Heat transfer through a double-glazed unit with an internal louvered blind: Determination of the thermal transmittance using a biquadratic equation

• Published in: International journal of heat and mass transfer Vol. 55; no. 4; pp. 1226 - 1235
• Main Authors: Karmele Urbikain, M., Sala, José M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 31.01.2012; Elsevier
• Subjects: Applied sciences; Blind; Blinds; Buildings; Buildings. Public works; Double-glazed unit; Emissivity; Exact sciences and technology; External envelopes; Heat transfer; Heat-transfer coefficient; Holes; Mass transfer; Mathematical analysis; Opening. Closure. Circulation (stairs, etc.); Slats; Thermal transmittance; Transmittance; U-factor; Window; Window; Blind; Thermal transmittance; Heat-transfer coefficient; Double-glazed unit; U-factor; Double glazing; Window blind; Numerical simulation; Natural convection; Windows; Heat transfer coefficient; Transmittance; Modeling; Heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2011.09.032

The aim of this research is to quantify the influence of a louvered blind in a double-glazed unit during night-time conditions. First, an analytical study of free convection was conducted to obtain a set of correlations for the Nusselt numbers of the cavity. Second, a parametric study was performed to calculate the total heat transfer (convective and long-wave radiative) during night-time conditions. The analysis accounted for aspect ratio, blind thermal conductivity, surface emissivity and slat angle. Using these data, a biquadratic equation was developed to calculate the U-factor of a double-glazed unit with an internal louvered blind in terms of the U-factor of the unit without the blind, slat surface emissivity and slat angle.