Parametric Analysis of Horizontal Air and Liquid Earth Loops

1991 ◽  
Vol 113 (2) ◽  
pp. 123-128 ◽  
Author(s):  
Donell P. Froehlich ◽  
Barbara J. Glawe
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Parametric Analysis ◽  
Unit Length ◽  
Fluid Velocity ◽  
Open Loop ◽  
Total System ◽  
Fluid Type ◽  
Soil Thermal Conductivity ◽  
Heat Exchange Effectiveness

Equations and parameter characteristics were examined for both closed and open-earth loops. Analysis and graphs are presented on the heat exchange effectiveness of air and liquid earth loops and how the heat transfer is affected by major parameters such as: pipe diameter, soil thermal conductivity, fluid velocity, and fluid type. The open loop will produce more heat per unit length of pipe while the closed produces more total system heat. However, final loop selection is based on many factors that are both site and system specific.

scholarly journals The Influence of Burial Depth and Soil Thermal Conductivity on Heat Transfer in Buried CO2 Pipelines for CCS: A Parametric Study

2020 ◽  
Author(s):  
Babafemi Olugunwa ◽  
Julia Race ◽  
Tahsin Tezdogan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Thermal Resistance ◽  
Parametric Study ◽  
Flow Assurance ◽  
Burial Depth ◽  
Soil Thermal Conductivity ◽  
Dense Phase ◽  
Pipeline Transportation

Abstract Pipeline heat transfer modelling of buried pipelines is integral to the design and operation of onshore pipelines to aid the reduction of flow assurance challenges such as carbon dioxide (CO2) gas hydrate formation during pipeline transportation of dense phase CO2 in carbon capture and storage (CCS) applications. In CO2 pipelines for CCS, there are still challenges and gaps in knowledge in the pipeline transportation of supercritical CO2 due to its unique thermophysical properties as a single, dense phase liquid above its critical point. Although the design and operation of pipelines for bulk fluid transport is well established, the design stage is incomplete without the heat transfer calculations as part of the steady state hydraulic and flow assurance design stages. This paper investigates the steady state heat transfer in a buried onshore dense phase CO2 pipelines analytically using the conduction shape factor and thermal resistance method to evaluate for the heat loss from an uninsulated pipeline. A parametric study that critically analyses the effect of variation in pipeline burial depth and soil thermal conductivity on the heat transfer rate, soil thermal resistance and the overall heat transfer coefficient (OHTC) is investigated. This is done using a one-dimensional heat conduction model at constant temperature of the dense phase CO2 fluid. The results presented show that the influence of soil thermal conductivity and pipeline burial depth on the rate of heat transfer, soil thermal resistance and OHTC is dependent on the average constant ambient temperature in buried dense phase CO2 onshore pipelines. Modelling results show that there are significant effects of the ambient natural convection on the soil temperature distribution which creates a thermal influence region in the soil along the pipeline that cannot be ignored in the steady state modelling and as such should be modelled as a conjugate heat transfer problem during pipeline design.

Parametric Analysis of Floor Cooling

2016 ◽  
Vol 861 ◽  
pp. 401-408
Author(s):  
Lucie Horká ◽  
Jan Weyr
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Parametric Analysis ◽  
Cooling Water ◽  
Total Heat ◽  
Design Parameters ◽  
Total Heat Transfer ◽  
2D Numerical Simulation ◽  
Cooling Pipes

This study is aimed at parametric analysis of floor cooling. Impact of several design parameters such as air temperature, temperature of cooling water, distance of cooling pipes, thickness and thermal conductivity of top layer on total heat transfer of cooling floor is studied. The issue is solved by steady-state 2D numerical simulation of heat transfer to the floor construction. These parametric simulations are performed in software CalA. Impact of variable input parameters on total heat transfer is observed. Results of parametric analysis are displayed in a nomogram. This nomogram is useful for faster designing of floor cooling.

