And I feel like I've been here before.
Yes I feel like I've been here before.

("Deja Vu," by David Crosby of CSNY, 1970)

PTOA Segment 57: WHERE DO WE GO FROM HERE (#2)?

The very first PTOA Focus Study segments featured the Process Variable Temperature.

The second PTOA Focus Study was all about Temperature-Changing Process Industry Equipment.

The progression to the announced PTOA Focus Study on Heat Transfer was logical and the expected outcomes of the focus study were predicted to be:

• Clarification of expressions such as "the hot process stream indirectly transfers heat into the cold process stream" and "the fin fan tubes are finned to enhance heat transfer. " These two frequently used phrases (and several more like them) were stated as fact but never explained in the Temperature-Changing Process Industry Equipment Focus Study.
• PTOA Readers and Students that understand the definitions and parameters which define each type of  heat transfer will become more effective Process Operators with respect to optimizing the operation of temperature-changing equipment.

PTOA Readers and Students learned that Heat Transfer is one of the "Transport Phenomena" that human beings have defined by mathematical expressions in an effort to better understand the movement of heat, fluids, and electricity.

These additional outcomes of the PTOA Heat Transfer Focus Study Area were listed:

• The PTOA Heat Transfer Focus Study Area will clarify the difference between "temperature" and "heat."
• The upcoming PTOA Heat Transfer Focus Study Area will introduce and explain the concepts of heat transfer via Radiation, Conduction, and Convection.
• The PTOA Heat Transfer Focus Study Area will introduce how the three types of heat transfer are used in the design of temperature-changing process industry equipment and the impediments that inhibit heat transfer.

 

PTOA Segment 58: CAN'T LIVE WITHOUT IT

Using an example of an unattended cup of hot coffee cooling down to ambient temperature over a period of time, this PTOA Segment defined "Heat" and "Heat Transfer."

PTOA Readers and Students learned that:

• Heat is a form of flowing thermal energy that is automatically created whenever and wherever two  unequal temperatures are present.
• The difference between the hot and cold temperatures is called the Temperature Differential, aka Delta T.
• The Temperature Differential is the driving force for heat transfer; the greater the Delta T, the more heat will be transferred over a given time.
• Heat will ALWAYS flow from the hotter area to the colder area until a temperature equilibrium is reached. When the temperature equilibrium is attained, heat ceases to exist yet the new, equalized temperature of the environment can be measured.
• A "Heat Sink" exists when the equalized temperature is the same as the cold temperature of the Temperature Differential. When the equalized temperature is the same as the cold temperature, the amount of substance that is cold is much greater than the amount of substance that is hot. Ergo, the heat that was transferred into the cold area was insufficient to raise the temperature.

 

PTOA Segment 59: I'M SO HOT 4 U & YUR SO COLD

The situations Fred the Stickman found himself in at a bar and in the ocean challenged PTOA Readers and Students to mentally process the differences between "Temperature" and "Heat."

Prior to rationalizing the fate of Fred the Stickman, PTOA Readers and Students had learned these differences between "Temperature" and "Heat":

• "Temperature" is measured in degrees Fahrenheit, degrees Celsius/Centigrade. "Heat" is measured in BTUs (British Thermal Units) and Joules (the international scientific unit for measuring thermal energy).
• A link to a BTU Calculator was included in this PTOA Segment to help PTOA Readers and Students begin to acquire a sense of magnitude for a BTU or Joule.
• PTOA Readers and Students learned that the Rate of Heat Transfer (aka Heat Transfer Rate) is a more helpful way to conceptualize heat because heat is always in motion and a heat rate establishes how much heat is transferred over a unit of time.
• PTOA Readers and Students learned that the phrase "Rate" means "divided by a specified amount of time" and applies to anything ...  not just heat transfer. To reiterate, whenever the word "rate" is verbally said that means to put units of time in a denominator when the rate is expressed in a written format.
• An alternate way of verbally expressing the concept of Rate is to say phrases like "per hour" or "per minute."
• Once again it was reiterated that Temperature can exist without Heat, but Heat requires two temperatures to exist and one of those temperatures must be hotter than the other.

 

PTOA Segment 60: I AM THE WALRUS

This PTOA Segment started the process of demolishing math anxiety related to the upcoming mathematical expressions that will be used to define heat transfer.

PTOA Readers and Students learned that any mathematical expression is just mankind's attempt to model the relationship between "Mass", "Length or Distance"and "Time."

Ergo, every weird, long-named concept that PTOA Readers and Students have been exposed to throughout their lives can be broken down into a relationship between mass, length/distance, and time.*

PTOA Readers and Students learned that the word "Mass" simply refers to stuff made of the elements found on earth which are usually bonded together.  An example of two hydrocarbons showed how a small change in chemical structure can cause significant changes in the chemical and physical properties of stuff.

Mass is measured in pounds and grams or kilograms in the SI system.

Length is measured in inches and feet or millimeters, centimeters, meters and kilometers in the SI system.

The term Distance is typically reserved for long lengths like miles kilometers.

Time is measured in milliseconds, seconds, hours, days,months, years, decade, centuries, millenia and up to ages and light years.

*A postscript at the bottom of this PTOA Segment demonstrated how the factor-labelling process incorporates a string of conversion factors to reduce commonly used process industry terms into the three basic components of mass, length/distance, and time.

 

PTOA Segment 61: I AM STILL THE WALRUS

The upcoming PTOA Segments defined the three types of heat transfer with mathematical expressions.

The purpose of this PTOA Segment was to prepare PTOA Readers and Students to accept man-made definitions of concepts that are expressed by mathematical relationships.

The familiar man-made definition for constant "Velocity" (aka "Speed") was scrutinized and found to be mathematically expressed by a well known relationship between Distance and Time.

V (Velocity) = d (distance) / t (time)

Human beings defined "velocity" and "speed" as a convenience for everybody to have a common understanding of how far something moved over a period of time.

PTOA Readers and Students were encouraged to extend this simple example of defining velocity to the upcoming definitions for heat transfer which would likewise be described by mathematical relationships.

PTOA Readers and Students were reminded that the parameters used in the upcoming heat transfer definitions simply represent the best guess human beings have made to conveniently define heat transfer so that everybody has a common understanding of the concepts.

PTOA Readers and Students were instructed to evaluate each parameter in the mathematical expression to fully realize its impact on the defined concept.

For example, a complete understanding of  "velocity/speed" requires asking oneself how would "velocity" change when the distance is increased/decreased but the time remains the same? Likewise, how would  "velocity" change when the time is increased/decreased but the distance remains the same?

©2015 PTOA Segment 00080
PTOA Deja Vu Review 3-1

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