Science universe: Physics articles

Combustion Several of the devices we have considered in our study of thermodynamics have involved heat transfer from an external source. Most often, the source of the energy supplied by the heat transfer comes from a combustion process, such as in an internal combustion engine or in a power plant. In this chapter, we will consider the process of the combustion of one of the substances included in Table B.6. We will balance the combustion equation, present complete and incomplete combustion, apply the first law with an energy balance, and calculate the temperature of the products of combustion. 9.1 Combustion Equations Combustion involves the burning of a fuel with oxygen or a substance containing oxygen such as air. A chemical-reaction equation relates the components before and after the chemical process takes place. Let us begin our study of this particular variety of chemical-reaction equations by considering the combustion of propane in a pure oxygen environment. The chemical r...

8.3 The Psychrometric Chart A convenient way of relating the various properties associated with a water vapor-air mixture is to plot these quantities on a psy c h r ometri c chart , displayed in App. F, and   shown in Fig. 8.3. Any two of the properties ( T , φ, ω, T dp , T wb ) establish a state from   which the other properties are determined. As an example, consider a state A that is located by specifying the dry-bulb temperature ( T or, simply, T ) and the relative   humidity. The wet-bulb temperature would be read at 1, the dew-point temperature at 2, the enthalpy at 3, and the humidity ratio at 4. Referring to App. F, a dry-bulb tem perature of 30°C and a relative humidity of 80% would provide the following: T dp =   26°C, T wb = 27°C, h = 85 kJ/(kg dry air), and w = 0.0215 kg water/(kg dry air). The   chart provides us with a quick, relatively accurate method (large charts are used in the   industry) for finding the quantities of interest. If the pr...