Heat Engines

Question 1

What is a Heat Engine?

Answer 1

• system that converts thermal energy into useful mechanical work
  1. receives heat
  2. converts part to work
  3. rejects remaining to sink
  4. repeats

Question 2

6 main components of a reciprocating engine?

Answer 2

TDC - Top dead centre, lowest volume
BDC - Bottom dead centre, highest volume
Intake - Brings in fuel/air mixture
Exhaust - Expels waste
Bore - Diameter of the piston
Stroke - Length from BDC to TDC

Question 3

4 stages of a Four Stroke Engine.

Answer 3

1. Intake / Expansion. - brings mix in
2. Compression - contracts
3. Ignition /Expansion - ignites, expands piston, creates useful work
4. Reject / Repeat - waste exits

Question 4

MEP Equation.

Answer 4

MEP = w(net) / V(max) - V(min)
// q(in) - q(out) / v1 - v2

Question 5

Reciprocating Engine: Displacement Volume Equation.

Answer 5

pi*D^2 / 4 * stroke

Question 6

Equation: Mass of Fluid (m)

Answer 6

PV / RT

Question 7

Air Standard Assumptions.

hint: 4

Answer 7

1. working fluid is assumed to be air - acts as an ideal gas
2. all processes reversible
3. compression replaced with heat addition
4. exhaust replaced with heat rejection

Question 8

Cold Air Standard Assumptions.

hint: 1 :(

Answer 8

1. Specific heats constant (take at 25C)