​（选自The economist 2021年7月23日版）

A new, green air-conditioning system manages without nasty gases

一套新型、绿色无污染的空调系统

And has few moving parts at its core

它的核心几乎没有活动件

In a warming world it helps to stay cool. But doing so also threatens the planet. Most air conditioners use refrigerant gases called hydrofluorocarbons (HFCS). Though these do not deplete Earth’s ozone layer in the way the chlorofluorocarbons they replaced back in the mid-1990s did, they are hundreds of times more effective at trapping heat in the atmosphere than carbon dioxide is. Less-potent greenhouse gases are now being phased in as refrigerants, but these are not without problems of their own. They can be expensive, and some are inflammable.

在一个变暖的世界里，保持凉爽是有益的。但这样做也威胁到了地球。大多数空调使用氢氟碳化物（HFCS）的制冷剂。尽管这些气体不会像在90年代中期所用的含氯氟烃那样消耗地球的臭氧层，但它们在大气中捕获热量的效率比二氧化碳高数百倍。现在正在逐步采用效力较低的温室气体作为制冷剂，但这些气体并非没有自身的问题。它们可能很昂贵，而且有些还易燃。

Researchers have long sought ways to produce cooling systems that do without these troublesome gases, but none has come close to being a direct replacement. A small Irish company, however, now claims to have come up with an answer. Exergyn, based in Dublin, has developed a new type of air conditioning which not only avoids HFCS, but also has the benefit of having few moving parts at its core.

长期以来，研究人员一直寻找方 法生产没有这些麻烦的气体的冷却系统，但没有一个接近于直接替换品。但是，一家爱尔兰小公司现在声称已经找到了答案。总部位于都柏林的Exergyn公司已经开发出一种新型的空调，不仅避开了氢氟碳化物，而且其核心部分没有什么活动件。

Exergyn has been working secretly on the project for two years, in collaboration with a multinational company which it is not at liberty to name (though its partner is understood to be Carrier, a giant American manufacturer of heating and cooling equipment). The two firms are currently testing a 60kw version, which would have the capacity to cool 15-20 apartments. Exergyn has also begun talks with carmakers and aerospace companies about setting up similar joint-development projects. With cars, and some small aircraft, going electric, it is not just cooling the cabin that manufacturers are having to think about, but also cooling the batteries.

Exergyn已经秘密进行这个项目两年了，与一家跨国公司合作，但它不愿透露该公司名字（尽管据了解其合作伙伴是开利公司，一家美国热冷设备制造巨头）。这两家公司目前正在测试一个60千瓦的方案，它将有能力冷却15-20套公寓。Exergyn也已经开始与汽车制造商和航空航天公司就建立类似的联合开发项目进行谈判。随着汽车和一些小型飞行器走向电动化，制造商不得不考虑的不仅是冷却机舱，还包括冷却电池。

Squeeze me

Exergyn’s system uses a substance called a shape-memory alloy. smas, as they are known for short, are a group of materials with the unusual ability to return to a predetermined shape when heated. They are sometimes employed to make spectacle frames, and also in medical implants such as stents. Nitinol, the sma chosen by Exergyn, is a blend of nickel and titanium.

只要压一压

Exergyn的系统用的是“形状记忆合金”，一组材料，加热时具有恢复到预定形状的不寻常能力。它们偶尔被用来制造眼镜框，也被用于像支架的医用植入物。Exergyn公司选择的 “形状记忆合金”是镍和钛的混合物。

All smas release heat when deformed by compression, and then absorb it when the pressure is released and they return to their original shape. But Exergyn’s version of nitinol displays this property to a remarkable degree. For its prototype, the company produced 4cm-square plates of the alloy, each pierced by holes intended to permit the passage of a heat-carrying liquid or gaseous medium. A range of benign substances can be employed in that role. The firm’s engineers have tested water, brine, glycol and air, all with success.

