Class 2 (2nd Engineer) MEKG 📅 Jun 2025

Exam Question

With Reference to Refrigeration systems uses onboard:

(a) How do we choose environmentally friendly refrigerants for ships? (2)

(b) How do CFCs, HCFCs, HFCs, and natural refrigerants like ammonia and carbon dioxide compare in terms of ozone depletion (ODP) and global warming potential (GWP)? (3)

(d) Explain the steps you will take to ensure that release of refrigerant gases from the plant in minimized during normal operation and during maintenance activities. (5)

Reference Answer

### (a) Criteria for Choosing Environmentally Friendly Refrigerants (2 Marks)
The selection of environmentally friendly refrigerants for marine applications is governed by a multi-faceted approach that balances regulatory compliance, operational efficiency, and safety. The primary criteria are:
1. **Ozone Depletion Potential (ODP)**: As mandated by the **Montreal Protocol** and **MARPOL Annex VI**, the foremost criterion is an ODP of zero. This immediately disqualifies CFCs and HCFCs from use in new installations.
2. **Global Warming Potential (GWP)**: Following the **Kigali Amendment** and EU F-Gas regulations, a low GWP is critical. Refrigerants are benchmarked against Carbon Dioxide (CO2), which has a GWP of 1. The aim is to select refrigerants with the lowest possible GWP to minimize their contribution to the greenhouse effect.

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