Retrofitting and Thermal Insulation
- Retrofitting is the process of modifying old refrigeration and air conditioning systems to replace CFC (Chlorofluorocarbon) refrigerants with environmentally friendly alternatives like HC (Hydrocarbon) refrigerants.
- Changes in Components & Practices during Retrofitting
| Component | Required Change |
|---|---|
| Compressor | Check oil compatibility with HC refrigerant. Some compressors need oil replacement. |
| Expansion Valve | Adjust or replace to match the pressure-temperature characteristics of HC refrigerants. |
| Refrigerant Oil | Replace mineral oil (used with CFCs) with synthetic oil compatible with HC refrigerants. |
| Drier Filter | Install a new drier to remove moisture and contaminants. |
| Charge Amount | Reduce refrigerant charge as HC refrigerants require less quantity than CFCs. |
| Safety Modifications | Add leak detectors, proper ventilation, and flame-proof electrical components for HC safety. |
- Properties of Hydrocarbon (HC) Refrigerants
- ✔ Eco-Friendly: No ozone depletion, low global warming potential (GWP).
✔ Highly Efficient: Better heat transfer, reducing energy consumption.
✔ Flammable: Requires safety precautions during handling.
✔ Lower Charge Required: 40-50% less than CFCs. - Common HC Refrigerants & Applications:
| HC Refrigerant | Application |
|---|---|
| R-290 (Propane) | Domestic refrigerators, small commercial freezers. |
| R-600a (Isobutane) | Household refrigerators, deep freezers. |
| R-1270 (Propylene) | Industrial refrigeration. |
- Function of Thermal Insulation
- Thermal insulation prevents heat gain or loss in refrigeration and air conditioning systems, improving energy efficiency.
- ✔ Reduces heat transfer between the system and the environment.
✔ Minimizes energy loss, reducing power consumption.
✔ Prevents condensation on pipes and ducts.
- Types of Thermal Insulation
| Type | Material | Application |
|---|---|---|
| Fiberglass | Glass fibers | Duct insulation, AHUs, HVAC systems. |
| Polyurethane Foam (PUF) | Rigid foam | Cold storage, refrigeration units. |
| Extruded Polystyrene (XPS) | Plastic foam boards | Wall and floor insulation in cold rooms. |
| Expanded Polystyrene (EPS) | Lightweight foam | Refrigerated transport, insulation panels. |
| Rubber Foam (Nitrile Rubber) | Flexible foam | Pipe insulation, air conditioning systems. |
| Reflective Foil Insulation | Aluminum foil-based | Duct systems, heat-sensitive areas. |
- Thermodynamic Properties of Heat Insulation Materials
- ✔ Thermal Conductivity (k): Lower k-value means better insulation.
✔ Heat Resistance (R-value): Higher R-value means better insulation.
✔ Density: Affects insulation performance and mechanical strength.
✔ Moisture Resistance: Prevents condensation and mold growth.
