Not only do people need to stay cool, especially in record-breaking heat. Many machines, including cellphones, data centers, cars and airplanes, become less efficient and wear out more quickly in extreme heat. Machines also generate their own heat, which can make the warmer temperatures around them even hotter.
We are engineering researchers who study how machines manage heat and ways to effectively recover and reuse heat that would otherwise be wasted. Excessive heat affects machines in many ways.
No machine is perfectly efficient – all machines encounter some internal friction during operation. Machines lose some heat because of this friction, so the hotter it is outside, the hotter the machine will be.
Cellphones and similar devices with lithium ion batteries stop working even when used in weather above 95 °F (35 °C) – this is done to avoid overheating and increased stress on the electronics .
Cooling designs using innovative phase-change fluids can help keep machines cool, but in most cases the heat still eventually dissipates into the air. Therefore, the hotter the air, the more difficult it is to keep a machine cool enough to function efficiently.
Also, the closer the machines are, the more heat is lost to the surrounding area.
degradable material
High temperatures, either from the weather or from excess heat from machinery, can cause materials in machinery to fail. To understand this, consider what temperature means at the molecular level.
On a molecular scale, temperature is a measure of how much the molecules are vibrating. So the hotter it is, the more the molecules that make up materials from the air to the ground and machinery vibrate.
When a metal is heated, its molecules vibrate rapidly and the space between them moves apart. This causes expansion of the metal.
As the temperature increases and the molecules vibrate more, the average space between them increases, causing most materials to expand when heated. Roads are one place to see this – hot concrete expands, contracts and eventually cracks. This phenomenon can also happen with machinery, and thermal stress is just the beginning of the problem.
Roads crack due to heat because the higher temperature creates more space between the vibrating molecules, causing the material to expand and deform. Priscilla Zamboto/Moment via Getty Images
Travel delays and security risks
High temperatures can also change the way the oil in your car’s engine behaves, which can lead to possible engine failure. For example, the viscosity – or thickness – of typical car engine oil can change by a factor of three if a heat wave makes it 30 degrees F (16.7 degrees C) hotter than normal.
Liquids such as engine oil tend to thin out when heated, so if it gets too hot, the oil may not be thick enough to properly lubricate and protect engine parts from increased wear and tear.
In addition, a hot day will cause the air inside your tires to expand and increase tire pressure, which can increase wear and increase the risk of skidding.
Airplanes are also not designed to fly in extreme temperatures. As it gets warmer outside, the air expands and takes up more space than before, making it thinner or less dense. This decrease in air density reduces the amount of weight the aircraft can bear during flight, which can lead to significant travel delays or flight cancellations.
battery failure
In general, the electronics present in devices such as cellphones, personal computers, and data centers consist of a variety of materials that react differently to temperature changes. All of these materials are located next to each other in tight spaces. So as temperatures rise, different types of materials deform in different ways, potentially leading to premature wear and failure.
Lithium ion batteries in cars and general electronics degrade rapidly at high operating temperatures. This is because higher temperatures increase the rate of reactions within the battery, including corrosion reactions that deplete the lithium in the battery. This process reduces its storage capacity. Recent research suggests that electric vehicles can lose about 20% of their range when exposed to frequent 90-degree Fahrenheit weather.
Data centers, which are buildings filled with servers that store data, dissipate a significant amount of heat to keep their components cool. On very hot days, the fans must work harder to ensure that the chips do not overheat. In some cases, powerful fans are not enough to cool the electronics.
Data centers, which store massive amounts of data, can overheat and require massive cooling – which adds to their environmental footprint. AP Photo/Julie Carr Smith
To keep the centers cool, dry air from outside is often first sent through a damp pad. The water from the pad evaporates into the air and absorbs the heat, cooling the air. This technique, called evaporative cooling, is generally an economical and effective way to keep chips at proper operating temperatures.
However, evaporative cooling may require a considerable amount of water. This problem is problematic in areas where there is a shortage of water. Water for cooling can exacerbate the already intensive resource footprint associated with data centers.
struggling air conditioner
Air conditioners struggle to work effectively as the heat outside rises—right when they’re needed most. On hot days, air conditioner compressors have to work harder to send heat out of homes, resulting in a disproportionate increase in power consumption and overall power demand.
Heat waves can put a strain on air conditioners, which are already working hard to eliminate heat. AP Photo/Paul White
For example, in Texas, each increase of 1.8 °F (1 °C) increases electricity demand by about 4%.
Hot countries experience an astonishing 50% increase in electricity demand during the summer, leading to high greenhouse gas emissions as well as a serious risk of power shortages or blackouts.
How to prevent heat damage
Heat waves and warming temperatures around the world create significant short- and long-term problems for people and machines. Fortunately, there are some things you can do to minimize the damage.
First, make sure your machines are kept in an air-conditioned, well-insulated location or out of direct sunlight.
Second, consider using high-energy appliances like air conditioners or charging your electric vehicle during off-peak hours when fewer people are using electricity. This can help avoid local power outages.
reusing heat
Scientists and engineers are developing ways to harness and recycle the massive amounts of heat emitted from machines. A simple example is using waste heat from data centers to heat water.
Waste heat can also drive other types of air conditioning systems, such as absorption chillers, which can actually use heat as energy to support a cooler through a series of chemical and heat-transfer processes. .
In either case, the energy needed to heat or cool something comes from heat that would otherwise be wasted. In fact, waste heat from power plants could hypothetically support 27% of residential air conditioning needs, reducing overall energy consumption and carbon emissions.
Extreme heat can affect every aspect of modern life, and heat waves will not go away in the coming years. However, opportunities exist to harness the extreme heat and put it to work for us.
Source: theconversation.com
