First, the concept and working principle of seawater source heat pump Sea water source heat pump technology is the use of shallow surface water (sea water) absorbed by the solar and geothermal energy and low temperature low heat energy resources and the use of heat pump principle, through a small amount of high energy input, A technique to achieve the transfer of low heat to high heat. The sea water absorbs the considerable amount of radiant energy that the sun enters the earth, and the temperature of seawater is generally very stable. Sea water source heat pump unit is based on the principle of seawater as the basic "source body" to extract and store energy, it uses the compressor system, consumes a small amount of electricity in the winter to the low-grade energy stored in the sea "taken" to the building Heating; summer energy inside the building "take" out into the sea water in order to achieve the purpose of regulating the indoor temperature. The biggest advantage of this unit lies in the efficient use of resources, first of all, although the seawater as a "source body", but does not consume sea water, nor pollute seawater; secondly, its thermal efficiency, consumption of 1 kilowatts of electricity, you can get 3 The kilowatts to 4 kilowatts of calories or cold, radically changed the traditional way of energy use. As shown in Figure 1. Second, the current situation and development trends at home and abroad There are many foreign examples of sea water heat pump heat source. Such as the Sydney Opera House built in the early 1970s, Japan built in the early 20th century Osaka Nangang Cosmos Square District heating and cooling projects, the use of seawater heat pumps to provide heat and heat 23300kW. The Nordic countries have rich practical experience in using seawater heat sources, of which Sweden is a typical application of seawater source heat pump central cooling / heating of the country. Stockholm, the capital of Sweden, has built the world's largest seawater heat pump station with a total capacity of 180MW for district heating, accounting for 60% of the total delivery from the city center network. Heat pump station by the six heating capacity of 30MW / Taiwan heat pump units, 1984-1986 commissioning completed, put into operation. The first seawater source heat pump project in China was completed and put into use in Qingdao Power Plant in 2004. The total area of ​​1871 square meters of the canteen workers, become China's first heating does not require coal, fuel, only the use of sea water to provide heating for the building. In addition, Dalian Xinghai Holiday Hotel seawater source heat pump central air conditioning project has also been officially launched, the seawater source heat pump central air conditioning will provide 40,000 square meters of building cooling and heating, which is the first case in China. Recently, through the procedures of declaration and expert review, Dalian was selected as the only demonstration city of large-scale application of water source heat pump technology in China by the state. This indicates that Dalian will be expected to take the sea water as the energy source for the hot and cold air conditioning in the future. According to the national "Building Energy Efficiency Implementation Plan" requirements, "Eleventh Five-Year" period, the model city water source heat pump heating, cooling area to reach 5 million square meters and above. Demonstration includes water source heat pump heating, cooling and related technology research and development integration and industrialization. For demonstration city demonstration projects, the state will provide special funds to subsidize the incremental costs of 70%. Currently, Dalian is actively promoting the preliminary work of seawater heat pump technology in areas such as Xiaoping Island New Area, Xinghai Bay Business District and software industry belt. Water source heat pump technology for heating (cooling) is mainly the use of large heat pump on the pre-extraction of seawater for processing, the heat extracted for heating and cooling, and the energy through the city's original heating (cooling) system Delivered to households, which completed the original need to use coal as fuel to complete the heating process. In winter, large heat pumps can be used for district heating; in the summer, large heat pumps rely on similar principles to complete seawater-powered cooling and cooling. Water source heat pump driven by electricity, due to its heating efficiency of 4 times the power consumption, plus it can also be cooling, energy conversion efficiency will be further improved. Third, the current sea water source heat pump system engineering problems Sea water source heat pump as a new type of refrigeration heating mode, from a technical point of view, especially heat pump unit point of view is quite mature. However, taking into account China's national conditions, as well as the seawater source heat pump refrigeration and heating as a whole system engineering to promote the application, there are still some problems: 1, the water system of water systems, water intake, water temperature, water quality and water supply stability Important factors affecting the operation of water source heat pump system. In terms of water intake: the problem of optimal choice of the location of water supply and return points needs to be studied in order to guide the laying of water supply and return pipelines on the actual project. 2. Economy of Investment Due to the influence of energy policy and fuel price in different regions, different users and countries, the basic conditions of water resources are different. The one-time investment and operating costs will vary from user to user. Although, on the whole, the seawater source heat pump is more efficient to operate. However, compared with the traditional air-conditioner cooling and heating methods, the investment economy of seawater source heat pumps will be different under the different needs of different regions. In particular, in terms of the water system at the front end, the location of the seawater supply and return pipelines (distance from the seafloor and depth from the seafloor) and the laying method (vertical to the sea current and the same direction with the sea current) and their actual investment in construction costs The economic issues deserve further study. 3, the overall system design Sea water source heat pump energy-saving as a system, we must consider from all aspects, if the water source heat pump units can be done using less water to provide more energy, but the system design of pumps and other energy-consuming equipment Improper or improper control can also reduce the energy savings of the system. Similarly, if the unit provides a high water temperature, the end of the air-conditioning system being designed has not been considered appropriately and may either reduce the overall system effectiveness or allow the initial investment in the overall system to increase. Therefore, the popularization and application of water source heat pump requires more professionals in all fields to work together to work together, from the government policy, design and manufacture of units, system design and operation management and other aspects to consider together. Fourth, the sea water source heat pump is to adapt to create a resource-saving and environment-friendly society and the development of a new set of heating / cooling in one of the air-conditioning system. In the coming years, China faces enormous energy pressure. On the one hand, China's economy needs to maintain its rapid growth. On the other hand, it must also consider environmental protection and sustainable development. Therefore, it is imperative to accelerate the industrialization of seawater source heat pumps in China.