Weak current College】 【solar heating systems and equipment.

<br> <br> I. preface <br> <br> With the development of the national economy, increasing energy demand, energy utilization, and extensive use of conventional energy sources will have adverse effects on the environment. Solar power as a renewable .energy, inexhaustible, without increasing the environmental load, will become the future energy mix, an important part. China in the case of solar energy resource-rich countries, the annual amount of radiation is about 3300-8300MJ / (m2.a), .the nation's more than 2 / 3 area region annual sunshine hours annually than 2000h receives land equal to the Sun's radiant energy 2.4 trillion tonnes, a solar energy utilization in good condition. In building energy consumption, domestic hot water and heating energy consumption accounts for a .significant proportion of the use of solar energy for hot water, heating those requirements of low grade energy consumption has tremendous energy efficiency, solar heating technology is becoming more and more attention. <br> <br> II. Overview of the solar heating system < .br> <br> 1. the solar heating system <br> <br> Solar heating system refers to the use of solar energy as heat source for heating systems, solar collectors will be converted into heat energy, solar energy supply buildings throughout the winter .heating and other systems with heat. Solar heating can be divided into active and passive ways. Passive solar heating through the building's orientation and surrounding environment of reasonable layout, internal space and external shape of skillfully handled, as well as construction materials and structures constructed properly .select the buildings in the winter to the full collection, storage and distribution of solar radiation. Active solar heating system is mainly composed of solar thermal systems, thermal storage system, at the end of the heating system, automatic control system and other energy-assisted .heating and heat exchange equipment collection, compared to passive solar heating, heating condition more stable, but at the same time, the investment costs are also increasing, the system more complex. With the economic and social development, active solar heating to start large- .scale applications. <br> <br> In recent years of solar heating and construction projects, more concentrated and representative is around Beijing's suburban counties in new residential solar heating engineering. Due to the relatively dispersed rural residence, density is low, taking the level .of investment, the maintenance of central heating mode, while traditional coal-fired heating and low efficiency, pollution of the environment, the cost is high, the promotion of safety and environmental protection in rural areas, low running cost of the solar heating system in .line with the objective of the new rural construction requirements. Solar heating the required collector area much larger than the solar hot water system, the installation location requires a large, tall buildings or residential density in the larger urban areas there are installation construction deficiency conditions, .limits the application, and rural residential general building volume rate is low, no significant occlusion with the construction of solar heating project in good condition. <br> <br> 3. solar heating equipment <br> <br> 1. collectors <br .> <br> Common solar collector with flat plate and evacuated tube type two, one, tube-type can be divided into all-glass vacuum tube-shaped, u-shaped tube heat pipe vacuum tube and the vacuum tube collector. Currently in China .solar water heater market, flat solar water heaters accounted for about 10% of market share, while the rest are vacuum tube solar water heater, but the flat solar water heater abroad accounted for 90 percent of market share, and the mainstream world solar energy market .there is a huge difference. Since the solar heating system is tightly integrated with building, collector product and architecture integration and failure rates, service life and performance requirements are relatively high, flat-plate collector is simple in structure, impact compressive force, resistance, .suitable for pressure run, from the overall appearance, structure, strength, install, run, and so are very suitable for combining with the building. In thermal performance, despite flat-plate collector of insulation does not perform as well as vacuum tube collectors, .but because of its efficient lighting surface is greater than the vacuum tube collectors, so its efficiency is higher than the vacuum tube collector. Early flat-plate collector does not disadvantage of frost winter as the technology advances have already been resolved. Solar heating engineering, .non-heating season energy surplus, vacuum tube collector prone burst pipe, vacuum degree, while the lower flat-plate collector you can more easily address this issue, therefore, at present, Beijing area solar heating engineering, many projects use a flat-plate .collectors. <br> <br> 2. auxiliary heat source <br> <br> Provide for residential solar heating hot water heating systems and domestic hot water available for residential solar hot water system in water supply characteristics are different, domestic hot water does .not require a continuous supply and heating hot water supply must be continuous and stable and reliable. Solar radiation is diurnal, seasonal, latitude and altitude, and other natural conditions and rainy weather, and other random factors, there is considerable intermittent and instability, consequently .in the solar heating system, you must set the auxiliary heat source. Auxiliary heat source according to the local solar resource conditions, General conditions of supply of energy, building heat load and ambient conditions and other factors, do a comprehensive economic analysis to determine appropriate .auxiliary heat source and reasonable proportion of solar heating. Solar heating in the auxiliary heat source can be selected mainly small boiler fuel (gas), urban heating network or regional boiler room, industrial waste heat, electric boiler, heating pipes, heat pump and biomass .fuels, etc. <br> <br> In the countryside of solar heating project, due to urban heat networks and difficult to reach the gas pipeline, oil, electricity prices are higher, therefore, the application of auxiliary energy source is biomass fuel types .. As Beijing Pinggu district hanging a Valley village, auxiliary heat source used for biomass boilers, biomass briquette forming equipment, the local fruit trim branches after smashing into fuel rods or fuel block as a biomass boiler fuel, also used for cooking fuel, biomass briquette .compression than the traditional biomass burning high density, high combustion efficiency, storage is also easier to use the labor intensity, is a better way of auxiliary heat source. <br> <br> 3. heating Terminal <br> <br> Solar energy .as heat density is low, the collector temperature is very difficult to achieve a high level. Ordinary radiator htm temperature high (70 ° c or above), and solar system is not easy to reach the water temperature requirements. Therefore, in a solar heating .system, usually the end of the radiant heating heating mode. Floor heating-temperature hot water required in 35 ℃ ~ 55 ℃, the solar collectors can provide suitable temperature. <br> <br> <br> <br>.