Increase In Fluid Temperature Research Articles

Analysis of temperature dependent properties of a peristaltic MHD flow in a non-uniform channel: A Casson fluid model

The current work pertains to the peristaltic motion of a Casson fluid through a non-uniform channel with exposure to a radial magnetic field. The wall properties of the channel are taken into consideration. Moreover, the fluid is considered to possess variable viscosity which shows exponential variation across the width of the channel. The investigations also consider the mass and heat transfer properties of the Casson fluid, where convective boundary conditions are used and the thermal conductivity is taken be varying with fluid temperature. The model is built to give insight into blood flow through small vessels. Solution to the problem is obtained by the method of perturbation. The graphical analysis reveals an increase in the effect of variable viscosity on the fluid velocity close to the walls of the channel and also on the size of the bolus formed during trapping. Furthermore, an increase in fluid temperature was observed due to variable thermal conductivity.

A study on utilization of ground source energy for space heating using a nanofluid as a heat carrier

AbstractGround source heat pump (GSHP) systems are well established as an energy‐efficient space conditioning device. However, for better utilization of the ground source, improvement in GSHP performance is desirable, which limits the small temperature difference between the ground and the circulating fluid. In this study, efforts have been made to investigate the performance of a ground heat exchanger (GHX) with a nanofluid as a heat carrier. Mathematical modeling is performed for the closed‐loop vertical U‐tube GHX with six different (Al2O3, CuO, graphite, multiwalled carbon nanotube, graphene, and Cu) water‐based nanofluids. The effect of different operating parameters on GHX length, fluid temperature, and pressure drop with nanofluids is determined. On the basis of the analytical results, it is found that the graphite particle‐based nanofluid plays a prominent role to enhance the performance of the GHX as compared with other nanoparticles. The maximum enhancement in the increase in outlet fluid temperature and reduction in pipe length with graphite particle‐based nanofluid are 68.3% and 63.3%, respectively, for an increase in temperature difference from 7°C to 15°C between the atmosphere and the ground. Also, with the graphite particle‐based nanofluid and the increase in pipe diameter from 20 to 50 mm, the fluid outlet temperature increases up to 11.2%, and the requirement in GHX length reduces up to 55%.

Analytical modeling of a radiant cooling system for thermal performance analysis

The aim of this paper is to investigate the energetic and exergic performance of the close loop radiant cooling panel system using mathematical modeling. In this study, efforts have been made to determine the COP, cooling capacity and second law efficiency of radiant panel at different operating parameters. Based on results, it is found that mass flow rate of heat carrying fluid plays a major role as compared to plate thickness and pipe thermal conductivity in the thermal performance radiant panel system. The increase in mass flow rate of circulating fluid from 0.01 kg/s to 0.04 kg/s leads to increase the cooling capacity of the radiant panel around 20.9%. Whereas the reduction in inlet temperature of 22% increases the rate of heat transfer to around 62% and the maximum COP is observed as 2.26 at 0.01 kg/s. Further, COP of the panel is found to increase with the increase in plate thickness and with the increase in inlet fluid temperature the exergy of the panel reduces.

Molecular dynamics simulation of effect of temperature on Cu nanoparticles agglomeration of nanofluids

The agglomeration of nanoparticles is a key factor which affects the stability of nanofluids. In order to analyze the effect of temperature on the agglomeration of nanoparticles from a micro perspective, molecular dynamics method is adopted to investigate the agglomeration characteristics of Cu nanoparticles in liquid water. Two conditions of stationary state and flow state are considered in the simulation. The results show that the collision and agglomeration accelerate with the increase of fluid temperature for either stationary state or flow state. The aggregation of particles can be divided into the Brown movement stage, the adhesion stage, and the coalescence stage. The centroid distances of nanoparticles no longer change when the aggregation process completes. The potential energy of the system increases with the fluid temperature. The total potential energy of the system decreases with each collision of Cu particles. The total potential energy of the system no longer changes until all the Cu particles collide and agglomerate. The obtained results can provide useful understanding of the stability of nanofluids affected by the temperature. And the stability further affects the thermal behavior of nanofluids.

