There are many situations where someone only needs a small portable air conditioner unit. Perhaps it is only needed for a few weeks of each year, or simply to supplement central air conditioning. It is much easier to use than a ductless split air conditioner as it requires virtually no installation. These type of units simply sit on the floor and then plug in to an electrical socket. They do need to be vented, thereby usually need to be installed close to a window.
Their ability to adequately cool down a room depends largely on their size. Naturally, the larger units will be able to cool down a larger area while the smaller units are usually sufficient for a smaller room such as a bedroom. Most of these portable units also have a built-in dehumidifier and some additionally are able to purify the air. In order to circulate the cool air they usually have built-in fans. Most also need to be vented, this is very easily accomplished and a window kit usually comes with the unit when you buy it. Once you have the kit it is very easy to ensure that the unit is vented properly.
There are many very good brands of these on the market. Some cost more than others and the prices are not always only dependent on the size of the unit but also what capabilities they have. DeLonghi makes very good portable air conditioners; they are known for being very dependable and they come with a five-year warranty. Other good brands to check into are Sunpentown, Soleus, Sharp, and Danby. If you are looking for something that is fairly cheap you may want to check out the selection offered by American comfort. They are readily available online for very decent prices.
When buying a portable air conditioner unit, you should look for something that is large enough to cool down the room it is needed for, one that is easy to install and run, and one that has all of the options you need.