Heating Values of Fuels

Heat Value of Fuel Lower heating value... 

Lower Heating Value of Anode Fuel(s) Produced Lower Heating Value of Fuel Used... 

These equations can be used to calculate the gross heating value or higher heating value of fuel whereby water formed during combustion is condensed and combustion gases are cooled to the initial fuel-air temperature. 

Btu. (British thermal unit). The quantity of heat required to raise the temperature of 1 pound of water 1 degree F (usually from 39 to 40F). This is the accepted unit for the comparison of heating values of fuels. For example, fuel gases range from 100 (low producer gas) to 3200 (pure butane) Btu/cu ft. The usual standard for a city gas is approximately 500 Btu/cu ft. 

Figure 3. Effect of wood moisture on heating value of fuel gas...

Coal-water slurry fuels. High-percent-solid slurries that are stable against settling, so they can be pumped, stored, handled, and burned much like heavy fuel oil. Coal-water fuels have about half the heating value of fuel oil, and because of their water content they burn cooler than pulverized coal, leading to lower production of nitrogen oxides. 

Calorimeters are devices that are commonly used to measure the heating value of fuels. For example, a Junkers flow calorimeter is used to measure the heating value of gaseous fuels. A bomb calorimeter, on the other hand, is used to measure the heating value of liquid or solid fuels, such as kerosene, heatii oil, or coal. Perform a search to obtain information about these two types of calorimeters. Write a brief report discussing the principles behind the operation of these calorimeters. 

Used to denote heating value of fuel gas the temperature and pressure should be stated usually 0 C and 1 atm in scientific work. The U.S. natural gas industry uses. slaridard conditions of 5D°F and 14T7 lb 5i ... 

In most cases, Qf ei is calculated based on the lower heating value of fuel. G,- is quantified in different units according to specifications in the marketplace, namely, Btu/h for fuel, Ib/h for steam, and kWh for power. Thus, specific FE factors can be developed as follows based on this general definition of fuel equivalent. Energy are required for making boiler feed water (BFW), condensate and cooling water. The FE factors for these utilities will be discussed in Chapter 3. 

Energy efficiency = total fuel cell system effidency/fiiel cell stack efficiency or lower heating value of hydrogenxO.95/lower heating value of fuel. 

The main application of such a calorimeter, the burning of substances inside a sealed, pressure-tight reaction vessel, was developed by Berthelot (1827-1907) into a standard procedure. Berthelot was the first to fill the reaction vessel with pure oxygen to excess pressure in order to obtain a quick, thorough combustion into definite reaction products. Calorimeters of this type were soon given the name bomb calorimeter because of the bomb-like appearance of the reaction vessel. Berthelot s numerous thermochemical measurements owe their success to this experimental procedure. Even today, this instrument remains a valuable aid for the determination of the standard enthalpies of formation of chemical compounds, of the combustion heats of foodstuffs, and of the gross heating values of fuels (Rossini, 1956 Skinner, 1962). 

In this example fuel A is a gas over which we have no control. Fuel B is a liquid and its flow may be manipulated to control the heater outlet temperature. The scheme includes a bias feedforward scheme so that changes in fuel A are immediately compensated for by adjusting the flow of fuel B. For this to succeed we have to convert the units of measure of fuel A to be consistent with those of fuel B. By including the heating value of fuel B (NHVi,) in Equation (10.5) we get... 

Methanol 5500 Based on lower heating value of fuel... 

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