A Study on the Calculation Model of Rock Soil Thermal Conductivity in the Design of the Ground Source Heat Pump System

2014 ◽  
Vol 889-890 ◽  
pp. 1347-1352
Author(s):  
Hong Wen Jin ◽  
Qing Shen Fang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Pump ◽  
Soil Layer ◽  
Heat Extraction ◽  
Ground Source Heat Pump ◽  
Soil Thermal Conductivity ◽  
Pump System ◽  
Heat Pump System ◽  
Ground Source

The rock soil thermal conductivity is the most important design parameter for the ground source heat pump system. Based on the equation applied for the heat transfer between the geothermal heat exchanger and its surrounding rock soil, a quasi-three dimensional heat conduction model showing the heat transfer inside the borehole of the U-tube was established to determine the thermal conductivity of the deep-layer rock soil. The results obtained show that the average thermal conductivity got through calculation and actual determination in a tube-embedding region of the ground source heat pump engineering were 1.895 and 1.955W/(m·°C), respectively. The soil layer, which has a great thermal conductivity and a strong integrated heat transfer capability, is suitable for the use of the ground source heat pump system with the tubes embedded underground. The soil layer, with a body temperature of 19 °C and a higher initial temperature, is suitable for the heat extraction from underground in winter. The deviation between the calculation and the determination of the average thermal conductivity in the abovementioned region was 0.06, which could meet the required precision, indicating that the results from the calculation could be used for design.

Instability of Variable Thermal Conductivity Magnetohydrodynamic Nanofluid Flow in a Vertical Porous Channel of Varying Width

2017 ◽  
Vol 378 ◽  
pp. 85-101
Author(s):  
Md. Sarwar Alam ◽  
Oluwole Daniel Makinde ◽  
Md. Abdul Hakim Khan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Differential Equations ◽  
Entropy Generation ◽  
Fluid Velocity ◽  
Nonlinear Partial Differential Equations ◽  
Vertical Channel ◽  
Porous Wall ◽  
Variable Thermal Conductivity ◽  
Physical Parameters

A numerical investigation is performed into the heat transfer and entropy generation of a variable thermal conductivity magnetohydrodynamic flow of Al2O3-water nanofluid in a vertical channel of varying width with right porous wall, which enable the fluid to enter. The effects of the Lorentz force, buoyancy force, viscous dissipation and Joule heating are considered and modeled using the transverse momentum and energy balance equations respectively. The governing nonlinear partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations using appropriate similarity transformations and then solved numerically using power series with Hermite-Padé approximation method. A stability analysis has been performed for the local rate of shear stress and Nusselt number that indicates the existence of dual solution branches. Numerical results are achieved for the fluid velocity, temperature as well as the rate of heat transfer at the wall and the entropy generation of the system. The present results are original and new for the flow and heat transfer past a channel of varying width in a nanofluid which shows that the physical parameters have significant effects on the flow field.

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.

scholarly journals An experimental study of soil thermal conductivity using a guarded hot plate apparatus

2021 ◽  
Author(s):  
Ivan Nikolaev
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Moisture Content ◽  
Measurement Errors ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Soil Thermal Conductivity ◽  
Hot Plate ◽  
Guarded Hot Plate ◽  
Plate Apparatus

A guarded hot plate apparatus was used to generate comprehensive sets of thermal conductivity for two types of soils, namely Ottawa sand and Richmon Hill clay-loam, for temperature variation from 2 to 92°C and moisture content variation from complete dryness to full saturation with measurement errors of less than 3%. Numerical simulation of heat transfer within the apparatus with sample inside was performed to validate the experimental design and setup. To prepare the samples, a consistent specimen preparation technique was developed for the cases of dry, barely-to-moderately moist, and highly-to-fully saturated moist soils. On the basis of gathered datasets, empirical correlations for soil thermal conductivity were developed as a function of both temperature and moisture content. The proposed correlations produced excellent fit to majority of the experimental data, and could be easily integrated into numerical analysis of underground heat transfer. As an application example, one of the correlations was employed to evaluate soil thermal conductivity in a numerical study of underground heat loss from a basement wall and floor, in order to illustrate the importance of considering the dependence of soil thermal conductivity on soil texture, temperature and degree of saturation.

