Natural refrigerants are a hot topic. With more and more onshore utility-based installations switching to natural gas, what’s the situation in the maritime industry? Selecting the right refrigerant is no easy task as each type has its own pros and cons. In this series of blogs we explore the most common natural refrigerants to help you decide which best suits your specific application.
Ammonia is one of the oldest refrigerants there is, used from the days of the first cooling machines. A common gas in nature, ammonia (NH3) consists of one nitrogen and three hydrogen atoms.
To give you a comprehensive overview we are comparing every refrigerant on the following fixed set of properties:
Latent heat capacity
All starting points are the same for every refrigerant, including the temperatures below:
Evaporation temperature: -10°C
Condensation temperature: 25°C
Figure 1: H-log/P diagram R717 (NH3)
Ammonia has one of the best thermodynamic properties of all refrigerants. With a broad temperature spectrum, relatively low working pressures and a massive latent heat capacity, it is a great gas to use as a refrigerant.
Looking at the safety classification, R717’s specs are less favourable than other natural refrigerants. It is classified as B2L.
No flame propagation
Although toxic to humans, R717 is a substance that occurs naturally on earth. With low GWP and ozone depletion values, leakages have hardly any effect on the environment. The high efficiency contributes to fewer CO2 emissions from generators.
R717 is a wonderful refrigerant with excellent thermodynamic properties, a high efficiency and a low environmental impact. The downside is the high degree of toxicity, which means that many safety measures are required.
Please note that the values and calculation given in this article have been simplified in order to give you a general overview of the pros and cons of this refrigerant. More specific information is needed for a detailed calculation and we strongly recommend contacting one of our engineers if you are considering the use of natural refrigerants.