Physical aspects and streamline analysis on hydromagnetic nonlinear radiative flow of Carreau-Yasuda fluid

The physical aspects of flow and heat transport analysis of non-Newtonian (Carreau-Yasuda) fluid through an upper paraboloid surface of revolution has been scrutinized. Non-linear radiation, magnetic field, heat generation are considered in this study. The governing flow equations are modeled in the formulation. The governing flow equations (PDE’s) are changed into a system of ODE’s by employing the related transformation variables. The highly non-linear and coupled ODE’s are resolved aid of Runge–Kutta fourth-order along shooting numerical procedure. The physical flow and temperature phenomena have analyzed for both Newtonian and Non-Newtonian fluid cases through plots for the dimensionless sundry variables. The fluid velocity dwindled with the escalation of the magnetic field. An increase in fluid temperature is observed against the temperature ratio variable. Behaviour of fluid temperature of Newtonian fluid is excessive as compared to the Carreau-Yasuda fluid case for the exponential parameter N. The present model (Carreau-Yasuda fluid) is simplified to the viscous fluid (Newtonian fluid) case when n = 1. The streamline flow patterns are reduced for higher thermal Grashof number Gr. The numerical comparison has been deliberated with existing outcomes for a limit case. The heat augmentation analysis through Carreau-Yasuda liquid has prominent applications in non-linear science and industrial technology.

Thermal performance of a flat-plate solar collector using aqueous colloidal dispersions of multi-walled carbon nanotubes with different outside diameters

ABSTRACT The thermal performance of a flat-plate solar collector (FPSC) using novel heat transfer fluids of aqueous colloidal dispersions of covalently functionalized multi-walled carbon nanotubes with β-Alanine (Ala-MWCNTs) has been studied. Multi-walled carbon nanotubes (MWCNTs) with outside diameters of (< 8 nm) and (20–30 nm) having specific surface areas (SSAs) of (500 m2/g) and (110 m2/g), respectively, were utilized. For each Ala-MWCNTs, water-based nanofluids were synthesized using weight concentrations of 0.025%, 0.05%, 0.075%, and 0.1%. A MATLAB code was built and a test rig was designed and developed. Heat flux intensities of 600, 800, and 1000 W/m2; mass flow rates of 0.6, 1.0, and 1.4 kg/min; and inlet fluid temperatures of 30, 40, and 50°C were used to perform the test runs. Using water and nanofluids, the efficiency of the FPSC was found to increase with the increase in heat flux intensity and flow rate, and decrease with the increase in inlet fluid temperature. When applying nanofluids in the FPSC and as weight concentration and SSA increased, a reduction in the values of absorber plate temperature (AP) and tube wall temperature (TW) was observed down to 2.86% and 3.03%, respectively, while the FPSC’s efficiency increased up to 9.55% for 0.1-wt% Ala-MWCNTs < 8 nm at 1.4 kg/min, compared with water. Good agreement was obtained between the experimental values and MATLAB code predictions for AP, TW, and efficiency with maximum differences of 3.02%, 3.19%, and 3.26% for water, and 4.24%, 3.94%, and 12.64% for nanofluids, respectively. Consequently, the MATLAB code was judged suitable for modeling the nanofluid-based FPSC with suitable precision. It was proved that the positive effects of using nanofluids in the FPSC were higher their negative effects on pressure drop because all the calculated values of performance index (PI) were more than 1. As weight concentration and SSA increased, PI increased up to 1.095 for 0.1-wt% Ala-MWCNTs < 8 nm. Therefore, it was concluded that the nanofluids considered in this research can usefully be employed as working fluids in FPSCs for improved thermal performance, and the 0.1-wt% water-based Ala-MWCNTs < 8 nm nanofluid was fairly the distinguished one.

