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Portable air conditioners are small machines on wheels that turn hot, stale, and humid air into cool, dry, and pleasant air. To do this, they rely on the refrigeration cycle. You don’t need to delve into this cycle to understand it and appreciate its awesomeness.
Any air conditioner (and your refrigerator) relies on the incredible process of pumping pressurized chemicals (called refrigerants) through loops of metal pipes to remove heat energy where it’s not needed. At one end of the loop, the refrigerant is compressed into a liquid, and at the other end it expands into vapor. The purpose of this machine is not just the endless switching of the refrigerant between liquid and vapor. There is no benefit. The purpose of switching between these two states is to remove heat energy from the air at one end and concentrate it at the other end. In fact, this is the creation of two microclimates: hot and cold. The microclimate that forms on the cold coil (called the evaporator) is the air that is expelled into the room. The microclimate created by the coil (condenser) is the air thrown out. As is your refrigerator. Heat moves from inside the box to the outside. But in the case of an air conditioner, your house or apartment is a box for heat removal.
In the cold part of the piping circuit, the refrigerant changes from liquid to vapor. We need to stop here because something amazing has happened. The refrigerant boils in the cold circuit. Refrigerants have amazing properties, among them an affinity for heat, even the warm air in the room is enough to boil the refrigerant. After boiling, the refrigerant changes from a mixture of liquid and vapor to full vapor.
This vapor is sucked into the compressor, which uses a piston to compress the refrigerant to the smallest possible volume. The steam is squeezed out into the liquid, and the thermal energy concentrated in it is removed to the wall of the metal pipe. The fan blows air through the heat pipe, the air is heated and then blown out.
There you can see the mechanical miracle of cooling, as happens in portable air conditioners.
Air conditioners not only cool the air, but also dry it. Suspension of liquid moisture in the air as vapor requires a lot of thermal energy. The heat energy used to weigh moisture cannot be measured with a thermometer, it is called latent heat. Removing steam (and latent heat) is important because dry air makes you feel more comfortable than humid air. Dry air makes it easier for your body to evaporate water, which is your natural cooling mechanism.
Mobile air conditioners (like all air conditioners) condense moisture from the air. The steam contacts the cold evaporator coil, condenses on it, drips and flows into the collection pan. Water that condenses from the air is called condensate and can be treated in a number of ways. You can remove the tray and pour. Alternatively, the unit may use a fan to supply moisture to the hot part of the coil (the condenser), where the moisture is converted back into steam and expelled through the exhaust. In rare cases, when a portable air conditioner is located near a floor drain, condensation may flow through the pipes. In other cases, the piping from the air conditioner drain pan may lead to a condensate pump that will pump water to a sewer outside or elsewhere. Some portable air conditioners have a built-in condensate pump.
Some portable air conditioners have one air hose, while others have two. In both cases, the device is shipped with the hose disconnected. You connect one end of the hose to the appliance and the other end to the window bracket. In any case, no tools are required, you just screw the hose on like a big plastic bolt. Single hose units suck in cooled room air and use it to cool the hot condenser coil. They blow hot air outside. Dual hose models are a bit more complex and can be more expensive than some single hose models. One hose draws in outside air and uses it to cool the hot condenser coil, then exhausts the heated air through a second hose. Some of these dual hose devices are configured as a hose within a hose so only one hose is visible.
It is logical to ask which method is better. There is no simple answer. The single hose model draws in room air while the condenser cools, thus creating a small pressure drop in the house. This negative pressure allows the living space to draw in warm air from outside to balance the pressure.
To solve the pressure drop problem, manufacturers have invented a twin hose design that uses warm outside air to lower the condenser temperature. The device does not atomize the air in the room, so the air pressure in the house remains more constant. However, this is not a perfect solution because you now have two large warm hoses in your living room that you are trying to cool down. These warm hoses dissipate heat into the living space, reducing equipment efficiency. Whether you buy a unit with one or two hoses, choose the one with the highest seasonally adjusted cooling capacity (SACC) you can afford. This state energy efficiency rating is mandatory for portable air conditioners in 2017.