Energy in refrigeration

Any one or combination of several chanes may take place when heat, which is a form of energy, is added to a material or a substance:
1. A rise in temperatur may occur
2. The substance may melt or vaporize
3. The substance may change size or color
4. The substance may be caused to exert a greater pressure
When the heat energy is removed, the reverse of these effects takes place.

Sensible Heat: refers to that heat which produces a temperature rise as it is added to a material. The temperature rises because the molecules absorb heat energy and move faster when heated. As sensible heat is removed, the temperature drops. The molecules are said to move slower when there is a loss of heat energy.
Latent Heat of Vaporization: this heat-carrying ability of the refrigerant is called the "refrigerating effect". The refrigerating effect is found by determining the amount of heat that one pound of the refrigerant is capable of absorbing as it passes through the evaporator. The refrigerant, as it boils in the evaporator and changes state from a liquid to a gas, must absorb its "heat of evaporizaion". Thus, the refrigerant vapor (gas) contains a great deal more heat energy than does the refrigerant in liquid form.
This in true even through the temperature of both the vapor and the liquid is the same.
This mount of heat is the "latent heat of vaporization". It differs in the amount per pound for each refrigerant. The "net refrigerating effect" is only a little less than the heat of vaporization. This loss is represented by:
1. the emaount of heat required to precool the liquid refrigerant, and
2. the heat added to the gaseous refrigerant when it is compressed.

Heat of Condensation : the refrigerant which is a gas at the condenser is changed back into the liquid state by the removal (rejection)of heat. The emount of heat to be removed per pound of refrigerant is called the "heat of condensation". The heat of condensation is equal to the heat of evaporation at a given temperature.

Latent heat of fusion : another kind of latent heat which has only an indirect relation to refrigeration is "latent heat of fusion" Because mechanical refrigeration system followed refrigeration where natural ice was used, it is understandable why the capacity of a cooling ability compares with that of ice.

The standard of measurement which is used is known as the "cooling effect". The cooling effect refers to the effect produced by the melting of one ton of ice as it absorbs heat energy over a 24 hour period. A machine with capacity to produce this same cooling effect is classed as a "one ton machine". Thir does not mean that the machine can produce one ton of ice in a similar period.

The ability to produce ice is referred to as "ice making capacity". A refrigeration system may produce ice by removing latent heat to bring about a required change of state. However, there must first be the removal of a large amount of sensible heat in order to cool water down to the temperature at which it freezes (solidifies).
The water freezes as a result of realising the potential energy of the molecules. Thus, one pound of ice has less energy than one pound of water even though they are both at the same temperature. This difference in energy is the "heat of fusion" or the "heat of solidification".

Latent heat of fusion means the amount of heat which must be added to a pound of material to cause it to melt (change from a solid to a liquid state without any change of temperature). The "latent heat of solidification" is just the reverse and refers to the liquid to become a solid.
In review, it may be said that the heat energy is a combination of the kinetic energy and the potential energy continuous motion.