S R C C Alternatives to H F s in the efrigeration and Air Conditioning Sector ection 01 25 Ammonia is a well-proven refrigerant in larger commercial and industrial applications. Ammonia has technical properties that make it considered incompatible with copper which is a preferred material for tubing and motor winding for mass produced hermetic systems. The toxicity and risk to human safety if released, limit the applications where ammonia can be used safely and at an acceptable cost. The extremely strong and irritating odour emitted by ammonia when released may incite people to panic as they try to evacuate the area. On the positive side however, this odour also acts as a useful early warning signal in case of system leakage. The use of ammonia in its traditional sectors has increased on many markets due to the desire to avoid the use of high GWP refrigerants such as HFCs. Ammonia is still used mainly in the traditional application of larger industrial refrigeration systems although it has also been introduced in certain new segments such as large central air conditioning systems and smaller commercial systems on some markets. One way of reducing the risk when using ammonia is to minimize the charge by building compact chillers that can be placed in machine rooms specially designed for the purpose of eliminating the risks. There are also systems designed to absorb any releases of ammonia in water sprays before it can reach the area with public access. The introduction of soluble oils for ammonia resulted in the development of “dry expansion” systems with lower charge and simplified oil return versus flooded systems with non-miscible oil. 1.4.1 Ammonia 1.4.2 hydrocarbons Su mmary Ammonia Ammonia is a well-established refrigerant requiring special personnel competencies and system design. There are a number of experienced companies and technicians with these competencies. An increased use of ammonia will depend on more technicians and engineers receiving training in this sector. There are environmental benefits from the use of ammonia because it has zero ODP and negligible GWGWP. Technically it is a good refrigerant, but it has some safety drawbacks and technical challenges associated with material compatibility and high temperatures occurring during compression. The investment cost is typically higher than for conventional systems, at least in lower capacities. Well designed systems can have very good energy efficiency and new designs are extending the application range with lower charge and new oils suitable for non-flooded evaporators. The flooded systems typically require procedures for oil return and are typically used in locations where there are qualified personnel on site. Su mmary hydrocarbons Hydrocarbons are good refrigerants with zero ODP and negligible GWGWP. Their flammability requires specific competencies in design, manufacturing and service. To ensure safe use, there are restrictions on where and how they can be applied. Hydrocarbons as refrigerants are gradually being covered in International Standards detailing the necessary requirements for safe use (i.e. in EN 378 and ISO5149). Isobutane (R-600a) has become the standard refrigerant in new domestic appliances in many markets. The small amounts used in a domestic appliance are not considered to be a significant risk after redesign of the refrigerators Fig. 1.7 Ammonia installation typical for industrial applications.