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...doors. accompanying text notes that the values given "are generic values, and product-specific values determined in accordance with standards should be used whenever available." This is better than no information at all, but it provides little guidance. The most widely cited national standard for thermal performance of doors in the United States is NFRC 100 (NFRC 2004a), which does not address revolving doors or many types of overhead doors.
The thermal performance of emergency-exit doors and large rolling or sliding cargo doors is not considered at all in the current Handbook. In response to the needs expressed by its members and the HVAC community, ASHRAE issued a request for proposal with the following objectives:
* updating the information in chapter 30 of Fundamentals to include more door types,
* developing correlations to characterize convective flow and related heat transfer in enclosed chambers of revolving doors, for simplified calculation procedures,
* evaluating the variation in thermal performance as a function of temperature conditions and product size, and
* developing recommendations for testing and simulation of various door products, to provide guidance to designers for evaluation of products not in the current scope of work and to assist in the development of national standards to evaluate such products.
Part of the resulting project, ASHRAE 1236-RP, involved determining total product U-factors of seven representative specimens using computer simulation, for comparison to U-factor results from hot-box testing. If the results compared favorably, the computer models were assumed to be validated and were then used to provide a wider range of design values for similar products.
This paper describes the procedures for evaluating the U-factor of the seven specimens using computer simulation. A separate paper (McGowan et al. 2006) has been written to describe the testing procedures conducted in parallel to these simulations. The entire project is described in the final report for this research project, ASHRAE 1236-RP (ASHRAE 2006). The report includes test and simulation results for all seven specimens and design values generated for the ASHRAE Handbook--Fundamentals.
Test Specimens
All specimens were simulated as configured in the test chamber to allow direct comparison between test and simulation results. Therefore, it is appropriate to review the as-tested configurations to describe the simulation conditions. The project report describes all seven test specimens that were simulated, but space considerations restrict this technical paper to a discussion of only three products:
* Specimen 1 was a steel sectional overhead-type door (similar to Figure 1). The door sections were nominally 50 mm (2 in.) overall thickness, constructed of 24-gauge galvanized steel. Meeting rails were rabbeted to form a weather seal (but not an air seal) between sections. Each of the five sections in the door assembly is reinforced with two steel ribs, with end channels wrapped around each section and spot-welded in place. Galvanized hardware provided with the door included adjustable top roller brackets, end-roller, and intermediate hinges and galvanized steel roller channels on either side to represent typical installation. The roller channels normally extend along the ceiling of a garage, to guide the door sections as the assembly opens, but the channels in the test specimen had to be cut at the top of the door to avoid interference with the constant-temperature baffle and the convective flow of room-side air during the thermal testing. Figure 1 shows the installation for Specimen 2, but Specimen 1 was installed in the same way. All specimens were installed in the mask wall and moved with the mask wall from the air-leakage test chamber to the thermal test chamber as a unit.
[FIGURE 1 OMITTED]
The bottom of the door included a weather seal made of a U-shaped extruded vinyl bulb seal, typical of this type of installation. Perimeter seals at the jambs and head of the door assembly are optional accessories but are often not installed as they may interfere with door operation. The perimeter seals were not installed on this specimen.
* Specimen 3 was a three-wing glazed revolving door (Figure 2), comprising three panels, two curved sidewalls, and a canopy manufactured from aluminum extrusions. The sidewall construction utilized a vertical end post on each side and one post in the center (where the door assembly connects to the exterior wall of a building or in this case to the mask wall of the test chamber). The door panels are attached to the center shaft with two hangers on each wing, which allow the panels to be held in position with a preset tension and to be folded outward to allow for emergency egress.
[FIGURE 2 OMITTED]
The hardware that allows the door panels to collapse during an emergency exit is housed in the floor below the central shaft. This hardware cannot be removed from the specimen, as the integrity of the door panels rests on it. This necessitates that the specimen must...
NOTE: All illustrations and photos
have been removed from this article.
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