What is refrigeration? How does it work and which are the main applications?
Refrigeration is defined as the process that continuously extracts heat from a substance, body or environment, bringing it to a lower temperature. The refrigeration machine was invented by the American Oliver Evans in 1805. It was however in 1876 that the first machines that produce cold using the process of liquefaction of a gas appeared.
The most widely used refrigeration systems is the Vapor Compression Cycle, consisting of a refrigeration machine in which a refrigerant fluid passes from a liquid to a gaseous state in a coil, subtracting the amount of heat required for evaporation from the environment (cold rooms) in which the coil itself is placed; once heated by compression in a piston compressor, the steam condenses in a condenser in which the heat transfer to the cooling medium (air or water) takes place.
Air conditioning systems and industrial and commercial refrigeration are both based on this principle, although there are some substantial differences (in the components, in the design methods, in the places of installation etc.).
Refrigeration process plays a fundamental role for humanity, just think of the household refrigerators and the food cold chain: from the production, to the processing and packaging, to transport and distribution, it allows you to store fresh meat, fruits and vegetables, dairy products and other foods making them safe for consumers (the temperature, which varies on average from -1 to + 8 ° C slows down biochemical reactions). In the “controlled atmosphere” refrigeration, the refrigerant treatment is accompanied by a qualitative change in the atmosphere surrounding the food.
In the healthcare sector, refrigeration technology can be used for the conservation of cells, embryos, tissues, organs, for the transport of medicines and vaccines, for cryosurgery and cryotherapy; it is also necessary in many industrial processes (in the chemical, plastics sector etc.), as well as in research laboratories (for experiments on superconductivity, on vacuum systems etc.) and in astronomy (for cooling the CCD and CID sensors used in telescopes).
Increasingly efficient and environmentally friendly technologies
Considering the many applications and the great importance of the refrigeration sector, it is easy to understand that it continually faces new challenges related to environmental sustainability and energy efficiency.
Regarding the first aspect, refrigeration and air conditioning have a strong impact on global warming. The use of Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) has been banned because these gases contribute to the depletion of stratospheric ozone. They have largely been replaced by Hydrofluorocarbons (HFCs) which are however potent greenhouse gases.
Today we are witnessing the use of new synthesis gases in the refrigeration cycle, but above all a return to natural refrigerants including carbon dioxide. In recent years, companies have invested heavily in transcritical CO2 refrigeration (systems that use CO2 for both low and medium temperatures).
However, the use of lower environmental impact refrigerants must go hand in hand with improved energy efficiency: in fact, energy consumption generally contributes 60-80% to the climatic impact caused by a refrigeration system in its useful life. Restrictions on the use of gas have given a new boost to research and experimentation aimed at making systems more efficient. Performance improvements involved all components: exchangers, valves, probes, flowmeters, control systems, etc.
Measure, Control, Save.
The sustainability of the refrigeration units must also be guaranteed economically. Refrigeration costs often represent a high percentage of total energy costs and a small reduction in energy consumption can lead to significant savings.
To evaluate the system efficiency, it is necessary to quantify the contribution of all the components: it is necessary to measure exactly the consumption of cooling energy per production unit, per m³ or per year.
This is possible thanks to the advent of Industry 4.0, which has completely transformed the refrigeration industry thanks to the interconnection between the various components through control systems (PLC). The PLCs are made up of different electronic and electromechanical devices which, through the sensors, receive the information they subsequently process from the cooling circuits, and thus regulate the activation of the various components. In this way, significant amounts of energy can be saved.
The electromagnetic flowmeter CS8100 ISOMAG
Are you wondering how much cooling energy is really needed for your refrigeration system? The ISOIL Industria flowmeter CS3900, inserted in the right place of a system, can offer the answer to this question.
It is a compact electromagnetic flowmeter that integrates both the sensor and the converter in a single body. It is ideal for measuring fluid temperature and for flow rate adjustments based on process temperature, cooling systems for machine tools and similar.
The tests carried out on the CS3900 flowmeters have revealed that they, even in comparison with mass meters that measure CO2, are able to offer excellent performance and ensure maximum system yield.