Thermodynamics 1 (Fully Explained + 102 Solved Examples)

Define thermodynamics as the study of heat and work and how thermal properties produce power in devices, and explain system types such as closed, open, isolated, boundaries, and energy transfer.

Identify a system's state from temperature, pressure, and specific volume, and recognize equilibrium when no unbalanced driving forces exist. Define the state postulate, and distinguish isothermal, isobaric, and isochoric processes.

understand prefixes like kilo and mega, perform unit conversions for kinetic energy and work, and connect newton-metre to joule with practical examples such as km/h to m/s.

Master solving thermodynamics questions by extracting information (temperature, pressure, state, mass, volume, density, heat or work), selecting the appropriate rules or equations, and connecting them to find the unknowns.

Solve a warm-up on static equilibrium of a two-arm tube with water and oil. Use pressure equality and densities to find the water height and the oil height.

Explain why P_A cannot equal P_B for points A (water) and B (oil) on a horizontal line, with P_A = atmospheric pressure and P_B = atmospheric + rho g h_b.

Solve warmup example 1.3 by using pressures at points 1 and 2 to obtain h_w and h_o, via hydrostatic p = rho g h, with h0 = 4 h_w.

Convert one kilowatt hour to kilojoules and joules using 3600 seconds per hour and unit prefixes. The method shows that 3600 kilojoules equal 3.6 megajoules, with seconds canceling out.

Convert speeds from kilometer per hour to meter per second using unit equivalence and cancellation, illustrated by turning 20 km/h into 5.55 m/s.

convert temperatures between Celsius, Fahrenheit, and Kelvin and analyze pressure in static liquid columns, using p2 = p1 + rho g h and density differences to plot pressure versus height.

Demonstrates solving hydrostatic pressure relationships in steady state, linking p1 and p2 through vertical distances and fluid densities, including multi-fluid layers, and calculating cylinder air pressure from forces in equilibrium.

Solve hydrostatic and hydraulic problems by applying gauge and absolute pressure concepts, rho g h, and static equilibrium to vertical fluids, including blood and mercury, plus piston force calculations.

Explore how total energy equals the sum of kinetic, potential, electrical, chemical, and thermal energies, distinguish macroscopic and microscopic energies, and relate delta e to delta U in stationary systems.

Explore heat and work as energy transfer mechanisms across system boundaries, adiabatic systems, path dependence, state versus process, and the first law for closed systems.

Explain the steady flow process in a control volume, where properties are constant at each point but vary along the flow, and discuss flow work and the steady-flow first law.

Explore gravitational and spring potential energy, kinetic energy from linear and rotational motion, and electrical energy from current, voltage, and resistance, and learn their governing equations.

Explain the first law of thermodynamics for a closed system by applying energy conservation, showing how heat and work in and out cause changes in internal, kinetic, and potential energy.

Differentiate heat and work for energy crossing a closed system boundary; heat arises when a temperature difference exists, while all other energy interactions are work.

Use first law of thermodynamics for a closed system to compute work to accelerate a 1300 kg car from 10 to 60 km/h up 40 m, with no heat transfer.

Treat the room as a closed system and apply the first law; with no heat transfer, the energy-rate change equals the sum of electrical powers, 1650 watts.

Apply the first law to a closed car to compute power for accelerating from 70 to 110 km/h in seconds; 78.4 kW for 1400 kg, 39.2 kW for 700 kg.

Solve a steady-flow pump example to determine ideal and real power needed to lift water 200 m at 0.3 m^3/s, using density 1050 kg/m^3 and 0.74 efficiency.

Apply the steady-flow first law to a hydraulic turbine generator, using a 5000 kg/s flow at 50 m to determine turbine efficiency and the power transferred to the generator.

Analyze steady-flow transfer in a pump by calculating heat rejected to the surroundings due to frictional effects when moving water 45 m upward at 0.03 m³/s with 20 kW input.

Determine the pump motor unit efficiency for lifting water 15 m at 70 l/s using the steady-flow first law, yielding about 10.3 kW ideal input power and ~67% efficiency.

Apply the steady-flow first law to a pump, compute w dot out by subtracting gravitational potential energy gain from w dot in, yielding about 5.1 kw.

Apply the steady-flow first law to a pump, neglect delta u and delta z, and use volume flow rate to compute the inlet–outlet pressure difference of 147 kPa.

Apply conservation of mass for a steady flow pump to show inlet velocity equals outlet velocity, relating mass flow rate, density, area, and volume flow rate.

Compute the pump's mechanical efficiency from the first law for a control volume in a steady, incompressible flow, comparing ideal input power (36.3 kW) to 44 kW to yield 91.8%.

Apply the first law to insulated closed systems and steady-flow devices, determine the change in internal energy, and compute ideal power generation for turbines and wind turbines.

Examine ideal power generation from a water jet at 60 m/s with a 120 kg/s flow and from a wind turbine, using the steady-flow first law and kinetic energy change.

Apply steady-flow thermodynamics to estimate river hydro power with a 90 m head and 500 m³/s, and compare equal work with power when lifting weights in 10 vs 20 s.

