MECE 2334 Thermodynamics Exam 1 Review

Vocabulary and core concepts extracted from the MECE 2334 Thermodynamics Exam 1 lecture materials and problem sets.

State Principle (Simple Compressible System)

The requirement that two independent intensive properties are needed to fix the state of a simple compressible system.

Closed System

A system where energy transfer occurs across the boundary but mass transfer does not.

Thermodynamic Properties

Characteristics of a system such as Internal Energy ($u$), Quality ($x$), and Temperature ($T$) that depend only on the state and not the path.

Heat and Work

Energy transfer mechanisms that are considered path functions rather than properties of a system.

Moving Boundary Work

The energy transfer by work associated with the change in volume of a system, calculated as $W = \int P \, dV$.

Polytropic Process

A process in which pressure and specific volume are related by the expression $pv^n = \text{constant}$; in the lecture notes, an example is given as $pv^2 = \text{constant}$.

Quality ($x$)

A thermodynamic property that determines the ratio of vapor mass to total mass, applicable only to liquid-vapor mixtures.

Saturated Mixture

A state where liquid and vapor phases are present at equilibrium, occurring when the specific volume ($v$) is between $v_f$ and $v_g$ (e.g., $T = 30^{\circ}C$ and $v = 5\,m^3/kg$).

Superheated Vapor

A phase where water exists entirely as a gas at a temperature or specific volume higher than the saturation point for a given pressure (e.g., $P = 1\,bar$ and $v = 5\,m^3/kg$).

Subcooled Liquid

A phase where the internal energy ($u$) or temperature ($T$) is lower than the saturation value for a given pressure (e.g., $T = 10^{\circ}C$ and $u = 40\,kJ/kg$).

Energy Balance Equation (Closed System)

The equation representing the conservation of energy: $\Delta KE + \Delta PE + \Delta U = Q - W$.

Specific Internal Energy Mixture Formula

The calculation used to find the internal energy of a saturated mixture: $u = u_f + x(u_g - u_f)$.

Piston-Cylinder Isobaric Heating

A process where fluid pressure remains constant because it balances the combined constant weight of the piston and the atmospheric pressure.

Piston Stops

Mechanical constraints in a cylinder that, once reached, result in a constant volume (isochoric) process during further heating.

Negligible Kinetic and Potential Energy

An assumption made when elevation changes are small, the mass is small, or the system starts and ends at rest.