scholarly journals Effect of periodic surface temperature on heat transfer in layered saturated soil

2020 ◽  
Vol 205 ◽  
pp. 04003
Author(s):  
Chu Wang ◽  
Patrick J. Fox
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Fluid Velocity ◽  
Oscillation Amplitude ◽  
Soil Layer ◽  
Effective Porosity ◽  
Solid Particles ◽  
Saturated Soil ◽  
Retardation Factor ◽  
Solid Matrix

This paper presents numerical analyses of one-dimensional heat transfer in layered saturated soil with effective porosity and under a periodic temperature boundary condition using the numerical model HT1. The model characterizes the soil layer using separate columns to represent solid matrix and mobile pore fluid components, and a series-parallel approach to model soil thermal conductivity. Numerical simulations are presented to illustrate the effect of fluid velocity, thermal retardation factor, thermal conductivity of solid particles, effective porosity and layer heterogeneity. Numerical results indicate that increasing downward fluid velocity and decreasing retardation factor can increase the distance that temperature oscillations from the surface can propagate into the layer. In addition, decreasing fluid velocity, increasing retardation factor, and increasing thermal conductivity of solid particles can decrease the temperature oscillation amplitude in the soil. Temperature profiles also indicate the significance of soil effective porosity and multiple soil layers on heat transfer behavior.

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.

Investigation of Thermal Conductivity of a Polymer Solution as Function of Shearing Rate

1999 ◽  
Author(s):  
Milivoje Kostic ◽  
Haibo Tong
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Virtual Instrument ◽  
Fluid Velocity ◽  
Fluid Motion ◽  
Conductive Heat ◽  
Fluid Temperature ◽  
Concentric Cylinders ◽  
And Control ◽  
Measurement And Control

Abstract A novel research apparatus is developed to measure the fluid thermal conductivity while in shearing flow, and to determine its dependence on the shearing itself, contrary to the current state-of-the-art of measuring thermal conductivity under the condition of motionless fluid. A concentric cylinders’ apparatus was developed to provide controlled heat transfer in the radial direction, orthogonal to the circumferential fluid velocity, thus virtually preserving pure conductive heat transfer mode. The measurement and control are accomplished and integrated by using a computerized data acquisition system and a comprehensive virtual instrument, developed using the LabVIEW application software. It was found that the thermal conductivity of a Newtonian fluid, such as distilled water, was virtually independent of the fluid motion, as expected. However, for non-Newtonian fluids such as 1000 and 2000 wppm aqueous polyacrylamide (Praestol) solutions, there was up to 10–20% increase of thermal conductivity in the operating shear rate range (40 ≤ γ ≤ 510 sec−1) at 27°C average fluid temperature.

scholarly journals An experimental study of soil thermal conductivity using a guarded hot plate apparatus

2021 ◽  
Author(s):  
Ivan Nikolaev
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Moisture Content ◽  
Measurement Errors ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Soil Thermal Conductivity ◽  
Hot Plate ◽  
Guarded Hot Plate ◽  
Plate Apparatus

A guarded hot plate apparatus was used to generate comprehensive sets of thermal conductivity for two types of soils, namely Ottawa sand and Richmon Hill clay-loam, for temperature variation from 2 to 92°C and moisture content variation from complete dryness to full saturation with measurement errors of less than 3%. Numerical simulation of heat transfer within the apparatus with sample inside was performed to validate the experimental design and setup. To prepare the samples, a consistent specimen preparation technique was developed for the cases of dry, barely-to-moderately moist, and highly-to-fully saturated moist soils. On the basis of gathered datasets, empirical correlations for soil thermal conductivity were developed as a function of both temperature and moisture content. The proposed correlations produced excellent fit to majority of the experimental data, and could be easily integrated into numerical analysis of underground heat transfer. As an application example, one of the correlations was employed to evaluate soil thermal conductivity in a numerical study of underground heat loss from a basement wall and floor, in order to illustrate the importance of considering the dependence of soil thermal conductivity on soil texture, temperature and degree of saturation.

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