Solve example 2.8 using the first law for a closed system to find the time for a 1500 kg car to reach 100 km/h at 75 kW.

Apply the first law of thermodynamics to a 1150 kg car climbing a 100 m, 30-degree hill in 12 s; analyze closed-system energy changes for constant velocity, rest-to-30 m/s, braking.

Apply the first law to a closed water pan heated by a paddle wheel, with 30 kJ in, 5 kJ out, 0.5 kJ work, yielding internal energy 35.5 kJ.

Define pure substances as homogeneous with fixed composition, contrast with oil-water mixtures; illustrate isobaric heating of water from compressed liquid to superheated vapor across saturated regions on a t-v diagram.

Explore saturation temperature and saturation pressure on the liquid-vapor saturation curve, showing how pressure shifts boiling and phase regions, and define enthalpy, latent heat, and the critical point.

Study saturated liquid–vapor properties in the two-phase region, using quality x to relate the liquid and vapor volumes and masses, and compute average specific volume, internal energy, and enthalpy.

Properties tables in thermodynamics help determine a system’s properties such as H, u, v, s and identify its state—compressed liquid, saturated liquid, saturated vapor, or superheated vapor—using water tables.

Learn to use property tables to identify regions—compressed liquid, saturated mixture, and superheated vapor—from temperature and enthalpy or pressure and enthalpy, and apply interpolation to find unknown enthalpy.

Learn where to find the thermodynamics properties tables: at the end of textbooks as an appendix or online via PDFs, including Google searches and Wayne State University resources.

Determine water’s phase and specific volume from the given temperature and pressure using saturation at 500 kPa (151.8°C); 250°C lies in the superheated region and yields 0.474 m³/kg.

Interpolate for water in warm-up example 3.2 to obtain hf at 365 kPa, yielding 590.5 kJ/kg, and reference chapter 3.10 for the interpolation method.

Solve a warm up problem for water at 50°C with v = 7.72 m3/kg to identify its phase as saturated mixture and determine the saturation pressure around 12.35 kPa.

Compute the total volume and the quality of a saturated liquid–vapor mixture in a rigid tank at 200°C, given 1.4 kg of liquid and 25% liquid volume.

Heat a four-liter rigid tank with a two-kilogram saturated water mixture to a single phase, and determine if the final state is liquid or vapor using the critical specific volume.

Apply the ideal gas law in a rigid tank to determine nitrogen mass change as pressure falls from 600 to 400 kPa and temperature shifts.

Solve example 3.1 for water; determine phase and temperature from pressure and internal energy using property tables, including saturated mixture, saturated vapor, compressed liquid, and interpolation in the superheated region.

Analyze example 3.2 for refrigerant 134a using the properties table to determine temperature, pressure, and phase, then apply example 3.3 on water boiling at sea level to compute evaporation.

Analyze an isobaric process of refrigerant 134a in a piston-cylinder, determine final temperature and the change in internal energy using superheated and saturated mixture states and property tables.

Explore isobaric heat transfer in a piston-cylinder with water, solving saturated mixture at 600 kPa and transitions to saturated and superheated vapor using property tables.

apply the ideal gas law to solve gauge and absolute pressures for air and oxygen tanks, converting volumes to cubic meters and temperatures to kelvin.

Analyze the expansion of an ideal gas in a rigid two-part tank after removing the partition, until p2 = p1; derive t2 = 3 t1, yielding 3600 kelvin.

Learn boundary work in closed systems, with p dv and delta wb, explore polytropic processes p v^n = c, and isothermal ideal-gas cases, plus specific heats c_v and c_p.

Explore how internal energy and enthalpy of ideal gases depend only on temperature, relate cp, cv, R, and k, and apply the first law to closed systems.

Apply the first law for a closed, isobar piston-cylinder system with saturated liquid and vapor at 600 kPa, determine heat transfer to reach 200°C, accounting for boundary work.

Apply the enthalpy method to a closed isobaric water system by computing h2 and h1, then q = m(h2 - h1), and compare with the internal-energy approach.

Solve boundary work in polytropic piston-cylinder processes for nitrogen and steam, using ideal gas relations and isobar steps, through examples 4.1 and 4.2.

Analyze a rigid tank with refrigerant 134a, from saturated mixture (x=0.4) to superheated vapor, computing mass, heat transfer, and a PV diagram path.

Solve example 4.5 and 4.6 in thermodynamics 1, analyzing an insulated, rigid tank with water and hydrogen to determine final temperature, tank volume, and final pressure via the first law.

Apply the first law to an insulated, rigid tank; after removing the partition, the ideal gas expands, keeping temperature at 50°C and reducing pressure to 400 kPa.

Solve a polytropic compression of argon (ideal gas) in a piston-cylinder, calculating boundary work and heat transfer in kilojoules per kilogram using the first law for a closed system.

Solve an isobaric heating of 5 kg saturated water vapor at 300 kPa to 200 °C and determine the boundary work using p dv, yielding 165.9 kJ.

Solve the rigid isochoric heating of a saturated water mixture from 100°C to 150°C. Apply the first law for a closed system to compute heat transfer q_in.

