The storage of thermal energy as the latent heat of a phase change material (PCM) represents a good, attractive option for thermal energy storage. If heat is stored as latent heat, a phase change of the storage material is used. There are several options with distinct advantages and disadvantages. The phase change solid-liquid by melting and solidification can store large amounts of heat or cold, if a suitable material is selected. Melting is characterized by a small volume change, usually less than 10 %.
Intake charge air densities shown in the fig are hard to obtain without charge air-cooling. The effect of charge air- cooling on density ratio is a function of the effectiveness of the charge air cooler and the pressure loss from compressor discharge to intake manifold. The effectiveness is defined as the ratio of temperature drop of charge air across the cooler to maximum temperature potential available for cooling. E = 12 T3: Intake manifold temperature T2: Compressor discharge temperature T1: Ambient temperature, which is assumed to be the same as compressor inlet temperature medium, above equation directly applies. In cases where water is used as intermediate cooling medium, the overall effectiveness is composed of the charge air cooling effectiveness and the corresponding radiator effectiveness.
Evaporation Evaporation is a phase transition from the liquid phase to vapor that occurs at temperatures below the boiling temperature at a given pressure. Evaporation occurs on the surface. Evaporation only occurs when the partial pressure of vapor of a substance is less than the equilibrium vapor pressure. Boiling Boiling is also a phase transition from the liquid phase to gas phase, but boiling is the formation of vapor as bubbles of vapor below the surface of the liquid. Boiling occurs when the equilibrium vapor pressure of the substance is greater than or equal to the environmental pressure.
Heat exchanger is an equipment to exchange heat energies with the surrounding fluid. They are widely used in chemical plant, petroleum refineries and HVAC systems. Heat exchanger are typically categorised with type of arrangement and type of construction. In the pallbearer flow arrangement, the hot and cold fluid flows in the same direction whereas in the counter flow arrangement the fluids enter at the opposite end. The counter flow is more efficiency at exchanging the heat energy due to its larger average temperature difference.
Fractional distillation produces the same result as a series of simple distillations, which yield a more pure product after each consecutive distillation. In fractional distillation, a second condenser is added between the round bottom flask and the second condenser, and is used as a fractionating column in order to create a temperature gradient. The temperature is highest at the bottom of the column, where it is in contact with the round bottom flask, and lowest at the top of the column. As the vapors rise through the column, the vapors for the liquid with higher boiling condense as the temperature drops, and fall back into the boiling flask. The vapors from the liquid with the lower boiling point pass into the second condenser, and are condensed and collected in a flask or other vessel.
Thermal stability: NaOH and KOH exhibits elevated thermal stability. Because of its high stability along with relatively low melting point, this is often melt cast like pellets or rods, form with the purpose of have low surface area and convenient handling properties. As a base, KOH is highly basic, creating strong alkaline solutions in water and other solvents. In analytical chemistry, titrations using solutions of KOH are used as test acids. 3.1.5 Mixed
Stirling cycle Overview of Stirling cycle The Stirling cycle consists of a closed system, which uses compression an expansion of the working fluid at different temperatures in a cycle. Volume changes allow for a net change in transferring heat to work and vice versa (Thombare & Verma, 2008) Four steps make up the Stirling cycle. These are as follows: State 1-2: Isothermal expansion: While the expansion piston moves away from the regenerator, the compression piston remains constant. As the volume increases from V1 to V2, the pressure decreases from P1 to P2. During this process, heat is added to the system for the maintaining of constant temperature T1=T2.
• The Gases are ideal. • Fuel cell is fed with Hydrogen and air. • The ratio of pressure between the inside and outside of the electrode channel is large enough to assume chocked flow. Fig. 2 V-I Characteristics Fig 2 shows the V-I Characteristic of PEM fuel cell which operate in three potential region.in PEM fuel cell the voltage across the cell is related with low current and it is due to activation loss inside cell; output voltage at the end of the curve will drop sharply as the load current increases.
RECEIVER The receiver generally consists of a secondary reflector mounted above the receiver tube which contains the heat transfer fluid. The receiver may consist of a single tube or several tubes, which may be contained in a vacuum glass tube enclosure. Typical designs are shown in given figure . Figure 2: Receiver of LFS System The collector concentration ratio is the ratio of mirror aperture to receiver aperture. The low-profile setting of LFR collectors maximizes the concentration ratio, which enables high temperature output.
2.1 Joule Thomson effect: The phenomenon of producing lowering of temperature when a gas is made to expand adiabatically from a region of high pressure into a region of low pressure, is known as joule Thomson effect. The experimental set up is shown in figure 2(a). it consists of a thermally insulated tube fitted with a po-rous plug and two weightless and frictionless pistons X and Y. two sensitive thermometers are fitted on both the sides of the porous plug to record temperature. Consider that a certain amount of the gas is passed through the porous plug by slow movement of piston X, i.e. a volume V1 of the gas at pressure P1 be forced through the plug on the left side of the plug.