Radiant panel

ASTM E162-87 radiant panel flame spread... 

Artificial surfaces must be resistant to cigarette bums, vandaUsm, and other harm. Fire resistance is most critically evaluated by the NBS flooring radiant panel test (10). In this test, a gas-fired panel maintains a heat flux, impinging on the sample to be tested, between 1.1 W/cm at one end and 0.1 W/cm at the other. The result of the bum is reported as the flux needed to sustain flame propagation in the sample. Higher values denote greater resistance to burning results depend on material and surface constmction. Polypropylene turf materials are characterized by critical radiant flux indexes which are considerably lower than those for nylon and acryflc polymers (qv) (11). 

FIGURE 8.51 Heat balance for a black bulb in front of a radiant panel. 

Radiant cooling The cooling of a human body or other surface by means of a radiant panel. 

Roulet, C. Rossy, J. and Roulet, Y. (1999). Using Large Radiant Panels for Indoor Climate Conditioning." Energy and Buildings 30 121-126. 

Somewhat similar arrangements can be used when radiant panels or unit heaters heat large areas. Some 10-15 per cent of the heaters are separated from the high-pressure steam supply and supplied instead with low-pressure steam flashed off the high-pressure condensate. The heating demands of the whole area remain in step, so supply and demand for the flash steam are balanced. 

There are several measure sets with immediate payback SE, SF, SH, SI. Measures SE and SF are radiant panel systems with displacement ventilation. These systems have a similar cost to the base case, but they offer energy savings. Furthermore, significant sizing reductions, mainly in the cooling tower and chiller sizes, offset the incremental cost of the envelope and heat recovery measures. Because the elevator efficiency measures offer a net savings in capital cost, the capital cost of the other measures is further offset. 

Figure 2. The Radiant Panel Test was designed to measure both critical ignition energy and rate of heat release. A sample is mounted facing a controlled heat flux but at a 3CP angle to it such that the upper part of the specimen is more severely exposed. Since irradiance decreases down the specimen, the time progress of ignition down the specimen serves to measure central ignition energy. Thermocouples in the stack above the specimen serve as a measure of heat release rate.

Table IV. Radiant Panel Test Results for Structural Foam Samples...

A.L. Bridgman and G.L. Nelson, Heat Release Calorimetry and Radiant Panel Testing A Comparative Study, Proceedings of the International Conference on Fire Safety (Jan. 13-17, 1986), 11, 128-139 (1986). 

An initial experiment involved determination of Arapahoe Smoke Chamber results for samples with and without the zinc coating present. Data are presented in Table II. Depending upon orientation of the sample, an increase in char occurred for some samples with zinc present, while no change in smoke formation was seen. Initial pyrolysis GC/mass spectroscopy results at 90CPC in helium showed no difference in volatiles formed with or without zinc. These results suggested enhanced char formation as the origin of the Radiant Panel results for zinc on modified-polyphenylene oxide (m-PPO). Zinc oxide is a known, effective thermal stabilizer in the alloy. The next work then focused on DSC/TGA studies. 

The choice of the radiant panel only depends upon the rate of development of the international test procedure. If this is not available in sufficient time, the French method will be taken. 

Surface Flammability of Building Materials Using a 8 Ft. Tunnel Furnace, 1984. Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat Energy Source [NIST(NBS) Flooring Radiant Panel], 1993. 

Burners may be located in the floor or on the ends of the heaters. Liquid fuels are atomized with steam or air or mechanically. A particularly effective heater design is equipped with radiant panel (surface combustion) burners, illustrated in Figure 17.16(a), (b). The incandescent walls are located 2-3 ft from the tubes. The furnace side of the panel may reach 2200°F whereas the outer side remains at 120°F because of continual cooling by the air-gas mixture. Radiant panel burners require only 2-5% excess... 

A certain amount of excess air is needed to ensure complete combustion. Typical minimum excess requirements are 10% for gaseous fuels and 15-20% for liquids. Radiant panel burners may get by with 2-5% excess air. 

Figure 17.15. A fired heater as a high temperature reactor, (a) Arrangement of tubes and burners (1) radiant tubes (2) radiant panel burners (3) stack (4) convection chamber tubes (Sukhanov, Petroleum Processing, Mir, Moscow, 1982). (b) Radiant (surface-combustion) panel burner (1) housing (2) ceramic perforated prism (3) tube (4) injector (5) fuel gas nozzle (6) air throttle Sukhanov, Petroleum Processing, Mir, Moscow, 1982). (c) Fired tubular cracking furnace for the preparation of ethylene from naphtha.

As can be seen from Equation 3.20, the short-time solution for the pyrolysis time, tPi is independent of the total heat-transfer coefficient term, hT = (h, + h,). Thus, the pyrolysis time tp is only a function of the energy absorbed aq" due to radiation from the radiant panel and the properties (k, p, Cp) of the solid fuel sample. 

Quintere, J.G., A simplified theory for generalizing results from a radiant panel flame spread apparatus,... 

Bench-scale reaction-to-fire tests are used to characterize the behavior of materials under more severe thermal exposure conditions that are representative of the growing pre-flashover stage of a compartment fire. These tests essentially determine how a material responds to the temperatures and heat fluxes in a growing fire. In these tests, the fire conditions are simulated with a radiant panel or by inserting the specimen into a small furnace. A pilot may be used to ignite the flammable gases and vapors that are generated as a result of thermal decomposition of the... 

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