Thermodynamics

Explore the history of temperature scales, compare Celsius and Fahrenheit via water's melting and boiling points at atmospheric pressure, and introduce Kelvin and linear interconversion formulas.

Explore the ideal gas equation PV = nRT and the distinction between the universal constant R and the characteristic constant R*, varying with molecular weight, illustrated by air and CO2.

Construct a pressure-volume diagram for an ideal gas, showing PV = constant, horizontal and vertical lines, and P inversely proportional to V, with compression and expansion paths.

Analyze work in a closed system using a piston-cylinder with gas; apply w = ∫ P dV for expansion and -∫ P dV for compression.

Isentropic process in air-standard cycles: use pv^gamma = c to relate pressure, volume, and temperature, derive p2/p1 and t2/t1, and compute work with zero heat transfer.

Analyze an ideal gas undergoing a constant pressure process followed by a constant volume step, yielding a final-to-initial volume ratio of 3/4 (0.75).

Explore how the internal energy of an ideal gas depends on temperature, emphasizing that internal energy is a function of temperature for ideal gases.

Calculate the work for an isothermal compression of an ideal gas in a piston-cylinder, from V1 0.4 m3 to V2 0.1 m3 at P1 100 kPa, yielding about -55.45 kJ.

This lecture explains work done in open and closed thermodynamic systems, using the steady-flow energy equation, pv diagrams, and process families—isochoric, isobaric, isothermal, isentropic, and polytropic—and their respective work formulas.

Explains a heat pump between cold exterior and warm room, extracts heat from outside, delivers to the room using work, and defines the coefficient of performance as Q1 over W.

Explain how a refrigerator uses work to remove heat from a cold space into a warm surround, define the cooling effect and cop, and contrast heat pumps with refrigerators.

Explore how refrigerators and heat pumps produce cooling and heating effects between thermal reservoirs, the ton of refrigeration (3.5 kW), and analyze two heating engines in series.

Analyze and solve GATE level problems on heat engines, heat pumps, and refrigerators using the second law, coefficient of performance calculations, reversible cycles, and heat transfers between reservoirs.

Explore entropy changes across isochoric, isobaric, isothermal, and polytropic processes in thermodynamics, deriving formulas using Cv, Cp, gamma, and temperature ratios.

Explore how entropy changes in a system, surroundings, and the universe, with positive, negative, or zero system entropy changes, and how the universe's entropy never decreases, increasing in irreversible processes.

Clarify the critical point with inflection and zero slope, and identify correct statements about saturated liquid, saturated vapor, and compressed liquid. Apply PV and temperature–enthalpy insights to solve gate problems.

Explore entropy as a function of temperature and volume, derive the first entropy equation via Maxwell relations, and relate heat transfer at constant volume to cv.

Explains the Clausius-Clapeyron equation derived from the Maxwell relation, applied to liquid–vapor phase change on a temperature–pressure diagram, using saturated liquid and vapor curves and latent heat of vaporization.