Showing posts from November, 2013

Cryogenics

The term cryogenics is used to de­scribe the use of, or the creating of, temperatures in the range of -250 F.…

Entropy

Entropy is the heat available measured in Btu per pound degree change for a substance. Entropy calculations a…

Enthalpy

Enthalpy, for practical purposes, is the total amount of heat in one pound of a sub­stance calculated from an…

Critical Pressure

The critical pressure of a substance is the pressure at or above which the sub­stance will remain a liquid an…

Critical Temperature

The critical temperature of a substance is the maximum temperature at which the substance may be liquefied, r…

Dry Ice

Solid carbon dioxide (CO2) is some­times used for refrigeration. It is a white crystalline substance formed b…

Brine and "Sweet Water"

Salt (NaCI) or calcium chloride (CaCI) added to water raises the temperature at which water will boil and low…

Ice and Salt Mixtures

Refrigerating by ice will not provide refrigeration temperatures below 32 F. Therefore, to obtain lower tempe…

Control of Heat Flow

The flow of heat by each method can be controlled. That is, the transfer of heat by each of the methods can b…

Convection

Convection is the moving of heat from one place to another by heating a substance (fluid) such as air or wate…

Conduction

Conduction is the flow of heat from one part of a substance to another part of the same substance, or from on…

Radiation

The earth receives its heat from the sun by radiation. The heat rays from the sun are turned into heat as the…

Heat Transfer

There are three methods by which heat may be transferred from one body to another. These methods are radiatio…

Elementary Refrigerator

In Fig. 1-19, refrigerant cylinder A is shown with the valve closed. The pressure, the temperature (inside an…

The Function of a Refrigerator

The basic purpose of a refrigeration System is to remove heat from one space and deposit it into another spac…

Energy Conversion Units

In refrigeration work, three common forms of energy must be considered: me­chanical, electrical and heat. The…

Heat of Compression

As a gas is compressed its temperature is raised. The gaseous refrigerant return­ing to the compressor from t…

Ambient Temperature

The term ambient temperature is used to denote the temperature of the air sur­rounding a motor, a control mec…

"Ton" of Refrigeration Effect

The common unit used to measure the refrigeration effect is the "ton." This is the amount of heat a…

Refrigeration Effect of Ice

Ice is still an important item in the refrigeration industry. As stated before, ice changes to water at 32 F.…

Application of Latent Heat

In refrigeration work, the physics of latent heat is of special importance be­cause it is this heat which pro…

Latent Heat ( Refrigeration )

A physical phenomenon of all pure substances is their ability to change their state, such as solid to liquid…

Load More
That is All