These days we are talking a lot about heat pumps. Firstly, because European regulations have brought them to the fore as a result of the ban on gas boilers. But also, because we have already seen how even in very cold climates, a heat pump is still more efficient than other heating systems.
And when it seems that we have to start getting used to the heat pumps that we all know, now comes a new development that proposes replacing the classic operation of this type of device with a much more efficient one. Are the solid state electrocaloric heat pumps.
Without refrigerant gases
Regarding heat pumps, we already know how they work, which is based on the use of a thermodynamic cycle to transfer heat from one place to another. Its main function is to move heat from a space at a low temperature to another at a higher temperature, so that, in the destination space, the heat is more concentrated. There are two main types of heat pumps: compression heat pumps and absorption heat pumps.
The first, the compression heat pumps, use a cycle of compression and expansion of a refrigerant to transfer heat, components that circulate through a closed cycle of evaporation, compression, condensation and expansion. On the evaporator side, the refrigerant absorbs heat from the surroundings, and on the condenser side, it releases heat to the destination environment.
The second ones, the absorption heat pumps they use an absorbent and a refrigerant instead of a compressor in a cycle that includes absorption, desorption, condensation and evaporation in which heat is absorbed into a solution, and then this solution is heated to release the heat.
These two types are the most common and those typically used in all types of heating and cooling applications in residential and commercial buildings, as they can extract heat from outside air (even in cold temperatures) to heat the interior of a building. But now a new proposal arrives.
It was a group of engineers from the Luxembourg Institute of Science and Technology (LIST), with work that has been published in Scienceresponsible for creating a prototype of a regenerative electrostatic heat pump that It is much more efficient than a classic heat pump.
Instead of relying on gas compression and expansion cycles as in conventional heat pumps, solid-state electrocaloric heat pumps can directly harness the electrocaloric effect to transfer heat.
A solid-state electrocaloric heat pump is a device that uses solid materials with ferroelectric or magnetic properties to generate temperature changes through the application of an electric field. Unlike traditional heat pumps that use compressors and refrigerants (both of which are harmful to the environment), solid-state electrocaloric heat pumps have no moving parts and do not require refrigerants.
The basic principle behind these heat pumps is ability of certain solid materials to undergo changes in temperature when an electric field is applied to them. When a voltage is applied to these materials, the particles in the material can change their orientation and a temperature change occurs as a result. This phenomenon is known as the electrocaloric effect.
To make it They have used some strips of lead tantalate and scandium, placed one on top of the other, submerged in silicone oil, a liquid that serves as both a lubricant and a thermal fluid (it transmits heat very well), since it is an excellent electrical insulator. As explained by Emmanuel Defay, head of the Nanotechnology unit of the Materials Research and Technology (MRT) department of LIST:
“Our proposed solution involves an array of multilayer condensers stacked within an electrically connected fluid-filled pipe. The fluid flows back and forth between the condensers, creating a temperature gradient.”
To operate, they add electricity, which causes the capacitors to heat up, causing the fluid to push in one direction, while if it cools, the fluid circulates in the opposite direction and in this way the temperature is raised or lowered without using gases. refrigerants. With this premise, they carried out tests in which 64% of Carnot efficiency has been achieved (it is a maximum theoretical measurement of the efficiency of a reversible heat engine operating between cold and heat), the maximum achieved to date in a heat pump.
These heat pumps can be more energy efficient and have a more compact design by eliminating the need for compressors and refrigerants. However, despite the advancement, solid-state electrocaloric heat pump technology is in a developmental stage and is not as common compared to traditional heat pump systems.
Cover photo | Alpha innotec on Unsplash
Via | Omicrono
More information | Luxembourg Institute of Science and Technology
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