Thermal resistance of airspaces and fibrous insulations bounded by reflective surfaces

Robinson, Henry E; Cosgrove, L A; Powell, Frank J

doi:10.6028/nbs.bms.151

Cited by 18 publications

(22 citation statements)

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“…Thereafter, the convective heat transfer coefficients were obtained from the data by subtracting a calculated radiative heat transfer rate from the total corrected heat transfer rate; and the radiative heat transfer was calculated using an emissivity of 0.028 for the aluminum surfaces. Robinson et al ( , 1956 …”

Section: This Paper Focuses On Determining the R-values Of Enclosed Amentioning

confidence: 99%

“…The R-values of enclosed airspaces were calculated by many investigators (e.g. see , 1956) for various orientations of airspaces and reflective boundaries by using heat transfer coefficient data that was published by Robinson et al ( , 1956. The heat transfer coefficient data were obtained from measurements of panels of different thicknesses using the test method described in the ASTM C236-53 (ASTM 1953).…”

Section: This Paper Focuses On Determining the R-values Of Enclosed Amentioning

confidence: 99%

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Practical correlation for thermal resistance of low-sloped enclosed airspaces with downward heat flow for building applications

Saber

2014

HVAC&R Research

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Section: This Paper Focuses On Determining the R-values Of Enclosed Amentioning

confidence: 99%

Section: This Paper Focuses On Determining the R-values Of Enclosed Amentioning

confidence: 99%

Practical correlation for thermal resistance of low-sloped enclosed airspaces with downward heat flow for building applications

Saber

2014

HVAC&R Research

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“…see [14 -17]) for various orientations of airspaces and reflective boundaries by using heat transfer coefficient data that was published by Robinson et al [15,16,17]. The heat transfer coefficient data were obtained from measurements of panels of different thicknesses (0.625 in to 3.375 in (15.9 mm to 85.7 mm)) using the test method described in ASTM 236-53 [18].…”

Section: Introductionmentioning

confidence: 99%

“…The 2009 ASHRAE Handbook of Fundamentals (Chapter 26) [14] provides a table that contains the R-values for an enclosed airspace and these were determined on the basis of the heat transfer data reported by Robinson et al [15,16,17]. These values were obtained by combining the convective and radiative components of heat transfer from which the total thermal resistance value for an enclosed airspace was provided for airspaces of different thickness ( = 13, 20, 40, and 90 mm), mean temperature (T avg = 32.2, 10.0, -17.8 and -45.6 o C), temperature difference across the airspace (T = 5.6, 11.1 and 16.7 o C), effective emittance ( eff = 0.03, 0.05, 0.2, 0.5 and 0.82), and direction of heat flow through the airspace.…”

Section: Introductionmentioning

confidence: 99%

“…The model was used to calculate the R-values using the heat transfer coefficients derived by Robinson [15,16,17] combined with a term accounting for repeated reflection of energy between infinite parallel planes based on the Stefan-Boltzmann law. The R-values obtained using the REFLECT model are thus independent of the aspect ratio of the enclosed airspace [4].…”

Section: Introductionmentioning

confidence: 99%

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Practical correlations for the thermal resistance of vertical enclosed airspaces for building applications

Saber

2013

Building and Environment

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Many parts of the building envelope contain enclosed airspaces. The thermal resistance (Rvalue) of an enclosed airspace depends on the emissivity of all surfaces that bound the airspace, the size and orientation of the airspace, the direction of heat transfer through the airspace, and the respective temperatures of all surfaces that define the airspace. The 2009 ASHRAE Handbook of Fundamentals (Chapter 26) provides a table that contains the R-values for an enclosed airspace. The ASHRAE table is extensively used by modellers, architects and building designers in the design of building enclosures. T his table provides R-values for enclosed airspaces for different values of the thickness of the airspace, effective emittance, mean airspace temperature, and temperature differences across the airspace. The effect of the airspace aspect ratio (height/thickness of airspace) on the R-value is not included in the ASHRAE table. However, in a recent study on the R-value of reflective insulations using a numerical simulation model, it was shown that the aspect ratio of the airspace can affect the Rvalue of the enclosed airspace. The numerical simulation model used in this study had been benchmarked against experimental data obtained using two standard test methods: ASTM C-518 and ASTM C-1363.In this paper, a numerical simulation study was conducted, that was based on previous work focused on enclosed airspaces, to investigate the effect of the aspect ratio on the R-value of vertical enclosed airspaces of different thicknesses and having a wide range of values for effective emittance, mean temperature, and temperature differences across the airspace. The R-values predicted from numerical simulation are compared with those provided in the ASHRAE table. Considerations were also given to investigating the potential increase in R-values of enclosed airspaces when a thin sheet is placed vertically in the middle of the airspace and whose surfaces have different values of emissivity. Finally, practical correlations are developed for determining the R-values of an enclosed airspace for future use by modellers, architects and building designers. The simplicity of these correlations suggests that these could be included in the ASHRAE Handbook of Fundamentals.

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Overview of Thermal Performance of Air Cavities and Reflective Insulations

Saber

2022

Thermal Insulation and Radiation Control Technologies for Buildings

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Thermal resistance of airspaces and fibrous insulations bounded by reflective surfaces

Cited by 18 publications

References 0 publications

Practical correlation for thermal resistance of low-sloped enclosed airspaces with downward heat flow for building applications

Practical correlation for thermal resistance of low-sloped enclosed airspaces with downward heat flow for building applications

Practical correlations for the thermal resistance of vertical enclosed airspaces for building applications

Overview of Thermal Performance of Air Cavities and Reflective Insulations

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