A coupled thermo-hydrologic-mechanical (THM) model to study the impact of hydrate phase transition on reservoir damage

Thermal fluid injection is proven to be one of the effective methods to dissociate hydrate. The injection of thermal fluid can destroy the hydrate phase equilibrium, resulting in hydrate decomposition and hydrate saturation decline, which further cause reservoir damage. Previous works separated the study of hydrate saturation variation caused by thermal fluid injection and the reservoir damage caused by hydrate saturation variation. In this paper, a novel thermo-hydrologic-mechanical (THM) coupling model is proposed to simulate the thermal fluid injection in hydrate reservoir, and its effects on reservoir damage were analyzed. The results showed that thermal fluid injection causes the decomposition of hydrate, resulting in the decrease of hydrate saturation. The solid phase hydrates decompose into methane and water, which increases the pore pressure of hydrate reservoir and further affects the in-situ stress field. The change of effective stress induces pore deformation, and the hydrate decomposition also releases the space occupied by hydrate in reservoir pores, both affecting the reservoir permeability. Hydrate phase transition weakens the cementation of hydrate on rock particles and reduces the reservoir rock cohesion. In addition, the elastic modulus of hydrate decreases due to hydrate decomposition. The temperature and injection rate of thermal fluid are the main external factors affecting the hydrate phase transition. With the increase of thermal fluid temperature, hydrate saturation decreases due to hydrate decomposition, resulting in variation of reservoir parameters. Enhancing fluid injection rate can increase the reservoir pore pressure, which inhibits the hydrate decomposition.

Heat measures in performance of electro-osmotic flow of Williamson fluid in micro-channel

Present study signifies the thermal analysis of the electroosmotic flow of Williamson fluid in the presence of peristaltic propulsion and asymmetric zeta potential at the walls. The present study addresses this thermal configuration for the very first time. The state of art of study is to explore the heat transport in electroosmotic biological flows with applications like smart sensors, food diagnostics and DNA chips. The governing equations are simplified by using reliable approximation, namely lubrication and Debye-Hückel approximation. The resulting equation is then solved analytically and numerically by the perturbation technique and using Mathematica software. Physical quantities are analyzed under various dominant parameters. The heat transfer coefficient and shear stresses are also determined. Bolus dynamics are also visualized. It is observed from the analysis that an increase in electroosmosis effect leads to an increase in temperature and temperature of Newtonian fluid is more as compared to Non-Newtonian fluid. The presence of asymmetric zeta potential is a key phenomenon in controlling fluid flow in the microchannel. Temperature increases for increased electroosmotic strength me, mobility of the medium β and Brinkman number Br.

Experimental investigation in the local heat transfer of supercritical carbon dioxide in the uniformly heated horizontal miniature tubes

This study experimentally investigated the local heat transfer characteristics of supercritical carbon dioxide, which was uniformly heated in horizontal circular smooth tubes with inner diameters of 1.0 mm, 0.75 mm and 0.5 mm. The experimental results illustrated heat transfer enhancement with an increase in fluid temperature before the pseudocritical point and a decline in heat transfer just after the pseudocritical point. Subsequently, the heat transfer coefficient increased again when the fluid temperature was sufficiently higher than the pseudocritical value due to the enhancement of turbulence resulting from the decrease in viscosity. In addition, the parametric effects of outlet pressure, heat flux, mass flux, inlet temperature, and tube diameter on local heat transfer were investigated. The system demonstrated the optimal heat flux with the highest thermal performance when the outlet fluid condition was close to the corresponding pseudocritical point, at which both the specific heat and Prandtl number attained peak values. With other parameters fixed, the system with a higher mass flux, lower inlet temperature, or smaller diameter exhibited higher heat transfer performance. A new empirical correlation developed on the basis of the experimental data can reasonably predict the local Nusselt number of supercritical carbon dioxide along the flow path in uniformly heated horizontal tubes.

