Effects of temperature and fluid velocity on beer pasteurization in open and closed loop heating systems: numerical modeling and simulation

2020 ◽  
Vol 16 (7) ◽  
Author(s):  
Wei Guo ◽  
Sanjeevi P ◽  
Seyed Mohammad Taghi Gharibzahedi ◽  
Ya Guo ◽  
Yingkuan Wang
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Closed Loop ◽  
Heating Temperature ◽  
Fluid Velocity ◽  
Open Loop ◽  
Transfer Model ◽  
Heating Systems ◽  
Effects Of Temperature ◽  
Better Than

AbstractA two-dimensional symmetric heat transfer model and a fluid rotation model were established to study beer pasteurization process through the COMSOL Multiphysics software. Two heating modes, including closed-loop heating (CLH) and open-loop heating (OLH), were considered. There was a significant natural convection phenomenon in both heating systems. However, the natural convection became weaker with a gradual increase in the heating temperature of the beer. The maximum fluid velocity (FV) in CLH and OLH modes was 69.34 and 43.74 mm/s, respectively. After heating at 333.13 K for 20 min, the minimum and maximum pasteurization unit (PU) values in CLH were 55 and 59, respectively, while the corresponding values for OLH were 30 and 55, respectively. The pasteurization effect under the CLH mode was better than the OLH one. The heat transfer was also affected by fluid flow (laminar and turbulence) patterns. The PU value was nonlinearly related to the FV. The optimal FV can be obtained at ∼50 mm/s.

Numerical Simulation of Heat Transfer in Laminar Natural Convection of Mixed Newtonian-Non-Newtonian and Pure Non-Newtonian Nanofluids in a Square Enclosure

2021 ◽  
pp. 1-44
Author(s):  
Ajay Vallabh ◽  
P.S. Ghoshdastidar
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Base Fluid ◽  
Volume Fraction ◽  
Numerical Study ◽  
Transfer Model ◽  
Nanoparticle Concentration ◽  
Left Wall ◽  
Square Enclosure ◽  
First Case

Abstract This paper presents a steady-state heat transfer model for the natural convection of mixed Newtonian-Non-Newtonian (Alumina-Water) and pure Non-Newtonian (Alumina-0.5 wt% Carboxymethyl Cellulose (CMC)/Water) nanofluids in a square enclosure with adiabatic horizontal walls and isothermal vertical walls, the left wall being hot and the right wall cold. In the first case the nanofluid changes its Newtonian character to Non-Newtonian past 2.78% volume fraction of the nanoparticles. In the second case the base fluid itself is Non-Newtonian and the nanofluid behaves as a pure Non-Newtonian fluid. The power-law viscosity model has been adopted for the non-Newtonian nanofluids. A finite-difference based numerical study with the Stream function-Vorticity-Temperature formulation has been carried out. The homogeneous flow model has been used for modelling the nanofluids. The present results have been extensively validated with earlier works. In Case I the results indicate that Alumina-Water nanofluid shows 4% enhancement in heat transfer at 2.78% nanoparticle concentration. Following that there is a sharp decline in heat transfer with respect to that in base fluid for nanoparticle volume fractions equal to and greater than 3%. In Case II Alumina-CMC/Water nanofluid shows 17% deterioration in heat transfer with respect to that in base fluid at 1.5% nanoparticle concentration. An enhancement in heat transfer is observed for increase in hot wall temperature at a fixed volume fraction of nanoparticles, for both types of nanofluid.

Impact of Thermal Stratification on Unsteady Natural Convection Couette Flow Formation in a Vertical Channel Filled with Anisotropic Porous Material

2021 ◽  
Vol 408 ◽  
pp. 67-82
Author(s):  
Basant Kumar Jha ◽  
Muhammad Kabir Musa ◽  
Abiodun O. Ajibade
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Differential Equations ◽  
Porous Material ◽  
Couette Flow ◽  
Fluid Velocity ◽  
Vertical Channel ◽  
Stratified Fluid ◽  
Fluid Temperature ◽  
Riemann Sum

