We can’t live without refrigeration
From birth onwards, refrigeration and air conditioning technology accompanies us all the way. It plays a crucial role in the functioning of the global economy: it ensures our food supply, human health and the experience of wellbeing in our everyday lives. It mostly operates hidden from view – but every single day it helps to make our lives more comfortable and safe.
Today, supermarkets sell a wide variety of meat, fish, dairy products and fruit and vegetables. Whether we're talking about regional products or international specialities, such an abundant offer is only possible if refrigeration can be guaranteed at all times, from the point of harvesting and production to the goods on display. This is because only a constant low temperature can guarantee that foods reach the consumer in a fresh condition. For this reason, fish is deep-frozen these days while still at sea, apples are stored at just above 0°C in a special atmosphere before they reach the shops and the temperature of dairy products must not exceed 8°C from the factory to the chilled shelves. Refrigeration chains of this kind, which sometimes stretch from one continent to another, are the prerequisite for our daily supply of food. Modern refrigeration technology makes it all possible.
The history of the refrigerator goes back to the second half of the 19th century. The German engineer Carl von Linde, who worked on the theory of the cooling machine and had some prototypes constructed in an engineering works in Augsburg (Maschinenfabrik Augsburg – MAN), is often credited with being the father of refrigeration technology.
Breweries, that no longer wanted to be dependent on natural ice, were the driving force behind the economic success. Up to that time, they had to harvest ice from frozen lakes to cool their fermentation and storage cellars. Large-scale breweries in particular invested in the new technology that enabled them to maintain a constant low temperature during the fermentation process.
Just as in the case of food production, we can't imagine global transport without refrigeration, and refrigeration technology plays a key role too in the manufacture of pharmaceutical products and in the chemical industry. However, these are just a few examples that show how significant the achievements of refrigeration and air conditioning are for our modern industrial and service society. Without them, Google, Facebook & co. would never have made their way onto smart phones and tablets – for the simple reason that electric current always generates heat. If we bear in mind that the Internet and all digital networks are based on bits and bytes – in other words, the switch from "current on" to "current off" – we quickly appreciate what a huge amount of heat this data flow produces. Cooling equipment of corresponding dimensions is at work round the clock in the server rooms to prevent the servers from overheating. The volume of heat developed by the servers is so great that operators have server farms built in the polar regions in order to save energy.
The human organism too is protected by refrigeration technology in the form of air conditioning when the heat can already be unbearable in the morning in high summer. Even a temperature of 30 °C in the shade makes life difficult for older and sick people, although healthy individuals too suffer from lethargy and poor concentration on hot days. At 33 °C our efficiency falls on average by half.
Air conditioned living rooms and offices keep out the summer heat and help office workers to keep a cool head. Moreover, modern air conditioning equipment not only controls the temperature in individual rooms but also filters out dust and dirt particles. Especially in open-plan offices, where a lot of electrical equipment, printers and copiers are kept in a confined area, air conditioning combats poor air quality. Air conditioning is just as helpful when you are travelling.
These days, you hardly ever see the opening windows that used to be the source of fresh air for passengers in buses and trains. Instead, you find that automatically operating air conditioning is increasingly being used. Air conditioning has long since become the norm in the car market, and even in the small car segment it is often fitted as standard. Experts are pleased for a very good reason: the right temperature in a car not only makes you feel more comfortable but also means it doesn't take a driver longer to react. So on hot days air conditioning improves safety on the roads.
In terms of how they function, air conditioning units are not different in principle from the fridge you can buy in the shops: a refrigerant flows round a closed cold circuit and is subject to changes in aggregation. It takes up heat at a low temperature and, with the input of electricity, dissipates it in the environment at a higher temperature – which is why the back of your refrigerator is warm.
The warm side of an air conditioning unit is positioned on the outside of a building where the heat can be dispersed. But air conditioning units have to work much harder to achieve this: it would take more than a dozen refrigerators to produce the cooling effect of a compact air conditioning unit designed to cool single rooms.
The spread of refrigeration and air conditioning technology in all walks of life is accompanied by the high level of energy it takes to operate the units. In Germany alone, refrigeration consumes more than 14 % of total end energy, with the provision of fresh food accounting for well over a half – in figures more than 77, 000 gigawatt hours – enough to keep an 11 watt energy-saving light burning for around 800 million years. In view of figures like these, raising energy efficiency in the refrigeration and air conditioning sector is one means of saving energy globally. A ten per cent reduction in the consumption of energy means saving the amount of electricity used annually by around two million four-person households.
Heat pumps use the warmth in the surroundings for heating purposes. They work on the same principle as a refrigerator or air conditioning unit. However, in the case of the heat pump, the main feature is the use of the warm side, which is where heat energy is moved from a reservoir at low temperature to a higher temperature and then discharged.
Thus, a heat pump means existing sources of heat – the air outside or the groundwater – can be used to heat domestic and commercial buildings. Today, almost all air conditioning equipment can be used for both cooling and heating. More than 54, 000 heat pumps were sold in the German market last year.
Refrigeration and air conditioning industry: focus on energy efficiency
There is no difference between the basic principle of today’s refrigeration and air conditioning equipment and that of the first cooling and air conditioning machines invented over 150 years ago. However, modern components have scarcely anything in common with what was used in those days. Our electronic control systems, optimal flow ventilators made from high-tech materials and climate-friendly refrigerants are state of the art. Overall, the components produce units that operate with increasing energy efficiency. The refrigeration and air conditioning industry, which meets every two years at the Chillventa trade fair in Nürnberg, benefits from the global trend to lowering the consumption of energy.
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