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Views: 2 Author: Site Editor Publish Time: 2019-04-17 Origin: Site
Taking "solar air source coupling hot water system" as an example, the annual energy-saving rate of solar energy is analyzed and calculated in detail. From the perspective of the calculation process and calculation basis, this calculation method is more scientific and reliable, and has important reference significance for the analysis and calculation of energy saving and emission reduction of solar thermal application system.
Guangxi has a subtropical monsoon climate with a mild climate. The average annual sunshine hours are 1,600 hours, and the average annual solar radiation is about 4,578 MJ/m2. It is rich in solar energy resources and has great potential to use solar energy. At present, the society is to promote and popularize centralized supply solar hot water system, air source coupling, however, solar air source hot water coupling system in the design and the project application must first calculation and analysis on energy-saving, solar-thermal calculation and analysis of the energy-saving application system there is no a more scientific and reliable, strong persuasive analysis method to calculate, as a result, based on the environmental protection bureau of guangxi change of dilapidated housing renovation project subproject "solar air source hot water coupling system" as an example, the practice of a new method of calculation and analysis.
Guangxi environmental protection department housing reconstruction construction project is the original low, short, old residential buildings for workers demolished, in the original land to build a new 33-storey high-rise, the project address is Nanning city, Guangxi Minzu avenue 78. In response to the national call, for energy conservation and emission reduction, the project adopts a renewable energy building application form, solar air source coupling hot water system, which provides 186 households with hot water for about 651 people. The designed daily per capita hot water quota is 80 L, the service time is 24 hours, and the total amount of hot water used every day in the biggest hot water season is 52 m3. In this hot water project, a total of 2,600 solar vacuum heat collection pipes are installed, and a total of 60 air source heat pumps are equipped. The energy saving effect is very significant.
The solar air source coupled hot water system realizes complete automatic control through the control of automatic control module. When there is sufficient solar energy radiation, the hot water system has the priority to use solar energy to produce domestic hot water. In rainy weather or when the solar energy radiation is insufficient, you can start the air source heat pump as the auxiliary heat source to produce domestic hot water.
The annual energy-saving rate of the solar hot water system refers to the proportion of the electricity saved by the solar heat-collecting system (excluding the electricity saved by other auxiliary heat sources) in the electricity consumed by the conventional hot water heating method in the annual operation of the solar hot water system compared with the conventional hot water heating method.
2.3.1 Thermal efficiency of solar energy collection system
Thermal efficiency calculation method of the solar system to central solar heating system equipped with a circulating pump. For example, usually solar heating system in under the irradiation of the sun hot water from the initial temperature of heating to set temperature, the solar heating system only consumption of circulating water pump a small amount of electricity and any other equipment not consume electricity, in this system, for example of circulating water pumps are equipped with the rated input power is 0.265 kW, circular 1000 kg has temperature 35 ℃ water needed time to 0.128 h, power consumption 0.034 degrees. Therefore, it can be concluded that the actual calorific value of the centralized solar energy collection system equipped with circulating water pump is:
35000/0.034 = 1029411.76 kcal/degrees;
Comprehensive thermal efficiency was 1029411.76/860=119699%
Conventional heating equipment of domestic hot water for residents in this area is the electric water heater independently installed by each household. The working principle of the electric water heater is actually resistance heating, and the thermal efficiency of the electric water heater is 95%. That is, the energy efficiency ratio is 0.95.
Nanning is located in the south of the tropic of cancer, geographic coordinates, 22 ', longitude 108 ° latitude 22 ° 48 ', sunshine, abundant rainfall, less cream without snow, mild climate, summer long winter short, annual average temperature 21.6℃. The coldest winter in January, on average, 12.8℃, the hottest in July and August summer average 28.2 ℃. The average annual rainfall was 1304.2mm and the average relative humidity was 79%. It's perfect for sightseeing all year round. Subtropical monsoon climate.
According to climate characteristic of Nanning city, domestic hot water demand is divided according to summer, winter and transition season. The summer lasts from may be to September, a total of 153 days, and the hot water demand coefficient is 0.6. Winter is January, February and December, a total of 90 days, the hot water demand coefficient is 1; The transition season is marching, April, October and November, a total of 122 days. The hot water demand coefficient is 0.8.
According to this method to calculate each 58 x 1800 ￠in each month of the solar glass vacuum heat-collecting tube set heat into form in table 3.
The calculated 58 x 1800 ￠per year set the solar glass vacuum heat collecting tube heat totaled 91.313 kW/H. The total number of solar vacuum collector tubes of this specification is 2,600 throughout the whole residential area of this energy saving project, and the total annual heat collection is 237,4138 kW/H.
To collect the heat, the energy consumed by the solar-thermal system is:
2374138 present 119699% = 198.34 (kW/H)
Namely, the annual saving energy of the solar energy collection system of this project is:
2374138-198.34 = 237215.46 kW/H)
The annual energy-saving rate of the solar energy collection system of this project is:
Annual energy savings of solar thermal system annual power consumption of conventional hot water heating method 100%
= 237215.46 present 563980.5 x 100%
= 42.1%
The annual energy-saving rate of solar energy collection system in this project is 42.1%.
Based on the analysis of the calculation process and calculation basis, the calculation method of the annual energy-saving rate of the solar energy collection system in this project can be called "daily calculation method". There are errors in the results of daily calculation, which are mainly related to several parameters.
(1) The solar radiation amount data are obtained by referring to China meteorological radiation data yearbook (2001). The climate of each year is more or less the same as that of 2001, but the change is usually small.
(2) The heat-collecting efficiency of solar vacuum collector tube is 92%. This is the experimental data provided by the manufacturer of solar vacuum collector tube. This parameter can also be measured through the experiment.
(3) The heat loss rates of pipelines and water tanks. In practical projects, if the insulation measures are well done, the heat loss rate can be directly reduced.
(4) The sum of the actual heat used by users each year. The actual heat used each year is related to seasons and weather, so the heat coefficient used in each season is different.
Conventional calculation and analysis methods are shown in literature [1].
Under the pressure of the energy crisis, the state vigorously promotes the development and utilization of renewable and clean energy. Among them, solar-thermal application technology is one of the most mature and widely used technologies in the development and application of renewable and clean energy. "Daily calculation method" is used to middle-aged solar thermal applications system calculation and analysis of energy-saving rate, relative to the conventional method, from the point of calculation process and calculation basis, the calculation method is more scientific and reliable, strong persuasive, adopting the solar thermal application system of analysis and calculation, energy-saving and emission reduction has important reference significance.
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