EGB322 Week 13 Review Lecture: Thermodynamics Final Exam Preparation

Comprehensive vocabulary and core concepts covering exam format, multiple-choice questions, Otto, Diesel, Brayton, Rankine, and refrigeration thermodynamic cycles from the EGB322 Week 13 review lecture.

EGB322 Final Examination Structure

A closed-book, on-campus invigilated exam lasting $3\text{ hours and }10\text{ min}$ (including $10\text{ minutes}$ reading time) worth $100\text{ marks}$ total ($60\text{\%}$ of unit grade), containing SECTION A (10 multiple-choice questions, $20\text{ marks}$) and SECTION B (4 numerical problems, $80\text{ marks}$).

Carnot Heat Pump and Refrigerator COP Relation

The mathematical relationship between the coefficient of performance of a Carnot heat pump and a Carnot refrigerator operating between the same two thermal energy reservoirs, given by $\text{COP}_{\text{HP}} = \text{COP}_{\text{R}} + 1$.

Entropy (Thermodynamics)

A thermodynamic property defined as a measure of disorder or randomness in a system.

Single-Stage Isentropic Compressor Work

The work required per unit mass to compress an ideal gas reversibly and adiabatically between two pressures, given for air with constant specific heats compressed from $100\,\text{kPa}$ and $300\,\text{K}$ to $900\,\text{kPa}$ as $263.2\,\text{kJ/kg}$.

Turbine Isentropic Efficiency ($\eta_T$)

The ratio of the actual work output of a turbine to the work output that would be achieved if the process were isentropic between the inlet state and the exit pressure ($\eta_T = \frac{w_a}{w_s}$).

Ideal Otto Cycle

The ideal cycle for spark-ignition reciprocating internal combustion engines consisting of four internally reversible processes: isentropic compression ($1 \rightarrow 2$), constant-volume heat addition ($2 \rightarrow 3$), isentropic expansion ($3 \rightarrow 4$), and constant-volume heat rejection ($4 \rightarrow 1$).

Ideal Diesel Cycle

The ideal cycle for compression-ignition reciprocating internal combustion engines consisting of isentropic compression ($1 \rightarrow 2$), constant-pressure heat addition ($2 \rightarrow 3$), isentropic expansion ($3 \rightarrow 4$), and constant-volume heat rejection ($4 \rightarrow 1$).

Compression Ratio ($r$)

The ratio of the maximum cylinder volume at Bottom Dead Center (BDC) to the minimum clearance volume at Top Dead Center (TDC) in an internal combustion engine ($r = \frac{V_{\text{BDC}}}{V_{\text{TDC}}}$).

Mean Effective Pressure (MEP)

A fictitious constant pressure that, if it acted on the piston during the entire power stroke, would produce the same net work output as the actual cycle ($\text{MEP} = \frac{W_{\text{net}}}{V_{\text{max}} - V_{\text{min}}}$).

Ideal Brayton Cycle

The ideal cycle for gas-turbine power plants consisting of four internally reversible processes: isentropic compression in a compressor ($1 \rightarrow 2$), constant-pressure heat addition ($2 \rightarrow 3$), isentropic expansion in a turbine ($3 \rightarrow 4$), and constant-pressure heat rejection ($4 \rightarrow 1$).

Back Work Ratio ($r_{\text{bw}}$) in Brayton Cycles

The ratio of the work input required by the compressor to the work output produced by the turbine ($r_{\text{bw}} = \frac{w_{\text{comp,in}}}{w_{\text{turb,out}}}$).

Pressure Ratio ($r_p$)

The ratio of the compressor exit pressure to the compressor inlet pressure in a Brayton cycle ($r_p = \frac{P_2}{P_1}$).

Simple Ideal Rankine Cycle

The ideal thermodynamic cycle for vapor power plants consisting of isentropic pumping of liquid ($1 \rightarrow 2$), constant-pressure heat addition in a boiler ($2 \rightarrow 3$), isentropic expansion in a turbine ($3 \rightarrow 4$), and constant-pressure condensation in a condenser ($4 \rightarrow 1$).

Ideal Vapor-Compression Refrigeration Cycle

The standard refrigeration cycle consisting of isentropic compression in a compressor ($1 \rightarrow 2$), constant-pressure heat rejection in a condenser ($2 \rightarrow 3$), throttling in an expansion valve ($3 \rightarrow 4$), and constant-pressure heat absorption in an evaporator ($4 \rightarrow 1$).

Ideal Otto Cycle Diagrams

The state property diagrams ($P\text{-}v$ and $T\text{-}s$) displaying the ideal Otto cycle, featuring isochoric heat addition ($q_{\text{in}}$) and isochoric heat rejection ($q_{\text{out}}$) between two isentropic processes.

Ideal Diesel Cycle Diagrams

The state property diagrams ($P\text{-}v$ and $T\text{-}s$) displaying the ideal Diesel cycle, featuring isobaric heat addition ($q_{\text{in}}$) and isochoric heat rejection ($q_{\text{out}}$) between two isentropic processes.

Closed-Cycle Gas-Turbine Engine Schematic

A closed-loop power plant configuration where air circulates steadily through a compressor, a high-temperature heat exchanger, an expansion turbine, and a low-temperature heat exchanger.

Simple Ideal Rankine Cycle $T\text{-}s$ Diagram

A temperature-entropy plot showing liquid compression in a pump ($1 \rightarrow 2$), heating and vaporization in a boiler ($2 \rightarrow 3$), isentropic expansion through the vapor dome into superheated or two-phase steam ($3 \rightarrow 4$), and condensation back to saturated liquid ($4 \rightarrow 1$).

Vapor-Compression Refrigeration System Schematic

A cyclic cooling configuration consisting of an evaporator taking in heat ($Q_L$), a compressor driven by work ($W_{\text{in}}$), a condenser rejecting heat ($Q_H$), and an expansion valve reducing refrigerant pressure.