Thermal performance investigations of the melting and solidification in differently shaped macro-capsules saturated with phase change material

Abstract The storage of phase change material in the macro-capsules used for a latent thermal energy storage system significantly enhances the thermal performance compared to the conventional shell and tube heat exchanger. The geometrical shape and dimensions of these capsules have a major impact on the melting and solidification characterization. Most of the research is, however, carried out using a spherical capsule only. Hence, the influence of the differently shaped macro-capsules is required to be evaluated to obtain thermal performance enhancement. An experimental setup is developed to validate numerical observations. The primary objective of the present study is to visualize the phase change phenomenon and compare the thermal behavior of differently shaped capsules (spherical, cubical, triangular, and plus-shaped) during the melting and solidification processes. Results show that the triangular capsule exhibits better thermal performance with melting and solidification time of 41 min and 133 min, respectively. In addition, the increase in the heat transfer fluid temperature increases the melting rate. Furthermore, it is found that the 27% reduction in the capsule size decreases melting and solidification time by 12.19 and 19.17%, respectively. Hence, the capsule size has more influence on the solidification process compared to the melting process.

The combined effect of variable viscosity and variable thermal conductivity on natural convection couette flow

Abstract The present work analyses the combined effects of variable viscosity and thermal conductivity on fluid flow and thermodynamics in a vertical channel. Equations of energy and momentum that describe the flow situation are solved using Homotopy perturbation method. The influence of various flow parameters are presented graphically and discussed. The analysis carried out revealed that fluid temperature and velocity increase with an increase in heat generation and decrease with an increasing heat absorption. Also, fluid velocity decreases with the increase of the viscosity. While both fluid temperature and velocity decrease with an increase in thermal conductivity. The comparison of the present work with Jha and Ajibade [18] shows an excellent agreement when the viscous dissipation, variable viscosity as well as the variable thermal conductivity terms are neglected.

Analytical and Numerical Study on Cross Diffusion Effects on Magneto-Convection of a Chemically Reacting Fluid with Suction/Injection and Convective Boundary Condition

The purpose of this paper is to investigate the Soret and Dufour effects on unsteady mixed convective boundary layer flow of a viscous fluid over a stretching surface in a porous medium in the presence of magnetic field with heat generation/absorption, chemical reaction, suction/injection and convective boundary condition. The governing time-dependent partial differential equations are transformed into non-linear ordinarydifferential equations using similarity transformations. These equations subject to the appropriate boundary conditions are solved analytically by homotopy analysis method (HAM) and numerically by Runge-Kutta fourth order method and shooting technique.The numerical solution is compared with analytical solution. The influence of the different parameters on velocity, temperature and concentration profiles are discussed in graphical as well as in tabular form. It is observed that the fluid velocity and temperature increase on increasing the buoyancy ratio parameter and heat generation/absorption parameter. Also found that the surface heat and mass transfer rates increase on increasingthe suction/injection and heat generation/absorption parameters.

Performance on Buoyancy Driven Flow in Square Duct Fitted with Twisted Strip

This experimental investigation aims to study the effect of inlet fluid on flow and heat transfer characteristics for buoyancy driven flow in square tube fitted with twisted strips. Twist pitch, heat supply, inclination of the tube and Inlet fluid temperature were changed during experimentation. The study revealed that with increase in pitch the percentage enhancement in heat transfer coefficient decreases. With decrease in the pitch the flow rate decreases. Moreover with increase in inlet fluid temperature both heat transfer coefficient and flow rate tends to decrease. Perhaps it is due to higher heat loss at the tube surface which results in reduction in Rayleigh number.

Numerical Solution of Unsteady A12O3 -Water Nanofluid Flow Past A Magnetic Porous Sliced Sphere

This study aims to investigate the MHD stagnation point flow of Al2O3 -Water nanofluid with mixed convection effect pass a sliced magnetic porous sphere. The unsteady Al2 O3 -Water nanofluid mixed convection boundary layer flows the stagnation point is an interesting study. This implementation of this concept can use in the problems of engineering and industrial fields such as propulsion ships system, oil drilling, chemical piping, and nuclear reactor coolant. In this paper, we consider the effect of magnetic, porosity, and slicing angel parameters towards the velocity and temperature profiles. We construct a mathematical model of MHD flow in Al2O3 -Water nanofluid to obtain dimensional governing equations. Then, the equations converted into non-dimensional equations by using non-dimensional variables and unsimilarity equations using stream function. The solution of the model solved by numerically using the Keller-Box scheme. The velocity and temperature profiles are determined for various non-dimensional parameters such as magnetic parameter, sliced angle, and porosity parameter. We obtain that the velocity of Al2O3 -Water nanofluid decreases but the temperature decreases when magnetic parameters increases. For the porosity parameter increases then the velocity of the fluid decreases but the temperature of the fluid increases. For the sliced angle parameter increases then the velocity of the fluid increases but temperature of the fluid decrease. For the volume fraction parameter increases then the fluid velocity decreaes but the fluid temperature increases.

