A pure radiant cooling Device provides air conditioning without conditioning air

Good news! I write this blog post while our very old A/C is humming!

But this is so far only a proof of concept and a prototype!

"Researchers have made a cooling device that they say can chill environments with 50% of the energy used by conventional air conditioning.

They are using the physics of radiative cooling. ...

But it’s difficult to make them powerful enough, and hard to stop water in the atmosphere condensing on the surface of these cooling devices (like it does on a glass of cold water), lowering their performance further.

This research team ... developed a prototype radiant cooling device that could overcome these problems.

Their device uses a thermoelectric cooling module, which they describe as “in essence, a heat pump”, connected to 4 pipes and a fan on one side, and an aluminium panel on the other.

While the pipes and fan act as a heat sink, the aluminium panel is used to make a radiant surface extremely cold.

The researchers tested their device on a human skin simulator, and found it was able to cool the simulator by 7.3°C. ..."

From the highlights and abstract:

"Highlights

• A pure radiant cooling device for personalized thermal management

• A proof-of-concept prototype with thermoelectric cooler and polyethylene films

• Breakthrough in radiant cooling energy density (RCED) of up to 220 W/m2

• Energy saving ratio up to 50.4% in a typical building environment in summer

Summary

Ever since the birth of the first air conditioner (Carrier air conditioner) in 1902, over one hundred years ago, it has been accompanied by several technical problems, e.g.,
(1) low energy efficiency in large open spaces,
(2) spread of pollutants, airborne pandemic transmission (e.g., severe acute respiratory syndrome [SARS], COVID-19) through air-conditioning systems, and (3) low comfort caused by fan noise and blowing sounds.
Here, we report a personalized pure radiant cooling device that decouples the fresh air supply from space cooling to achieve air conditioning without conditioning the air. Condensation-free radiant cooling with a radiant cooling capacity of 152 W/m2 is achieved with a polyethylene (PE) film-covered super-cold infrared-emissive surface. By optimizing the design and operation parameters, the device saves up to 50.4% of cooling energy in a typical summer building environment. Our concept opens up the possibility of pandemic-free personalized thermal management with high energy efficiency and thermal comfort."

Device provides air conditioning without conditioning air

A pure radiant cooling device for “air conditioning” without conditioning air (open access)

Graphical abstract

Scientists develop AC that uses solid refrigerants and doesn’t hurt the environment

Good news!

This is my second blog post regarding A/C technology today!

"Solid refrigerants could be an ideal solution. Unlike gases, solids won’t leak into the environment from A/C units. One class of solid refrigerants, called barocaloric materials, work similarly to traditional gas-liquid cooling systems. They use pressure changes to go through heat cycles, but in this case, the pressure drives a solid-to-solid phase change. That means the material remains a solid, but the internal molecular structure changes. ...

A disadvantage of barocaloric systems, however, is that most of these materials require massive pressures to drive heat cycles. To produce these pressures, the systems need expensive, specialized equipment that’s not practical for real-world cooling applications. Mason and his team recently reported barocaloric materials that can act as refrigerants at much lower pressures. They’ve now shown that the refrigerants, which are called metal-halide perovskites, can work in a cooling system they’ve built from scratch. “The materials we reported are able to cycle at about 3,000 psi, which are pressures that a typical hydraulics system can work at,” ...

The team has now built a first-of-its-kind prototype that demonstrates the use of these new materials in a practical cooling system. The device has three main parts. One is a metal tube packed with the solid refrigerant and an inert liquid — water or an oil. Another piece of the device is a hydraulic piston that applies pressure to the liquid. Finally, the liquid helps transfer that pressure to the refrigerant and helps carry heat through the system. ..."

"... Other scientists have investigated using plastic crystals or shape-memory alloys as potential solid state refrigerants. With more work, this new class of materials could help make cooling devices more environmentally friendly. ..."

Scientists develop AC that uses solid refrigerants and doesn’t hurt the environment It could one day replace existing air conditioning that uses refrigerants that are thousands of times more powerful than CO2 at trapping heat.

Solid-state refrigerant works under pressure for greener cooling

A more environmentally friendly air conditioner

The team's prototype set up to test the solid-state refrigerant

AI Could Make Air Conditioners 10x Better

Good news! When was the last time A/C technology saw a major innovation? Billions of people do not even have any significant access to air conditioning!

"The energy we spend on cooling indoor spaces has tripled since 1990, and it’s going to triple again by 2050 as developing and middle-income countries embrace air-conditioning. Researchers are putting a lot of sweat into innovative cooling technologies that consume less energy, but none seem ready for prime time in the near future. ...

Cooling consumes over 16 percent of the energy used by buildings today, with the heat exchanger being the most energy-intensive component of an A/C unit. ...
By using AI to generate a radically new heat-exchanger design that can then be printed with a 3D metal printer, Hyperganic says it is developing a residential A/C unit that is 10 times as efficient as conventional air conditioners, while costing the same amount of money to buy and operate for a year. [Remark: Costs the same to operate???] ...
Hyperganic’s AI-based design platform allows engineers to make heat exchangers with radically different structures, using elements inspired by the intricate designs found in nature, like corals, ... By increasing the surface area and optimizing air flow, these designs boost the component’s energy efficiency. “We take knowledge from engineering about how to build a heat exchanger, but now you can do it automatically,” ... “You can create, test, and iterate faster.” ..."

AI Could Make Air Conditioners 10x Better - IEEE Spectrum Hyperganic is using AI to design new heat exchangers that can be 3D-printed in metal