instrument

refrigerator

A device that removes heat from a system to lower or maintain its temperature.
36 related articles

Description

A refrigerator is a device that transfers heat from a colder interior to a warmer exterior, using external work to drive the process. It operates on the principles of thermodynamics, specifically the second law, which states that heat naturally flows from hot to cold — a refrigerator reverses this flow by doing work. The key measure of its performance is the coefficient of performance (COP), which is the ratio of heat removed to work input.

History

The first practical vapor-compression refrigerator was built by Jacob Perkins in 1834, building on earlier experimental work by Oliver Evans. The concept of mechanical refrigeration dates back to the 18th century.

How it works

A typical refrigerator uses a working fluid (refrigerant) that undergoes a cycle of compression, condensation, expansion, and evaporation. The refrigerant absorbs heat from the interior when it evaporates at low pressure, then releases that heat to the surroundings when it is compressed and condensed at high pressure. The compressor provides the work needed to maintain the pressure difference.

In practice

Refrigerators are used everywhere from household kitchens to industrial cold storage, and in scientific research for cooling detectors and samples to cryogenic temperatures.

Fun fact

The most efficient refrigerators approach the Carnot limit, but real ones typically achieve only 30-50% of that theoretical maximum efficiency.

Concept graph →

Related articles · 36

A Pocket-Sized Fridge for Quantum Circuits
A quantum lab is like a kitchen where the chef waits a day for the stove to cool down. Superconducting qubits only work at temperatures of a few hundredths of a kelvin, and each 'cool, measure, warm up' cycle eats a whole day. A team of engineers built a fridge the size of a melon, weighing 3 kg, that does the job in just two hours.
Applied Physics2026-08-191 minarXiv:2608.19500express
Thermal Resonator: How to Release a Heat Burst Five Times More Powerful
A regular battery releases heat smoothly: what you store is what you get. The power is fixed once and for all, like a faucet that pours water in a single stream. But sometimes you don't need a steady flow; you need a short, powerful burst: to instantly heat a part, trigger a reaction, or dump excess heat.
Superconductivity2026-08-162 minarXiv:2608.15911express
The Switch That Won't Turn Off
Inside an MRI magnet, current flows through a closed superconducting loop, like water circling in a bucket after you give it a spin, it just keeps going on its own. To change that current, you heat the loop with a small heater: it stops being superconducting, becomes an ordinary resistor, and then an external source can 'top up' or 'draw off' current.
Plasma Physics2026-08-132 minarXiv:2608.13214express
The Vortex That Splits Carbon Dioxide
Microwave plasma in a vortex is like a kitchen mixer that simultaneously heats and stirs the gas. In the reactor, the gas is swirled, and microwaves heat it to thousands of degrees, tearing carbon dioxide molecules apart. Scientists created a computer model of such a reactor to understand how pressure affects the process.
Chemical Physics2026-08-032 minarXiv:2608.02536express
Catching the Moment a Protein Breaks
A mountain pass connects two valleys. In one, the protein is folded; in the other, it is unfolded. To get from one to the other, you must cross the saddle — the highest point on the path. In protein science, this point is called the transition state, and the coordinate that shows the distance to it is the committor.
Plasma Physics2026-07-291 minarXiv:2607.27024express
Spin, Mirror, Spin: A Shortcut to Fusion Energy
The race for fusion energy is like trying to bottle a lightning bolt. For decades, physicists have struggled to recreate on Earth the processes that power the Sun. The main challenge is getting light nuclei to fuse despite their mutual repulsion, while extracting more energy than was spent heating and confining the plasma.
Optics2026-07-252 minarXiv:2607.22990express
How to Make Heat Flow Backward in Milliseconds
Hot tea cools down, and ice cream melts — heat always flows from warm to cold, and this law seemed unbreakable. But in the quantum world, even familiar rules can be rewritten. Physicists placed a tiny mechanical resonator (a vibrating bridge the size of a microbe) in an optical cavity between two mirrors.
Thermal Split: How Uneven Heating Divides a Mixture
In a glass of water, oil gathers into droplets: that's equilibrium separation dictated by chemistry. But there are systems where order arises not from rest but from a constant flow of energy.
Statistical Mech2026-07-212 minarXiv:2607.18905express
Protein Courier: Why Speed Isn't Everything