Computation of electroconductive gyrotactic bioconvection under nonuniform magnetic field: Simulation of smart bio-nanopolymer coatings for solar energy

The water-based bioconvection of a nanofluid containing motile gyrotactic micro-organisms (moves under the effects of gravity) over a nonlinear inclined stretching sheet in the presence of a nonuniform magnetic field has been investigated. This regime is encountered in the bio-nanomaterial electroconductive polymeric processing systems currently being considered for third-generation organic solar coatings, anti-fouling marine coatings, etc. Oberbeck–Boussinesq approximation along with ohmic dissipation (Joule heating) is considered in the problem. The governing equations of the flow are nonlinear partial differential equations and are converted into ordinary differential equations via similarity transformations. These equations are then solved by the Finite Element Method. The effect of various important parameters on nondimensional velocity, temperature distribution, nanoparticle concentration, the density of motile micro-organisms is analyzed graphically in detail. It is observed from the obtained results that the flow velocity decreases with rising angle of inclination [Formula: see text] while temperature, nanoparticle’s concentration and density of motile micro-organisms increase. The local skin friction coefficient, Nusselt number, Sherwood number, motile micro-organism’s density number are calculated. It is noticed that increasing the Brownian motion and thermophoresis parameter leads to an increase in temperature of fluid which results in a reduction in Nusselt number. On the contrary, the Sherwood number rises with an increase in Brownian motion and thermophoresis parameter. Also, interesting features of the flow dynamics are elaborated and new future pathways for extension of the study identified in bio-magneto-nano polymers (BMNPs) for solar coatings.

Couette flow and heat transfer of heat-generating/absorbing fluid in a rotating channel in presence of viscous dissipation

Theoretical investigation is carried out on flow formation and heat transfer characteristics of viscous incompressible and heat-generating/absorbing fluid in a horizontal rotating channel in presence of viscous dissipation. Exact solution is obtained for two cases of interest: when the fluid considered is heat generating and also when the fluid is heat absorbing. Interesting effect of some governing parameters on fluid temperature, rate of heat transfer and critical Eckert number are identified and discussed using line graphs and tables for both cases. It is found out that the rate of heat transfer decreases with increase in heat source causing an increase in fluid temperature while the contrast is true for heat sink. In addition, critical Eckert number decreases with heat source while it increases with heat sink.

Condensation-induced flow structure modifications in turbulent channel flow investigated in direct numerical simulations

The turbulent flow of a fluid carrying trace amounts of a condensable species through a differentially cooled vertical channel geometry is simulated using single-phase direct numerical simulations. The release of latent heat during condensation is modeled by interdependent temperature and vapor concentration source terms governing the relation between the removal of excess vapor from the system and the associated local increase in fluid temperature. A coupling between condensation and turbulence is implemented via solutal and thermal buoyancy. When compared to simulations of an identical system without phase transition modeling, the modifications of the subcooled boundary layer due to the transient and highly localized release of latent heat could be observed. A separate analysis of fluid before and after phase transition events shows a clear increase in post-interaction streak spacing, with the release of latent heat during condensation events opposing the cooling effect of the channel wall and the associated damping of turbulence.

