Difficulty: Medium
Correct Answer: All of these
Explanation:
Introduction / Context:Ammonia (R-717) is a widely used industrial refrigerant prized for efficiency and low environmental impact, but it has important safety and materials-compatibility considerations. This question consolidates commonly taught properties relevant to plant design and operation.
Given Data / Assumptions:
Concept / Approach:Ammonia is toxic and has a sharp odor; materials of construction must avoid copper and many copper alloys due to chemical attack. In many exam and handbook treatments, ammonia is also noted to require larger compressor displacement per ton than certain halocarbons because of its suction specific volume characteristics, despite high mass-based latent heat; this affects volumetric sizing and selection of machines.
Step-by-Step Solution:
1) Safety: Ammonia is toxic and irritates mucous membranes; leak management is critical.2) Materials: Avoid copper and many copper alloys; use appropriate steels and compatible materials.3) Volumetric effect: For comparable duties, ammonia may demand larger volumetric displacement in many comparisons with fluoro-carbons; machine selection must account for this.4) Therefore, all three statements are accepted teaching points in refrigeration engineering.Verification / Alternative check:Design guides and safety resources emphasize ammonia’s toxicity, copper incompatibility, and the importance of volumetric capacity in compressor selection, supporting the combined statement.
Why Other Options Are Wrong:
Common Pitfalls:Confusing mass-based efficiency (high latent heat per kg) with volumetric sizing (specific volume and suction density drive displacement). Also, overlooking materials compatibility when retrofitting systems.
Final Answer:All of these
Discussion & Comments