Refrigeration Cycle Simulator

The Refrigeration Cycle Simulator models the vapor compression refrigeration cycle — the most widely used cooling technology in the world. It features an animated system schematic showing refrigerant flowing through the four main components (compressor, condenser, expansion valve, and evaporator), a real-time pressure-enthalpy (P-h) diagram with the saturation dome and cycle path, and comprehensive thermodynamic calculations including COP (Coefficient of Performance), cooling capacity, compressor power, and discharge temperature.

The simulator supports four refrigerants (R-134a, R-410A, R-22, and R-290) and lets you adjust evaporator temperature, condenser temperature, subcooling, superheat, compressor efficiency, and cooling capacity. It is designed for HVAC engineering students, refrigeration technicians, mechanical engineering trainees, and instructors teaching vapor compression cycles and refrigerant selection. A ton of refrigeration equals 3.517 kW of cooling capacity.

The simulator opens in Simulate mode showing a dual-canvas layout. The left canvas displays an animated refrigeration system schematic with the compressor, condenser, expansion valve, and evaporator. The right canvas shows the P-h diagram with the saturation dome, state points, and cycle path. Below, sliders control: refrigerant selection, evaporator temperature (−30 to 10 °C), condenser temperature (25 to 55 °C), subcooling (0–15 K), superheat (0–20 K), compressor efficiency (50–95%), and cooling capacity (0.5–5.0 kW). Each slider also has a companion number input for direct value entry.

Use the Preset dropdown to load a typical scenario instantly: Domestic Refrigerator, Air Conditioning, Heat Pump, or Industrial Freezer. Each preset sets evaporator and condenser temperatures to industry-standard values. You can fine-tune sliders after selecting a preset.

Click Start to begin the staged animation. The simulator walks through each process individually — Stage 1→2 (compression), 2→3 (condensation), 3→4 (expansion), then 4→1 (evaporation) — highlighting each process on both the machine schematic and the P-h diagram simultaneously. After all four stages complete, the cycle runs continuously. Use the Anim. Speed slider (0.3×–3×) to slow down or speed up the animation. Readout cards below display COP, cooling capacity, compressor power, heat rejected, mass flow rate, pressure ratio, quality at the expansion valve exit, and compressor discharge temperature.

The P-h diagram is the key analytical tool. The horizontal axis shows specific enthalpy (kJ/kg), the vertical axis shows pressure on a logarithmic scale, and the dome-shaped curve represents the saturation boundary. During staged animation, the P-h diagram builds progressively — each process line appears as its stage runs, with a traveling dot showing the current refrigerant state. After the first complete cycle, the saturation dome becomes visible; toggle it on or off with the Sat. Dome button at any time.

The machine canvas shows a stage progress banner at the top with the current process name (e.g. “STAGE 2→3 — CONDENSATION”), a time progress bar, and completion dots for all four stages. Each component glows during its active stage: red for the compressor, orange heat waves for the condenser, yellow for the expansion valve, and blue shimmer for the evaporator.

Experiment with the sliders to understand key relationships. Lowering the evaporator temperature widens the pressure ratio and reduces COP. Increasing superheat moves Point 1 further into the superheated region. Reducing compressor efficiency increases work input and discharge temperature. Compare refrigerants by switching between R-134a, R-410A, R-22, and R-290 to see how dome shape, pressures, and COP differ. Use ↓ CSV to export all state point data, ↓ PNG to save the P-h diagram, or right-click the diagram for more options. Toggle SI / IMP to switch readout units between SI and Imperial.

Switch to Explore mode to study concept cards across multiple categories covering the fundamentals of vapor compression, individual component operation, refrigerant properties, and environmental impact. Each card includes clear explanations, diagrams, and numerical examples.

Key topics include the four cycle processes (compression, condensation, throttling, evaporation), the definition and significance of COP, the P-h diagram as an analysis tool, subcooling and superheat effects on system performance, the difference between ODP (ozone depletion potential) and GWP (global warming potential), and the phase-out timeline for high-GWP refrigerants. The explore canvas provides additional diagrams to visualise concepts like the saturation dome structure, T-s diagram representation, and component energy balances.

Practice mode generates randomised refrigeration cycle problems. You might be asked to calculate the COP given evaporator and condenser enthalpies, find the mass flow rate for a given cooling capacity, determine the compressor power from the enthalpy difference and mass flow rate, or compute the heat rejected by the condenser. Enter your answer, click Check for instant feedback, or click Show Solution for a step-by-step walkthrough. Your score is tracked to measure progress.

Quiz mode presents five questions per session combining conceptual and numerical problems. Topics include identifying the isenthalpic process, ranking refrigerants by COP, calculating pressure ratios, understanding the role of superheat and subcooling, and comparing the environmental impact of different refrigerants. After completing the quiz, review your results and revisit specific topics in Explore mode.

• The COP = Q_evap/W_comp tells you how many kilowatts of cooling you get per kilowatt of compressor work. Typical values are 2–5 for well-designed systems. Higher COP means better efficiency.
• Increasing subcooling improves COP slightly by increasing the enthalpy difference in the evaporator without increasing compressor work. Try adjusting the subcooling slider to see this effect.
• Lowering the evaporator temperature or raising the condenser temperature increases the pressure ratio and reduces COP. This is why air conditioners work harder (and less efficiently) on extremely hot days.
• Compare all four refrigerants under identical conditions. R-290 (propane) often has the best COP but is flammable. R-410A operates at higher pressures than R-134a. R-22 is being phased out due to ozone depletion.
• Watch the quality at Point 4 (expansion valve exit). Lower quality means more liquid enters the evaporator, which is desirable for maximum cooling effect.
• Use this simulator alongside the Thermodynamics Cycles Simulator to compare the vapor compression cycle with heat engine cycles like Carnot and Otto, understanding the reversed cycle concept.