新疆25选7中多饯:Application scope analysis of centralized solar collector and household heating system
新疆25选7历史开奖结果 www.mpawbn.com.cn "Centralized Fractional System" is mainly applicable to high-rise, small high-rise buildings, according to the division of building structure specifications: 1-3 storeys for the low-rise (customarily one-storey residential buildings called bungalows, 2-3 storeys called low-rise residential), 4-6 storeys for multi-storey, 7-9 storeys for high-rise (customarily 4-7 storeys called multi-storey residential; 8-11 storeys called multi-storey residential; Small high-rise residential buildings, 10 floors and above for high-rise (usually 12 floors or more is called high-rise residential), the total height of more than 100 meters for high-rise. If the height of the building is 3m/, the number of storeys of the super tall building is above 33 stories.
From the current number of projects promoted by real estate developers, the majority of 6-30 storeys of residential projects, 1-5 storeys of the project is basically concentrated in villas, combined row houses and other relatively high-grade residential, for these projects, the general recommendation is to choose household solar water heater or split solar water heater, and "centralized" solar energy system The key to solve the problem is the use of solar water heating system in 6~30 level residential projects.
For multi-storey residential buildings below 6 stories, the choice of single solar water heater (including balcony wall hanging solar water heater) is more suitable. For residential projects above 6 floors and below 9 floors, the "distributed" solar water heating system is often rejected by developers because of its low cost performance. Here, a "distributed" solar water heating system is recommended. The "distributed" solar water heating system is a series of solar energy heat exchanger tanks connected to the return water pipe of the solar energy circulation system. The single pump circulation system is shown in Figure 1.
Fig. 1 Schematic diagram of distributed solar water heating system
"Distributed" solar water heating system is a primary cycle system, and its biggest difference from "distributed" system is that its water storage tank, circulating water pumps and other system components are located in the lower or lower floor of the building, "distributed" solar water heating system by a group of pumps to complete the heat collection cycle and heat transfer cycle is the prerequisite for the cycle. The flow and lift of the two circulatory systems are basically the same.
Firstly, the flow rate of two cycles is calculated: assuming the collector area of the "distributed" solar water heating system is 1.75 m2 per household, the circulating flow rate required by the solar collector can be calculated; and the optimal heat transfer flow rate of the indoor heat exchanger water tank is 100L/h, according to this data, the indoor heat transfer can be calculated. The circulating flow rate required by the water tank is shown in Table 1.
1. According to the Technical Manual of Solar Water Heating System for Civil Buildings (2nd edition), (edited by Zheng Ruicheng and published by Chemical Industry Publishing House in 2005), the flow rate of solar collector can be estimated according to 0.015-0.02L/(s.m2), and the flat solar collector can be estimated according to 0.02L/(s.m2). M2) estimate.
2. The circulating flow data of indoor heat exchanger water tank come from the test data of Beijing Solar Energy Research Institute Group Co.
3. the flow rate of the circulating water pump is based on the PH series rated flow of the water pump.
From the above calculation, it can be seen that the "distributed" solar water heating system can really meet the requirements of the heat collection cycle and heat transfer cycle if the appropriate pump is selected.
The calculation of the circulating head of the system: the head of the pump is proportional to the power of the pump. With the gradual increase of the floor, the energy consumption to meet the same demand is gradually increased. The average household energy consumption is compared by calculating the shaft power of the "distributed" system with different floor heights, as shown in Table 2.
1. Taking the common four-household building pattern of one ladder as an example, the indoor heat exchanger water tank is assumed to be 60L/household, and the circulating flow required by the heat exchanger water tank is unified as 100L/h.
2. the shaft power calculation formula of the circulating pump is:
N=Q * (H/367) /G
Formula: N - axis power, W;
Q - flow rate, m3/h;
H -- head, m;
G - the efficiency of the pump, fixed value (0.6~0.85), large value of the general flow, and the flow rate.
The small value is small; the table takes 0.7;
3. pump power = shaft power * safety factor (usually 1.1-1.2).
From the calculation results in Table 2, it can be seen that with the building height from 6 to 17 stories, the average household energy consumption rises from 11W to 30W. Assuming that the "distributed" solar water heating system can be operated for 6 hours a day to heat 60L cold water with an initial temperature of 15 degrees Celsius to 60 degrees Celsius, the obtained heat is 11.34kJ, and the average household energy consumption rises from 2% to 5.67%, and the energy consumption is close to high. Almost three times as much energy is consumed by a 6-17-storey "distributed" solar system with the same amount of heat as shown in Figure 2.
Figure 26~17 the proportion of energy consumption of the "distributed" solar system obtained by the same heat.
Theoretical pump selection does not necessarily select the right pump. Taking Willard PH hot water circulating pump as an example, PH751EH (prototype PH403EH): rated flow 130L/min, rated head 16m, input power 1kW, the average household energy consumption is 41. 67W, and the same 11-storey building, should choose PH2201QH (prototype PH2200Q), rated flow 308L / min, rated head 30m, input power 2.8kW, at this time the average household energy consumption reached 63.64W, compared with the theoretical calculation value has greatly improved.
As shown in Figure 3, the unit energy consumption of a "distributed" system in a residential building above the 9th floor is much greater than that of a residential building below the 9th floor.