Inside every cell, logistics is in full swing: tiny protein motors, like couriers, haul cargo along a network of microtubules. One of the main workhorses is kinesin, which steps using the energy of ATP (the cell's main energy currency). For a long time, researchers tried to evaluate it like a car: how much fuel it burns, how fast it gets there.
General Relativity2026-05-302 minarXiv:2606.00521express
A Thermometer on a Spaceship
Tea in a cup cools quietly on the table. But if you zoom past at near-light speed, the thermometer will read higher — even though no one heated the tea. Calculations confirm: the needle will creep up. A century ago, physicists split into three camps.
Materials2026-05-171 minarXiv:2605.17224express
Heat Turns into Electricity Even in Ordinary Glass
Heat a nail in a fire, and it will lengthen — everyone knows that. But heat only the tip and leave the other end cold, and the nail doesn't just get longer: it bends, because hot metal expands more than cold metal. It's this very bending, but at the atomic level, that physicists have turned into electricity.
Superconductivity2026-05-092 minarXiv:2605.08591express
Why a Superconducting Resonator Loses Its Purity of Sound
A tuning fork grows quieter not because someone stops holding it, but because the very hand that strikes it creates an invisible haze around it that damps the vibrations. A superconducting resonator behaves much the same way — a tiny track along which a microwave signal runs with almost no loss.
Quantum Physics2026-05-082 minarXiv:2605.07124express
A Quantum Motor Powered by a Double Pendulum
A heat engine doesn't have to be made of iron. In the microworld, a single electron can play the role of a piston, and the measurement process itself can serve as fuel. Two neighboring 'pockets' for electrons are connected by a narrow bridge.
Materials2026-04-041 minarXiv:2604.03547express
AI Finds Materials That Barely Conduct Heat
Heat flows through matter like water through pipes: sometimes fast, sometimes barely. Engineers seek materials that almost don't let heat pass — like clogged pipes. Such insulators are vital for energy saving and devices that turn heat into electricity. The neural network KappaFormer quickly evaluates the "throughput" of an atomic structure.
Materials2026-03-281 minarXiv:2603.27298express
Current Heats a Magnet to Room Temperature
Usually, current in a metal acts like boiling water on ice: it heats the material and destroys magnetic order. But in a layered structure of tungsten ditelluride and the ferromagnet Fe3GeTe2, current behaves differently.
Materials2026-03-261 minarXiv:2603.25429express
Magnetic Cold: Measuring Cooling with a Single Device
The magnetic refrigerator of the future won't hum with a compressor. Instead, it will cool your groceries by exploiting a special material that heats up in a magnetic field and cools down when the field is removed. This cycle resembles the compression and expansion of gas in a conventional fridge, but here a magnet does the work of a piston.
Fluid Dynamics2026-03-261 minarXiv:2603.25626express
Heat Pumps Water on Its Own
When servers in a data center run at full tilt, they get as hot as a forgotten iron. That heat goes to waste, and cooling them eats up even more energy. Engineers in Germany have proposed putting that heat to work: let it drive liquid through thin tubes all by itself, with no motors or pumps. Their device looks like a flat box with an asymmetric bottom.
Fluid Dynamics2026-03-151 minarXiv:2603.14237express
How a sharp jolt flips a system over
A quiet tube with a heated grid inside. The voltage on the grid is suddenly raised, and the tube starts to hum, sustaining itself. This is not a malfunction but a transition to another stable state, like a ball rolling over a hill into a neighboring hollow.
Optics2026-03-131 minarXiv:2603.12640express
Seeing Heat: A Camera Reads Gas Temperature from Its Shadow
Gas is nearly invisible, but it has a temperature, and you can read it from how the gas 'shadows' the thermal background. In the experiment, a camera looks at a warm screen through a jet of carbon dioxide. If the gas is cooler than the background, it appears as a dark spot; if warmer, it appears bright.
Fluid Dynamics2026-03-101 minarXiv:2603.09494express
Why Ice Slides on a Warm Slope
Ice on a warm frying pan doesn't just melt: it starts to move. A thin layer of water forms beneath it, and the piece glides as if on oil. The speed of this sliding depends on how quickly heat travels through the water film and how steep the incline is.
Statistical Mech2026-03-071 minarXiv:2603.07128express
Water Works on a One-Degree Difference
An ordinary heat engine is like a mill between the hot and cold banks of a river: the greater the drop, the stronger the current. Here, the drop is tiny, just one or two degrees, but water can still turn the wheel. The secret is that water is made to boil not by heating but by a sudden drop in pressure, so steam bursts out even from barely warm liquid.
