This clothesdryer has the clothes tumbler inside an airtight chamber, and has a vacuum pump, like the earlier version, but no heat pump. Instead, it has a heat exchanger.
During the first phase of drying, the following things are done simultaneously: 1) air / steam is continuously pumped / compressed
out of the clothes chamber, and sends this gas over the outside of the heat exchanger. 2) air / steam is circulated by a fan through the inside of the heat exchanger. The reduction in air pressure reduces the boiling point of water to below the temperature of the ambient air... the gas being expelled from the machine warms the gas remaining in the machine, keeping the temperature from dropping excessivly due to the absorbtion of heat by the liquid water in the clothing.
After 100% of the liquid water has been changed to steam, it needs to be removed... thus, in the second phase, air is allowed in (through a gas expansion motor, to reduce the energy costs of this phase), passed through the inside of the heat exchanger, and blown into the clothing.
At the same time, air/steam is still being pumped out. However, fresh air is let in slightly faster than wet air/steam is removed... so that the pressure gradually returns to atmospheric pressure at the same time as the steam is replaced by air.
This design now closely resembles that of a "mechanical steam compression dryer"... but at lower pressure and lower temperature.