所有“记忆合金”在被压缩变形时都会释放热量，而当压缩释放并恢复原状时又会吸收热量。但Exergyn公司的镍钛合金方案将这种特性发挥到极致。原型方面，该公司生产了4平方厘米的合金板，每块板上都有孔，以便导热的液体或气体介质通过。一系列良性物质都可以用于这一载热作用。该公司的工程师对水、盐水、乙二醇和空气进行了测试，都取得了成功。

To build a refrigerator involves assembling these plates into stacks of 50 or more. Four stacks make a unit. The stacks are compressed in turn by hydraulic rams or electric actuators, in a sequence that works a bit like a four-stroke engine, explains Kevin O’Toole, Exergyn’s managing director. At any given moment, one stack is being compressed, one released, one preheated and one pre-cooled.

造一台冰箱需要将这些板块组装成50个或更多为一堆的堆叠。四层堆叠构成一个单元。Exergyn公司的总经理K.O解释说，这些堆叠依次被液压油缸或电驱动装置依次压缩，这个工作顺序有点像四冲程发动机。在任何特定时刻，一个堆叠被压缩，一个被释放，一个被预热，一个被预冷。

To cool a room involves passing two circuits of the heat-carrying fluid through this four-stack unit. Fluid in a “cold” circuit first travels through a heat exchanger in the room to be cooled down, absorbing warmth as it does so (see diagram). It is then directed by a series of valves and pumps into whichever core is undergoing its relaxation stroke. The relaxing nitinol absorbs the heat burden and the fluid is pumped back to the heat exchanger for the cycle to be repeated.

要冷却一个房间，需要将两个回路的载热流体通过这个四堆叠装置。"冷"回路中的流体首先穿过 房间的热交换器得到冷却，在此过程中吸收热量（见图）。然后，再被一系列的阀门和泵导向正在进行放松冲程的任意一个核心。放松的镍钛合金吸收了热量，液体被泵送回热交换器，循环往复。

Heat thus accumulated is removed by the passage through the stack of fluid from the second, “hot”, circuit during the compression stroke. It is then dumped to the outside world via an external cooling unit. Using four stacks permits both the hot and the cold circuits to run continuously.

这样积累的热量在压缩冲程中通过第二"热"回路的液体堆叠而被移除。然后通过一个外部冷却装置将热量排到外界。使用四个堆叠可以使热回路和冷回路连续运行。

Tony Ennis, Exergyn’s chairman, reckons this method of cooling is not only more environmentally friendly than an hfc set-up, but will also be less expensive to buy and 30-40% cheaper to run. It will be lighter and smaller, too—an important requirement, not least because air-conditioning units often have to go up lift shafts to be installed. As for reliability, he says the prototype’s performance suggests the unit at its core could operate for more than 40 years without a problem.

Exergyn的董事长Tony Ennis认为，这种冷却方法不仅比氢氟碳化物装置更环保，而且购买成本更低，运行成本也会降低30-40%。它还将更轻更小，这也是一个重要的需求，尤其是因为空调设备经常需要上电梯井中去Exergyn的主席Tony Ennis认为，这种冷却方法不仅比氢氟碳化物装置更环保，而且购买成本更低，运行成本也会降低30-40%。它还将更轻更小，这也是一个重要的要求，尤其是因为空调设备经常需要上电梯井中安装。至于可靠性，他说，原型的性能表明，该设备的核心部分可以运行40年以上而不出现问题。

When Dr O’Toole, an expert in memory materials, co-founded Exergyn in 2012, his intention was to use nitinol to create a system that would generate electricity from low-grade waste heat. But the challenges presented by hfcs persuaded him that air conditioning would be a quicker way to bring the technology to market. Development is still continuing, but products may be only a few years away.

K.O博士， 记忆材料方面专家，2012年合创Exergyn公司时，他的意图是利用镍钛合金创建一个可以利用低级废热发电的系统。但氢氟化物带来的挑战说服了他，空调将是将该技术推向市场的更快方式。开发工作仍在继续，但产品可能只需要几年时间。

His thoughts of a generator have not diminished, though. Nor has interest in other products that could use the technology. These include refrigerators, and also heat pumps to extract warmth from the ground for domestic heating. When time allows, Dr O’Toole and his colleagues hope to get to work on those ideas, too.

不过，他对发电系统的念头并没有减少。对其他可以使用该技术的产品也没有兴趣。这其中包括冰箱和 从地下提取温气用于家庭供暖的热泵。时间允许的话，K.O和他的同事们也希望能在这些想法上下功夫。

This article appeared in the Science & technology section of the print edition under the headline "Cool ideas"