Numerical Study of Conjugate Heat Transfer in a BIPV-Thermal System

Solar Energy ◽  
2005 ◽  
Author(s):  
Liang Liao ◽  
Andreas Athienitis ◽  
Kwang-Wook Park ◽  
Michael Collins ◽  
Yves Poissant
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
Test Facility ◽  
Cfd Model ◽  
Transfer Coefficients ◽  
Model Average ◽  
T System

This paper presents a computational fluid dynamics (CFD) study of a building-integrated photovoltaic thermal (BIPV/T) system, which generates both electricity and thermal energy. The conjugate heat transfer in the BIPV/T system cavity is studied with a 2-D CFD model. The k-ε model is used to simulate the turbulent flow and convective heat transfer in the cavity, in addition to buoyancy effect. Longwave radiation between boundary surfaces is also modeled. Experimental measurements taken in a full scale outdoor test facility at Concordia University are generally in good agreement with the CFD model. Average and local convective heat transfer coefficients are generated and PV panel average temperature and local cell temperatures are calculated and compared with the experimental data.

Numerical and Experimental Study of Heat Transfer in a BIPV-Thermal System

2007 ◽  
Vol 129 (4) ◽  
pp. 423-430 ◽  
Author(s):  
L. Liao ◽  
A. K. Athienitis ◽  
L. Candanedo ◽  
K.-W. Park ◽  
Y. Poissant ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Wave Radiation ◽  
Measured Temperature ◽  
Cfd Model ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients ◽  
T System

This paper presents a computational fluid dynamics (CFD) study of a building-integrated photovoltaic thermal (BIPV∕T) system, which generates both electricity and thermal energy. The heat transfer in the BIPV∕T system cavity is studied with a two-dimensional CFD model. The realizable k‐ε model is used to simulate the turbulent flow and convective heat transfer in the cavity, including buoyancy effect and long-wave radiation between boundary surfaces is also modeled. A particle image velocimetry (PIV) system is employed to study the fluid flow in the BIPV∕T cavity and provide partial validation for the CFD model. Average and local convective heat transfer coefficients are generated with the CFD model using measured temperature profile as boundary condition. Cavity temperature profiles are calculated and compared to the experimental data for different conditions and good agreement is obtained. Correlations of convective heat transfer coefficients are generated for the cavity surfaces; these coefficients are necessary for the design and analysis of BIPV∕T systems with lumped parameter models. Local heat transfer coefficients, such as those presented, are necessary for prediction of temperature distributions in BIPV panels.

Numerical Study on the Mechanism of Heat Transfer Enhancement in Fe3O4 Nanoferrofluids With Magnetic Field

2019 ◽  
Author(s):  
Chenfei Wang ◽  
Dongdong Gao ◽  
Minli Bai ◽  
Peng Wang ◽  
Yubai Li
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Fe3o4 Nanoparticles ◽  
Volume Fraction ◽  
Numerical Study ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Enhancement Of Heat Transfer

Abstract Nanofluids is reported to significantly enhance heat transfer but with little cost of pressure loss. To further the enhancement of heat transfer using Fe3O4 nanofluids, a magnetic field is employed to control the trajectory of Fe3O4 nanoparticles. A numerical study is conducted with commercial soft ANSYS FLUENT and the simulations are done with a two-phase flow approach named Euler-Lagrange. By comparing heat transfer of laminar flow in a horizontal tube with magnetic field or not, various volume fraction (0.5%/2%) and Reynolds numbers (Re = 200–1000) are considered. Results show that magnetic field contributes an average 4% promotion in convective heat transfer coefficients compared with the condition of no magnet. The mechanism of the enhancement of heat transfer with magnetic field is explored based on the analysis of velocity field. Fe3O4 Nanoparticles move up and down under the magnetic force, and convective heat transfer is enhanced because of the disturbance of the Fe3O4 nanoparticles. Slip flow between the base fluid and nanoparticles also contributes to the enhancement of heat transfer.

