Energy of Charged Capacitors

The amount of work required to increase the charge on a capacitor from Q to Q + dQ is dJ = VdQ, where V is the potential difference and the charge is Q. Because V = QIC, the integration gives Equation 7-20, and substitutions give 

The units used in Equations 7-26 and 7-27 are usually C in farads, V in volts, Q in coulombs, and J in joules. 

Capacitances of various materials used in the chemical industry are given in Table 7-5. Charges can accumulate as a result of a streaming current dQldt = Is. Assuming a constant streaming current, 

The streaming current is a function of the velocity and the pipe diameter. The average velocity in the pipe is 

The capacitance between the two 1-in flanges is given in Table 7-4, that is, C = 20 x 10 12 farads = 20 x 10 12 coulomb/volt. The energy is determined using Equation 7-26  

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