Brief introduction Water ring heat pump air conditioning system advantages and disadvantages
October 02 09:00:45, 2025
**Abstract:** This paper introduces the history and current status of water-source heat pump air conditioning systems in China. It briefly explains the working principle and application of these systems, and provides a detailed analysis of their advantages and disadvantages.
**Keywords:** water ring heat pump; water-air heat pump; energy saving
**0 Introduction**
Heat pumps are essentially heat recovery devices that extract heat from low-temperature sources, upgrade it, and then release it at a higher temperature, thereby reducing the need for high-energy consumption. Since 1989, heat pump technology has experienced rapid growth in China. According to statistics, by 1996, the total cooling capacity of air-conditioning equipment (including electric chillers, absorption chillers, room air conditioners, and unitary air conditioners, but excluding imported units) reached approximately 20 million kW, with heat pump units accounting for about 60% of this capacity [1].
In the early 1980s, some foreign-invested buildings in China began using water ring heat pump air conditioning systems [2]. Today, these systems have become quite popular across the country. By the 1990s, they were widely applied, and by 1997, 52 projects had adopted them [2]. Not only major cities like Beijing, Shanghai, Guangzhou, Shenzhen, and Tianjin have implemented these systems, but also smaller cities such as Foshan, Shaoxing, Huizhou, and Quanzhou have started to use them. In addition, research on water ring heat pump systems has been fruitful. Starting from 1993, Harbin Institute of Construction conducted predictive analysis and evaluation of the system’s applications in China. Following this, many related studies were published, such as reference [3]. In 2005, the first domestic monograph on water ring heat pump air conditioning systems, "Design of Water Ring Heat Pump Air Conditioning System" [4], was published.
**1 Overview of Water Ring Heat Pump Air Conditioning System**
A water ring heat pump air conditioning system involves the use of small water-to-air heat pump units connected in parallel through a closed-loop water circuit. This system recycles waste heat within the building, using it as a low-temperature heat source for heating and cooling. A typical system consists of three main components: (1) indoor small water-to-air heat pump units, (2) the water circulation loop, and (3) auxiliary equipment such as cooling towers, heating devices, and thermal storage systems.
The basic working principle is as follows: during heating mode, the heat pump absorbs heat from the water loop and transfers it to the indoor space. During cooling mode, the heat pump extracts heat from the indoor environment and releases it into the water loop. When the heat absorbed during heating is less than the heat released during cooling, the water temperature in the loop rises, and the cooling tower is used to dissipate excess heat. Conversely, when the water temperature drops, the heating equipment compensates by absorbing heat. Only when the heating and cooling capacities are balanced can the system maintain stable operation and optimal efficiency.
**2 Advantages of Water Ring Heat Pump Air Conditioning System**
**2.1 Water Circulation Loop**
One of the key advantages of the water ring heat pump system is its ability to recover and reuse waste heat. For example, during cold weather, the outer zones of a building may require heating, while the inner zones may generate excess heat due to lighting, equipment, or people. The water loop allows this waste heat to be transferred from the inner zone to the outer zone, effectively reducing the need for external heating sources. This not only saves energy but also lowers operating costs significantly.
Compared to traditional four-pipe fan coil systems, the water ring system uses a two-pipe configuration, which simplifies installation and reduces initial costs. Additionally, since the water temperature in the loop is close to ambient temperature, the system consumes less energy and experiences lower heat loss during distribution. Overall, the energy-saving efficiency of this system is estimated to be between 8% and 15% compared to conventional systems [5].
**2.2 Small Water-to-Air Heat Pump Units**
Each room in a building equipped with a water ring heat pump system can be independently controlled, allowing occupants to adjust heating or cooling based on real-time conditions without affecting other areas. This flexibility improves comfort and reduces energy waste. Moreover, the small size of the heat pump units makes it easier to implement individual metering and billing.
From an economic perspective, the phased investment model of the water ring system is more flexible. Unlike traditional systems that require large upfront capital, the water ring system can be installed in stages, allowing for quicker return on investment. This feature makes it particularly suitable for retrofitting older buildings, where traditional systems may cause structural damage and require extensive renovation.
**2.3 Auxiliary Equipment**
Adding storage devices and other auxiliary equipment can further enhance the efficiency of the system. These components help balance the heat exchange between different zones over time, improving overall performance and reducing annual energy consumption.
**3 Disadvantages of Water Ring Heat Pump Air Conditioning System**
Despite its benefits, the system has some limitations. From a system perspective, in buildings where internal waste heat is minimal or non-existent, additional heating equipment may still be required, limiting the full utilization of the system's advantages. From an equipment standpoint, the performance of the system is highly dependent on the quality and maintenance of the heat pump units and auxiliary devices. Any malfunction or inefficiency in these components can reduce the overall effectiveness of the system.
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