Heat pipe with nano enhanced-PCM for electronic cooling application

In this study, the thermal performance of a heat pipe using nano enhanced Phase Change Material (PCM) as an energy storage medium for electronic cooling application is studied. The PCM is placed around the adiabatic section of the heat pipe in which heat is absorbed and released depending on the power inputs at the evaporator and fan speeds at the condenser. Experiments are performed to obtain the evaporator, condenser and PCM temperature distributions during the charge, discharge and simultaneous charge/discharge processes. In the present study, Water, Tricosane and nano enhanced Tricosane are used as energy storage materials. The nano enhanced PCMs are prepared by mixing different volume percentage (0.5%, 1% and 2%) of Al2O3 nanoparticles with Tricosane. Thermal conductivity of nano enhanced PCM is measured and found to be enhanced to a maximum of 32% compared to pure Tricosane. The effects of PCM filling volumes, fan speeds and heating power on the performance of cooling module are also investigated. From this study it is found that the evaporator temperature of heat pipe with nano enhanced PCM is decreased about 25.75%, which can save 53% of the fan power compared with the traditional heat pipe. Also found that the nano enhanced PCM can store almost 30% of the energy supplied at the evaporator leading to the reduction in fan power consumption.http://www.elsevier.com/locate/etfs2018-02-28hb2016Mechanical and Aeronautical Engineerin

Convection heat transfer with water based mango bark nanofluids

Numerous studies reveal that the heat transfer capability of thermal systems has been significantly enhanced with the use of nanofluids. On the other hand, the hazardous nature of the nanoparticles is evident. Recent studies clearly indicate that the nanoparticles affect the human health as well as the environment. Therefore environmentally safe bio-nanofluids are currently under investigation. In this study, a novel heat transfer fluid with bio-nanomaterial is prepared and its natural convection heat transfer characteristics are studied. The bionanomaterial considered in this study is powdered mango bark. A two-step process is employed to prepare stable nanofluids. The effect of particles concentration, the temperature difference between the hot and cold side, and Rayleigh number on the natural convection heat transfer process is studied. The experimental results show that the natural convection process is deteriorated with the addition of mango nanoparticles in deionized water.Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .International centre for heat and mass transfer.American society of thermal and fluids engineers

Natural convection enhancement in a porous cavity with Al2O3-Ethylene glycol/water nanofluids

The natural convection heat transfer of a differentially heated cavity filled with porous material and saturated with nanofluid is studied. The nanofluid used in the present study contains 60% Ethylene glycol, 40% DI-water and 30 nm size Al2O3 nanoparticles. The volume concentration of nanofluid used is in the range of 0.05% ⩽ ϕ ⩽ 0.4%. The range of Rayleigh number in the present study is 1.2 × 108 ⩽ Ra ⩽ 4 × 108 for clear cavity and 3 × 103 ⩽ Ra ⩽ 1.3 × 104 for the porous cavity. Viscosity of the nanofluid is also measured at volume concentration of 0.05% and found one available model works for the calculations. In order to explain the heat transfer behaviour of the present system, heat transferred by both clear and porous cavity, heat transfer coefficients of both hot and cold wall, as well as Nusselt number variation with concentrations of nanofluids are presented. It is found that the performance of porous cavity filled with a nanofluid volume concentration of 0.05% is enhanced while the other concentrations of nanofluids deteriorate the performance. At a volume concentration of 0.05%, the heat transfer capability of porous cavity is enhanced to a maximum of 10% compared to the base fluids.http://www.elsevier.com/locate/ijhmt2018-05-31hb2017Mechanical and Aeronautical Engineerin

Effect of the non-electrically conductive spindle on the viscosity measurements of nanofluids subjected to the magnetic field

The viscosity measurements of magnetic nanofluid subjected to the magnetic field are indispensable in various heat transfer studies. Intention of the present discussion is to critically analyze the magnetic field's influence on the working of two viscometers; a Glass capillary viscometer and a DV-E Brookfield viscometer. The novelty of the present study is in the identification of the underlying reason for the massive escalation in viscosity when the magnetic nanofluid is subjected to magnetic field and rectification of the error caused. The stainless-steel spindle in the viscometer is replaced with a non-electrically and non-magnetically conductive nylon spindle to rectify the error. The dynamic viscosity of magnesium ferrite nanofluid of different volume fractions at a temperature of 25 °C in the occurrence of magnetic field was measured. The viscosity of magnetic nanofluid measured using DV-E Brookfield viscometer escalated to a maximum of 725% over the same measured using glass capillary viscometer with the magnetic field application. The application of the nylon spindle in the viscometer eliminates the error caused due to the eddy current formation in the spindle. Therefore, this study recommends using viscometers with non-electrically and non-magnetically conductive spindles for accuracy while measuring the viscosity of magnetic fluids.The Karunya Institute of Technology and Sciences, India, through the Karunya Short Term Research Grant.http://www.elsevier.com/locate/colsurfa2022-08-05hj2022Mechanical and Aeronautical Engineerin

