Introduction
Any water source whose water quality does not cause corrosion damage to unit equipment can be used as water source for water source heat pump system, which can be either regenerated water source or natural water source.
Details
Water quantity, water temperature, water quality and water supply stability of water source system are important factors that affect the operation effect of water source heat pump system. When applying water source heat pump, the principle requirements for water source system are: adequate water quantity, moderate water temperature, suitable water quality and stable water supply. Specifically, the amount of water in the water source should be sufficient to meet the needs of users for heating load or cooling load. If the water quantity is insufficient, the heating capacity and cooling capacity of the unit will be reduced accordingly, which will not meet the requirements of users. The water temperature of the water source should be moderate and suitable for the operating conditions of the unit. For example, when the GHP water source central air conditioning system in Tongfang, Tsinghua is in heating operation, the water temperature of the water source should be 12-22℃; In refrigeration operation, the water temperature of source water should be 18-30℃. The water quality of water source should be suitable for the materials of system units, pipelines and valves, so as not to cause serious corrosion damage. The water supply guarantee rate of the water source system is high, and the water supply function has long-term reliability, which can ensure the long-term and stable operation of the water source heat pump central air conditioning system.
In principle, any water source that does not cause corrosion damage to the unit equipment can be used as the water source for the water source heat pump system, which can be either a renewable water source or a natural water source, as long as the water quantity and water temperature can meet the needs of users for heating load or refrigeration load.
1. Recycled water source
It refers to the water sources such as urban domestic sewage, industrial wastewater, mine wastewater, oilfield wastewater and cooling water of thermal power plants that are discharged after artificial utilization. Users who have the conditions to use renewable water sources can turn waste into profit, reduce initial investment and save water resources. But for most users, the alternative is the natural water source.
2. Water sources in nature
Water in nature is distributed in atmosphere, earth surface and crustal rocks, which are called atmospheric water, surface water and groundwater respectively. Surface water and groundwater on land come from atmospheric precipitation.
Seawater in surface water accounts for about 96.5% of the total natural water reserves. Coastal cities have the conditions to use seawater, and there are examples of using seawater as water source of heat pump in foreign countries. Some coastal cities in China have used seawater as industrial cooling water source for many years. In recent years, seawater has been used as heat pump water source in China, but it will take time for seawater source heat pump technology to be put into practical use. Terrestrial surface water, i.e., river, lake and reservoir water, has lower salinity than seawater and groundwater, but contains more solid particles such as sediment, colloidal suspended solids, algae and other organic matters, and has higher sand content and turbidity, so it can be used as heat pump water source only after necessary treatment.
Groundwater refers to water bodies buried and transported in aquifers below the surface of the earth. Groundwater is widely distributed, its water quality is better than surface water, and its water temperature changes with climate, so it is an ideal water source for central air conditioning.
3. Selection of water quantity and water source
Water quantity is the key factor affecting the working effect of water source heat pump system. The amount of water required for a project is determined by the load of the project and the performance of the unit. The selected water quantity of water source should meet the load requirements. If all other conditions are met, but the water quantity is slightly insufficient, some auxiliary remedial measures can be taken to solve the gap. If the water gap is large and can not meet the load requirements, other schemes should be considered. As far as a specific project is concerned, it should be judged from the actual situation whether there is available water source. The site environment and hydrogeological conditions of different projects vary widely, and the available water sources are different, so the suitable water sources should be selected according to local conditions. When there are different water sources to choose from, they should be determined by technical and economic analysis and comparison.
