Practical examples of thermodynamic cycles experiment examples for modern labs

Thermodynamic cycles are the backbone of how we generate power, cool buildings, and move vehicles. Textbooks are full of idealized PV diagrams, but students rarely internalize the concepts until they see real data from examples of thermodynamic cycles experiment examples they can touch, measure, and troubleshoot.

In 2024–2025, two trends are reshaping how instructors design these labs:

• Affordable digital sensors and USB data loggers make it easy to capture pressure–volume–temperature data in real time.
• The energy transition pushes courses to link classic cycles (Otto, Diesel, Rankine, Brayton) to modern applications like combined-cycle plants and heat pumps.

The best examples of thermodynamic cycles experiment examples do three things at once:

• Reproduce the basic steps of a known cycle.
• Generate data that can be mapped onto PV or TS diagrams.
• Connect directly to a real engine, turbine, or refrigeration device students recognize.

Below, I’ll walk through concrete setups you can actually build or purchase, organized by cycle type.

Otto cycle: spark-ignition engine bench experiment example

One of the most intuitive examples of thermodynamic cycles experiment examples is the small gasoline (or propane) spark-ignition engine running on a test stand. You’re not going to get a perfectly ideal Otto cycle, but you can get very close to its shape on a PV diagram.

Typical setup

• Single-cylinder spark-ignition engine (lawnmower-style or transparent teaching engine).
• In-cylinder pressure sensor with crank-angle encoder.
• Intake and exhaust thermocouples.
• Torque sensor or dynamometer for brake power.
• Data acquisition system (DAQ) with software to build PV and p–θ plots.

Core measurements and analysis

• Record in-cylinder pressure vs. crank angle over multiple cycles.
• Convert crank angle and geometry to instantaneous volume.
• Plot the experimental PV loop and compare to the ideal Otto cycle.
• Estimate indicated mean effective pressure (IMEP), indicated work, and thermal efficiency.

Teaching value

This example of a thermodynamic cycles experiment lets students:

• Identify compression, heat addition (combustion), expansion, and exhaust on the PV plot.
• Compare measured efficiency with the ideal Otto efficiency based on compression ratio.
• See real-world losses: heat transfer, incomplete combustion, pumping work.

For background on internal combustion cycles, the U.S. Department of Energy provides accessible overviews of engine efficiency and emissions trends: https://www.energy.gov

Diesel cycle: compression-ignition engine experiment example

A close companion to the Otto experiment is a small compression-ignition engine, often run on diesel or biodiesel blends. This is one of the best examples of thermodynamic cycles experiment examples if you want to highlight how changing the heat-addition process changes the cycle.

Typical setup

• Single-cylinder diesel engine on a test rig.
• In-cylinder pressure transducer and crank-angle encoder.
• Fuel flow meter and exhaust gas temperature probes.
• Eddy-current or hydraulic dynamometer.

Key activities

• Capture PV data and compare the shape to the ideal Diesel cycle (constant-pressure heat addition segment instead of constant-volume).
• Vary load and injection timing (if allowed by the rig) and examine how the PV loop and efficiency change.
• Compare indicated and brake thermal efficiencies to the spark-ignition case.

Modern angle (2024–2025)

With current attention on decarbonization, instructors often extend this example of a thermodynamic cycles experiment by:

• Testing biodiesel or renewable diesel blends and comparing brake-specific fuel consumption.
• Discussing how modern high-pressure common-rail injection alters the idealized Diesel cycle picture.

For more on diesel engine emissions and efficiency research, Oak Ridge National Laboratory maintains useful resources: https://www.ornl.gov

Carnot-style heat engine: ideal cycle approximation on the bench

The Carnot cycle is the theoretical efficiency limit, but it feels abstract until students see a working heat engine that approaches its logic. A classic teaching option is a low-power Stirling engine or a thermoelectric (Peltier) module configured as a heat engine.

Stirling engine experiment

• Place the Stirling engine on a controlled hot plate (e.g., 150–250 °F) with ambient air as the cold reservoir.
• Measure hot and cold side temperatures with thermocouples.
• Measure rotational speed and apply a small mechanical load (e.g., Prony brake or generator).
• Estimate output power and compare measured efficiency to the Carnot limit between the two reservoirs.

