Green Builder Media CEO Sara Gutterman explains how Arctic cold-climate heat pumps work, walking through the refrigeration cycle that lets them capture usable energy from outdoor air as cold as -25 degrees Celsius.
00:00:02:20 - 00:00:36:20
Sara Gutterman: Arctic cold climate. Heat pumps are specifically designed to work in temperatures below freezing as low as -25°C. Few people realize that the air below freezing has nearly the same amount of relative energy as it does above freezing. But understanding that concept, you can really understand how a cold climate heat pump works. When you look at these cold climate heat pumps, think about the fact that warm air has more energy and more molecules colliding compared to cold air.
00:00:36:20 - 00:01:05:08
Sara Gutterman: And will naturally migrate to cold air until an equilibrium is established. So using a colder liquid such as Freon, which does not freeze until about -50 degrees. These Arctic cold climate heat pumps can use warmer air to transfer its energy to the colder Freon inside the heat. Different substances have different boiling points, and this can be changed by adding or removing pressure.
00:01:05:10 - 00:01:46:08
Sara Gutterman: In cold climate heat pumps, the refrigeration cycle uses freon, which transitions from a liquid to a gas at a much lower or colder temperature compared to water, and by adjusting the pressure of Freon, these cool climate heat pumps can manipulate. When this phase change occurs so these heat pumps use a refrigerant called R4 ten A, which is more suitable for storing energy in colder conditions, and the temperature of this refrigerant can be made to boil at as cold as -50°C by reducing the pressure inside of the heat pump.
00:01:46:10 - 00:02:21:09
Sara Gutterman: So the cold -50 freon passes through the heat exchanger and the warmer energy of the outside air. Even if it's a -25°C, naturally moves from the cold Freon across the heat exchanger. This causes the freon to absorb the energy, and it heats up the freon so that it evaporates or boils and turns into a gas. And the freon gas is then brought to a compressor where it's compressed, causing it to greatly increase in temperature as its volume decreases.
00:02:21:11 - 00:02:48:11
Sara Gutterman: This hot gas is then transferred over another heat exchanger, in which the other side is colder. Using water and glycol and the energy again transitions from hot to cold and heats as water and glycol loop. As that enters into the home, the refrigerant loses its heat, causing it to cool back to a liquid, and the cycle begins again.
00:02:48:13 - 00:02:58:07
Sara Gutterman: So that's the basics of the refrigeration cycle in a cold climate. Heat pump. A heat pump is simply a means of transferring energy from one source to another.