HEAT

So, Temperature can be defined as how fast the dance is going; the Tempo.

• LATENT HEAT: The additional heat required to change the state of a substance from solid to liquid at its melting point, or from liquid to gas at its boiling point, after the temperature of the substance has reached either of these points. This is often referred to as a substance's "Change of State" energy.

Ops, this quality doesn't equate directly to the thermometer !

So, Temperature Does Not tell you How Much Heat there is !

At any given temperature, a cubic centimeter of iron has more kinetic heat energy, than a cubic centimeter of Aluminum.

Different materials can hold different amounts of heat. The amount of heat that a material can hold is Specific for that material. We refer to it in the reference books as .... Yup .... " Specific Heat ".

Specific Heat is largely the result of Density. The number of dancers on the dance floor. You all know how Hot, a crowded dance floor can be.

When we want to know " How Much Heat ", we have, or need, we must consider the temperature in relation to " Specific Heat ", and weather-or-not there is any " Change of State Energy " involved.

It is possible to "Pump Heat" from one place to another, even if the destination is at a higher energy level than the source. This technology is derived from the Science of Thermodynamics.

Lucky for us, Mother Nature has established a consistent set of rules or laws that remain constant throughout the ages. Various people have discovered these "Laws" through observation and experimentation, and often these relationships are named after them.

"The volume of a gas varies inversely as the pressure, provided the temperature remains constant."

This means that, if a certain quantity of gas has its pressure doubled, the volume becomes one half of the original. Conversely, if the volume becomes doubled, the gas has its pressure reduced by one half.

This law is based on absolute temperature and absolute pressure.

Absolute   Zero =   – 460 degrees Fahrenheit or – 273 degrees Centigrade.

Absolute Pressure is based on the pressure of outer–space being equal to 0. The average "absolute pressure" at sea level is equal to 14.7 pounds per square inch.

The total pressure of a mixture of gases, is the sum of the partial pressures of each of the gases in the mixture. The law further explains that each gas behaves as if it occupies the space alone. Also, according to this law, the temperature at which a liquid boils, or at which a gas condenses in an enclosed space corresponds to the partial pressure exerted by that gas.

Let me repeat! Each gas behaves as if, it were the ONLY gas in the room. This is a Very Important Point, as we will quickly experience, as we study how Water moves about in your "Tortoise Shell".

Substances always exert a pressure upon the surfaces supporting them. Therefore, the Force of our Planet's Atmosphere, is the result of accumulated partial pressures.

Charles' Law

At a constant pressure, the volume of a gas varies directly as the absolute temperature, and at a constant volume, the pressure varies directly as the absolute temperature.

The Math for Perfect Gases

P_A = absolute pressure

T_A = absolute temperature

V_SI = volume in square inches

P X V = a constant number

P_a X V_a = P_b X V_b ( at a constant temperature )

P₁ X T₂ = P₂ X T₁ ( at a constant volume )

V₁ X T₂ = V₂ X T₁ ( at constant pressure )

Now that we have the basics, we can learn how to move heat around.

The Heat Pump

Elements of simple compression system.

143K audio *.wma file

Elements of simple absorption system.

The absorption system makes use of the high affinity that water has for ammonia vapor. One cubic foot of water can absorb as much as 800 cubic feet of ammonia gas at 39 degrees F.

The action of this system depends also, on Dalton's Law which states that two gases within a closed container exert a total pressure equal to the sum of the individual (partial) pressure of the gases. Also, according to this law, the temperature at which a liquid boils, or at which a gas condenses in an enclosed space corresponds to the partial pressure exerted by that gas.

The ammonia / water absorption refrigeration system can be used with almost any source of heat which produces a temperature of 300 degrees F. or more.

The operation of the ammonia / water heat pump depends on three different cycles which take place simultaneously and are repeated continuously:

• The Ammonia Cycle
• The Hydrogen Cycle
• The Ammonia / Water Cycle

Elementary Operation of the Intermittent Absorption Cycle.

Elementary solid absorbent cycle

Various solids also can be used to absorb and release a refrigerant.

The Faraday Cycle

The air-cooled Servel refrigeration cycle

The complete Servel Design

The Electrolux air-cooled cycle

The 1935 model Electrolux air cooled unit has a charge pressure of 380 lb./sq. in.; 8 cubic feet of hydrogen; 1 pint liquid ammonia and 2 pints of water.

The Gibson shelf and condensing unit

The Gibson unit used sulphur dioxide as a refrigerant.
( Very, Very Toxic ! )

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References

Modern Refrigeration and Air Conditioning
Andrew D. Althouse and Carl H. Turnquest
The Goodheart - Willcox Co. Inc. Chicago, 1956

Modern Electric and Gas Refrigeration
Andrew D. Althouse and Carl H. Turnquest
The Goodheart - Willcox Co. Inc. Chicago, 1933

Household Electric Refrigeration
Wostrel and Praity
Mcgraw - Hill, 1948

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