While the Stirling cycle is not identical to Carnot, this is still one of the cleaner examples of thermodynamic cycles experiment examples to illustrate how temperature difference limits efficiency.

Thermoelectric module experiment

• Use a commercial Peltier device sandwiched between a hot plate and a heat sink.
• Run it as a generator with a controlled temperature difference.
• Measure output voltage, current, and temperatures.
• Compare measured efficiency to the Carnot limit and to manufacturer data.

Students quickly see how far real devices sit below the ideal curve, which opens a good discussion about irreversibilities and material limitations.

For a solid theoretical refresh on Carnot efficiency and entropy, MIT OpenCourseWare offers free lecture notes and problem sets: https://ocw.mit.edu

Rankine cycle: bench-top steam power plant experiment example

If your lab has the budget and safety infrastructure, a small steam power plant trainer is one of the most authentic real examples of thermodynamic cycles experiment examples. These units typically include a boiler, a small steam turbine or piston engine, a condenser, and a feed pump.

Typical components

• Electric boiler with pressure and temperature control.
• Miniature steam turbine driving a generator.
• Surface condenser with cooling water loop.
• Feedwater pump and flow meters.
• Pressure and temperature taps at boiler outlet, turbine inlet/outlet, condenser, and pump.

Student tasks

• Measure state points around the cycle and locate them on TS and h–s diagrams using steam tables.
• Calculate cycle thermal efficiency, turbine work, pump work, and heat input.
• Compare the measured cycle to an ideal Rankine cycle without superheating or reheat.
• Explore the impact of boiler pressure or degree of superheat on efficiency.

This example of a thermodynamic cycles experiment ties directly to real power plants. You can connect it to current U.S. power generation data from the Energy Information Administration (EIA): https://www.eia.gov

Refrigeration and heat pump cycles: vapor-compression experiment examples

Thermodynamics courses increasingly emphasize climate control and heat pumps. A small vapor-compression refrigeration trainer is one of the most versatile examples of thermodynamic cycles experiment examples, because you can cover both refrigeration and heat pump performance.

Standard trainer layout

• Compressor, condenser, expansion valve, and evaporator in a closed loop.
• Multiple pressure and temperature taps for refrigerant at each component inlet and outlet.
• Electrical power measurement on the compressor.
• Optional transparent sections to visualize two-phase flow.

Core experiments

• Use measured pressures and temperatures to infer refrigerant enthalpy at each state (with property tables or software).
• Plot the cycle on a pressure–enthalpy (P–h) diagram.
• Compute coefficient of performance (COP) for both cooling and heating modes.
• Investigate how condenser temperature (e.g., varying cooling water flow) affects COP.

This is a clean example of a thermodynamic cycles experiment that connects immediately to air conditioners, refrigerators, and residential heat pumps. For broader context on heat pump adoption and building energy use, the U.S. Department of Energy’s Building Technologies Office has accessible reports: https://www.energy.gov/eere/buildings

Brayton cycle: gas turbine and jet engine experiment examples

Brayton cycle experiments used to be rare in teaching labs, but small gas-turbine and turbojet trainers have become more accessible. Even a turbocharger-based rig can approximate a Brayton-style compression–combustion–expansion loop.

Small gas-turbine trainer

• Compressor–combustor–turbine assembly with fuel control.
• Inlet and outlet temperature and pressure measurement across compressor and turbine.
• Shaft torque and speed measurement.
• Air and fuel flow measurement.

Students can:

• Determine compressor and turbine isentropic efficiencies.
• Map the measured cycle on a TS diagram and compare to an ideal Brayton cycle.
• Investigate the effect of compressor pressure ratio and turbine inlet temperature on overall efficiency.

A simpler example of a thermodynamic cycles experiment for Brayton-like behavior uses a turbocharger rig:

• Drive the turbine with compressed air.
• Measure compressor pressure ratio and temperature rise.
• Explore how speed affects performance and relate to gas-turbine cycle concepts.

