Military Models,Military Model Kits,Army Models,Model Military International Nanjing Great Century Art Model Co., Ltd. , , https://www.dsjysmx.com
Application Analysis of Surface Water Source Heat Pump System (middle)
3 hot and cold load estimation and feasibility of water flow According to the specification, Beijing outdoor air-conditioning calculation parameters are as follows: Annual average temperature 11.4 ℃ Winter air-conditioned outdoor calculation Dry-bulb temperature -12 ℃ Winter outdoor calculation of dry ventilation Dry bulb temperature -5 ℃ Winter air conditioning Outdoor calculation Relative humidity 45% Summer air-conditioning Outdoor calculation Dry-bulb temperature 33.2 ℃ Summer ventilation Outdoor calculation Dry-bulb temperature 30 ℃ Summer Air-conditioning Outdoor calculation Wet-bulb temperature 26.4 ℃ R & D base building interior design parameters initially set: summer interior design temperature 25-27 ℃, indoor relative humidity is less than 60%; winter interior design temperature is 18-20 ℃, indoor relative humidity is not required. According to the preliminary calculation, the design cooling load index is about 100W / m2, the design thermal load index is about 50W / m2. According to the first phase of 100,000 square meters and the simultaneous use coefficient of 0.9, the total air conditioning system cooling load is 9000 kW, Heat load 4500 kW. Assuming that the COP value of a water-source heat pump unit under cooling conditions is about 4.3, and the COP value under heating conditions is about 2.6, the amount of heat required to be removed by the surface water under cooling conditions is 11,093 kW. Under heating conditions The amount of heat to be supplied is 2769 kW. According to "Introduction to R & D Base", the water injection surface of waste pit ponds is about 150 mu with an average water depth of 3.5 m. The total water storage capacity of this pit body is 3.5 × 105 m3. Consider the base of the summer air conditioning running 12 hours a day, the daily heat dissipation to the water body Q = 11093 kW × 12h × 3600 = 479 × 106kJ. The water temperature rise is Q / CM = 479 × 106 / (4187 × 3.5 × 105) = 0.33 ℃. Considering the temperature difference of 5 ℃ of the heat exchanger, the water flow required to remove 11093 kW of heat is: G = 0.86 × 11093 × 1000 / (1000 × 5) = 1908 m3 / h, About 7 days. This shows that summer water temperature is very small, taking into account the water and air and the earth heat exchange, water temperature is smaller or even negligible. The base winter air conditioning to run 24 hours a day to consider, the daily heat extracted from the body of water for the Q = 2769 kW × 24h × 3600 = 239 × 106kJ. Beijing is located in a cold area where surface water will freeze. Considering the relatively conservative ice thickness during ice age, the water depth will drop to 2.5 m on average. The total water storage capacity of this water body is 2.5 × 105 m3. The temperature drop Q / CM = 239 × 10 6 / (4187 × 2.5 × 10 5) = 0.23 ° C. Considering the temperature difference of 2 ℃ of the heat exchanger, the water flow required for taking away 2769 kW of heat is: G = 0.86 × 2769 × 1000 / (1000 × 2) = 1191 m3 / h, and the entire water body is circulated once for about 210 hours, About 9 days. It can be seen from this that the temperature drop of winter water body is smaller than that of summer and the required water volume is smaller than the effective water quantity that can be provided by reservoirs. Considering the heat exchange between water body and air and earth, the temperature drop of water body is smaller Can even be ignored. Taking into account the winter may be sustained low temperature, water decreases, leading to water temperature is too low, the water is too small extreme cases, in order to ensure that the normal heating in this case, the need to consider the use of auxiliary heat source to enhance heat pump chilled water temperature, according to The actual situation of the base, the auxiliary heat source can be considered in the form of gas-fired boiler to the most extreme conditions, that is, surface water has been unable to provide heat, all the heat provided by the gas boiler, boiler feed water temperature difference of 25 ℃ to consider, The water flow required for removing 2769 kW of hot water produced by the boiler is: G = 0.86 × 2769 × 1000 / (1000 × 25) = 95 m3 / h. In addition, the above water flow and other parameters are considered as a whole base as a whole, in the actual construction, for the convenience of regulation and management, the same or similar functions of the single building, respectively, to build power stations, so that pumps, boilers, The specifications of the equipment such as the heater will be reduced. It can be seen from the above analysis that according to the known conditions, it is feasible to adopt surface water source heat pump system in this research and development base. 4 water source heat pump system on the environment According to the principle of water source heat pump system shows that surface water source heat pump air conditioning system on the use of surface water is limited to heat extraction and conversion, and strictly limit the use of surface water for any chemical treatment , The limited treatment is limited to physical treatment such as filtration, precipitation and heating and cooling, and the composition of surface water does not change during the whole process. In strict compliance with the above principles under the premise of the operation of water source heat pump system will not bring the region's surface water pollution problems. In the system design and construction is reasonable, and the surface water source heat pump system under the premise of normal use, the general will not have a negative impact on the environment.