Refrigerants
- Refrigerants are classified based on chemical composition and environmental impact:
Based on Chemical Composition
| Type | Examples | Characteristics |
|---|---|---|
| CFC
(Chloro-fluoro-carbon) |
R-11, R-12 | High ODP (Ozone Depletion Potential), banned under Montreal Protocol. |
| HCFC
(Hydro-chloro-fluoro-carbon) |
R-22, R-123 | Less ODP than CFCs, but phased out due to Montreal Protocol. |
| HFC
(Hydro-fluoro-carbon) |
R-134a, R-410A, R-404A | Zero ODP, high GWP (Global Warming Potential), phasedown in progress. |
| HFO
(Hydro-fluoro-olefin) |
R-1234yf, R-1234ze | Zero ODP, very low GWP, used in new systems. |
| HC (Hydrocarbon) | R-290 (Propane), R-600a (Isobutane) | Zero ODP, low GWP, flammable but efficient. |
| Inorganic Refrigerants | Ammonia (R-717), CO₂ (R-744), Water (R-718) | Zero ODP, ammonia is toxic, CO₂ requires high pressure. |
Properties of Refrigerants
| Property | Importance |
|---|---|
| Ozone Depletion Potential (ODP) | Should be zero to protect the ozone layer. |
| Global Warming Potential (GWP) | Should be low to reduce climate change impact. |
| Latent Heat of Vaporization | High value ensures better cooling efficiency. |
| Non-Toxicity | Safe for human health. |
| Non-Corrosive Nature | Prevents system damage. |
| High Critical Temperature | Improves efficiency in high ambient conditions. |
Chemical Names & Formulas of Common Refrigerants
| Refrigerant Type | Chemical Name | Formula |
|---|---|---|
| R-12 (CFC) | Dichlorodifluoromethane | CCl₂F₂ |
| R-22 (HCFC) | Chlorodifluoromethane | CHClF₂ |
| R-134a (HFC) | Tetrafluoroethane | C₂H₂F₄ |
| R-600a (HC) | Isobutane | C₄H₁₀ |
| R-290 (HC) | Propane | C₃H₈ |
| R-717 (Inorganic) | Ammonia | NH₃ |
| R-744 (Inorganic) | Carbon Dioxide | CO₂ |
Ozone Rules & Environmental Regulations
- Montreal Protocol (1987)
- Global agreement to phase out CFCs & HCFCs due to their ozone depletion impact.
- Developed countries: CFCs banned by 1996, HCFCs phased out by 2020.
- Developing countries (including India): CFCs phased out by 2010, HCFCs to be phased out by 2030.
- India’s CFC/HCFC Phase-Out Schedule
| Refrigerant | Phase-Out Year |
|---|---|
| CFCs (R-11, R-12) | Phased out by 2010 |
| HCFCs (R-22, R-123) | To be fully phased out by 2030 |
| HFCs (R-134a, R-410A, R-404A) | Phase-down under Kigali Amendment (2016) |
- Ozone Rules, 2000 (India)
- Ban on CFC production, import, and use.
- Gradual phase-out of HCFCs under government control.
- Promotion of alternative refrigerants (HFCs, HFOs, HCs, CO₂, and Ammonia).
Refrigerant Leak Detection Methods
| Method | Procedure | Advantages |
|---|---|---|
| Soap Bubble Test | Apply soapy water to suspected leak area and look for bubbles. | Simple, cheap, effective for small leaks. |
| Electronic Leak Detector | Uses a sensor to detect refrigerant gas leaks. | Fast and accurate. |
| Ultraviolet (UV) Dye Test | Injects UV dye into system; leaks are visible under UV light. | Good for detecting small leaks. |
| Halide Torch Test | Flame changes color when exposed to refrigerant gas. | Used for detecting CFC/HCFC leaks. |
| Pressure Decay Test | Checks pressure drop in a sealed system. | Used for system integrity checks. |
Substitute Refrigerants & Comparison with CFCs
| Refrigerant Type | Substitutes for CFCs | Comparison |
|---|---|---|
| HFCs (R-134a, R-410A, R-404A) | R-12, R-22 | Zero ODP, High GWP. |
| HFOs (R-1234yf, R-1234ze) | R-134a, R-410A | Zero ODP, very low GWP, non-toxic. |
| HCs (R-290, R-600a) | R-12, R-22 | Zero ODP, low GWP, flammable. |
| CO₂ (R-744) | R-12, R-134a | Zero ODP, low GWP, high pressure system needed. |
| Ammonia (R-717) | R-22 | Zero ODP, low GWP, but toxic. |
