Fountain, as an artificial landscape, has increasingly appeared in various fields across the country and even the world. A beautifully designed fountain can not only beautify the urban environment and enhance the taste of public places such as squares and parks, but also provide people with aesthetic enjoyment, allowing them to feel the harmony between humans and nature. At the same time, during the fountain spraying process, a considerable amount of air negative ions are generated in the surrounding environment, which have a wide range of biomedical effects and can effectively improve human health and make people feel happy [1,2,3]. However, due to the fact that most fountains are built outdoors, they are inevitably contaminated by various pollutants, such as Legionella bacteria, which can reproduce, disperse, and spread through fountains. Therefore, in the design and construction of a good fountain, on the one hand, the huge investment and operating costs should be considered, and on the other hand, environmental protection and energy-saving measures should be taken into account to prevent the situation of "being built but not used" in the later operation process.
Due to the fact that the main energy consumption during the construction and operation of fountains is water, electricity, etc., this article will explore some possible environmental protection and energy-saving technologies in the design and construction process of fountains, hoping to provide environmental protection and energy-saving ideas for the construction and development of fountains in China.
1. Fountain water source conservation technology
During the operation of a fountain, various patterns are mainly created by changing the shape of the water and combining various water shapes, providing people with aesthetic enjoyment. Therefore, the primary energy conservation for fountain operation is water resources. Based on the current construction and development status of fountains in China, combined with my years of experience in fountain construction and design, I believe that water resources can be saved from the following aspects.
1) Fountain water circulation technology
At present, domestic fountains, whether they are pool fountains or dry land fountains, can basically achieve water recycling. The main problem currently existing is that: 1) Fountain water is not treated during the recycling process. Untreated water will inevitably have pollution problems when used repeatedly. Especially for dry spraying, a large amount of pollutants on the ground will be circulated in the water tank. If not treated properly, the contaminated fountain water will pose a threat to human health when in contact with the human body. 2) The process of treating fountain circulating water is too simple, and most of them only undergo simple filtration treatment without disinfection. Filtering treatment can only remove some suspended and floating solids, but it is difficult to eliminate pathogenic bacteria in water. Therefore, long-term use of fountain water can also have adverse effects on human health. 3) Long term use of fountains requires water replacement and replenishment, which consumes a significant amount of water resources. If untreated water is used for a long time, after a period of time, it is necessary to completely replace or supplement the water in the fountain pool with fresh water. The larger the fountain, the higher the cost of replacing water at once, and some can even reach tens of thousands of yuan. Meanwhile, during the operation of the fountain, water loss may occur due to evaporation, drift, and other factors, requiring periodic replenishment of the pool. Therefore, adopting appropriate circulating water treatment technology can greatly reduce the frequency of water replacement and replenishment.
Based on the author's experience and following the principle of putting people first, and drawing on relevant research experience [4], it is suggested that when the water volume of the fountain is less than 50m3, the fountain water can be completely replaced without treatment. When the water volume of the fountain is greater than 50m3, it is necessary to recycle the fountain water. Considering human health reasons, it is necessary to increase the filtration water treatment equipment and disinfection equipment. Chemical agents such as sodium hypochlorite can be used for disinfection, and methods such as electric sterilizers can also be used.
2) Rainwater utilization technology
Due to the fact that most fountains are built in public places such as parks and squares, there will inevitably be large areas of impermeable spaces available for visitors to use around the fountain. These impermeable surfaces generate a large amount of rainwater when rainfall reaches a certain intensity. If these rainwater can be collected, on the one hand, it can be used as fountain water replenishment, and on the other hand, it can also be used as green water for squares or parks, reducing the waste of tap water and saving water resources. However, attention should be paid to the following issues when utilizing rainwater: 1) The initial rainwater needs to be discarded. According to research, many of the pollution indices in the initial rainwater generated by rainfall are comparable to general urban sewage, and some are even higher than general urban sewage [5-7]. Therefore, it is necessary to install drainage devices for the collected initial rainwater. According to relevant research [8], the author suggests that the initial amount of abandoned rainwater should be controlled at around 5mm, and only the later rainwater should be collected for reuse. 2) Rainwater needs to be treated before use. According to the "Technical Regulations for Water Fountain Engineering" standard of the China Engineering Construction Standardization Association, the water used for fountains must meet certain water quality standards. The author suggests referring to the "Technical Regulations for Fountain Water Landscape Engineering" for the design of fountain water quality treatment.
3) Wind speed control fountain technology
Most large fountains are built outdoors, so during the use of fountains, water loss is inevitable due to evaporation, drift, and other reasons. Among them, drift loss caused by wind accounts for a large part of the loss. At the same time, wind can also have a great impact on the floral effect of fountains [10]. Therefore, it is necessary to reasonably control the spray height of the fountain or use related technologies to control the spray height of the fountain to reduce water loss. At present, large fountains mostly use frequency conversion control technology. Therefore, the author suggests using an anemometer to measure the wind speed at the location of the fountain, and converting the collected signals into pump control parameters through digital to analog conversion software to change the fountain's spray height and reduce water loss.
