Never feel guilty about raiding the fridge again! Refrigerators and air-conditioning units could be chilled using crystal powders found in everyday cosmetics, paints and plastics to help cut carbon emissions
- Scientists say that solid crystal plastics may be a greener alternative to gases
- Fridges cool by compressing gas forcing it between a liquid and gaseous state
- The new system achieves the same by applying pressure to the crystals
- This forces them between an ordered and disordered molecular structure
- This process also absorbs heat and creates a cooling effect in the prototype
You may soon be able to reach into the fridge without feeling guilty that you are contributing to greenhouse gases, if a new way to power fridges is adopted.
A solid substance known as plastic crystals offers a greener alternatives to the gases currently used in fridges and air conditioning, experts say.
Fridges cool by compressing gas, forcing it between a liquid and gaseous state – a reaction that takes in heat and gives out cold.
The new system achieves the same feat with the same pressure being applied to the crystals.
This changes their molecular structure, going from a disordered state to an ordered state, which also absorbs heat and creates a cooling effect.
The plastics are are already used in everyday products such as makeup and paints, experts say.
You may soon be able to reach into the fridge without feeling guilty that you are contributing to greenhouse gases, if a new way to power fridges is adopted. A solid substance known as plastic crystals offers a greener alternatives to the gases currently used in fridges (stock)
Refrigeration units like fridges and air conditioning currently account for more than a quarter of the world’s electricity usage.
Scientists from the Chinese Academy of Sciences’ Institute of Metal Research in Shenyang say that plastic crystals are not only efficient at cooling air, but also use less energy.
In terms of their chemistry, they have a disordered structure, says Dr Bing Li, who spoke to New Scientist, meaning they don’t have a regular lattice formation.
By applying pressure to the plastic, it can absorb energy to become more ordered and hence cool the contents of a fridge.
Dr Li said: ‘We identified plastic crystals as promising materials for solid-state refrigeration
‘A tiny pressure can switch the materials between the disordered state and the ordered state, resulting in a large change in energy.’
You may soon be able to reach into the fridge without feeling guilty that you are contributing to greenhouse gases, if a new way to power fridges is adopted. A solid substance known as plastic crystals offers a greener alternatives to the gases currently used in fridges and air conditioning, experts say (stock image)
HOW DO FRIDGES WORK?
Fridges cool by compressing gas, forcing it between a liquid and gaseous state – a reaction that takes in heat and gives out cold
- Compressor: Gas at low pressure and low temperature enters the compressor. The gas is compressed to a higher pressure and its temperature rises (just like a bicycle pump which gets warmer pumping up a tyre). This process requires electricity.
- Condenser: The hot gas is then transferred to a condenser where the heat is removed and the gas begins to condense into a liquid.
- Ventilation fins: The heat is released via cooling fins on the back of the fridge unit
- Expansion valve: The liquid then goes through an expansion device where its pressure is suddenly lowered, it expands and some of the liquid turns very quickly into a vapour. This change of state has a cooling effect.
- Evaporator: The cold liquid absorbs the warmth from the air inside the refrigerator and turns back into a low temperature gas, at low pressure. It now starts its journey again through the compressor.
The crystals have a powder like texture, and one particular type is known as neopentylglycol, which absorbs ten times more energy than any other solids capable of the same function.
This means that it is much more effective at cooling its surroundings that other solid coolants at the same pressure.
But at the moment, there is still too much heat loss from in the cooling process when using the plastic and more work is needed to match the efficiency of gaseous coolants like HCF.
HCF is a chemical that alternates between being a hot gas and a cool liquid and have a ‘global warming potential’ that is 100-3000 times that of carbon dioxide.
Heating the liquid turns it into a gas and applying pressure to the gas causes it to become a hot liquid, releasing energy in the process.
But the leakage of these gases, which occur during production and disposal of fridges and aircons, contribute to the destruction of the ozone layer.
