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Saudi Research Tests New Energy-Efficient Cooling System

KAUST's new cooling system
KAUST's new cooling system
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Saudi Research Tests New Energy-Efficient Cooling System

KAUST's new cooling system
KAUST's new cooling system

The King Abdullah University of Science and Technology (KAUST) has conducted observational experiments in the houses located inside the campus to create a new cooling system that consumes energy less than the currently used systems.

These experiments aim at testing the efficiency of the new system under different weather conditions in Saudi Arabia.

Air conditioning systems in use today typically achieve only 35–40 percent of the cooling possible for the amount of electricity they consume. As well as their principal task of cooling air, they remove moisture from the air by lowering its temperature to the level at which the water in it condenses. But this double step wastes a lot of energy.

A team led by Kim Choon Ng, professor of Environmental Science and Engineering at KAUST, has now devised a way to reduce the amount of energy consumed by decoupling the two processes.

Instead of dehumidifying air by cooling it, the system uses a more efficient process called adsorption. This binds the water in the air to the surface of a specially developed nanomaterial. Made of calcium chloride salt embedded in a silica gel lattice, this material can adsorb up to 20 times as much water as conventional silica gel in proportion to its weight.

Ng is now testing prototypes, and findings to date show an improvement in efficiency of 30–60 percent over conventional air conditioners. “This new type of air conditioner could offer a much-needed mean to slow down the increasing contribution of cooling systems to climate change,” says Kim Choon Ng.

In this new system, the proprietary adsorbent coats the coils of a mechanical vapor compressor, which cools the air the adsorbent has dehumidified in the manner of a conventional AC system. Air flow through the system is reversed and then reversed again in a period cycle to regenerate the saturated adsorbent.

Global consumption of air conditioning electricity, mainly generated from burning fossil fuels, has risen from 600 TWh in 1990 to 2,200 TWh in 2020, and based on current trends, could reach 6,300 TWh in 2050. By then, half of all electricity used by the world’s hottest countries, including Saudi Arabia, would be used just for keeping people cool.

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Should You Stretch before Exercise? After? Never? Here’s What to Know

Philadelphia Eagles stretch as they get ready during practice at NFL football training camp, Thursday, July 25, 2024, in Philadelphia. (AP)
Philadelphia Eagles stretch as they get ready during practice at NFL football training camp, Thursday, July 25, 2024, in Philadelphia. (AP)
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Should You Stretch before Exercise? After? Never? Here’s What to Know

Philadelphia Eagles stretch as they get ready during practice at NFL football training camp, Thursday, July 25, 2024, in Philadelphia. (AP)
Philadelphia Eagles stretch as they get ready during practice at NFL football training camp, Thursday, July 25, 2024, in Philadelphia. (AP)

For many people of a certain age, high school gym class began with reaching for their toes. Then, over the years, we were told it was better to stretch after exercise.

It turns out, both those things can be true, but the differing advice has created some confusion.

Stretching can help make you more flexible, improve range of motion in your joints — and feel good. David Behm, who researches human kinetics at Memorial University of Newfoundland in St. John’s, Canada, offers this advice on when to stretch and how to do it safely:

Warm up first

It’s almost always good to stretch, but it’s better if you warm up first, said Behm, author of "The Science and Physiology of Flexibility and Stretching." He recommends a light aerobic activity such as jogging, walking or cycling for five or 10 minutes.

Follow that with some static stretching, the traditional way of reaching and holding a position (think back to that gym class). You can then do activity-specific dynamic stretching, in which you warm up the muscles with repetitive movements like leg lifts.

Behm says one minute is "the magic number" for how long to do static stretching per muscle group without fatigue.

Expand your definition of 'stretching'

Should you always stretch before exercising? If it's traditional stretching, not necessarily.

The better question, Behm says, is, "Should people increase their range of motion? Should people have better flexibility? And that is yes, because it helps prevent injuries. It helps with health. But you don’t have to stretch to achieve that."

Resistance training, for instance, can be an effective form of stretching, he said. Doing a chest press increases range of motion in your deltoids and pecs, whether with barbells, dumbbells or machines, so there is no need to stretch beforehand. Just make sure to start with a small amount of weight to warm up and then add more to train.

"You probably don’t have to do extra stretching unless you’re a gymnast, a figure skater, or even a golfer who needs a great range of motion through that swing," Behm said.

Nor do you need to stretch first if you’re going for a leisurely run. Simply start with a slow jog to warm up and then increase the pace.

Don't do it if it hurts

After exercise, "light stretching is OK, as long as you don't reach a point where you're feeling pain," Behm said. Since your muscles will be warm by that point, overdoing it makes you more likely to injure yourself.

Foam rollers can help with muscle recovery and have been shown to increase range of motion as well as stretching.

Do some static stretching before sports

If you’re playing a sport, Behm said, static stretching beforehand helps reduce muscle and tendon injury.

"If you’re going to do an explosive movement, change of direction, agility, sprint, any of these explosive activities that involve your muscles and tendons," he said, "you’re going to be stronger if you do static stretching."

People can especially get in trouble when they go back to a sport they used to play, whether it's tennis, surfing or any sort of team activity.

Also, stretch both sides equally. Lacking flexibility on one side also can lead to injury.

Sounds simple. Why all the confusion? Different studies over the years have either encouraged or discouraged stretching before exercise. Behm says that partly because some studies didn't reflect real-life conditions, or were designed with elite athletes in mind, not regular people.

"If you’re Usain Bolt, it makes a difference," said Behm. Not so much for the rest of us.