Intro & Thermodynamic Limits Flashcards
What are the units of energy and power?
Energy- Joules
Power - Watts
About how much power does a large nuclear power station produce?
Around 1 GW of power
What was the approximate energy consumption in the UK in 2012?
8*10^18 J
About how much energy does a nuclear power station produce per year?
3.15*10^16 J
Approximately how much electricity does a UK person require?
4kW
About how much energy and power did the world consume in 2012?
5.6*10^20 J (17.7 TW)
Name 9 sources of electrical power.
- Coal
- Oil
- Gas
- Nuclear
- Solar
- Fusion
- Hydro
- Biofuel
- Wind
How do AC power stations generate emf?
- Spinning magnets past loops of wire
- Induces emf drives current
What is the equation for the efficiency of an idealised heat engine?
n = Work done/heat in = (Qin-Qout)/Qin
What are the 4 steps in the carnot cycle?
- Adiabatic expansion
- Isothermal compression
- Adiabatic compression
- Isothermal expansion
What are the characteristics of adiabatic expansion?
- Temp decreases
- Work greater than zero
- Heat transferred = 0
What are the characteristics of isothermal compression?
- Temp the same
- Work less than zero
- Heat out = Q(L) <0
What are the characteristics of adiabatic compression?
- Temp increases
- Heat transferred = 0
- Work done less than zero
What are the characteristics of isothermal expansion?
- Temp the same
- Work > 0
- Heat in = Q(H) > 0
What is the equation for Carnot efficiency of an engine?
n = 1 - T(out)/T(in)
What is the Carnot efficiency?
The maximum possible efficiency for converting heat to work (much lower in real life)
How do turbines work?
High pressure steam from furnace makes high velocity steam turn turbine.
How does the efficiency vary with T(in)?
Higher T(in) = higher efficiency
