Absortion of Radiation in the Transwall

Greveniotis, Konstantinos (1986) Absortion of Radiation in the Transwall. MSc(R) thesis, University of Glasgow.

Abstract

This thesis is concerned with the study of the absorption of solar radiation in a transwall module, an element of a passive solar system. The transwall system is reviewed and its merits discussed. The design criteria of the transwall module and the costs associated with the various module design variations are given. It is concluded that the best design for building is a 10 mm thick glass tank 1.5 m long x 0.75 m high filled with a water/dye solution. The calculation of the insolation absorbed by the transwall requires knowledge of the fractional energy in various wavebands and the absorption coefficients of the transwall materials. A standard atmosphere is defined for the Glasgow area, its parameters listed, and the fractional energy levels for beam and diffuse radiation (clear sky) are derived. Plots demonstrate how the extraterrestrial spectrum is modified by various atmospheric parameters. The absorption coefficients for the transwall dyes, Lissamine Red 3GX, Carbolan Rubine, Methyl Orange and Acid Green have been measured and their individual use described. The performance of a transwall module has been analysed by assuming the module to have an infinite thermal conductivity (a lumped system) and predictions tested against measurement. It is shown that the predicted temperature rise is liable to be in error by 20% due mainly to elevated glass temperatures, and by 8%, when cooling on the cessation of insolation. The effect of other parameters on the accuracy of this method is examined, and the curious temperature profiles described. After demonstrating that the lumped system approach has fundamental problems a case is made for a two-dimensional finite difference solution. As a first step in this work a computer program has been written to give the absorption of radiation in the various volumes of the transwall and it has been validated by measurement. The methodology of internal shade and acceptance factors for the volumetric slabs of the transwall is given. The program is used to quantify various factors, such as the sensitivity of slab numbers, the effects of dyes and solar absorbing glass, the effects of solar spectra and the number of wavebands, the effect of taking into account room reflected radiation. This thesis concludes by suggesting directions for future work.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Mechanical engineering, Alternative Energy
• Date of Award: 1986
• Depositing User: Enlighten Team
• Unique ID: glathesis:1986-76602
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 14:04
• Last Modified: 19 Nov 2019 14:04
• URI: https://theses.gla.ac.uk/id/eprint/76602