A4 Energy systems

Mean log Temp

U total, with fouling factor

Change in entropy

Heat exchanger effectiveness, ε

ε = rate of heat transfer / rate of max possible heat transfer

Number of transfer units, NTU

Capacity ratio, c

Transformer, max efficiency condition

Voltage regulation

Resistance equation (for infinitesimal area/length)

Current flow for infinitesimal area

Transformer short circuit test

Neglect core & magnetising components

Transformer open circuit test

Neglect copper & flux leakage components

Cavitation: requirement & equation

Reaction, r (for turbine)

Velocity potential, φ

gradφ = V, for φ to exist vorticity, ζ, = 0

Heat exchanged, ΔQ (heat exchangers)

Equilibrium constant (equilibrium reactions)

What is different about high frequency transformers?

• can be smaller for same power ratio

• losses are higher so need different core construction

DC Brushed Motor (Permanent magnet DC motor)

Separate Excitation PMDC motor

PMSM, AC Permanent magnet synchronous motor

Linear Regulator

Buck converter

Boost converter

Buck - Boost converter

Half-bridge (circuit)

Half-bridge (avg power model)

Bridge rectifier

Full bridge rectifier