scholarly journals Influence of insulation defects on the thermal performance of walls. An experimental and numerical investigation

2018 ◽  
Author(s):  
Iole Nardi ◽  
Stefano Perilli ◽  
Tullio de Rubeis ◽  
Stefano Sfarra ◽  
Dario Ambrosini
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Comsol Multiphysics ◽  
Insulating Material ◽  
Damaged Material ◽  
Vertical Walls ◽  
Damaged Materials ◽  
Numerical Approaches

The addition of insulating layers on vertical walls of buildings is a common practice for providing a higher thermal insulation of the envelope. Workmanship defects, however, might influence the effectiveness of such insulation strategy. Damaged materials, incorrect installation, use of aged or weathered materials might alter the capability of reducing heat transfer through the envelope, whether vertical or sloped. In this work, drawbacks caused by the wrong installation of insulating material and by damaged material are assessed. A specimen wall was investigated by experimental and numerical approaches, the latter carried out by using COMSOL Multiphysics®. Results are compared and discussed.

scholarly journals Heat Transfer Behaviour Inside a Sinusoidal Cavity Using Water Based Tio2 Nanofluid

2018 ◽  
Vol 37 ◽  
pp. 121-129 ◽  
Author(s):  
Goutam Saha
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Average Heat ◽  
Water Based ◽  
Vertical Walls ◽  
Left And Right ◽  
Lower Temperature

A numerical investigation is carried out to observe the augmentation of heat transfer because of the presence of TiO2 nanofluid inside a sinusoidal cavity. In this study, upper and lower walls of the cavity are considered adiabatic, higher and lower temperature are maintained at left and right vertical walls respectively. Also, 2D contour of velocity and temperature with average heat transfer rate are presented and discussed. Our findings show that augmentation of heat transfer is feasible with the increase of concentrations of nanoparticles.GANIT J. Bangladesh Math. Soc.Vol. 37 (2017) 121-129

scholarly journals Transient Thermal Analysis in an Intermittent Ceramic Kiln with Thermal Insulation: A Theoretical Approach

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ricardo S. Gomez ◽  
Túlio R. N. Porto ◽  
Hortência L. F. Magalhães ◽  
Clotildes A. L. Guedes ◽  
Elisiane S. Lima ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Thermal Insulation ◽  
External Surface ◽  
Energy Gain ◽  
Ceramic Fiber ◽  
Microsoft Excel ◽  
Insulating Material ◽  
Transient Thermal ◽  
Thermal Insulations

Increasing the thermal efficiency of drying and firing processes of ceramic products plays an important role for industries that want to remain competitive in the market. Thus, this work aims to evaluate the influence of the type and thickness of thermal insulations, applied on the external sidewalls of an intermittent ceramic kiln, on heat transfer, temperature distribution in the insulating material, maximum external surface temperature, and energy gain, compared to the kiln without thermal insulation. All proposed mathematical formulations are based on the energy conservation, and mathematical procedures are implemented in Microsoft Excel software. Here, it was tested four types of thermal isolators: fiberglass, rockwool, calcium silicate, and ceramic fiber. Results indicate that the greater the thickness of the thermal insulation, the lower the maximum external surface temperature and the greater the energy gain when compared to the kiln without thermal insulation. In addition, fiberglass is the insulating material, among the four types analyzed, which provides greater energy gain and greater reduction in maximum external surface temperature.

scholarly journals Compressible Time-Dependent Steam Flow And Thermal Heat Analysis In Squared Cylinder: A Numerical Investigation

2021 ◽  
Author(s):  
Azad Hussain ◽  
Muhammad Arsaln ◽  
Ali Hassan ◽  
Aysha Rehman
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Velocity Distribution ◽  
Drag Coefficient ◽  
Pressure Distribution ◽  
Numerical Investigation ◽  
Flow Regime ◽  
Lift Coefficient ◽  
Time Dependent ◽  
Comsol Multiphysics

Abstract This paper investigates time-dependent compressible steam laminar flow coupled with heat transfer in fluids in a squared cylinder. The present problem has been designed in COMSOL-Multiphysics. The laminar flow is selected keeping the Mac number low. The flow possesses a no-slip condition with the wall of geometry. The pressure kept on flow is 0 Pas and the temperature of the flow regime is 305.13. The flow is initiated with a velocity of 0.5m/s. The effects of time on velocity distribution and pressure distribution are described with the help of graphs. Different results like drag coefficient, lift coefficient, heat distributions are also discussed. The technique used to solve modeled problem is BDF.

scholarly journals Numerical investigation of the performance of perforated baffles in a plate-fin heat exchanger

2020 ◽  
pp. 90-90 ◽  
Author(s):  
Houari Ameur ◽  
Djamel Sahel ◽  
Younes Menni
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Investigation ◽  
Thermal Performance ◽  
Viscous Fluids ◽  
Performance Factors ◽  
Performance Factor ◽  
Thermal Performance Factor ◽  
Smooth Channel ◽  
Inelastic Shear

