scholarly journals THERMAL ANALYSIS OF DIFFERENT CONFIGURATIONS FOR BUILDING INSULATION SYSTEMS WITH ACTUAL MATERIALS USING REAL SOLAR RADIATION AND TEMPERATURE DATA

2021 ◽  
Vol 20 (1) ◽  
pp. 52
Author(s):  
C. B. P. Sa ◽  
M. F. Curi
Keyword(s):  
Heat Flow ◽  
Air Conditioning ◽  
Temperature Data ◽  
Heat Diffusion ◽  
Launch Vehicles ◽  
Heat Diffusion Equation ◽  
Insulating Material ◽  
Building Insulation ◽  
Insulation Systems ◽  
Flow Through

Thermal insulation is present in several engineering areas, such as in civilconstruction, in industrial ovens, in satellites and launch vehicles and even indomestic applications, such as refrigerators. This work aims to presentmultilayer insulation for civil construction, thus reducing electrical energyexpenditure on air conditioning the environment and increasing thermalcomfort. To determine the heat flow through the wall, it was necessary tosolve the heat diffusion equation in rectangular Cartesian coordinates for eachinsulation layer, and the boundary conditions of each differential equationdepend on the neighboring layers, thus forming a system of equations. TheWolfram Mathematica computational software was used to solve themathematical equations. The heat flow was determined for the four seasonsof the year throughout the day for different configurations of thermalinsulation, varying the insulating material and its thickness. After analyzingthe results, it was possible to observe the great efficiency of the models withthermal insulation compared to traditional walls, making the internal wall'stemperature profile more constant throughout the day.

Solving cylindrical geothermal problems using the Gaver‐Stehfest inverse Laplace transform

Geophysics ◽  
1985 ◽  
Vol 50 (10) ◽  
pp. 1581-1587 ◽  
Author(s):  
Heinrich Villinger
Keyword(s):  
Heat Flow ◽  
Laplace Transform ◽  
Numerical Procedure ◽  
Heat Diffusion ◽  
Inverse Laplace Transform ◽  
Flow Measurements ◽  
Model Calculations ◽  
Heat Diffusion Equation ◽  
Laplace Domain ◽  
Whole Space

The inhomogeneous one‐dimensional heat‐diffusion equation is solved semianalytically in a cylindrically layered whole space. An analytic solution of the problem can be derived in the Laplace domain in a straightforward way assuming continuity of temperature and heat flow at the layer boundaries. The time‐dependent heat sources can be distributed spatially over the layered whole space. Due to the complexity of the solution in the Laplace domain, the inverse Laplace transform is calculated using a numerical procedure (Gaver‐Stehfest algorithm). It is shown that the algorithm is fast, stable, easy to use, and simple to adjust to various models and boundary conditions. The results obtained are accurate to about 0.01 percent. Therefore, it is an excellent tool for geothermal model calculations with cylindrical symmetry and could be useful for the correction of BHT-values or marine heat flow measurements.

scholarly journals Determining the heat flow through the cabinet walls of household refrigerating appliances

2021 ◽  
Vol 121 ◽  
pp. 235-242
Author(s):  
Andreas Paul ◽  
Elmar Baumhögger ◽  
Andreas Elsner ◽  
Lukas Moczarski ◽  
Michael Reineke ◽  
...  
Keyword(s):  
Heat Flow ◽  
Flow Through

Mapping Thickness Dependent Thermal Conductivity of GaN

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Elbara Ziade ◽  
Jia Yang ◽  
Gordie Brummer ◽  
Denis Nothern ◽  
Theodore Moustaks ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pump Beam ◽  
Continuous Wave ◽  
High Electron Mobility Transistors ◽  
Heat Diffusion ◽  
Phase Lag ◽  
High Electron ◽  
Heat Diffusion Equation ◽  
Phase Images ◽  
Gan Film

Frequency domain thermoreflectance (FDTR) is used to create quantitative maps of thermal conductivity and thickness for a thinning gallium nitride (GaN) film on silicon carbide (SiC). GaN was grown by molecular beam epitaxy on a 4H-SiC substrate with a gradient in the film thickness found near the edge of the chip. The sample was then coated with a 5 nm nickel adhesion layer and a 85 nm gold transducer layer for the FDTR measurement. A piezo stage raster scans the sample to create phase images at different frequencies. For each pixel, a periodically modulated continuous-wave laser (the red pump beam) is focused to a Gaussian spot, less than 2 um in diameter, to locally heat the sample, while a second beam (the green probe beam) monitors the surface temperature through a proportional change in the reflectivity of gold. The pump beam is modulated simultaneously at six frequencies and the thermal conductivity and thickness of the GaN film are extracted by minimizing the error between the measured probe phase lag at each frequency and an analytical solution to the heat diffusion equation in a multilayer stack of materials. A scanning electron microscope image verifies the thinning GaN. We mark the imaged area with a red box. A schematic of the GaN sample in our measurement system is shown in the top right corner, along with the two fitting properties highlighted with a red box. We show the six phase images and the two obtained property maps: thickness and thermal conductivity of the GaN. Our results indicate a thickness dependent thermal conductivity of GaN, which has implications of thermal management in GaN-based high electron mobility transistors.

Research of Multi-Channel Hygrothermoscope Acquiring System

2012 ◽  
Vol 214 ◽  
pp. 177-182
Author(s):  
Xiao Bing Wu
Keyword(s):  
Air Conditioning ◽  
High Reliability ◽  
Temperature Data ◽  
Simple Circuit ◽  
Control Room ◽  
Host Machine ◽  
Humidity Transducer ◽  
And Control ◽  
Humidity Monitoring ◽  
Conditioning Control

The paper introduces a multipoint remote Hygrothermoscope monitoring system based on the MAX485 bus. The system of remote multipoint temperature control is composed of the host machine and slave machine; the host system for display and control, the slave system is responsible for collecting temperature data. Between master machine and slave machine communicate through the RS-485 bus, can realize the distant control room of the scene monitoring. The STC89C54 MCU is used as the controller and DHT11 is used as the temperate and humidity transducer. The hardware and software of the system are outlined. The system has realized multiple measuring points, easy expansion, and high reliability, anti-interference. The whole system has the advantages of simple circuit, reliable, and can be used for measuring temperature, humidity, temperature of building air conditioning control temperature and humidity monitoring and other fields.

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