**Abstract**

In Brazil, there has been a significant change in the types of refrigerants used in air conditioning and refrigeration systems. This chapter seeks to compare, based on legislation established by the European Parliament and of the Council, which has been understood and obeyed all over the world, the use of F-gas and different types of fluids intended for use in such systems and also discuss the use of natural fluids such as hydrocarbons, ammonia, and carbon dioxide (CO2), in refrigeration or air conditioning systems, considering the characteristics and properties of these types of fluids, such as thermodynamic and psychometric parameters, the global warming potential (GWP), application limits, flammability factor, and performance as refrigerant. Some specific examples of the use of fluids such as R-R290, R-410a, and R-600a, instead of R-22 fluid, will also be discussed. For this purpose, a test bench was developed with an equipment chiller in the Climatization and Thermal Comfort Laboratory—ClimaTConT—of the Federal University of Pará, in order to compare the types of refrigerant fluids, usually used in air conditioning systems, considering the conditions, evaluating the possibilities of reuse of these fluids, without performance losses, in significant values, always seeking the reduction of the use of synthetic fluids, which are more aggressive to nature, generating pollution and degradation to local environments.

**Keywords:** F-gas, hydrocarbons, natural refrigerants, synthetic fluids, chiller bench

#### **1. Introduction**

When it comes to environmental pollution, the first idea is the one caused by the operation of a motor vehicle, consuming a fossil fuel, nonrenewable, or the irregular disposal of garbage in areas near urban centers. However, refrigeration and air conditioning systems are highly polluting the local environment, because these systems use refrigerants with specific characteristics, and some of their components can react with the ozone layer or be released into the atmosphere, which is equivalent to a few hundred or thousands of times the emission of CO2.

A great example is a cooling system that works with R-404A refrigerant, which is a synthetic fluid. Under normal operating conditions, this system has

#### *Low-temperature Technologies*

no ozone-depleting chemical component. But, if an approximately 10 kg of this refrigerant leaks into the atmosphere, the contribution to the greenhouse effect/ global warming will be equivalent to the emission of 40 tons of CO2 [1, 2].

In Brazil, all refrigerants, currently available on the market, are the basis of HCFC and HFC, but these fluids have their days counted for their discontinuation given the contribution to environmental pollution and the action of the Montreal and Kyoto Protocols that made societies aware of the harmful action of these products when released into the local environment [1–3].

Due to these prohibitions imposed by world laws and protocols, the air conditioning and refrigeration market in Brazil aims solutions for the use of refrigerants, which vary between synthetic fluids that has a high value of global warming potential (GWP) and natural fluids, which has a lower value of global warming potential (GWP) than the synthetic ones. However, natural fluids have some impasses that are directly related to their composition, such as ammonia, which has excellent thermodynamic qualities, but it is a highly toxic fluid. The CO2 itself is another fluid that can be used in refrigeration systems, but as a downside, it works under high pressures, close to 100 bar. The hydrocarbon refrigerants, which are better known as R-290 and R-600a, are also excellent thermodynamic fluids, but these fluids are highly flammable and have their maximum amount to be applied to limited climate systems for security reasons [4–10].

In order to encourage the use of natural fluids in air conditioning and refrigeration systems, some laws and protocols have been created in the world to regulate, standardize, and inform mainly about safety issues related to the use of these types of refrigerants [4–6, 11]. From the point of view of use, there are scholarly works in air conditioning and refrigeration systems produced by companies that already work with some natural fluids and have great yields, both on the issue of capacity and cooling efficiency, as the issue of energy consumption [12, 13].

The present work intends to develop a test bench so that reliable data on synthetic and natural fluids can be obtained. In the experimental stage, the refrigerants R-22 and R-290 were used. Nevertheless, in the simulation stage, some data were taken of Danfoss software in order to evaluate the thermodynamic, psychometric, and electric parameters, the ozone depletion potential (ODP), the GWP, the working pressure limits, and the local conditions. Hence, it has become possible to indicate the ideal fluid that should operate in a safe condition and with less aggressive potential to the environment.
