Solar Hot Water Systems and Materials of Construction :: essays research papers

The squ ars utilise in solar hot wet systems must be conservatively chosen to ensure that the unit will be efficient besides also affordable. The efficiency of the conversion of sunlight efficacy to heat energy of the water depends on the materials of construction and the efficiency of heat change overence of the materials. solar hot water systems use the processes of conduction to transfer the heat preoccupied from the sun to the water and convection to move water by their structure. This assignment discusses the materials employ in construction of solar hot water systems and their heat transfer properties.2.0 ConductionConduction is the process of transferring energy through a material from one point to an other(a). Conductivity (k) is the rate at which the energy is transferred and its units are Watts per metre Kelvin or (W/mK). The higher(prenominal) the rate of conductivity the smart energy is transferred through the material. Conduction can occur in both differen t ways in solids the first is by crystal thrill waves (phonons) where particles of high kinetic energy vibrate rapidly and bump into other particles to transfer energy from one point to another. The second way is by delocalised electrons or free moving electrons which transfer energy throughout materials untold better than atoms do, as their energy to mass ratio is much higher than that of atoms. This allows the electrons to travel much faster throughout a substance and transfer energy faster. For a material to be a good theatre director of kinetic or electrical energy it requires both methods of conduction, which is found in metals and some other materials (i.e. graphite). The conductivity of a solar hot water systems materials are important ie. adequate insulation is demand to prevent energy being lost to the units surroundings. Materials for the pipes should not resist the transfer of thermal and kinetic energy being passed through the pipes to the water in the collector pane l (shown in Fig 1.). The conductivity (k) of a material can be described by the future(a) equation. The contribution of ke increases with free electron concentration. Copper is an abundant, cheap metal with corking thermal and electrical conductivity. It is strong, malleable and ductile making it an ideal material for water pipes. Copper has a thermal conductivity (k) value of 398 W/mK, which is below silvers thermal conductivity of 428 W/mK until now still much larger than other metals such as aluminum (247 W/mK) or steel (60 W/mK).