A time-domain estimation of wall conduction transfer function coefficients
- Univ. of Liverpool (United Kingdom). School of Architecture and Building Engineering
The wall and roof transfer function coefficients, b{sub n} and d{sub n}, listed in the 1993 ASHRAE Fundamentals Handbook, have up to now been derived using laplace and Z-transform methods. This paper shows that they can be readily evaluated using straightforward time-domain solutions of the Fourier continuity equation. These include the response of a wall to a ramp increase in temperature and its transient response. The values of d{sub n} can be found from the first few terms in the series of wall decay times in the transient solution. The solutions are combined using a form of Fourier analysis. Appropriate layer transmission matrices enable one to find the wall`s overall characteristics readily. The wall response factors {phi}{sub j} can thus be found. The b{sub n} transfer coefficients are related to the {phi}{sub j} and d{sub n} values. The approach is illustrated using the data for wall group 6. Allowing for conversion from I-P to SI units, the present approach gives results that are almost identical to those listed. It shows, however, that the performance of the coefficients is very specific to the wall from which they were derived. The b{sub n} and d{sub n} values listed in the Handbook permit an estimate to be made of the wall response factors, including the time of peak flow and the first decay time. For heavy walls, however, values beyond d{sub 6} may be needed.
- OSTI ID:
- 392460
- Report Number(s):
- CONF-960254-; TRN: IM9647%%314
- Resource Relation:
- Conference: Winter meeting of American Society of Heating, Refrigeration and Air Conditioning Engineers, Atlanta, GA (United States), 17-21 Feb 1996; Other Information: PBD: 1996; Related Information: Is Part Of ASHRAE transactions 1996: Technical and symposium papers. Volume 102, Part 1; PB: 1278 p.
- Country of Publication:
- United States
- Language:
- English
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