Brief introduction Water ring heat pump air conditioning system advantages and disadvantages

Keywords: water ring heat pump water / air heat pump energy saving
0 Foreword

Heat pump is essentially a heat recovery unit, which absorbs heat from the low-temperature heat source and enhances the grade, and then heat at a high temperature heat source, to save high-energy rental. Since 1989, heat pump technology in China's application and development has entered a boom. According to statistics, in 1996, the total cooling capacity of air-conditioning equipment (electric chiller-heater units, absorption chiller-heater units, room air conditioners and unit air conditioning units, but excluding imported units) is about 20 million kW, of which the heat pump The cooling capacity of the unit accounts for about 60% [1].

In the early 1980s, China adopted a water ring heat pump air conditioning system in some foreign-invested buildings [2]. Today, the water ring heat pump air conditioning system in our application has been no small popularity. Water ring heat pump air conditioning system in the 90's in China has been widely used. According to statistics, a total of 52 projects were adopted in China in 1997 [2]. Not only it has been adopted by some projects in big cities such as Beijing, Shanghai, Guangzhou, Shenzhen and Tianjin, but also small and medium-sized cities such as Foshan, Shaoxing, Huizhou and Quanzhou have begun to adopt water-ring heat pump air-conditioning systems. In addition, the research on water-ring heat pump air-conditioning system is also fruitful. From 1993 onwards, the original Harbin Institute of Construction began the water ring heat pump air conditioning system in our application of predictive analysis and evaluation. After that, many related papers were published, such as the literature [3]. In 2005, domestic water ring heat pump air conditioning system engineering monograph, namely literature [4] - "water ring heat pump air conditioning system design" published.

1 water ring heat pump air conditioning system overview

Water ring heat pump air conditioning system is a small water / air heat pump unit application, that is, the water circuit will be small water / heat pump units connected in parallel to form a closed loop to form a set of recycling waste heat inside the building as a Its low heat source heat pump heating, cooling air conditioning system. A typical water ring heat pump air conditioning system consists of three parts: (1) indoor small water / air heat pump units; (2) water cycle; (3) auxiliary equipment (such as cooling towers, heating equipment, thermal storage devices, etc.).

Water ring heat pump air conditioning system's basic working principle is: in the water / air heat pump unit heating to the water cycle loop water as a heating source; unit cooling, the water as a heat source. When the water ring heat pump air conditioning system heating operation heat absorption is less than the heating operation of the heat release, the water temperature in the loop increases, to a certain extent, the use of cooling tower release heat; the other hand, the temperature of the water loop loop Reduce, to a certain extent through the auxiliary heating equipment to absorb heat. Only when the heat capacity of the heating operation of the water / air heat pump unit is substantially equal to the heat release capacity of the cooling operation, can the water in the circulation loop be maintained within a certain temperature range and the system operates efficiently at this time.

2 water ring heat pump air conditioning system advantages

Some water ring heat pump air conditioning systems used in our country in the early 1980s showed many advantages: such as the unique function of recycling building waste heat; unlike the traditional boiler that would pollute the environment; saving or reducing the cost of conventional air conditioning system Cold and heat source equipment and room; easy to household metering and billing; easy to install, manage and so on. According to the predictions of the literature, a promising energy-saving air-conditioning system for water-ring heat pump air-conditioning systems [2]. In the following, this article analyzes the advantages of water-ring heat pump air-conditioning systems one by one from the three aspects that make up the system.

2.1 water cycle loop

First of all, according to the water ring heat pump air conditioning system in buildings, it belongs to heat recovery heat pump system. In the case of low outdoor air temperature, the building's peripheral area requires additional heat to maintain a stable and comfortable indoor temperature; at the same time, the inner area of ​​the building is cooled down by indoor heat sources (such as lighting, equipment, and human body) ), But need to reduce the indoor temperature.

Water ring heat pump air conditioning system can transfer the waste heat generated in the inner zone to the peripheral zone by connecting the water circulation loop in the peripheral zone and the inner zone of the building at the same time and heat the peripheral zone while cooling the inner zone but does not exist or A small amount of conventional air conditioning system in the same situation of heat and energy offset by the waste of energy. Therefore, the system of building heat recovery effect, make full use of waste heat while saving energy. When the inside of the building is operated at the same time by the heating condition unit and the cooling condition unit mode, the running cost of the water ring heat pump air conditioning system can be reduced to about 50% at most.

Second, similar to the above, in order to achieve the same effect of cooling and heating, the water circulation loop of the water ring heat pump air-conditioning system is still two-pipe system, compared with the conventional air-conditioning system which needs the expensive four-pipe fan coil system. In this way, the conventional four-tube fan coil system will not exist or reduce the heat and heat offset in the room air conditioners requiring different conditions, thus avoiding the unnecessary consumption of energy and saving the piping system The initial investment costs.

Third, because the water temperature in the water circuit is within the range of normal temperature and not much different from the ambient temperature, normal-temperature water consumes much less energy than a conventional air conditioning system. At the same time, the heat loss of the loop is much smaller than that of the conventional air-conditioning system because of the reduction of loss of heat and cooling in the process of transmission and distribution. Overall, the water-ring heat pump air-conditioning system compared with the conventional air-conditioning system, only the pipeline heat loss to reduce this one, energy-saving efficiency of about 8% to 15% [5]. Moreover, due to water circulation loop pipe insulation and moisture can be separated from the wet, but also reduce the insulation layer and other materials costs.

2.2 small water / air heat pump unit

In general, water ring heat pump air conditioning systems are used indoors, according to the size of the indoor load were installed in each room. Users in each room can freely adjust the heating or cooling in the room at any time of the year according to the outdoor temperature changes and their different requirements without affecting the temperature in other rooms. As easy to adjust the room will not appear too cold, overheating and so on, both to avoid the conventional air conditioning system, energy waste, but also to create a good indoor environment. At the same time, indoor small water / air heat pump units also facilitate household metering and household charges.

For the owners, if the conventional air-conditioning system is used, it is necessary to purchase the chiller units and other equipment at one time, which often causes great financial pressure. In addition, the chiller units generally need to be installed for one to two years before they can benefit. The water ring heat pump Air-conditioning system in small water / air heat pump units can be phased investment, construction in batches, or even before the user to move into the layer by layer, the return on investment of its high efficiency, quick. This feature also makes the water ring heat pump air conditioning system in the renovation of old buildings or system quite market, because the conventional air conditioning system can not avoid damage to the original structure, and not easy to find a suitable refrigeration room, the general also need to shut down the whole building Renovation project, resulting in greater economic losses.

For the designer, the system is more compact, simple and flexible because of the indoor small water / air heat pump unit and no bulky air duct, water chiller, etc., and the air conditioner room (or Reduce the engine room area), but also for the owners to increase the use of space and effective space. Water ring heat pump air conditioner. For the construction side, the installation work on the site is reduced because the small water / air heat pump unit can be assembled in the project.

2.3 Auxiliary equipment

If the water ring heat pump air conditioning system to add storage devices and other ancillary equipment, the system can improve the economy. Because the heat storage device can achieve the balance between the condensation heat released into the water circulation loop by the inner area refrigeration unit and the heat absorbed by the peripheral heating unit from the water circulation loop over a period of one day or more, And the annual energy consumption of water heaters.

3 water ring heat pump air conditioning system shortcomings

The development of water-ring heat pump air-conditioning system mainly from two aspects: First, from the system point of view, some buildings in the domestic waste heat is small or no preheating, still need to add heating equipment, resulting in it can not give full play to Some of the original advantages; the second is from the equipment in this regard,

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