Parametric Study of Convective Heat Transfer Coefficients at the Tire Surface

1980 ◽  
Vol 8 (3) ◽  
pp. 37-67 ◽  
Author(s):  
A. L. Browne ◽  
L. E. Wickliffe
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal State ◽  
Convective Heat Transfer Coefficient ◽  
Operating Conditions ◽  
Test Facility ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Abstract Analyses have shown that the thermal state of a tire is influenced by both the size of and variation in the value of the convective heat transfer coefficient at the tire surface. In the work reported here, a test facility was constructed to permit the determination of convective heat transfer coefficients under a broad range of operating conditions. Data were obtained to show the effects of air speed, boundary layer thickness and turbulence level, humidity, tire surface contamination, tire surface roughness and unevenness, and tire surface wetness on convective heat transfer coefficients. The significance of these results to tire power loss is discussed.

Experimental Characterization of Rotor Convective Heat Transfer Coefficients in the Vicinity of a Leaf Seal

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Juan-Diego Pelegrin-Garcia ◽  
David R. H. Gillespie ◽  
Michael J. Pekris ◽  
Gervas Franceschini ◽  
Leonid Ganin
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Test Method ◽  
Test Facility ◽  
Interface Temperature ◽  
Gas Temperature ◽  
Transfer Coefficients ◽  
Rotating Shaft

Leaf seals are filament seals for use at static to rotating interfaces in the engine secondary air system. They offer reduced leakage rates and better off-design performance over conventional labyrinth seals. If compared with advanced brush seals, leaf seals are more compliant due to their lower stiffness and can withstand higher axial pressure differences. Although leaf seals can exhibit hydrodynamic air-riding, this is not always the case and seal–rotor contact can occur. As a result, friction between the leaf tips and the rotor causes heat generation and wear. To predict the diameter of the rotating shaft and the seal life, the shaft and seal interface temperature needs to be estimated. In the steady state, this is determined by the ratio of convective heat transfer through the seal to that through the shaft. To that end, the convective heat transfer characteristics of the flow over the shaft around the seal are required to build accurate thermal models. In this paper, the convective heat transfer coefficient (HTC) distribution in the close vicinity of a typical leaf seal is investigated in a new test facility. The experimental setup and test method are described in detail, and accuracy considerations are included. The methodology employed to derive HTC is explained with reference to an analogous computational fluid dynamics (CFD) model. The importance of the choice of an appropriate driving gas temperature is demonstrated. Experimental HTC maps are presented for a blow-down seal geometry operating over a range of engine representative pressure ratios. Insight is gained into the flow field characteristics and heat transfer around the seal.

Experimental Characterization of Rotor Convective Heat Transfer Coefficients in the Vicinity of a Leaf Seal

2016 ◽  
Author(s):  
Juan D. Pelegrin-Garcia ◽  
David R. H. Gillespie ◽  
Michael J. Pekris ◽  
Leonid Ganin ◽  
Gervas Franceschini
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Test Method ◽  
Test Facility ◽  
Interface Temperature ◽  
Gas Temperature ◽  
Transfer Coefficients ◽  
Rotating Shaft

Leaf seals are filament seals for use at static to rotating interfaces in the engine secondary air system. They offer reduced leakage rates and better off-design performance over conventional labyrinth seals. If compared with advanced brush seals, leaf seals are more compliant due to their lower stiffness and can withstand higher axial pressure differences. Although leaf seals can exhibit hydrodynamic air-riding, this is not always the case and seal-rotor contact can occur. As a result, friction between the leaf tips and the rotor causes heat generation and wear. To predict the diameter of the rotating shaft and the seal life, the shaft and seal interface temperature needs to be estimated. In the steady state this is determined by the ratio of convective heat transfer through the seal to that through the shaft. To that end, the convective heat transfer characteristics of the flow over the shaft around the seal is required to build accurate thermal models. In this paper the convective heat transfer coefficient (htc) distribution in the close vicinity of a typical leaf seal is investigated in a new test facility. The experimental setup and test method are described in detail and accuracy considerations are included. The methodology employed to derive htc is explained with reference to an analogous CFD model. The importance of the choice of an appropriate driving gas temperature is demonstrated. Experimental htc maps are presented for a blow-down seal geometry operating over a range of engine representative pressure ratios. Insight is gained into the flow field characteristics and heat transfer around the seal.

scholarly journals Experimental And Numerical Study On The Thermal Performance Of A Vertical PCM Panel

