    (Elsevier, 2021) Belgamwar, Sachin U.
    Nowadays, the heat transfer of surface material is a significant challenge faced by boiling and cooling industries. Therefore, several researchers are taking efforts to develop surface material coatings for enhancement of pool boiling. This paper provides a comprehensive review of previously published articles on the different surface coating materials used in boiling heat transfer enhancement and the various surface coating techniques employed for the development of the coating surfaces. Material coatings are covering thin film layers applied to metallic surfaces in various engineering applications to improve heat transfer performance. In addition, different types of coatings such as polymers, metals, ceramics and aerogels coatings applied on metal surfaces through different coatings techniques to enhance surface temperature are included. The rate of heat transfer during boiling depends upon the coating method and the properties of the surface material such as thermal conductivity, heating surface area, roughness and porosity. The surface modification using various material coating techniques results in the enhancement of the active nucleation site of the coating surface, which leads to an improvement of the critical heat flux (CHF) and the heat transfer coefficient (HTC). This is mainly due to increased surface temperature attained in the boiling prosses because of the high thermal conductivity of the surface coating materials. The current status of the surface coating techniques for boiling heat transfer along with their prevailing challenges, enhancement potentials and their possible industrial appliances are discussed in detail.