Fat in the body is created by the body. It is not simply taking fat that you eat and putting it someplace. As soon as you eat anything (sugar, oil, fat, etc) the substance is broken down by your body into the smallest units. In the case of all of these, the unit is glucose, or something similar like glycogen. If the body has too much glucose, then it will convert it to fat.
The whole process is quite complicated but the basic idea is that once it is in your body a substance is converted by your body to smaller simpler molecules. These are then used to create larger molecules of various kinds. In the case of energy, we obtain energy from eating sugars and fats, the basic unit of which is glucose. This has nothing to do with freezing, because the temperature in your body is always about 36 degrees C. Fat is accumulated when more energy containing foods such as fats, oils and sugars are eaten than the amount of energy expended by exercise to burn them up.