- Author
- Fong, J. T. | Treado, S. J.
- Title
- Finite Element Analysis of Advanced Technology Laboratories (ATL) Isolation Slab Conditioning System. An Interim Progress Report.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Report
- NISTIR 5528, November 1994, 139 p.
- Distribution
- Available from National Technical Information Service
- Keywords
- convective heat transfer | heat transfer | temperature control | heat transmission
- Identifiers
- finite element analysis; mathematical analysis; partial differential equations; Poisson's equation; slab conditioning system
- Abstract
- Using a finite-element analysis package named ANSYS (v. 5.0a), we model a precision temperature-control slab conditioning system in order to solve a steady state and transient heat transfer problem for a new NIST facility known as the Advanced Technology Laboratories (ATL). The problem arises because the concrete floor slabs of some of the ATL laboratories are exposed to warm room air above and cold earth below, and a supplementary heating source consisting of embedded electric cables and heated water pipes (hydronic system) is proposed to alleviate the difficulty of achieving precision temperature control due to a constant heat loss to the ground. For this interim report, two sets of computer codes, one for the steady state and the other for the transient phenomenon, were developed for a two-dimensional slab/insulation/soil configuration, and applied to three steady-state and six transient loading cases. Preliminary results of this study are: (a) The time constant for the slab conditioning system is estimated to be between 10 to 20 hours. (b) The temperature distribution along the top surface of the slab is not uniform, with a significant discrepancy between the center and the edge of the slab in the order of 0.06 deg C. (c) The proposed hydronic heating system is found to be beneficial to temperature stabilization and slab isolation. Additional questions to be answered in the final report include (d) the effect of the heating cable system, (e) the influence of the long time constant to the performance of the laboratory temperature control system, and (f) the "goodness" of the 2-D approximate model solution to the actual 3-D physical configuration.