Thermal Engineering, Refrigeration & Power

The standard step-by-step procedure to apply Thevenin's theorem is:

• Remove the load resistance $R_L$ from the terminal points A and B.
• Calculate the open-circuit voltage across terminals A and B, which is $V_{th}$ / $E_{th}$.
• Deactivate all independent sources (short voltage sources, open current sources) to find internal Thevenin resistance $R_{th}$ across A and B.
• Construct the Thevenin equivalent circuit containing $E_{th}$ in series with $R_{th}$ and reconnected load $R_L$.
• Calculate the load current: $I_L = \frac{E_{th}}{R_{th} + R_L}$.

Devices used to modulate (vary, increase, or decrease) AC voltage include Variac (variable auto-transformer), step-up transformers (increase AC voltage), and step-down transformers (decrease AC voltage). Dynamos (generate DC) and alternators (generate AC from mechanical energy) are electrical generators, not voltage modulation devices.

Kick's law states that energy required for size reduction is proportional to the reduction ratio of the initial to final particle diameters ($E = K_K \ln(d_1/d_2)$). It is based on stress-strain behavior within elastic limits (plastic deformation/strain within elastic limits) and applies accurately to coarse grinding / primary crushing where ratio of sizes is moderate.