2021 ◽  
Author(s):  
Fabio Almeida
Keyword(s):  
Heat Transfer ◽  
Energy Consumption ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Numerical Study ◽  
Peak Load ◽  
Thermal Storage ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Due to an increased awareness of climate change and other environmental issues, methods to reduce the energy consumption of buildings has become of great importance. One way to improve the efficiency of a building is to use thermal storage material. A recent thermal storage strategy is to use phase change material (PCM) which allows for the storage and release of thermal energy. One of the main advantages of using PCM over traditional thermal storage (like concrete) is that PCM can achieve the same level of thermal storage as concrete while using less material. Using PCM can also reduce and delay peak load, improve the thermal comfort, and reduce the overall energy consumption of a building. One of the main parameters that affect the performance and effectiveness of PCM in buildings is the convective heat transfer between a PCM wall and room air. Current convective heat transfer coefficients used in whole building simulation and in building codes (such as ASHRAE) may not be adequate for PCM applications. The present study investigates thermal performance of a vertical PCM panel. The investigation includes experiments using laser MachZehnder Interferometry (MZI) and a comparative numerical study using computational fluid dynamics (CFD). The study focuses on a vertical flat plate filled with PCM (soy wax) undergoing transient convective heat transfer by natural convection while the PCM solidifies. A novel method was developed to make interferometric surface temperature measurements using partial fringes as a reference temperature. The experimental results show a deviation from predicted heat transfer coefficients from established correlation and significant subcooling was observed as a temperature jump. The subcooling effect was reproduced using CFD by implementing the speed of crystallization within the PCM cavity.

DETERMINATION OF THE CONVECTIVE HEAT TRANSFER COEFFICIENT OF HOT AIR RISING THROUGH TERRACOTTA FLUES

2012 ◽  
Vol 36 (4) ◽  
pp. 413-427 ◽  
Author(s):  
Taylor A. Oetelaar ◽  
Clifton R. Johnston
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Transfer Coefficients ◽  
Hot Air ◽  
Roman Baths

We experimentally studied natural convection processes inside terracotta flues as a part of a larger numerical study of ancient Roman baths. The air, heated in a plenum below the wall, rose through the tubes. Two clusters of thermocouples, equally spaced in the flues, measured temperatures throughout the thickness of the wall. The data from the two clusters proved to be measurably different. The resulting convective heat transfer coefficients determined using the bottom cluster, showed no dependence on the plenum temperature. The measured convective heat transfer coefficient was between 6.2 and 7.6 W/m2·°C, with an average of 7.0 W/m2·°C.

scholarly journals Experimental And Numerical Study On The Thermal Performance Of A Vertical PCM Panel

2021 ◽  
Author(s):  
Fabio Almeida
Keyword(s):  
Heat Transfer ◽  
Energy Consumption ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Numerical Study ◽  
Peak Load ◽  
Thermal Storage ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

Due to an increased awareness of climate change and other environmental issues, methods to reduce the energy consumption of buildings has become of great importance. One way to improve the efficiency of a building is to use thermal storage material. A recent thermal storage strategy is to use phase change material (PCM) which allows for the storage and release of thermal energy. One of the main advantages of using PCM over traditional thermal storage (like concrete) is that PCM can achieve the same level of thermal storage as concrete while using less material. Using PCM can also reduce and delay peak load, improve the thermal comfort, and reduce the overall energy consumption of a building. One of the main parameters that affect the performance and effectiveness of PCM in buildings is the convective heat transfer between a PCM wall and room air. Current convective heat transfer coefficients used in whole building simulation and in building codes (such as ASHRAE) may not be adequate for PCM applications. The present study investigates thermal performance of a vertical PCM panel. The investigation includes experiments using laser MachZehnder Interferometry (MZI) and a comparative numerical study using computational fluid dynamics (CFD). The study focuses on a vertical flat plate filled with PCM (soy wax) undergoing transient convective heat transfer by natural convection while the PCM solidifies. A novel method was developed to make interferometric surface temperature measurements using partial fringes as a reference temperature. The experimental results show a deviation from predicted heat transfer coefficients from established correlation and significant subcooling was observed as a temperature jump. The subcooling effect was reproduced using CFD by implementing the speed of crystallization within the PCM cavity.

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