Recently, heat transfer problems where anisotropic porous medium or stably stratified fluid are taken into account have been separately studied. Developing a mathematical model that combines these physical quantities naturally results to complex coupled differential equations. In this paper, a fully developed time dependent natural convection Couette flow of stably stratified fluid between vertical parallel channels filled with anisotropic porous material is investigated. The governing partial differential equations are transformed into ordinary differential equations using Laplace transform techniques and then decoupled using D’Alembert method. Exact solutions in Laplace domain for the velocity and temperature equations are then obtained. A numerical method: Riemann-sum approximation is then used to invert the expressions for the velocity and temperature profiles, as well as the resulting skin friction, rate of heat transfer and volumetric mass flow rate into their corresponding time domain. The research establishes that both the anisotropic and the stratification parameters aid in regulating the fluid temperature and velocity. The research further reveals that the fluid velocity attains its maximum (or minimum) velocity when θ = 900 (or θ = 00) for k*<1 and when k*>1, the fluid velocity is least (or maximum) when θ = 900 (or θ = 00).

Thermal and Visual Observation of Water and Acetone Oscillating Heat Pipes

2008 ◽  
Author(s):  
C. Wilson ◽  
B. Borgmeyer ◽  
R. A. Winholtz ◽  
H. B. Ma ◽  
D. Jacobson ◽  
...  
Keyword(s):  
Neutron Radiography ◽  
Fluid Velocity ◽  
Fluid Motion ◽  
Heat Pipes ◽  
Visual Observation ◽  
Open Loop ◽  
Condenser Temperature ◽  
Rich Liquid ◽  
Two Sides ◽  
Better Than

Identical oscillating heat pipes (OHP) charged separately with water and acetone were observed thermally and visually at varying condenser temperatures and heat inputs. Neutron radiography allowed visualization of hydrogen rich liquid water and acetone within the copper OHP. Four identical 6 turn OHPs were constructed; two as open loop and two close loop. One set of open and close loop OHP was charged with acetone and an open and close loop OHP were charged with water at fill ratios of 50%. The OHPs were also instrumented with 24 thermocouples, heated with a strip heater and cooled with heavy water. Both thermal and visual data were collected simultaneously. The experiments show that at low heat flux and condenser temperature, the acetone OHP performed better than the water OHP. Using neutron radiography, the acetone OHP was seen to have higher fluid velocity than the water OHP. The fluid flow pattern was also more consistent throughout the entire close loop acetone OHP including full circulation of the fluid. The close loop water OHP never fully circulates through the turn connecting the two sides. Lastly, neutron radiography shows that the open loop OHPs not only have less fluid motion at the side turns, the interior turns also have reduced fluid motion compared to the close loop OHPs.

Numerical Analysis of Natural Convection and Radiation for Tube Solar Receiver With Glass Window

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Zhang Guojun ◽  
Liu Changyu ◽  
Li Dong
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Natural Convection ◽  
Heating Temperature ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Surface Emissivity ◽  
Heating Wall ◽  
Convective Coefficient ◽  
Solar Receiver

Conjugate laminar natural convection heat transfer and air flow with radiation of tube solar receiver with glass window were numerically investigated. The discrete ordinate method was used to solve the radiative transfer equation. And the three-dimensional steady-state continuity, Navier–Stokes, and energy equations were solved. The temperature difference based on environment and high temperature surface of receiver is varied from 100 K to 1000 K. The influence of the surface emissivity, heating temperature, convective coefficient, and convective temperature of environment on the heat transfer from the receiver with glass window has also been investigated. The numerical results indicated that the highest temperature of glass window increases and the high temperature area becomes wide, with the temperature of heating wall and surface emissivity increasing. Adopting higher convective coefficient of glass window can reduce the peak magnitude of temperature distribution on glass window of tube receiver up to 45%.

scholarly journals Numerical Evaluation of the Transient Performance of Rock-Pile Seasonal Thermal Energy Storage Systems Coupled with Exhaust Heat Recovery

2020 ◽  
Vol 10 (21) ◽  
pp. 7771
Author(s):  
Leyla Amiri ◽  
Marco Antonio Rodrigues de Brito ◽  
Seyed Ali Ghoreishi-Madiseh ◽  
Navid Bahrani ◽  
Ferri P. Hassani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Waste Heat ◽  
Fluid Velocity ◽  
Transfer Model ◽  
Mining Operations ◽  
Exhaust Heat ◽  
Wide Range