2. Electrical energy-saving technology
1) Water pump control technology
After years of development in China, fountains have made great progress from the initial inability to automatically control them, to colored fountains, to programmable fountains, music fountains, and sound controlled fountains. But from the perspective of the power equipment of the fountain, it still relies on the water pump. Therefore, energy saving during the operation of the fountain is mainly achieved through the control of the water pump. The author believes that the following aspects can be considered. 1) Selection of water pump. At present, the water pumps used on fountains mainly include centrifugal pumps and submersible pumps. From the performance and usage of water pumps, centrifugal pumps have significantly lower performance, efficiency, and maintenance rates than submersible pumps, but submersible pumps are far more flexible than centrifugal pumps. Therefore, due to the many limitations in the use of centrifugal pumps, such as the need for a separate pump room, although the head can be controlled by frequency conversion, it cannot be applied to fountains with diverse water types. Centrifugal pumps can be used in the construction of rockery fountains, waterfalls, matrix fountains, and other projects that require uniform head. And in fountain designs that are limited by the site or require a single nozzle to change the head at any time, submersible pumps should be considered. 2) Variable frequency pump and power frequency pump. With the maturity of frequency conversion technology, frequency conversion pumps have been adopted by most large fountains. Compared to industrial frequency pumps, variable frequency pumps have higher efficiency, more flexible control, and relatively diverse fountain patterns. However, due to the relatively high price of variable frequency pumps, the initial construction cost is relatively high, but the later operating costs will be relatively low. The author suggests that when designing fountains, it is advisable to consider using variable frequency pumps within the acceptable range of the investors.
2) Color light usage
The reason why fountains are colorful and vibrant is largely due to the use of colorful lights. A large fountain can have thousands of colorful lights, so colorful lights are essential in the construction and use of modern fountains. Previously, the fountains in our country were mostly equipped with ordinary underwater colorful lights and underwater spotlights, with a power of generally 80W or more. However, with the development of technology, LED lights, also known as light-emitting diodes, are becoming more and more mature and widely used. LED is a component made of semiconductor material that can convert electrical energy into light energy. It is not only small in size, but also has characteristics such as vibration resistance, low driving voltage, low power (3W-12W), low power consumption, low heat generation, fast switching speed, long service life, high color purity, and green environmental protection. Compared to ordinary underwater lights, LED lights are more energy-efficient and more suitable for the development of modern fountains.
3. Fountain control energy-saving technology
What attracts people to a fountain is not only its rich colors, but also its diverse forms, which are also a stunning aspect. And these changes in form mainly rely on the control technology of the fountain. The control technology of fountains has evolved from switch control to program control, and now to sound control, reflecting the development of technology. A good fountain control system can not only make the fountain more diverse, but also produce better energy-saving effects.
The currently advanced control systems include:
1) Network Control Technology
At present, centralized control systems are commonly used for fountain control, with industrial computers and electrical drive cabinets placed in a separate fountain control room, and cables directly connected to the equipment site (fountain pool) from the control room. This traditional control method has significant limitations and is only suitable for situations where there are not many control points and the distribution is relatively concentrated. However, currently, the control points (including analog and digital quantities) of large fountain systems reach hundreds or thousands, and tend to be designed with multiple pools. The equipment is also becoming increasingly decentralized. If traditional control methods are used, it will inevitably consume a large amount of cables, which is too expensive and difficult to maintain and expand. The distributed architecture based on Ethernet proposed by Li Chenxi et al. has the advantages of flexible structure, high reliability, and good scalability [11]. Therefore, with the rapid development of Internet technology, the adoption of decentralized control network technology has made it possible to control the fountain remotely, freely and conveniently. Distributed control has strong scalability and can save investment in equipment such as cables, as well as reduce losses during operation, achieving energy-saving effects.
2) Expert control system
Expert control is an important branch of intelligent control, which essentially combines the theory and technology of expert systems with control theory, methods, and technology, and simulates the intelligence of experts in unknown environments to achieve control of the system.
In the music fountain expert controller, the empirical knowledge and general knowledge of experts in the field of music fountain are stored in a certain representation form in the knowledge base. When performing a music fountain performance, the inference engine searches for matching knowledge in the knowledge base based on the current music feature information according to a certain search strategy, derives certain intermediate conclusions, and then uses these intermediate conclusions as evidence to conduct further searches in the knowledge base. This process is repeated until the final conclusion is reached, which is the fountain control scheme that matches the music feature information [12]. By optimizing the design of the expert control system, on the one hand, the optimal integration of music, fountain design, and on-site atmosphere can be achieved, and on the other hand, energy-saving effects can be achieved under certain circumstances.
3) Other advanced control technologies
With the development of various fountain constructions, more and more large music fountains are emerging, and their control requirements are also increasing. The main challenge to overcome in the control process of a fountain is the lag between the music and the fountain design. Therefore, in the process of design and construction, a large amount of hardware is often required to compensate for the problems that arise. In recent years, with the continuous advancement of software and hardware, various advanced control technologies have emerged. For example, the predictive algorithm based computer music fountain control technology proposed by Zhang Hongye et al. [13] greatly eliminates the impact of large lag links on the system transition process by improving the control algorithm. At the same time, it uses a small amount of hardware, which can ensure the length of delay time and achieve flexibility in delay. Therefore, the use of predictive compensation control and software signal delay methods greatly improves the synchronization of music and water flow coordination.
4. Conclusion
The design and operation of a fountain is a relatively complex process. In many practical fountain projects, only the basic selection of fountain nozzles, pipelines, water pumps, electrical equipment, and the combination design of various fountain patterns are emphasized. These often meet the basic functions of the fountain, but the long-term operation and environmental protection and energy saving design of the fountain are often overlooked. This article briefly summarizes the possible energy-saving and environmental protection aspects in the design and operation of fountains, and proposes some energy-saving and environmental protection suggestions for fountains in the design and operation process, hoping to provide reference ideas for the construction of fountains in China.