Materials2026-02-211 minarXiv:2602.18979express
Metal Cocktail: How to Predict Its Heat and Current
A metal alloy is like a cocktail: mix a few elements and you get a material with new properties. But while a bartender tastes the drink, engineers need to know in advance how an alloy will behave in service.
Instrumentation2026-02-101 minarXiv:2602.09513express
Cold Without Extra Steps
Your kitchen fridge cools everything to a single temperature. But in labs where quantum phenomena are studied, you often need two different levels of cold at once. Previously, that meant assembling two separate cooling circuits — bulky and heavy.
Biological Physics2026-01-231 minarXiv:2601.16654express
Nanoflowers Heat Up and Take Their Own Temperature
Tiny particles that look like flowers can do two things at once: heat up and tell you how hot they are. This isn't science fiction: it's the result of working with nanoparticles made of cobalt ferrite, a magnetic material that responds to magnetic fields.
Chemical Physics2026-01-182 minarXiv:2601.12573express
Freezing Without Ice: How Thermodynamics Saves Cells
In a freezer, ordinary water turns to ice, but in living cells, such ice is a disaster: sharp crystals tear membranes apart like needles popping a balloon. Scientists who preserve cells for medicine have learned to avoid this calamity, but each method speaks its own language. A new study offers a common vocabulary — thermodynamics.
Vibrations at the Edge of Absolute Zero
Inside a refrigerator that cools matter to near absolute zero beats a mechanical heart — the pulse tube. It pumps gas and extracts heat, but along with the cold it brings tremors. Each beat of this heart shakes the instruments sitting next to the sample and ruins delicate measurements.
Ice Has a Memory: How Antarctica Responds to Carbon Dioxide
An ice core from Antarctica is a time machine that recorded the climate for 130,000 years straight, year after year, with no gaps. Air bubbles trapped in the ice preserve the carbon dioxide of those ancient eras.
Quantum Physics2026-01-092 minarXiv:2601.05514express
A Wire Heats Up from Knowledge
Run a current through a wire, and the wire heats up. Anyone who has ever touched a phone charger knows this. Physicists call this heating Joule heating, after James Joule, who in the mid-19th century measured how much heat electricity produces. Since then, the formula has been simple: the greater the resistance and the current, the hotter the wire.
General Relativity2026-01-051 minarXiv:2601.01851express
The Universe is a Giant Heat Engine
The idea of a expanding universe, proposed by Georges Lemaître, finds an unexpected analogy. Space behaves like a piston in a cylinder: dark energy pushes it, much like steam. The relationship between pressure and volume in this 'engine' is strikingly similar to that of a steam boiler.
Quantum Physics2026-01-011 minarXiv:2601.00198express
Quantum Physics2025-11-181 minarXiv:2511.14552express
Hot Cools Faster: The Quantum Mpemba Effect
The Mpemba paradox, hot water sometimes freezes faster than cold, has gained a quantum sequel. In the microworld, a particle pushed farther from the finish line gets there first. Experimenters demonstrated this on a single spin: like a racer, they pushed it farther from equilibrium, and it reached it faster than after a weak nudge.
Quantum Physics2025-11-061 minarXiv:2511.04028express
Heat in Reverse: When Hot Freezes from Cold
Water always flows downhill, and heat from hot to cold. That's what энтропия dictates. But the quantum world finds loopholes. Physicists made light particles interact with hot and cold environments in an uncertain sequence — like a flipped coin that hasn't landed yet.
Quantum Physics2025-10-131 minarXiv:2510.12017express
Glowing Atoms Create a Nearly Perfect Engine
Atoms, like a swarm of fireflies, shine in unison. When they flash together, the light multiplies — a hundred atoms shine ten thousand times brighter than one. Physicists have turned this trick into a heat engine. A typical motor needs both a hot and a cold source, but here the atoms operate with just a cold one.
Wind in the Sails of a Heat Engine: How Motion Bypasses the Carnot Limit
A heat engine is like a sailboat: to move forward, it needs a difference. Usually that means a temperature difference between hot and cold reservoirs. But what if the reservoir itself starts moving? The wind that fills the sails is created not only by a pressure difference but also by the motion of air masses.
Motion as Fuel: A Quantum Engine Beats Carnot
Two qubits, quantum bits, two-level systems, glide through hot and cold thermal baths. One moves at 0.8 times the speed of light. At that moment, familiar thermodynamics cracks: a moving qubit senses temperature differently than a stationary one. For it, the cold bath can feel hotter, and the hot bath colder.