The present paper is a numerical investigation on the performance of perforated baffles in a plate-fin heat exchanger. Two types of perforations are studied, namely the circular and elliptical shapes. Values of heat transfer coefficient, pressure drop and thermal performance factor are determined for both cases and compared with those for a smooth channel. Also, the flow fields and heat transfer characteristics are determined for different fluids and various Reynolds numbers. The working fluids are complex, non-Newtonian and have an inelastic shear thinning behavior. The obtained results showed a good enhancement in the thermal performance factor by the suggested design in baffles. In the case of low viscous fluids, the elliptical perforated baffle performs better (by about 63.4%) than the circular one for all values of Re. But for highly viscous fluids, the elliptical perforation shows higher thermal performance than the circular hole by about 25% for low Re and 27% for high Re. The overall thermal performance factors are about 1.55 and 1.74 for the circular and elliptical perforations, respectively.

scholarly journals Residential Buildings Thermal Performance to Comply With the Energy Conservation Code of Saudi Arabia

2019 ◽  
Vol 9 (2) ◽  
pp. 3949-3954 ◽  
Author(s):  
F. A. AlFaraidy ◽  
S. Azzam
Keyword(s):  
Heat Transfer ◽  
Saudi Arabia ◽  
Energy Conservation ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Residential Buildings ◽  
Transfer Coefficients ◽  
Climate Zones ◽  
Heat Transfer Coefficients ◽  
Insulation Thickness

About half of the total generated electricity in Saudi Arabia (SA) is consumed for the air conditioning of residential buildings. To reduce this burden on the economy as outlined by the country's 2030 vision, the implementation of the Saudi energy conservation code (SBC602) needs to be enforced. This code divided KSA into three climate zones with maximum overall heat transfer coefficients. This study aims to facilitate the use of thermal insulation by analyzing optimum thermal insulation thickness for each zone and calculate the payback period of initial insulation costs. Three cities were selected to represent the three climate zones, Riyadh, Arar, and Turaif. The code-compliant thermal insulation thickness is calculated using these variables: thermal properties of three insulation materials, overall heat transfer coefficients, and three insulated wall structures. It is concluded that external insulation and finish system utilizing polyurethane is the most feasible option with the best thermal performance. Polyurethane thicknesses are ranging from 45mm to 65mm, wall widths are ranging from 250mm to 320mm, while the overall costs are ranging from 20.02 to 24.57 US$/m2. This system is used to conduct a comparison between energy-efficient-building and base-case-building in terms of cooling loads and electrical consumption using hourly-analysis-program (HAP) with international weather data. The simulated annual savings in energy consumption for the three zones are 67.4%, 66.56%, and 67.91%. The economic analysis shows promising payback years, which are 3.1, 3.9, and 4.3 for zone one, zone two and zone three respectively.

Development of Load-Bearing Thermal Insulation Recycled Concrete Block and Research on its Thermal Performance

2014 ◽  
Vol 1004-1005 ◽  
pp. 1503-1507 ◽  
Author(s):  
Xi Xi He ◽  
Xing Ming Liang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Masonry Walls ◽  
Insulation Material ◽  
Load Bearing

A new kind of 310mm thick load-bearing thermal insulation block utilizing construction waste as coarse aggregate was developed and produced. Internal thermal bridge is reduced by special design of holes pattern and cut off by mal-posed thermal insulation layer arrangement. By testing heat transfer coefficient of four kinds of masonry walls, different aggregate type, masonry unit type and insulation material which affect thermal performance of masonry were studied. Results show that heat transfer coefficient of walls with recycled aggregates is lower than that with natural aggregates under the same condition. By filling thermal insulation material in block holes, heat transfer coefficient is dramatically lowered. Among four types of masonry walls, heat transfer coefficient of 310mm thick load-bearing block wall with recycled aggregate is the lowest, and its thermal insulation performance is the best.

Structure Designing and Property Investigation of Flexible Multilayer Thermal Insulation Materials

2011 ◽  
Vol 15 (3) ◽  
pp. 21-27 ◽  
Author(s):  
Jinjing Chen ◽  
Weidong Yu
Keyword(s):  
Heat Transfer ◽  
Thermal Insulation ◽  
Thermal Performance ◽  
Thermal Contact ◽  
Radiation Heat Transfer ◽  
Insulation Material ◽  
Insulation Materials ◽  
Compressive Loads ◽  
Multilayer Insulation ◽  
Gas Conduction

In this paper, a method of designing flexible multilayer insulation is analyzed and discussed, with focus on reducing the three basic modes of heat transfer (thermal radiation, solid spacer and residual gas conduction). The foundation for designing the new flexible thermal insulation material is provided. The insulation performances of different types (by choosing different reflection shields and spacers) of flexible multilayer insulation materials are obtained through measurements using a KES-F7 Thermal Labo II apparatus. The thermal performance of flexible multilayer insulation materials at different layers are also presented, and the best is about 20∼25 layers. To improve the thermal performance of multilayer insulation materials, treble spacers between double aluminized shields are applied. Aluminized shields with air, meshes, wool fibres, etc. are compared with each other. The aluminized shields with meshes fixed with down can reduce thermal contact, which reduces the radiation heat transfer more fully and can be more steady than the other spacers in the project applications. With the same layers and spacers, the thermal conductivity of crinkled aluminized shields is lower than that of the smooth aluminized shields. The effects of compressive loads on layer density and thermal performance are also investigated.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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