Explore open system control volumes where mass and energy cross boundaries, with real or imaginary control surfaces, recognizing devices like turbines, pumps, nozzles, and apply mass conservation.

Examine steady flow in a control volume where mass and energy stay constant over time while properties vary by location. Apply the first law using enthalpy changes for single-stream devices.

Apply the steady-flow first law to a pipe with superheated vapor, using m dot, cp, and a 30 deg C delta t to compute q dot out (heat loss).

Apply the first law of thermodynamics for a control volume to a jet engine diffuser with no heat or work interactions. Compute v2 from v1=350 m/s, 30–90°C, using cp interpolation.

Solve steady-flow examples: calculate air inlet volume and mass flow in a pipe using ideal gas relations, then find water inlet and outlet velocities in a pump under incompressible flow.

solve a steady-flow thermodynamics lecture covering refrigerant 134a in a pipe, including inlet volume flow rate, mass flow rate, exit velocity, and a diffuser example with no heat or work.

Explore solving nozzle problems using the steady-flow first law, adiabatic and no-work assumptions, and ideal-gas properties to find exit temperature, pressure, and velocities.

Analyze example 5.7 on refrigerant-134a in an adiabatic compressor to determine power input and inlet volume flow from saturated vapor at -24°C to 0.8 MPa and 60°C.

Determine the exit temperature of refrigerant R134a using the first law for control volumes; inlet saturated vapor at 180 kPa, outlet 700 kPa, 2.5 kW input, T2 about 50 °C.

Solve an adiabatic turbine problem. Determine the kinetic energy change, power output, and inlet area using the first law for a control volume with a superheated inlet and saturated outlet.

Compute the mass flow rate for an adiabatic turbine with inlet 10 MPa and 500 °C, outlet 10 kPa with 90% quality, using the first law.

Explore the second law of thermodynamics, with Kelvin-Planck and Clausius statements. See how heat engines convert heat from a high-temperature source into work and reject waste heat to a sink.

Explore how refrigerators transfer heat from a low to high temperature space using a vapor compression cycle with a compressor, condenser, expansion valve, and evaporator, and define coefficient of performance.

Explore the Carnot cycle, a four-step reversible cycle with two isothermal and two adiabatic processes, its P-V diagram, and the maximum efficiency 1−Tl/Th for engines and COP limits for refrigerators.

Analyze a heat engine that takes in 80 MW from a furnace and rejects 50 MW to a river to yield 30 MW net output and 37.5% thermal efficiency.

Analyze heat and work balances in a steam power plant and an automobile engine to compute net output and thermal efficiency from furnace heat, heat losses, and fuel heating value.

Explore solving refrigeration problems in example 6.4–6.6 by applying the refrigeration cycle and the first law of thermodynamics to compute compressor power and coefficient of performance from heat transfer rates.

Explore a Carnot heat engine example solving for the heat source temperature using qh, ql, and Kelvin temperatures, and compute a 61.5% thermal efficiency.

Calculate the thermal efficiency and net power output of a Carnot heat engine operating between 1000 kelvin and 300 kelvin, with an 800 kilojoule per minute heat input.

Demonstrates how an ideal heat engine with 40% efficiency delivers 500 kilojoules of work from a 1200°C heat source. Yields 1250 kilojoules input, 750 kilojoules rejected, and 883.8 kelvin.

Solve example 6.10 by applying the reverse Carnot refrigerator model to compute the cooling load and refrigeration space temperature, yielding qdot l = 1800 kw and tl = -3 c.

Explore entropy as a measure of disorder and irreversibility, learn Clausius inequality, entropy change, and the link between heat transfer and the area under the Ts curve for reversible processes.

Explain how entropy increases in irreversible processes, quantify entropy generation (s_gen), and apply isentropic, reversible adiabatic conditions via TdS relations for simple compressible systems.

Explore entropy changes for incompressible liquids and solids using td relationships; derive delta s from q and t with average heat capacity, and contrast ideal gas formulas and isentropic conditions.

Demonstrate entropy calculations for heat reservoirs, the entropy principle, a Carnot cycle, and a rigid insulated tank with a saturated water mixture, using isothermal reversibility, quality, and interpolation.

Analyze a closed, rigid radiator tank containing superheated water vapor at 200 kPa and 150°C as it cools to 40°C, calculating the steam's entropy change using saturated and superheated tables.

Solve isothermal, closed-system example for refrigerant 134a from 320 kPa and 40°C to a 45% quality saturated mixture using the first law to get work and heat per unit mass.

Calculate heat transfer for a reversible process from state 1 to 3 by integrating temperature w.r.t. entropy; from 1 to 2 is 471.1 kJ/kg, from 2 to 3 is zero.

Compute the final equilibrium temperature and total entropy change for an aluminium block and an iron block in an insulated closed system; final temperature 109°C, total entropy change 0.25 kJ/K.

Compute the entropy generation rate in an insulated oxygen pipe by analyzing a single-input single-output control volume, using ideal gas relations and the inlet–outlet entropy change.