If you dont know how to answer it please dont bother to answ

If you don\'t know how to answer it please don\'t bother to answer to attempt.

Problem:

Fuel cells are used in spacecraft and proposed extraterrestrial bases for generating power and heat. The cell produces electric power by the reaction between liquid hydrogen and liquid oxygen 2H_2 + O_2 rightarrow 2H_2O Design a ratio controller to maintain the flows of liquid hydrogen and oxygen into the cell in the exact stoichiometric ratio (both hydrogen and oxygen are valuable in space, so we cannot supply either in excess). Calculate the design flows of hydrogen and oxygen required to produce 0.5 kg/h of water, and the design ratio of oxygen to hydrogen flow. Sketch a ratio control scheme that will manipulate the flow of oxygen to maintain the exact stoichiometric ratio between the two flows.

Solution

• A boiler drum with a conventional feedback control system is shown in Fig. 15.2. The level of the boiling liquid is measured and used to adjust the feedwater flow rate. • This control system tends to be quite sensitive to rapid changes in the disturbance variable, steam flow rate, as a result of the small liquid capacity of the boiler drum. • Rapid disturbance changes can occur as a result of steam demands made by downstream processing units.