This study seeks to investigate the concept of using large waste rocks from mining operations as waste-heat thermal energy storage for remote arctic communities, both commercial and residential. It holds its novelty in analyzing such systems with an experimentally validated transient three-dimensional computational fluid dynamics and heat transfer model that accounts for interphase energy balance using a local thermal non-equilibrium approach. The system performance is evaluated for a wide range of distinct parameters, such as porosity between 0.2 and 0.5, fluid velocity from 0.01 to 0.07 m/s, and the aspect ratio of the bed between 1 and 1.35. It is demonstrated that the mass flow rate of the heat transfer fluid does not expressively impact the total energy storage capacity of the rock mass, but it does significantly affect the charge/discharge times. Finally, it is shown that porosity has the greatest impact on both fluid flow and heat transfer. The evaluations show that about 540 GJ can be stored on the bed with a porosity of 0.2, and about 350 GJ on the one with 0.35, while the intermediate porosity leads to a total of 450 GJ. Additionally, thermal capacity is deemed to be the most important thermophysical factor in thermal energy storage performance.

scholarly journals Temperature Field in the Heat Transfer Process of PEEK Thermoplastic Composite Fiber Placement

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4417
Author(s):  
Zhongliang Cao ◽  
Mingjun Dong ◽  
Kailei Liu ◽  
Hongya Fu
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Process Parameters ◽  
Heating Temperature ◽  
Detection System ◽  
Composite Fiber ◽  
Temperature Data ◽  
Thermoplastic Composite ◽  
Transfer Model ◽  
Fiber Placement

Under the effect of different process parameters, the temperature field inside the thermoplastic fiber is very complex and directly affects the fusion quality between the resins. Considering the heat transfer behavior of thermoplastic fiber polyether ether ketone (PEEK) as the research object, a mathematical model of heat transfer in the thermoplastic composite fiber placement with the relevant boundary conditions was established. Ansys Parametric Design Language (APDL) was used to generate the finite element model and simulate the transient process, not only to explore the influence of various process parameters on the temperature field, but also to build an online temperature field measurement system. The influence rules of placement process parameters and mold initial temperature with respect to the temperature field in the first layer were obtained. Combining the relationship between heating temperature and placement speed, when the first layer was laid, the placement process temperature could be quickly reached by low speed and high temperature. The temperature data were collected by the online detection system. Compared with the temperature data from the simulation, the error was below 8%, which verified the correctness of the heat transfer model. The academic research results will lay a theoretical foundation for the thermoplastic fiber placement.

Computations for a Three-by-Three Array of Protrusions Cooled by Liquid Immersion: Effect of Substrate Thermal Conductivity

1995 ◽  
Vol 117 (4) ◽  
pp. 294-300 ◽  
Author(s):  
D. Mukutmoni ◽  
Y. K. Joshi ◽  
M. D. Kelleher
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Fluid Flow ◽  
Natural Convection ◽  
Computational Study ◽  
Fluid Velocity ◽  
Heat Sinks ◽  
Electronic Components ◽  
Liquid Immersion ◽  
Fluid Velocity Field

A computational study of natural convection in an enclosure as applied to applications in cooling of electronic components is reported. The investigation is for a configuration consisting of a three by three array of heated protrusions placed on a vertical substrate. The vertical sidewalls are all insulated, and the top and bottom walls serve as isothermal heat sinks. A thin layer at the back of each protrusion is the heat source, where heat is generated uniformly and volumetrically. The coolant is the flourinert liquid FC75. The code was first validated with experimental results reported earlier on the same configuration. The effect of the substrate conductivity, κs on the heat transfer and fluid flow was then studied for power levels of 0.1 and 0.7 Watts per protrusion. The computations indicate that the effect of increasing κs is dramatic. The protrusion temperatures which were found to be nominally steady, were substantially reduced. The percentage of generated power that is directly conducted to the substrate increased with an increase in κs. The fluid velocity field, which was unsteady, was not significantly affected by changes in κs.

Sign in / Sign up

Export Citation Format

Share Document