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Show Axial Temperature Profile 2 % 0 2 Emissions 1900 2000 2100 2200 2300 2400 2500 Emitter Surface Temperature (F) Temp. Profile Around Emitter Circumference at 2 % 0 2 360 1900 2000 2100 2200 2300 2400 2500 2600 Emitter Surface Temperature (F) Figure 8: Emitter temperature profiles Subsequent tests integrated the B E R with two P C A assemblies. The first P C A underwent several design changes to improve its efficiency. For example, the first P C A was water cooled, and the second was air cooled. The air-cooled P C A fabricated at J X C is illustrated in Figure 4. Cooling is required to maintain P V cell temperatures as close to room temperature as possible, since the electrical conversion efficiency of the cells decreases with increased operating temperature. The portable prototype will be designed to use air cooling with an arrangement similar to the one shown in Figure 2. The air was supplied with a compressor during experimentation. Water-cooling was used during early development to avoid P V cell operation at elevated temperature and allow initial assessment of the integrated systems with cells operating under ideal temperature conditions. However, the water-cooled inlet and outlet manifolds directly absorbed energy from the BER, reducing emitter temperature and lowering performance. Figure 9 shows the increase in emitter temperature with the air-cooled P C A . Energy input includes fuel energy and electrical energy supplied to preheat the combustion air. The figure also shows that further improvements to the P C A design are required to reach the targeted (ideal) P C A efficiency represented by the thinly insulated emitter. Another aspect to burner performance is life. Two issues arose in this regard. The first was the durability of burner materials at high temperature, and the second was the deposition of carbon in flow passages. |