Category: Physics of Solar Energy

Encapsulation of PCM

To mitigate the problem of low thermal conductivity of PCMs, the material is often encapsulated in various forms. Figure 12.6 shows an example of a PCM encapsulated in flat or tubular parcels. A heat transfer fluid is required to make it operational. Figure 12.6 Encapsulation of PCM. An example of PCM encapsulated in flat or […]

Salt Hydrates

Many inorganic salts crystallize with a well-defined number of water molecules to be­come salt hydrates. Heating a salt hydrate can change its hydrate state. For example, hydrated sodium sulfate (Glauber’s salt) undergoes the transition at 32.4°C Na2SO410H2O + AQ —> Na2SO4 + 10H2O. (12.16) In general, the transition is Salt mH2O + AQ —> Salt […]

Water-Ice Systems

As shown in Table 12.3, the latent heat of the freezing of water or melting of ice is one of the highest. The water-ice system has already used in industry to save energy in air-conditioning systems. Figure 12.3 is a photo of a water-ice energy storage system, named Ice Bear, designed and manufactured by Ice […]

Synthetic Oil in Packed Beds

Because the temperature range of water is limited, in order to store sensible heat at higher temperature, for example, in solar power generation systems, synthetic oil should be used. However, synthetic oil is expensive. A compromised solution is to use a mixture of synthesized oil and inexpensive solid materials, such as pebbles. Figure 12.2 shows […]

Water

As shown in Table 12.1, water has the largest heat capacity both per unit volume and per unit weight. And it is free. Therefore, it is logical to use water as the material for sensible heat storage. A typical case is the hot-water tank used in most homes. The tank is typically insulated by foam […]