Numerical transient and steady state analytical modeling of the wellbore temperature during drilling fluid circulation

In this paper, a transient model that describes the heat transfer processes in the wellbore during circulation is presented. A simulation of the transient effect on these heat transfer processes was achieved by using a numerical approach to solve the thermal balance equations that describe the heat flow in that system. The present model can be applied for both laminar and turbulent flow regimes through the convective heat transfer coefficient (CHTC). The run time of the present model is relatively short, hence it can be applied for real-time simulation applications. This was achieved by simplifying the model and reducing the calculation complexity. Moreover, the present model has gone through different validation processes. First, the present model is reduced to a steady state condition and solved analytically. This solution was used as a reference to verify the results of the numerical model. Additionally, a grid sensitivity analysis was performed. Second, the analytical solution was validated through a comparison with the known literature. Finally, the assumptions that were made to simplify the model were verified by comparing the results with the comprehensive version of the model. The effect of the flow rate and the flow regime on the wellbore temperature profile are examined. The results showed a reverse effect of the flow rate on the bottom hole temperature within each flow regime. However, a significant increase in the bottom hole temperature is observed as the flow regime changed from laminar flow to turbulent flow. Changing the flow regime from laminar to turbulent will affect the value of the CHTC leading to a significant increase in wellbore fluid temperature. It is also shown that the maximum temperature at the annulus is located where the rate of heat exchange between the annulus and the pipe and the heat from the formation to the annulus is equal.

Design and experimental investigation of a novel full solar spectrum utilization system

Coupling multi-devices is a promising way to achieve efficient utilization of full spectrum solar energy. After analyzing and summarizing the advantages and disadvantages of the four most representative full solar spectrum utilization systems (tandem photovoltaic-thermoelectric PV-TE system, tandem photovoltaics/thermal PV/T system, spectrum splitting PV-TE system, and spectrum splitting PV/T system), three recommendations for optimization design of a full solar spectrum utilization system with high efficiency are proposed based on the principle of spectral matching and cascade utilization of energy. Then, a novel full solar spectrum utilization system is presented, namely, the photovoltaics-thermoelectric/thermal (PV-TE/T) system. The PV-TE/T system is mainly composed of a tandem PV-TE component and a thermal collector with spectrally selective absorbing fluid. In order to prove that the PV-TE/T system has better performance, the experiments of performance comparison that a PV standalone system and a tandem PV-TE system are set to compare with the PV-TE/T system were conducted under the same concentration and ambient condition. Due to the fluctuation of solar energy, the experiments of performance comparison were conducted in sunny and cloudy day. In sunny day, the output power of PV-TE/T system is increased by 11.2% compared to the tandem PV-TE system, and this ratio is increased to 35.6% in partly cloudy day due to the thermal collector. Therefore, the thermal collector in PV-TE/T system can make the output power more stable, also diversify the methods of the solar energy utilization. Moreover, an experiment of matching effect between light and heat that a PV-TE/T system with single-layer antireflective glass is compared with that with double-layer antireflective glass was conduct. Although single-layer antireflective glass leads to better performance in PV-TE/T system, its advantage of the single-layer antireflective glass becomes small as the fluid temperature increases (in the end, the output power of the PV-TE/T system with single-layer antireflective glass is just 2.6% higher than that with double-layer antireflective glass). In conclusion, the PV-TE/T system has great potential for application, and its further improvements is supposed to focus on the photovoltaics and glass.

Heat Transfer Performance Improving for Brass Tubes Heat Exchanger Coated by Nanoparticles

A double tube heat exchanger type has been designed and built as a sub-scale sample of shell and tube heat exchanger that has been used in Midland Refineries Company-Iraq in order to evaluate the effect of nanocoating in heat transfer performance of the experimental rig with and without nanocoating of tubes made from brass alloy B-111 have been tested in order to evaluate the heat transfer performance at different inner fluid temperature (70, 75, 80)°C, different volume flow rate of inner flow at (100, 200, 300) L/h and different volume flow rate of outer flow at (60, 120, 180, 240 300, 360 420) L/h. The results have showed that the performance of coated tube has enhanced the heat transfer rate from 15.9 to 41.82 percentage compare with uncoated tube due to enhancing in heat transfer coefficient of coated surface. The percentage of enhancement heat transfer rate has increased with the increase of the inlet inner fluid temperature. From the experimental results, it has been noted that the percentage of enhancement of heat transfer depends on the heat transfer coefficient of the tube outer surface so it has increased the percentage of enhancement of heat transfer until its value has exceeded the heat transfer coefficient of tube inner surface then the percentage of enhancement has started to decrease with volume flow rate of outer fluid increased.