Air conditioner
đˇď¸ TĂ o lao
A: What is a heat pump?
B: A heat pump is a technology, where for every bit of energy you put in, you get three to five times as much heat out
A: What wizardry is that?
B: Heat pumps have been hailed as a climate-friendly heating solution to traditional heaters, most of which operate by burning fossil fuels. So much so that in 2021, heating buildings were responsible for about 10% of global energy-related CO2 emissions
A: How does the heat pump work?
B: Heat pumps reduce emissions in two ways. First, they run on electricity, meaning less fossil fuel use as grids make the switch to renewable energy. Second, theyâre more efficient than their counterparts, using less energy to produce the same amount of heat
A: How much is it efficient?
B: Where a typical oil or gas boiler is at best, about 90% efficient, some heat pumps can achieve 500% efficiency. Heat pumps rely on the same technology as air conditioners. In fact, they often double as air conditioners, heating your home in the winter and cooling it in the summer
A: How can it achieve that efficiency?
B: Air conditioners take heat from your home and move it outside. To do so, they harness the second law of thermodynamics, thatâs the one that says that heat will always move from a hotter object to a colder one. When you turn on your ac, a fan blows the hot air from your home over coils, containing a substance called a refrigerant. A refrigerantâs molecules turn to gas at relatively low temperatures. So as it collects thermal energy from the hot air in your home, it boils. Then it passes into a compressor, which pushes the gas molecules closer together, heating them up even more. Now that gas is hot, way hotter than the outside air. So when a fan blows over the refrigerant, thermo energy transfers to the comparatively cold air outside. As the refrigerant releases heat, it starts to liquefy. It goes through an expansion valve which decreases the pressure, causing it to get even colder.
A: Is that all?
B: Not yet. Now itâs ready to pick up more heat from your house and start the cycle again.
A: How do heat pumps work in the winter to keep my house warm?
B: In winter, heat pumps work exactly the same way, but this time they pick up heat from outside and move it into your home. Of course, itâs sometimes freezing outside when you want to use the heater. But the air doesnât need to be warm, it just needs to be warmer than the refrigerant to transfer its heat
A: This technology sounds great
B: Yes, but it has some drawbacks
A: What are they?
B: First, refrigerants can be potent greenhouse gases. While in use, the refrigerants stay contained in a closed loop. But when heat pumps, a/cs, and refrigerators are improperly installed or thrown into landfills, the refrigerant can leak out. So scientists are trying to create new refrigerants that are better for the environment. Also, the colder it is outside, the less efficient an air-to-air heat pump will be. Nevertheless, over half the buildings in icy Norway use heat pumps. Some people there have opted for pumps that draw heat from under the ground, which stay more consistently warm rather than heat from the air
A: Is that all?
B: Finally, there is a cost. In the US, installing a small heat pump usually costs several thousand dollars though some people need more powerful systems, depending on the size of their home or the temperature in winter. Often, theyâre only a little more expensive than installing a new a/c system, and a heat pump can save money on utilities in the long run. But replacing a working system requires an upfront investment that a lot of people just donât have. Still, as the risks of climate change loom, many countries are offering subsidies to help with the costs. Some cities are creatively harnessing seas, sewage, and data centers as heat sources. They also use heat pumps in manufacturing and even create giant pumps for entire districts
A: Are heat pumps actually breaking the first-law thermodynamics?
B: Of course not. Theyâre just not using their electricity to make heat. Theyâre using it to power their compressors and spin the fans. They get the extra energy for free from heat in the air or underground. Which is how, by putting in 1 unit of energy, you get 3 to 5 units of heat up. Seem like magic but itâs just physics