Characterisation of a grooved heat pipe with an anodised surface

A grooved heat pipe (GHP) is an important device for managing heat in space applications such as satellites and space stations, as it works efficiently in the absence of gravity. Apart from the above application, axial GHPs are used in many applications, such as electronic cooling units for temperature control and permafrost cooling. Improving the performance of GHPs is essential for better cooling and thermal management. In the present study, the effect of anodization on the heat transfer characteristics of a GHP is studied with R600a as a working fluid. In addition, the effects of fill ratio, inclination angle and heat inputs on the heat transfer performance of a GHP are studied. Furthermore, the effect of heat flux on dimensional numbers, such as the Webber, Bond, Kutateladze and condensation numbers, are studied. The inclination angle, heat input and fill ratio of GHPs are varied in the range of 0°–90°, 25–250 W and 10–70 % respectively. It is found that the above parameters have a significant effect on the performance of a GHP. Due to the anodisation, the maximum enhancement in heat transfer coefficient at the evaporator is 39 % for a 90° inclination at a heat flux of 11 kW/m2. The reported performance enhancement of a GHP may be due to the large numbers of nucleation sites created by the anodisation process and enhancement in the capillary force due to the coating.http://link.springer.com/journal/2312018-03-30hb2016Mechanical and Aeronautical Engineerin

Turbulent magnetohydrodynamic natural convection in a heat pipe-assisted cavity using disk-shaped magnesium ferrite nanoparticles

The prospect of altering the thermophysical properties of ferrofluid with an influence of magnetic field leads to improving natural convection in various heat transfer systems. This investigation principally focuses on the studies of electromagnetism-based turbulent natural convection heat transfer of low-density disk-shaped magnesium ferrite/water-based ferrofluid, filled in a novel heat pipe-assisted cubical cavity at various volume fractions. Two flat plate heat pipes were used to maintain temperature differences in the cavity. To advance the buoyancy of the working fluid inside the cavity, deliberately low-density ferrofluid containing disk-shaped particles was formulated using the hydrothermal method. The temperature difference between the two heat pipe-assisted vertical walls was sustained with four distinct temperature ranges from 10 to 25 °C. The ferrofluid filled in the cavity was then subjected to magnetic field ranging from 0 to 350 G to understand the thermomagnetic convection effects on heat transfer. The optimal volume fraction of ferrofluid for maximum heat transfer was found to be 0.05% at a wall temperature difference of 25 °C, owing to 23.51% improvement in average heat transfer coefficient along with 33.37% improvement in average Nusselt number when compared to water. With the application of a magnetic field of 350 G, the average heat transfer coefficient was further enhanced by 10.11%, and the average Nusselt number improved by 6.28% for 0.05% volume fraction in comparison to the condition where no magnetic field was applied.https://link.springer.com/journal/13204hj2023Mechanical and Aeronautical Engineerin

Development of weight grader for dehusked coconut

Manual grading of dehusked coconut often leads to low profit than expected by the farmers. Appropriate grading systems guarantee a better income for the coconut growers. Therefore, a simple machine was designed and developed to grade the de-husked coconut based on its weight. The developed grader consists of an electronic weighing assembly, carrier cups with four bar linkage mechanism, proximity sensor, pneumatic actuators, and drive mechanism. Before the fabrication of grader, the tilt angle of carrier cup mechanism was optimised to ensure a free falling behaviour of dehusked coconut. The performance test of weight grader was conducted by varying the angular velocities of carrier cups (12, 14 and 16 rad/min) and signal settling time of the load cell (2, 3 and 4 s). The highest grading efficiency of 84 % was obtained at an angular velocity of 16 rad/min and load cell settling time of 4 s. The developed weight grader can replace the manual grading system by fetching more income and also it is user-friendly to the coconut grower

Investigation of thermal conductivity and thermal performance of heat pipes by structurally designed copolymer stabilized ZnO nanofluid

Abstract The present study concentrated on estimating the thermal conductivity, stability, efficiency, and resistance of a heat pipe for heat exchangers, which were essential for many industrial applications. To achieve this, copolymer of amphiphilic poly (styrene-co-2-Acrylamido-2-methylpropane sulfonic acid) poly (STY-co-AMPS) was synthesized by free radical polymerisation technique. The dispersant were used for homogeneous solution and stabilization of ZnO nanofluids. The effect of dispersant on the thermal conductivity of nanofluids was analysed using a KD2 pro thermal property analyser. There is a significant increase in fluid conductivity had a nonlinear relationship with the volume fraction. The maximum enhancement was observed at an optimized concentration of dispersant at 1.5 vol%. Same time, the influence of dispersant agent on the thermal conductivity of nanofluids were compared with linear polyelectrolytes. Further, the experimental values were compared to the existing classical models based on the reasonable aggrement, the prepared nanofluids were employed as a working medium. The conventional screen mesh heat pipe and the temperature distribution to the thermal resistance of the heat pipe was investigated experimentally. The result shows, optimum concentration of dispersants on nanoparticles exhibits an enhanced heat efficiency as compared with the base fluids. Further, the thermal resistance and temperature distribution show decreased behaviour by increasing the particle volume fraction and dispersant concentration