Rod heaters

The furnace was preheated and the atmosphere conditioned by passing Ar (up to 300 mL/h) humidified with superheated steam for one hour prior to starting the test. The Ar was humidified by injecting water from a syringe pump into the Ar line, which was heated with an internal Kal-rod heater and is referred to as the superheated steam line (SHS). The temperature of the humidified Ar at the exit of the SHS was monitored with a thermocouple and was varied via a variac. 

A long rod heater with e = 0.8 is maintained at 980°C and is placed near a halfcylinder reflector as shown. The diameter of the rod is 7.5 cm, and the diameter of the reflector is 50 cm. The reflector is insulated, and the combined heater reflector is placed in a large room whose walls are maintained at I5°C. Calculate the radiant heat loss per unit length of the heater rod. How does this compare with the energy which would be radiated by the rod if it were used without the reflector ... 

The DST consists of a 5m diameter, 47.5m long drift heated by 9 cylindrical electric heaters placed on the floor. Each heater, 1.7m diameter and 4.6m long, is capable of generating a maximum of 15kW. Additional heating is applied by 50 rod heaters, referred to as wing heaters , emplaced in horizontal bore holes drilled into either side wali of the drift (Figure 1). 

A German company, Kuhne GmbH, has introduced a triple-bubble process, which uses infrared heat, rod heaters, and other annealing techniques in a thermofixa-tion station to impart precise shrink rates to coextruded film. 

The rod heater had some scale-like deposits on it but no sign of heat damage at all. 

Maintenance costs. Quartz tube heaters are fragile and must be carefully cleaned. Rod heaters are rugged but can rapidly lose efficiency. 

Typically, a single cell is fabricated by fixing the assembled MEA between two graphite bipolar plates machined with parallel or serpentine flow fields. Two metal end plates are placed at the outer sides of the two graphite bipolar plates to hold them in place. Rod heaters are inserted into the end plates to control the cell temperature. Figure 10.23 shows a photograph of a typical 50 cm HT-PEM fuel cell [83]. 

Heating may be provided by several band heaters. In the example pilot machine described, the total heat output is 11 kW. Various configurations may be used to achieve the desired output, including two 1.5 kW and one 3 kW heater around the main kier and two 2.5 kW rod heaters in the base of the mixing tank. A control panel may be provided for the manual control of these units. However, heaters could also be controlled via interface. Table 7.2 shows that the interface in this case includes eight TTL-level outputs, i.e. BlTs 0 to 7. BlTs 0 to 4 are connected to the heaters. In this implementation, single precision integers can be used to store the status of the heaters. 

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