HHV system of calorific determination of energy contents is based on what could be (in layman's terms...) considered the highest possible point that an exacting amount of fuel combusted (not useful in my research lines) with the proper oxidizer content will make. Kinda like a slingshot:
The distance of stretch will be the same each time on the rubber band, but the size and weight of the rock to be flung is the variable. Other variables are the age of the rubber and the remaining amounts of elasticity in the rubber when stretched, but we will omit those variables for the sake of argument and to keep it simple. Now the direction of travel is exactly vertical in relation to the surface of the earth, and perpendicular to the 'level plane' at that spot on this sphere (yeah get level on a beach ball will ya!) we call Earth. So we intend to sling a rock straight UP. There is NO WIND, and gravity is constant (representing the 25 degrees C). The only variables to contend with now are the following: Weight and shape. Let's assume that SHAPE will be the required oxidizer because the shape is what determines the aerodynamic drag on the rock. The weight will be the number of hydrogen atoms and carbon atoms represented in this layman's term of a HHV value system of measurement.
So the rock is launched after much hashing over details and the person whom is holding the slingshot has now currently BLUE FINGERS that are in severe pain! The rock travels upward X distance before returning to earth. This X Distance answer is and can be repeatedly made using the exact same rock in the exact same scenario. This X Distance is determined entirely by the drag (oxidizer requirement) and the weight (Hydrogen and Carbon Content).
So after much ado, we now only achieve a system of measuring the farthest reaches of the fuel in a set environment of conditions.
(Mixing Chemistry and Physics into laymans terms can be fun isn't it?)
Now the LHV is a tricky part....
We now COMBINE the HHV to get us PAST a specified X Distance with the vertical rock launch and have replaced the poor human with a machine that doesn't tire from the long winded talk whilst holding a rock in a slingshot pulled taut for extended periods of time causing sore muscles and a bad attitude toward the person talking (likely resulting with the rocks being launched at guest speaker or property of, like car windows....).
(I am trying to be funny here too...)
So with the LHV system not only do we get PAST a SPECIFIED POINT by keeping the constants of the HHV system, but now, we add a twist, like changing the rules in the middle of the game. Here's the twist:
So we put the cutoff point at 15 feet elevation. We ASSUME using the LHV process that anything below 15 feet is UNUSABLE ENERGY (I now refer you to the Aerothermal Engine....and note that I am using temperatures between -100 and + 100 F to run it) because this 15 foot mark is referenced to represent the 150 degree mark. They ASSUME that ANYTHING below 150 degrees C is NOT USABLE ENERGY in terms of relative heat either through enthalpy or entropy, and so our cutoff is 15 feet above the level plane of the ground.
We now launch Rock A. Rock A went from an elevation of 5 feet (starting point) to a total height of 160 feet and back to 5 feet (ending point must be same as starting point) . So Rock A has an HHV of 155.
Now.... Rock A when applied to the LHV end of the deal, is rated at an LHV of 145. This is because we cutoff at 15 feet from origination point to ending point. We cannot get something from nothing per say, so this arbitrary pick make it work out this way.
Rock B undergoes the same brutal abuse and consistently gives an HHV score of 200, but only receives an LHV score of 185.
Rock C same thing, but gets 105 HHV and 90 LHV.
So we have the HHV system in which the starting point and ending point are the SAME (which is good science) but ignores the Enthalpy and Entropy latent heat LOSSES of the material of the canister for testing (which is again another variable that SHOULD be calibrated to adjust for).
The LHV system the starting and ending points are different (bad science in my opinion only confusing, and based entirely on bad logic), but ignores the Latent heat, but accepts absorbed heat losses (partial picture here....) of the containment test vessel!!!
Both are a sour deal and will only confuse a person in the end. Too many variables, too much assumption, and an arbitrary pick of ASSUMING that any amount of heat that is below 150 Degrees C is USELESS and cannot be used in any possible or useful manner is not taken lightly by the poor guy who is suffering from hypothermia!
So If I had to pick a process, the HHV comes close, BUT I would have to calculate out ALL the variables to make it TRUELY a scientific method to be utilized for any REAL DATA COMPARISONS, so even the HHV system isn't proper. Let's do it right, and get the ENTIRE PICTURE.
AlaskaStarStatistics: Posted by AlaskaStar — Sat Oct 11, 2008 4:46 am
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