Low-cost piston-and-gas experiments: PV diagrams without engines

Not every lab can run combustion or steam. You can still build meaningful examples of thermodynamic cycles experiment examples using air, a piston–cylinder, and a few sensors.

Piston–cylinder with heated air

• Transparent cylinder with a low-friction piston and weight stack.
• Pressure sensor and thermocouple inside the gas volume.
• Hot plate or external heater for controlled heating.

Students can:

• Perform a quasi-static isothermal expansion by slowly heating while adjusting weights.
• Perform an approximately adiabatic compression by quickly adding weights without allowing time for heat transfer.
• Combine steps into a simple rectangular cycle on the PV diagram and compute net work.

This is one of the most accessible real examples of thermodynamic cycles experiment examples for institutions without engines or steam plants. It also reinforces the connection between area enclosed by the PV loop and cycle work.

Data acquisition, uncertainty, and modern lab practice

By 2024–2025, the gap between hobby-grade sensors and professional DAQ systems has narrowed dramatically. That shift changes how you design and assess examples of thermodynamic cycles experiment examples.

Modern best practices

• Use calibrated thermocouples and pressure sensors with known accuracy and response time.
• Log data at sufficiently high sampling rates for fast processes (e.g., in-cylinder pressure) and lower rates for quasi-static cycles.
• Teach students to propagate measurement uncertainty into efficiency, COP, and work calculations.

Many engineering programs now require a written uncertainty analysis alongside any example of a thermodynamic cycles experiment, aligning with ABET-style outcomes on measurement and data interpretation. NIST offers excellent guidance on uncertainty and measurement science: https://www.nist.gov

Designing your own thermodynamic cycle experiment examples

Once students see several examples of thermodynamic cycles experiment examples, encourage them to design their own. Common student projects include:

• A DIY solar-powered Rankine or organic Rankine micro-cycle using a low-boiling working fluid and a small expander.
• A heat-pump water heater experiment using off-the-shelf hardware and smart plugs for power monitoring.
• A Stirling cooler or cryocooler-style demonstration using commercially available Stirling modules.

The goal is not to build a perfect power plant in the lab. It’s to give students enough hands-on experience with real examples of thermodynamic cycles experiment examples that the abstract TS and PV diagrams start to feel like honest summaries of messy, noisy, real data.

FAQ: Common questions about thermodynamic cycle experiments

Q: What are some easy-to-build examples of thermodynamic cycles experiment examples for a basic undergraduate lab?
Simple piston–cylinder rigs with air, Stirling engines on hot plates, and small vapor-compression refrigeration trainers are all realistic starting points. They avoid combustion and high-pressure steam while still allowing students to trace cycles on PV, TS, or P–h diagrams.

Q: Can I run an example of a thermodynamic cycles experiment without specialized DAQ hardware?
Yes, especially for slow processes. You can use handheld digital manometers, thermocouples with simple displays, and manual data recording for quasi-static cycles. For fast cycles like Otto or Diesel engines, you’ll need higher-speed DAQ to get meaningful PV loops.

Q: How do I connect lab experiments to real power plants and engines?
Start each lab by showing a real system (e.g., a car engine, a power plant schematic, or a home heat pump), then map its operating principle to the lab hardware. Use public data from sources like the U.S. EIA or DOE to discuss how often each cycle type appears in the actual energy mix.

Q: Which examples include both thermodynamics and environmental topics?
Diesel engine labs with alternative fuels, Rankine cycle labs that discuss coal vs. nuclear vs. solar-thermal boilers, and heat pump experiments that consider refrigerant global warming potential all provide a bridge between thermodynamic analysis and environmental impact.

Q: How many different examples of thermodynamic cycles experiment examples should a typical course include?
Many programs aim for at least three: one heat engine (Otto, Diesel, or Rankine), one refrigeration or heat pump cycle, and one low-risk air or gas cycle with a piston–cylinder. If you can add a Brayton or Stirling setup, students get a much richer sense of how diverse real cycles can be.