Construction resources Essay

tress resources vex use of physics in numerous of their products. Two that I conduct picked argon solar collectors and their use of insutation. Insulators lead the purpose of preventing conduction, convection and beam to unwanted areas. There are a wide range of techniques and materials used in doing this and I am going to look for in depth at this idea. The company uses solar collectors in some variant directions, their main purpose is to collect solar cypher and alter skill. They bear be used to warmheartedness and ply many opposite appliances.Photovoltaic cells Photovoltaic cells transfer the energy carried by the electromagnetic waves that make up sunshine directly to an electrical circuit in say to make a current flow. Light excites electrons to propel from one mold to another through semi conductive silicon materials. Only a fraction of a volt is issued so a large tramp is needed to bring up appreciable currents, usually about 20W to 100W. The Photovo ltaic cells produce DC current so if alternate current AC is desire then an inverter is necessary.AC form is comm solitary(prenominal) available from the mains. Solar cells cheerfulness may as well as be used to heat water directly. This puke be done in two ways, water sack be circulated through pipes which run through the back of the solar cells, producing water at around 60oC suitable for household use. The other method is to focus sunlight from a large are to a small spot employ an array of mirrors, this can produce temperatures of up to 4000oC and its quite workable to produce power stations from this, even so it has not been implemented yet. present is on way in which the hot water can be used, this is quite economical and environmentally friendly. Solar panels are quite several(a) and can be put on many roofs of simply in the garden, which makes them popular when it comes to heating swimming pools of hot water for showers. Any material that is a poor conductor of heat and electricity can be used as an insulator. Thermal insulating materials reduce the flow of heat surrounded by hot and cold regions.Thermal insulation may have to cope with one or more of three functions to reduce thermal conduction in the material, in which heat is transferred by electrons to reduce thermal convection currents, which can be set up in air- or liquid-filled spaces and to reduce radiation heat transfer, in which thermal energy is transported by electromagnetic waves. These are three ways in which heat energy can be transferred. Conduction, where heat energy is transferred through solid materials, metals are normally the lift out conductors. There are a number of factors that affect thermal conductivity. change magnitude the area of the cross-section of the solid through which hear flows profits the graze of flow, however increasing the thickness of the wall decreases the flow of heat. Provided that a steady present has been reached (where the temperature of an y point is not changing through time) then the rate of flow of heat ? Q/? t is given by ?Q/? t A ? T/? x Besides the physical dimensions of the materials, another factor poignant rate of flow is the properties of the material, the Thermal Conductivity of the materials ? through which the heat energy is travelling is the constant of proportionality in this relationship, so?Q/? t = -? A ? T/? x The units for thermal conductivity are watts per metre per kelvin. The bill ?Q/? t is called the temperature gradient. On my visit to Construction resources I noticed that they have used these Physical conclusions in there insulation. One in picky is Homatherm a wall and roof insulator. The slabs are thick which means less(prenominal) flow of heat, and have a thermal conductivity is only 0. 04 W/mK. Conduction in terms of particles The particles in metals and non-metals are arranged differently, which gives them their different characteristics.In a non-metal the particles have forces betwee n them that can be draw like springs. When heat is delivered to the solid the oscillations of the particles being heated testament increase in amplitude. For heat to be conducted the neighboring particles must also mother the extra energy, as particles oscillations increase in frequency the neighboring particles also gradually increase in frequency as heat is transferred to them. This is a very slow process. In a metal the arrangement is different, metal-looking boding occurs between metal atoms where a sea of delocalized electrons hold the supreme metal ions together in a lattice.It is these free electrons that are accountable for the high conductivity character of metals. When a metal is heated the metals ions hover with an increase frequency. When an electron hits these ions with extra energy, they receive this extra energy and move faster. This electron can then travel to another parts of the lattice, to an ion that hasnt received any of this heat energy and collide with it, transferring its energy to this ion. outright that ion has extra energy and vibrates with a greater frequency. This process is a dance orchestra faster as there are many electrons in a metal lattice.U-Values Architects and heating engineers use U-Values to calculate the flow of heat energy through building materials. The U-Values is quoted for a given thickness of a extra material, and is based on actual measurements made using the material. The U-Value is defined as U-value = Rate of energy flow Area X Temperature difference Construction resources uses this knowledge of U-Values when designing building materials to reduce the energy wasted in the form of heat going out of the build and to achieve the last goal of reducing CO2 emissions.But there are apparent limitations with reducing thermal conductivity, you can only reduce it to a plastered amount, 0. 025 in air, so there will always be heat loss. Also too much insulation in the house will lead to what construction reso urces refers to as internal pollution. This has lead to construction resources researching in trying to lower the energy that is used to build and transport he construction materials. Bibliography Microsoft Encarta Heinemann Advanced Science Salters Horners AS Advanced Physics Strengths and Limitations of Photovoltaic cellsSince one photovoltaic cell only produces a small fraction of a volt, large arrays are required to produce appreciable voltages. This requires a lot of space and the cells need to be in a place where no shadows will be set on them. This limits what they can be used for. Also the amount of power produced by the photovoltaic cells directly depends on the amount of sunlight, so they cannot be relied on to produce power for something that constantly needs it. The only way this can be overcome is if some power was stored for a rainy day. But this again would take up space.Also an array of solar collector will be expensive and have a immense payment back time. Howeve r it is environmentally friendly and after the pay back time, savings can be made. Also photovoltaic cells can be made look attractive depending on where they are placed. Strengths and Limitations of solar cells The solar cells have similar limitations to the photovoltaic cells in regards to positioning and equal but a small array is only required to produce enough hot water for something like residential showers or primeval heating. This is economical and environmentally friendly and solar cells are quite versatile.